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Awards for the February 2016 cycle
Sujatha Jagannathan (Robert Bradley and Stephen Tapscott, mentors). Fred Hutchinson Cancer Research Center, Seattle, Washington. Novel role for reduced RNA quality control in FSHD pathogenesis. $ 59,225 for 1 year.
Specific Aims: Facioscapulohumeral muscular dystrophy (FSHD) is caused by the misexpression of the germline transcription factor DUX4 in muscle cells. Several mechanisms have been proposed to explain DUX4-induced myotoxicity, including activation of apoptotic pathways, perturbed proteostasis and protein aggregation, among others (Wallace et al., 2011; Wallace et al., 2012; Tassin et al., 2013; Homma et al., 2015). We recently observed profound inhibition of an essential RNA quality control mechanism – nonsense-mediated RNA decay (NMD) – following DUX4 expression that could potentially account for several aspects of FSHD biology (Feng et al., 2015). Temporal analysis of DUX4 expression in human myoblasts revealed proteolytic degradation of core NMD factors upon DUX4 expression and concomitant inhibition of NMD. Following NMD inhibition, the DUX4-expressing cells upregulated various protein folding stress response pathways, leading us to hypothesize that DUX4-induced NMD inhibition could allow synthesis of aberrant protein products and cause proteotoxicity and cell death. In support of this hypothesis, pilot quantitative mass spectrometry studies detected truncated proteins as well as a small number of novel peptides derived from NMD targets in the DUX4- expressing cells. To rigorously test whether NMD inhibition drives proteotoxicity and contributes to DUX4-induced cell death, we sought to identify the mechanism of NMD inhibition by DUX4 (Specific Aim 1) and to determine the contribution of inefficient NMD to DUX4 toxicity (Specific Aim 2).
Peter L. Jones/ Robert Bloch. University of Massachusetts Medical School, Worcester. CRISPR approaches targeting DUX4 in vivo. $ 240,014 for 2 years.
Specific Aims: We recently published the first, and still only, report utilizing the CRISPR/Cas system for reducing or eliminating DUX4-fl expression as an avenue to an FSHD treatment [Himeda et al. “CRISPR/dCas9-mediated transcriptional inhibition ameliorates the epigenetic dysregulation at D4Z4 and represses DUX4-fl in FSH muscular dystrophy. 2015. Molecular Therapy, (In Press)]. Importantly, in this work we showed that it is in fact feasible to design sgRNAs that target Cas9 to the 4q35 D4Z4 in primary human myogenic cells. The next phase is to move to an in vivo system and ask if we can target the D4Z4/DUX4 in an animal model; however, due to off target concerns, it is also vital to be targeting mature human muscle fibers. Fortunately, we have been collaborating with Dr. Bob Bloch and his colleagues at the University of Maryland School of Medicine on their humanized mouse models for FSHD. Recently, they published the first study on these mice and show that their technique produces spectacular engraftment and development of mature human muscle fibers, with minimal contamination by mouse myonuclei [Sakellariou et al. “Neuromuscular electrical stimulation promotes development in mice of mature human muscle from immortalized human myoblasts” 2016. Skeletal Muscle (In Press)]. Thus, the timing works out perfectly for us to continue our collaboration and merge our CRISPR/Cas studies with their mouse model. In this collaborative grant the Jones lab at UMMS will develop new sgRNAs targeting the D4Z4/DUX4 region that are compatible with the smaller Cas9s which fit into AAV. The Bloch lab at UMSOM will generate humanized FSHD mice, inject these CRISPR AAVs, and assess their effects on muscle physiology and morphology. The Jones lab will then analyze the expression of DUX4, downstream targets, and off targets. This project will test if AAV-mediated CRISPR technology is indeed a viable approach to treating FSHD.
Eugénie Ansseau (Frédérique Coppée and Alexandra Belayew, mentors). University of Mons, Belgium. Study of the unexpected cytoplasmic functions of double homeodomain proteins DUX4 and DUX4c during differentiation: focus on healthy and pathological muscle cells. $ 124,807 for 1 year.
Specific Aims: The DUX proteins are known as transcription factors and until now functional studies from several laboratories only focused on that perspective. Intriguingly, the transcriptional target genes of DUX4 identified to this date cannot explain the cytoplasmic alterations observed in FSHD muscle sections. In a search for DUX4/4c protein partners we have unexpectedly identified several classes of cytoplasmic or nucleo-cytoplasmic proteins. The functionality of these interactions was underscored by the observation of DUX4/4c cytoplasmic localization upon myoblast fusion. Moreover, our recently published (Ansseau et al 2016) and new preliminary data indicate that DUX proteins are associated to specific IGF2BP1-dependent ribonucleoparticles (mRNP). In these granules, IGF2BP1 is associated a.o. with ACTB mRNA and regulates the synthesis of non-muscle cytoskeletal actins that is essential in the first steps of myotube formation (elongation, fusion, nuclear dynamics). Later these actins will be replaced by the muscle forms in myofibrils. The DUX4 and DUX4c inductions observed in FSHD muscle cells could therefore interfere with this precise dynamics and contribute to the muscle pathology. Moreover, as DUX4c is normally expressed in almost all myoblasts and as many identified partners are identical for DUX4 and DUX4c, the pathological increase of DUX4/DUX4c proteins in FSHD muscle cells could titrate out some partners and interfere with the normal DUX4c function in muscle and would contribute to explain why this tissue is particularly sensitive to pathological DUX4 expression (one of the FSH Society research priorities for 2016). In this project which is with the follow up of our on-going FSH Society grant (see Annex for a progress report) we therefore want to define the DUX4/4c functions in the cytoplasm with the following specific aims : (1) to monitor DUX4/4c trafficking, cytoskeletal dynamics and nuclear movements during muscle cell differentiation in culture, (2) to identify the RNAs associated with DUX4/4c (3) to study the impact of DUX4/4c gain or loss of function on IGF2BP1-associated mRNP granules (4) to determine the pathological interactions caused by excess DUX4 or DUX4c in muscle cell cultures and in a FSHD mouse model in collaboration with the group of Yi-Wen Chen (George Washington University). The identification of the DUX4/4c peptidic domains involved in the interactions with partners will later be used to select either peptides (using a phage display library), or aptamers that suppress or decrease the interaction with partners involved in toxic pathways. The biological significance of the DUX4/4c-partner interaction will then be evaluated by introducing these agents in FSHD muscle cell cultures and analysing the resulting phenotype. This approach might present a therapeutic interest in FSHD by blocking some DUX4/DUX4c toxic functions. We expect this project will help (i) to define new functions for DUX4 and the poorly studied DUX4c, (ii) to discover their putative interactions through shared partners (iii) to bring new light on the mechanisms of DUX4 toxicity in FSHD muscle and (iv) to propose new therapeutic strategies preventing protein/protein or protein/RNA interactions.
Amber Mueller (Robert Bloch, mentor). University of Maryland, Baltimore. Assessing the pathologic role of DUX4 in a humanized mouse model of FSHD. $ 134,728 for 3 years.
Specific Aims: Facioscapulohumeral Muscular Dystrophy (FSHD) is a muscle wasting disease caused by a genetic mutation in the subtelomeric region of chromosome 4. Healthy individuals have 11-100 repeated D4Z4 microsatellite units, whereas individuals with FSHD have 1-10 D4Z4 units. This genetic contraction makes the 4q35 chromosomal region more accessible to transcriptional machinery and permits transcription of nearby genes including DUX4, the proposed pathological agent in FSHD. DUX4 is a transcription factor that when aberrantly expressed induces transcription of many genes implicated in muscle development, the actin cytoskeleton, regulation, apoptotic signaling pathways, and germline development. While many potential biomarkers of FSHD, including TRIM43, MBD3L2, ZSCAN4, and PITX1, all of which are downstream of DUX4, have been identified from studies of muscle biopsy and of muscle cells in vitro, the pathophysiological role of DUX4 and these target genes has yet to be studied in a humanized in vivo model. The D4Z4 contraction is not replicable in animal models, nor do the effects of DUX4 expression in murine muscle cells replicate those seen in human cells. To overcome these problems, the laboratory has developed a method of xenografting human derived muscle precursor cells, isolated from patients with FSHD and healthy controls, into the tibialis anterior compartment of immune-deficient mice. These cells grow, fuse, and mature into force-producing human muscle fibers within the mouse hind limb. These human muscle fibers can be studied in intact grafts or following dissociation and isolation in culture. This novel in vivo FSHD model will be used to study DUX4 and its potential downstream gene targets, TRIM43, MBD3L2, ZSCN4, and PITX1. The ultimate goal is to determine how their patterns of expression and localization in relation to DUX4 within individual fibers lead to dystrophy – experiments that have never been performed in an FSHD model system before. Further analyses will attempt to reveal the primary defect in FSHD muscle, leading to the creation of targeted FSHD therapies. This study hypothesizes that DUX4 expression in a small percentage of the nuclei of mature human muscle fibers is responsible for activating DUX4 gene targets in the same or nearby myonuclei and that together these induce local muscle wasting, leading to the phenotype seen in FSHD. The hypothesis will be tested by i) comparing the molecular phenotype of intact muscle as well as fibers isolated and cultured from FSHD-derived xenografts to controls and by ii) examining the functional phenotype of FSHD derived xenografts compared to controls. Molecular methods such as qRT-PCR, immunofluorescent labeling, and confocal microscopy combined with electrophysiology-based functional measures will be employed to explore the phenotype in living muscle from FSHD xenografts. This study overcomes the limitations of current models of FSHD associated with viral vectors or incomplete development in culture, as it examines the pathologic consequences of endogenous DUX4 expression and its downstream targets in mature human muscle fibers grown within the mouse hind limb.
Nizar Saad (Scott Q. Harper, mentor). Nationwide Children’s Hospital, Columbus, Ohio. MicroRNAs as potential modifiers of Facioscapulohumeral Muscular Dystrophy (FSHD). $ 90,000 for 1 year.
Specific Aims: My doctoral and postdoctoral studies aimed at investigating the implication of non-coding RNAs in the regulation of gene expression in bacteria. Therefore, I am quite familiar with gene expression processes as well as their implication in the control of cell homeostasis. One of my objectives for joining Dr. Harper’s lab is my interest in understanding dysregulation processes of gene expression in human diseases (e.g., FSHD). In fact, FSHD arises from complicated pathogenic mechanisms, with epigenetic origins, that ultimately cause overexpression of the transcription factor DUX4, which is toxic to muscle and numerous non-muscle cell types. FSHD presentation is non-uniform, and there may be extreme variability in severity of symptoms, rate of progression and age at onset, even in families with several affected relatives. Similarly, asymmetrical weakness is common. It has been hypothesized that this non-uniformity of presentation might be due to the regulation of DUX4 expression that becomes initiated upon the presence of various but yet undetermined factors. So far, the regulation of DUX4 gene expression is still relatively unexplored, and except SMCHD1, genes that directly modify DUX4 expression have not been identified. We think that DUX4 gene expression modifiers might influence DUX4 toxicity and FSHD disease penetrance. In this proposal, our central hypothesis is that endogenous DUX4-targeted microRNAs (miRNAs) are modifiers of DUX4 expression and toxicity. Specific Aim 1: To define miR-675 regulation of DUX4 gene expression. Specific Aim 2: To define the DUX4-targeted miRNome among all human microRNAs.
2016 Research Grant Award
Jeffrey Statland, MD, University of Kansas Medical Center, Kansas City, Kansas. To expedite the development of new therapies for FSHD by developing a core FSHD Clinical Trial Research Network (CTRN). $121,000 for one year. With the generous support of the Geraldi Norton Foundation and Anonymous Donor.
The overall, long term aim of this application is to expedite the development of new therapies for FSHD by developing a core FSHD Clinical Trial Research Network (CTRN) composed of 4 institutions (University of Rochester; Kennedy Krieger Institute, Baltimore; Ohio State University, Columbus; and the University of Kansas, Kansas City) with established expertise in FSHD and neuromuscular clinical trials. The specific aims are follows:
Aim 1: Establish an FSHD CTRN infrastructure. To this end, we will:
- a. Develop standard operating procedures (SOPs) and a governance document for the Network
- b. Establish reliance agreements between the IRBs in the CTRN using the existing CTSA IRB reliance model
- c. Institute a data sharing agreement between the network sites.
- d. Create common data dictionary for a RedCap database at the University of Rochester, which can be rolled out at multiple sites, to allow for distributed, online data entry of anonymized data from all four sites.
- e. Create a manual of operations and standard regulatory language for a core set of outcome measures, to improve the efficiency of IRB regulatory submissions.
- f. We will create standardized protocols and CRFs for important FSHD clinical outcomes – wherever possible we will incorporate established NIH FSHD common data elements
- g. Train site clinical evaluators to insure that outcome measure procedures are performed in an identical manner at all sites. Establish inter rater reliability for each of the outcome measures.
Deliverable: All components of Aim 1 will be drafted in CTRN Year 1, then completed by the end CTRN Year 2
Aim 2: Create a system of committees to ensure engagement of all major stakeholders. To this end we will convene:
- a) Patient Engagement Circles comprised of patients willing to convene focus groups on an as needed basis to address specific aims or difficulties encountered in developing the FSHD CTRN, for example defining what would be clinically meaningful to people with FSHD, addressing concerns related to participating in clinical studies, and issues with recruitment and retention.
- b) A Guidance Committee comprised of investigators, patient advocates, patients and industry. This committee will assist the network in fashioning network wide SOPs, public outreach, and selection of projects to be run on the FSHD CTRN.
- c) Steering committee will be fashioned from site investigators, and an FSH Society representative to assist in the day to day running of CTRN network activities
Deliverable: rosters for each committee will be established and meetings held at network start up and prior to implementing the first project in CTRN Year 1.
Aim 3: Conduct a prospective study of outcome measures with funding from the NIH, MDA, and personal philanthropy: A prospective study of 150 patients followed over 18 months will be needed to definitively validate the outcome measures. We will be applying simultaneously to the NIH in a new request for application announcement (http://grants.nih.gov/grants/guide/pa-files/PAR-16-020.html) designed to fund applications for trial readiness in rare neurologic and neuromuscular diseases. The MDA has implemented a new clinical trial pathway for study funding. We feel that we are well positioned for such an application. Moreover, our chances for funding will be significantly improved if we can show that we already have a core FSHD Clinical Trial Network in place.
Deliverable: Funding will be pursued through the NIH, MDA, and personal philanthropic support with a goal of securing funding for a study by the end of CTRN year 1, first patient entered beginning of CTRN Year2. If funding from these sources is limited than the scope of our prospective study will have to be curtailed as a consequence.
Awards for the August 2015 cycle
Alec DeSimone (Charles Emerson mentor), UMass Medical School, Worcester. Investigation of 4-methylumbelliferone as a C1QBP-targeting FSHD therapeutic. $150,000 for 2 years.
Summary: Development of FSHD has been linked to the de-repression of the DUX4 gene in the skeletal muscle of affected individuals. However, individuals have been identified who express DUX4 in muscle biopsies, but who do not manifest any clinical signs of the disease. Thus, while derepression of DUX4 may be necessary for the FSHD phenotype, it is not sufficient. This suggests that there may be other factors that modify the FSHD disease phenotype. We used a proteomic approach to screen for DUX4-interacting proteins that may act as disease modifiers and identified the multifunctional C1QBP as one such candidate. C1QBP is known to regulate several of the molecular pathways that are affected by DUX4 expression, including gene expression, oxidative stress, and apoptosis. In our preliminary results we have found C1QBP is dynamically regulated in myogenic cells. It is localized primarily to ribbon-like structures outside of the nucleus in myoblasts, but appears to relocate to the nuclear periphery when they are allowed to fuse into myotubes. Expression of DUX4 leads to increased C1QBP concentration in the nucleus, supporting the hypothesis that DUX4 and C1QBP form functional interactions. Importantly, C1QBP is known to bind to the intra- and extra- cellular signaling molecule hyaluronic acid (HA), which can regulate its phosphorylation state. We have found that that decreasing intracellular HA by treating cells with 4- methylumbelliferone (4MU), an inhibitor of HA synthesis, results in a sharp decline in DUX4-target gene expression. This raises the possibility that it could serve as an FSHD therapeutic. 4MU is of particular interest for development as a drug because it is already being used in Europe to treat biliary dyskinesia, and has had its short-term safety established in several studies. It is also being investigated in both cell culture and animal models as a treatment for specific cancers.
In this project we will evaluate the ability of 4MU to serve as an FSHD therapeutic and investigate its mechanism of action. We have observed that 4MU inhibits the expression of DUX4-target genes, both in myotubes and when DUX4 is overexpressed in myoblasts. We have hypothesized that this is a result of the loss of HA altering the post- translational modifications of C1QBP, which would interfere with its ability to interact with DUX4 and act as a transcriptional cofactor. This could take the form of preventing C1QBP from binding to DUX4 directly, altering the subcellular localization of C1QBP, or by causing changes in C1QBP stability. We will perform studies to evaluate each of these possibilities. Finally, we will use an FSHD mouse xenograft model, established in our lab, to conduct dose-escalation studies to determine if 4MU treatment can inhibit DUX4-target gene expression in vivo. This will better evaluate 4MU as a potential FSHD therapeutic.
Julie Dumonceaux. Association Institut de myologie, Paris, France. Development of antisense oligonucleotide drugs as a therapeutic agents for FSHD. $94,606 for 1.5 years.
Summary: Antisense oligonucleotides (AOs) are chemically modified single-stranded DNA, RNA or chemical analogue molecules which are able to modulate the expression of a specific targeted gene. The advances in the development of antisense chemistries, in particular phosphorodiamidate morpholino oligomers (PMOs), have led to numerous studies investigating the therapeutic potential of antisense technology. AO-mediated exon skipping is currently one of the most promising therapeutic options for Duchenne muscular dystrophy (DMD). Importantly, BioMarin and Sarepta have announced that U.S. Food and Drug Administration (FDA) has accepted for review the submission of a New Drug Application (NDA) for drisapersen (2’OMePS PRO051) and eteplirsen (PMO AVI-4658) for the treatment of DMD.
The overall objective of our project is to suppress DUX4 expression and develop a therapeutic approach for FSHD based on AOs. We have chosen to target the 3’ key elements of DUX4 mRNA and have already obtained robust results demonstrating the feasibility of such an approach. For the first time, we demonstrated in vitro that targeting a functional PAS can be an efficient therapeutic strategy for a genetic disease. We observed that targeting DUX4 3’key elements leads to an efficient extinction of DUX4, does not redirect polyadenylation and prevents aberrant expression of genes downstream of DUX4.
Our goal is now to (i) improve DUX4 mRNA extinction by developing sequence optimized AONs and to (ii) validate these AOs in vivo. Int the first aim, we will otpimize the sequence and chemistry of AO drugs targeting the 3’ key elements of DUX4 mRNA. In the second aim, we will test the body-wide administration of the most active anti-FSHD AO drugs for delivery and effectiveness in animal models after the creation of a new mouse model carrying a reporter gene (LacZ) with the 3’UTR of DUX4 mRNA. Two strategies will be developed: the direct injection of vivo-PMO and the vectorization of the PMO in an AAV vector. In the first case, mice will be subjected to treatment regimens of intravenous systemic delivery of therapeutic optimised AOs in naked form or conjugated to cell-penetrating moieties (eg octaguanidine or CPPs). In the second case, AOs will be vectorized under the control of the U7 promoter as it has been done for exon skipping for DMD for instance. AAVs are now well known to be able to target the muscles in a whole body without toxic effects.
Jocelyn Eidahl (Scott Harper mentor), Nationwide Children’s Hospital, Columbus, Ohio. Protein Chemistry and Protein-Protein Interactions of DUX4 and DUX4-FSHD mouse. $70,000 (request one year extension).
Specific Aims: Autosomal dominant Facioscapulohumeral muscular dystrophy (FSHD) is the third most prevalent muscular dystrophy, affecting 1 in 20,000 individuals. FSHD was formally classified as a major form of muscular dystrophy in 1954, but the pathogenic events leading to the disease have only recently started coming into focus. Several studies now support an FSHD pathogenesis model involving aberrant expression of the primate specific DUX4 gene, which encodes a myotoxic transcription factor. The emergence of DUX4 represented a momentum shift in the FSHD field as it provided an important target for therapy design. Indeed, as FSHD is currently untreatable, developing effective therapies is a critical need in the field. An FSHD treatment should center on inhibiting DUX4, which could be accomplished by silencing the gene or transcript, or negating the toxic effects of the DUX4 protein. The overall objective of this study is to identify, characterize, and ultimately inhibit DUX4 protein modifications that may contribute to its toxic properties in FSHD muscle. Delineating how DUX4 protein function is regulated is an important unmet need in the field.
The DUX4 gene encodes a transcription factor that activates downstream toxic pathways, including apoptotic cascades. I hypothesized that post translational modification (PTM) may be one important mechanism affecting DUX4 protein function. PTMs play key roles in ligand binding affinity, subcellular localization and protein stability. My primary goal was to first identify whether DUX4 could be post translationally modified, then subsequently map DUX4 PTMs and determine their contribution to DUX4-induced toxicity. My aims are designed to define the role of DUX4 PTMs, which will allow us to potentially understand its protein function and regulation. By accomplishing this goal, we hope to establish a framework for therapeutic intervention designed to disrupt DUX4 modifications and prevent myotoxicity.
Aim 1: To define DUX4 post-translational modifications The DUX4 transcription factor is associated with muscle pathology in FSHD and is toxic to numerous other non-muscle cell types. However, some cells and tissues seem to resist DUX4-associated damage, including the testes, where DUX4 is naturally expressed at high levels, as well as muscles of non-manifesting FSHD carriers. The mechanisms by which some cells resist DUX4-associated damage are unknown, but it is likely that DUX4-modifier genes may impact disease penetrance. Since PTMs can profoundly influence transcription factor activity, I hypothesized that the DUX4 protein may also be regulated by PTMs, and the enzymes that mediate these PTMs could therefore impact DUX4 toxicity. In preliminary studies, I found that the DUX4 protein is modified by methylation and phosphorylation using mass spectrometric analysis of DUX4. In this aim, I will define the PTM signature of DUX4 in numerous cell types, including human myoblasts and primate testes, which endogenously express DUX4. Differences in the modification signature of DUX4 isolated from these cell types will provide insight about tissue-specific regulation of DUX4 protein, and may provide information about the differential toxicity of DUX4 in tissues or cells.
Aim 2: To examine the role of phosphorylation on DUX4 function My preliminary results revealed phosphorylation of numerous DUX4 residues in both the N and C-terminal domains. In this aim, I propose to examine the effects of each phosphorylation event using mutagenesis to irreversibly mimic or ablate DUX4 phosphorylated residues. I will then determine the effects of these DUX4 mutants in vitro using several outcome measures that I have previously established in my preliminary studies. These include DUX4 DNA binding affinity, assessment of the impacts on key ligand interactions, DUX4 dimerization, cellular toxicity and gene target activation. This work will help establish an important first step toward developing therapies that could prevent DUX4-mediated toxicity, by differentially affecting the phosphorylation status of DUX4.
Scott Harper, Nationwide Children’s Hospital, Columbus, Ohio. Characterization of a Tamoxifen-inducible DUX4 knockin mouse. $25,000 for 3-6 month bridge funding.
Summary: We will submit formal grant applications to foundations, including MDA and the FSH Society, and are considering seeking some industry funding. However, this will take time (several months), and we no longer have discretionary funds to support the mouse colony. We want to expand, characterize, and publish this model as soon as possible, and we are seeking bridge funding for this purpose. It is our goal and priority to make this model available to anyone in the field who wants it, as soon as is practicable.
Sabrina Pagnoni and Constanza Cioffi (Alberto Rosa mentor), Catholic University of Cordoba (UCC) / National Research Council from Argentina (CONICET). Study of the co-regulatory role of DUX4 on sex hormone nuclear receptors and the protective effect of sex hormones on DUX4-mediated cell toxicity. $120,000 for 2 years.
Summary: Our laboratory, together with A. Belayew’s laboratory, originally proposed that aberrant expression of DUX4 is harmful to cells, contributing to the pathogenesis of FSHD. We demonstrated that DUX4 is a nuclear protein, endogenously expressed in cultured FSHD myoblasts, pro-apoptotic and cytotoxic when expressed in transfected cells. We recently analyzed the DUX4 molecular domains contributing to its toxicity, subcellular transit and nuclear location. In these studies we recognized an LLXXL motif at the C-terminal region of DUX4, which is present in co-regulators of nuclear hormone receptors (NRs). Preliminary studies from our laboratory showed that DUX4 is a co-regulator of the progesterone NR. We also found that progesterone protects cultured cells from the toxic effect of DUX4. In this project we will study the role of DUX4 as a co-regulator of NRs of sex hormones as well as the protective effect of sex hormones on the toxicity of DUX4. These studies are relevant to the understanding of the normal function of DUX4 as well as its pathogenic role in FSHD and the future rational approaches for the treatment of FSHD patients.
Angela Lek (Louis Kunkel mentor), Boston Children’s Hospital, Boston, Massachusetts. A genome-wide CRISPR knock-out strategy to identify modifiers of FSHD. $78,000 for 1 year.
Summary: Facioscapulohumeral dystrophy (FSHD) is a common but unique form of muscular dystrophy requiring multiple factors to create a ‘permissive’ state for disease manifestation. Over recent years, several genetic (DUX4) and epigenetic (hypo-methylation) factors have been linked to FSHD pathogenesis; however, it has become clear that the field has not elucidated all factors required for disease manifestation. Mounting clinical evidence suggests the existence of modifier genes with the capacity to regulate DUX4 transcript and/or protein function. Recent advances in genome-editing technologies proposed for use in this project now should enable us to uncover these remaining missing links. Through the systematic introduction of loss-of-function mutations into genomic DNA, we can interrogate the genome for answers that may explain the phenotypic variability between patients, as well as the non-penetrant effects of DUX4 in some individuals. In this project, we propose a targeted genome-scale knock-out screen to identify genes that can reduce the phenotypic impact of DUX4 expression when inactivated. We hypothesize that there exists gene targets of DUX4 whose loss will render DUX4 unable to trigger a dysregulated cascade of gene expression, thus abrogating its toxicity. These candidates likely serve as genetic modifiers of FSHD, and will be readily identified by downstream sequencing and computational analysis for detection of CRISPR target genes enriched within these DUX4 ‘resistant’ cell populations. This will allow the generation of a complete list of gene candidates with the potential to influence the pathogenic outcomes associated with DUX4 misexpression. Identified gene hits will be cross-referenced to our whole-genome sequencing data of nonmanifesting carriers to search for sequence variants that may enable us to narrow down promising candidates for functional follow up studies. Validation of candidate modifier genes will be performed in our established zebrafish model of FSHD for rescue of phenotype to confirm functional significance. Additionally, we will revert to our repository of FSHD patient cells to genome edit our candidate genes under these permissive allelic conditions, and subsequently measure changes in known FSHD biomarker expression. FSHD is a challenging disease whose remaining unanswered questions cannot be accomplished alone. Hence, our proposal involves a multi-institute collaboration, bringing together a wealth of patient resources (Wellstone Center), the latest in genomic technology (Broad Institute), and a well-established animal model of FSHD (Boston Children’s Hospital). Not only will the identification of these modifier genes for DUX4 resistance provide valuable insights into FSHD disease pathogenesis, but they will also present as solid leads that can be directly targeted for therapeutic intervention in humans with FSHD.
Jeffrey Statland MD, University of Kansas, Kansas City. To determine the initial responsiveness to FSHD disease progression of a system of synchronized wireless motion sensors. $39,044 for 1 year.
Summary: Facioscapulohumeral muscular dystrophy (FSHD), one of the most prevalent forms of muscular dystrophy, typically affects muscles of the face, shoulder, and arms early in the disease process but can affect any skeletal muscle over time. Twenty percent of FSHD patients over the age of 50 require the use of a wheelchair. Since molecular advances have identified potential therapeutic targets for future FSHD clinical trials, there is an urgent need to develop reliable and responsive outcome measures for FSHD treatments. Established FSHD outcome measures for evaluating changes in strength over time, manual muscle testing (MMT) and quantitative myometry (QMT), have been validated in a large natural history study, but fail to demonstrate disease progression in time periods less than one year. And it is unclear what the meaning of a small change in a combined strength score would mean to a patient. Functional tasks would seem to have more inherent meaning to patients, as they measure motor performance during everyday tasks, but are not sensitive to changes in FSHD in less than 3 years. Using such strength or functional outcome measures to show slowing of disease progression in early phase FSHD treatment trials will require large numbers of subjects and long treatment intervals which will significantly hinder the drug development process. This is problematic in a rare disease where access to patients is limited, especially if several therapeutic approaches are being considered. A more sensitive surrogate outcome measure for strength and overall disability status could significantly shorten the duration of early phase clinical trials and hasten the therapeutic discovery process. Measures of dynamic motion while performing functional motor tasks may be more sensitive than isometric strength measures to early changes in muscle function. A prior study using laboratory based motion analysis identified a subset of FSHD patients with abnormal motion parameters despite normal manual muscle testing. Whereas such measurements previously required dedicated motion laboratories, synchronized networks of portable wireless motion sensors make analysis of complex functional movements more accessible and practical in the clinical trial setting.
The long term goal of this research project is to establish a quantitative assessment tool to evaluate changes in mobility status of persons with FSHD. We will use a portable wireless motion analysis system to instrument a timed up and go, postural sway during quiet standing, and arm range of motion. We plan to build on an existing University of Kansas Medical Center Frontier’s pilot grant which will identify the specific outcome metrics obtained with portable wireless motion sensors which are important for examination in persons with FSHD and determine the reliability and cross sectional validity of those metrics. In the present FSHD Society study, we propose to extend our current pilot study to add 6 and 12 month follow up visits. We will conduct a 12 month longitudinal study in 20 genetically confirmed and clinically affected FSHD participants (10 mild to moderately affected, and 10 moderate to severely affected) to determine the responsiveness of wireless motion analysis to disease progression in FSHD, determine the minimal detectible change and minimally clinically important change in these metrics, and use factor analysis to create summary scores (e.g. upper extremity, lower extremity) for future clinical trials.
Tracy Zhang (Kathryn Wagner mentor), Kennedy Krieger Institute, Baltimore, Maryland. To cover the remaining months of graduate student Yuanfan “Tracy” Zhang in the Kathryn Wagner lab. FSH Society Musclepalooza graduate research award, $21,592 for 3 months.
Summary: Funds are being requested from the FSH Society to cover the remaining months of graduate student Yuanfan “Tracy” Zhang in the Wagner lab. Tracy is a 5th year Cellular and Molecular Medicine graduate student who works exclusively on FSHD. Her thesis work is to establish, validate and use a novel model of FSHD. She established and validated the human skeletal muscle xenograft for FSHD which she published as a first author in Human Molecular Genetics (Zhang et al., Hum Mol Gen 2014, 23: 3180-3188). She is now using the model to show proof-of-concept of antisense oligonucleotide knockdown of DUX4-fl in FSHD. While this work is generally supported by the FSHD Wellstone at UMMS, Tracy is no longer supported by the Wellstone and funds are being requested to cover her salary and benefits to finish this project.
Awards for the February 2015 cycle
Sachiko Homma, PhD / Jeff Boone Miller, PhD. Boston University, Boston, MA USA. Inhibited protein turnover in FSHD pathogenesis. $68,920 for 1 year
PROJECT SUMMARY: The goals of our studies are to identify pathogenic mechanisms and develop new therapeutic strategies for facioscapulohumeral muscular dystrophy (FSHD). We discovered that full-length isoform of double homeobox protein DUX4 (DUX4-FL), but not DUX4-S (short isoform of DUX4), inhibits protein turnover and leads to abnormal ubiquitin expression and nuclear aggregation of TDP-43, one of the aggregation-prone and an RNA/DNA-binding proteins previously associated with amyotrophic lateral sclerosis (ALS) and inclusion body myositis (IBM)(Homma et al., 2015). These phenotypes were not side effects of DUX4-FL-induced cell death and were enhanced when cell death was blocked by caspase inhibitors. These data suggest that DUX4-FL induces abnormal protein degradation, which can in turn lead to cytotoxicity. Importantly, the abnormal deposition of ubiquitinated protein and nuclear aggregation of TDP-43 were observed in DUX4-FL-expressing cells from its endogenous promoter as well as when exogenously expressed. Thus, DUX4-FL produced from its endogenous promoter is sufficient to promote pathogenesis, and our results identify inhibition of protein turnover and impaired proteostasis as potential pathological mechanisms in FSHD. We now propose to identify mechanisms that underlie the DUX4-FL-induced inhibition of protein turnover and promotion of abnormal protein aggregation. Under Specific Aim 1, we will identify the mechanisms by which DUX4-FL expression inhibits proteasome function. We will isolate proteasomes from DUX4- positive and -negative myotubes and the amount and activity of proteasome will be examined. If intrinsic proteasome activity and/or the amount are unchanged by DUX4-FL expression, then we will investigate indirect mechanisms by which ubiquitinated proteins could abnormally accumulate in DUX4-FL-positive myotubes. Under Specific Aim 2, we will examine FSHD muscle biopsies to identify if there are signs of dysfunction of protein degradation system. We will immunostain FSHD and control tissues with antibodies for ubiquitin, TDP-43 and other proteins that are associated with myopathies and protein aggregation diseases. The outcome of this study could use as clinical marker(s) for FSHD. Thus our proposed studies will provide valuable insights into the mechanisms of DUX4-FL induced pathology in FSHD that might share with some other myopathies and/or protein aggregation diseases. This new knowledge could develop potential new therapeutic strategies based on regulating proteasome activities and identify new clinical biomarker(s) for FSHD.
Yosuke Hiramuki, PhD / Stephen Tapscott, MD, PhD. Fred Hutchinson Cancer Research Center, Seattle, WA USA. Determining the effectiveness of increased SMCHD1 expression to suppress DUX4 in FSHD muscle cells and model mice. $101,132 for 2 years. FSH Society FSHD Canada Foundation research fellowship.
PROJECT SUMMARY: Facioscapulohumeral dystrophy (FSHD) is a muscular dystrophy clinically characterized by progressive weakness and wasting of the facial, shoulder and upper arm muscles. The causative gene is DUX4 that resides in D4Z4 macrosatellite repeat unit varied between 11 and 100 on chromosome 4. Normally D4Z4 macrosatellite array is hypermethylation and DUX4 is not expressed in normal skeletal muscle but D4Z4 macrosatellite array is hypomethylation and DUX4 is expressed in FSHD skeletal muscle. FSHD has two types, FSHD1 and FSHD2, and both are phenotypically indistinguishable, whereas the cause to induce the abnormal DUX4 expression in skeletal muscle is distinguishable. FSHD1 is caused by contraction of the D4Z4 macrosatellite repeat unit (1-10), whereas FSHD2 is caused by mutations in SMCHD1. Each of FSHD1 and FSHD2 is furthermore divided into two classes. D4Z4 macrosatellite repeat size in FSHD1 (1-6 unit and 7-10 unit) is involved in disease severity. Mutations in SMCHD1 are grouped into haploinsufficient and dominant negative mutations. In addition, SMCHD1 modifies disease severity in families affected by FSHD1. However there is no study to test whether SMCHD1 has a possibility of the effective treatment for FSHD1 and FSHD2. This proposal builds on the hypothesis that SMCHD1 overexpression decreases aberrant DUX4 expression in FSHD1 and FSHD2. The outline of research plan to test this hypothesis is as follows.
Aim 1. Doxycycline inducible lentivirus-SMCHD1 in FSHD1 and FSHD2 muscle cells. We will determine the effectiveness of increased SMCHD1 expression to suppress DUX4 in FSHD with different mutations using doxycycline inducible lentivirus-SMCHD1 (a and b). SMCHD1 is composed of exons 48 and has ATPase and Hinge domain. We will determine the critical region of SMCHD1 to suppress abnormal DUX4 in FSHD muscle cells using doxycycline inducible lentivirus-SMCHD1 that has short SMCHD1 coding sequence (c). a. Ability to suppress DUX4 in FSHD1 with i) Slightly lower than normal repeat size (7-10 unit) ii) Severe contraction (1-6 unit) b. Ability to suppress DUX4 in FSHD2 with i) Haploinsufficient mutation ii) Dominant negative mutation c. Ability to suppress DUX4 in a range of SMCHD1 coding sequence in FSHD muscle cells. i) Full length (exons 1-48) ii) Short length (exons 1-10, 1-20, 1-30, 1-40)
Aim 2. rAAV6-SMCHD1 in FSHD muscle cells and D4Z4-2.5 mice. We will determine the effectiveness of increased SMCHD1 expression to suppress DUX4 with recombinant adenoassociated virus 6 (rAAV6) – cytomegalovirus (CMV) – SMCHD1 in FSHD1 and FSHD2 muscle cells and D4Z4-2.5 mice (FSHD1 model mice). In addition, to distinguish the effect of SMCHD1 in whole body from muscle on suppression of DUX4 in FSHD, we will choose CMV promoter and enhancer/promoter regions of muscle creatine kinase and α-myosin heavy-chain (MHCK) genes and administrate rAAV6-CMV-SMCHD1 and rAAV6-MHCK-SMCHD1 into D4Z4-2.5 mice. a. Ability to suppress DUX4 in FSHD1 and FSHD2 muscle cells using rAAV6-CMV-SMCHD1. b. Ability to suppress DUX4 in D4Z4-2.5 mice using rAAV6-CMV-SMCHD1 and rAAV6-MHCK- SMCHD1.
In this application, Aim 1 will be the proof of principle experiments showing that higher SMCHD1 will be effective as a potential therapy and Aim 2 will develop a method for delivery that might eventually be suitable for pre-clinical or clinical studies based on rAAV6.
Eugenie Ansseau, PhD / with Frederique Coppee, PhD and Alexandra Belayew, PhD. University Mons, Mons, BELGIUM. Functional study of the DUX4 and DUX4c double homeodomain proteins in skeletal muscle. $93,450 for 1 year.
PROJECT SUMMARY: The Double homeobox (DUX) genes map in 3.3-kb repeated elements that constitute a family with hundreds of members dispersed into the human genome. Even if the evolutionary conservation of their sequences argues in favor of a functionality, they were long considered as pseudogenes and thus poorly studied. However, several DUX genes are expressed in healthy muscle cells. Our group has characterized the DUX4 gene that causes FSHD and the homologous DUX4c gene (both located at 4q35). Both encoded proteins are highly similar transcription factors and only differ in the carboxyl-terminal region. There is no known orthologue of these genes in rodent. However, mouse Duxbl, a paralogue sharing similarities with DUX4 and DUX4c, was previously shown to play roles during myogenesis. DUX4c is expressed in healthy muscle and induced in FSHD and Duchenne muscular dystrophy (DMD). Our previous data suggested a role for DUX4c in normal human muscle regeneration and its activation (as in FSHD) could impact muscle regeneration in several myopathies. Deciphering the function of unstudied human muscle proteins should increase our understanding of physiological and pathological mechanisms of the skeletal muscle. The present project stems from our identification of putative and validated protein partners that hint to unexpected cytoplasmic functions for the DUX4/DUX4c proteins in myofibril organization and mRNA translation control. Moreover, in addition to the endogenous DUX4c nuclear localization in myoblasts, we found a cytoplasmic localization of this protein in differentiating myoblast at particular times. We also observed DUX4 cytoplasmic translocation during myoblast differentiation following its overexpression. As a lot of identified partners are identical for DUX4 and DUX4c, the pathological increase of DUX4/DUX4c proteins in FSHD muscle cells could titrate out some partners and interfere with the normal DUX4c function in muscle and would contribute to explain why this tissue is particularly sensitive to pathological DUX4 expression (one of the FSH Society research priorities for 2015). To further investigate these observations, we would (1) monitor DUX4/DUX4c protein trafficking in live muscle cells (time-lapse microscope) by using fluorescent ligands to label DUX4/DUX4c expressed as HaloTag fusion proteins and by using different nuclear export/import inhibitors; (2) produce additional antibodies specifically targeting DUX4c (3) validate DUX4/DUX4c interactions with partners that play major roles in myofibril organization or mRNA translation using in situ proximal ligation assays; (4) compare the interactions of selected partners and DUX4/4c in healthy and FSHD differentiating myoblasts (5) map the specific DUX4/DUX4c peptidic domains that interact with validated partners using DUX4/DUX4c specific or deletion mutants and HaloTag pull down; The latter will be used to screen a phage display library with the mapped interaction domains to select peptides that suppress or decrease the interaction with DUX4/DUX4c of partners involved in toxic pathways. The biological significance of the DUX-partner interaction will then be evaluated by introducing the blocking peptide in FSHD muscle cell cultures and analysing the resulting phenotype. This approach might present a therapeutic interest in FSHD by blocking DUX4/DUX4c toxic functions. We expect this project will help (i) to define new functions for DUX4 and the poorly studied DUX4c, (ii) to discover their putative interactions through shared partners (iii) to bring new light on the mechanisms of DUX4 toxicity in FSHD muscle and (iv) to propose new therapeutic strategies preventing protein/protein interactions.
Jonathan Lonsdale, PhD. National Disease Research Interchange (NDRI), Philadelphia, PA USA. FSH Society-NDRI Tissue Procurement Project. $265,835 for 3.25 years -- was recommended for one year instead of three; and in addition one-third of the one year at $30,000 contingent on co-funding from other FSHD funding organizations. Fund if other FSHD research non-profits and FSHD Champions will co-fund.
PROJECT SUMMARY: In response to a request from the FSH Society, NDRI proposes to develop and implement a resource to recover surgical and post mortem human bio-specimens and distribute them to approved investigators. This resource will utilize NDRI’s experience, expertise and established systems to expand and enhance the type, number and quality of human tissues available to the FSH research community. lt is proposed that NDRI’s Private Donor Program will collaborate with FSH to recover and distribute tissues from patients who participate in the FSH Registry and who have provided consent for the recovery of tissues and organs for research. In addition to providing all resources required to recover tissues post mortem and from surgical procedures, NDRI will provide informational materials to the FSH Society for distribution to potential registry participants, as well as IRB-approved templates for obtaining informed consent from patients and authorization to donate from family decision makers.
2015 Grant renewal award
Exploiting genome editing technology to modify and regulate the FSHD disease locus. Michael Kyba, PhD. Lillehei Heart Institute, University of Minnesota, Minneapolis, Minnesota USA. $125,000 over 1 year. FSH Society FSHD Canada Foundation research fellowship.
Sequence-specific nucleases cut the DNA molecule at defined sequences. If the sequence-specific nuclease is designed to a particular site, for example the FSHD locus, they allow scientists to make designed changes at that site. The Kyba Laboratory has been using working with two types of sequence-specific nucleases, called a zinc finger-nuclease, and TALENs, however a new technology has recently come on the scene, referred to as CRISPR/Cas9. This technology allows much more rapid development and testing of genome editing approaches. This grant allows the lab to apply this new technology to genome editing projects. The grant has 3 overall goals: 1. They specifically plan to use CRISPR/Cas9 to modify the “pathogenic poly A sequence”, which is the FSHD-causing sequence that lies on the far side of the D4Z4 repeats. The cells they will use for these studies are human induced pluripotent cells from FSHD donors. These are cells from an adult donor that have been reprogrammed to behave like embryonic cells, with unlimited proliferation and differentiation potential, thus once genetically corrected they should be able to generate muscle stem cells that lack the FSHD mutation. 2. The funding will also allow the lab to perform genome editing on embryonic stem cells carrying the FSHD mutation. 3. The lab will use the technology to make defined changes in the way that DNA at the FSHD locus on chromosome 4 is packaged, in order to test models for the molecular mechanism underlying FSHD. These studies are proceeding apace and promise to shed light on new approaches for therapy development. For further details see awards from August 2013.
Awards for the August 2014 Cycle
“Detailed transcriptional analysis of stage-specific early FSHD myogenesis.” Gabsang Lee, PhD, DVM, Johns Hopkins University School of Medicine, Baltimore, Maryland. $70,977 for 1 year (FSH Society Max Weintraub Memorial Research Fellowship)
Abstract: The pathogenesis of facioscapulohumeral muscular dystrophy (FSHD) pathogenesis is complex and not yet fully understood. Recent detailed genetic studies have significantly increased our knowledge of this enigmatic and multifaceted disorder, suggesting the aberrant genetic events during very early myogenesis. The establishment of human induced pluripotent stem cells (hiPSCs) ushered a new era in biomedicine and provide unprecedented opportunities for modeling human genetic diseases. The Lee lab has developed a novel strategy to direct the hiPSCs into myoblasts as well as gene-targeting approach with CRISPR/Cas9 system. Here we propose to isolate pluripotent cells, somite cells and myoblast cells of FSHD-hiPSCs using the established techniques, followed by detailed transcriptional analysis. Our proposed studies will shed light on the FSHD pathogenesis in stage-specific manner during very early human myogenesis.
“Development of a new methylation assay for FSHD diagnosis.” Giancarlo Deidda, PhD, Institute of Cell Biology and Neurobiology, Rome, Italy. $56,000 for 18 months
FSHD is linked to chromosomal 4q35 region, that contains a D4Z4 array of up to 200 units. The most common form, autosomal dominant FSHD1, is caused by a contraction of the 4q D4Z4 array to less than 11 units, whereas FSHD2 is caused by reduced levels of functional SMCHD1 protein (Structural maintenance of chromosomes flexible hinge domain-containing 1). Although with different mechanisms, both genetic defects lead to DNA hypomethylation at D4Z4 on 4qter causing chromatin relaxation. This genomic modulation provides a transcriptionally permissive chromatin environment that is associated with the expression of DUX4, the best candidate FSHD gene, enclosed within each D4Z4 unit. DUX4 expression requires also the presence of a polyadenylation signal (PAS) distal to the last D4Z4 unit, which stabilizes DUX transcript. There are two different allelic forms of the region distal to the D4Z4 array, A and B. Although a D4Z4 array followed by an A “Telomere” is also present on 10q, a functional PAS sequence has been identified almost exclusively on 4qA alleles. Ultimately, vast majority of FSHD1 and FSHD2 subjects show hypomethylation at D4Z4 region followed by an A allele containing a functional PAS. Currently, FSHD diagnosis is based on the identification of shortened 4q arrays (FSHD1) or the presence of mutations in SMCHD1 (in FSHD2) and the assessment of the A/B genotype. In addition, methylation analysis of the proximal D4Z4 units is performed, using methylation sensitive restriction enzymes or by bisulfite sequencing of the overall D4Z4 units. Although hypomethylation is significantly associated with FSHD1 and FSHD2, it is not diagnostic per se because of the lack of information about the presence of permissive alleles (alleles that contains a polyadenylation signal – PAS) and of the interference of not-pathogenic arrays. For this reason, the diagnostic flowchart for FSHD considers hypomethylation as a secondary step to distinguish FSHD1 from FSHD2. Our project aims to the introduction of a new assay that combines the different key features found in FSHD subjects. We propose methylation analysis of 10 CpGs within the 3’ portion of the distal DUX4 copy (DUX4-fl), that is specifically expressed in muscles of FSHD patients. Despite the low complexity and the presence of repetitive elements in the region (pLAM), we were able to design PCR assays, on bisulfite treated DNA, that are specific for the presence of PAS sequence in the A allele. Preliminary results in a subset of FSHD1, FSHD2 and Control subjects showed highly significant differences of methylation levels between affected and unaffected subjects in 8 out of 10 CpGs tested, strongly supporting the potential usefulness of this assay for FSHD diagnosis. Here, we propose:
- To develop additional assays to quantify the number of permissive alleles in order to assess whether different allelic combinations are relevant in the identification of diagnostic threshold;
- To analyze a large cohort of well genotyped FSHD patients and normal controls for precise evaluation of methylation threshold between affected and unaffected subjects;
- To assess specificity of this assay for FSHD disease by testing peripheral blood leukocytes DNA (PBLs) from individuals with unrelated muscular dystrophies;
- To analyze the prognostic potential of this assay by correlating methylation levels with different clinical severity scores;
- To study possible methylation differences distal to the D4Z4 array, between PBLs and muscle biopsies.
“Physiological Studies of Muscle Weakness in FSHD.” Jun Udaka, MD, PhD, and Charles Emerson, PhD, University of Massachusetts Medical School, Worcester. $212,060 for 2 years (FSH Society Helen Younger and David Younger Research Fellowship)
Abstract: The pathophysiology of Facioscapulohumeral Dystrophy (FSHD) is poorly understood and understudied. This FSH Society fellowship award to Dr. Jun Udaka will support comprehensive and detailed physiological investigations of force generation and calcium signaling in skinned and permeabilized single fiber preparations ofFSHD and unaffected control muscle biopsies. Proposed studies address whether FSHD muscles are defective in: 1) troponin-mediated Ca2+ signaling for myofibrillar force generation, 2) sarcoplasmic reticulum (SR) calcium release, 3) myosin ATPase activity, and/or 4), contraction fatigue. Additional studies investigate the roles oftitin and extracellular matrix (ECM) in muscle fiber elasticity as contributing factors in FSHD disease pathology. Findings wiII identify muscle proteins and contractile processes that become dysfunctional during FSHD disease progression and reveal the underlying pathophysiology of FSHD muscle weakness to enable the development and evaluation of FSHD therapeutics in pre-clinical and clinical studies.
“Identification of the underlying genetic defect in a family with FSHD-like and optic atrophy phenotype.” Lionel Van Maldergem, MD, PhD, Université de Franche-Comté, Besançon, France, and Björn Fischer-Zirnsak, PhD, Charité-Universitaetsmedizin Berlin, Germany. $8,000 for 1 year
Abstract: Facioscapulohumeral muscular dystrophy (FSHD) is a disease group which can be subdivided into two groups (FSHD1, OMIM# 158900 and FSHD2, OMIM# 158901). All patients have in common a muscular dystrophy affecting the facial and the upper limb muscles. In both groups, additional features are known such as hearing loss and mild to moderate eye abnormalities. FSHD1 is inherited in an autosomal dominant fashion involving D4Z4 repeat on chromosome 4q35 . The inheritance of FSHD2 is more complex following a digenetic model which includes heterozygous mutations in SMCHD1 which modulate the severity and an haplotype on chromosome 4 which is permissive for DUX4 . Some years ago, a consanguineous family from Italy suffering from an FSHD-like phenotype came to our attention. Both parents were unaffected whereas all four children show a progressive phenotype. The patients show facial and upper limb muscular weakness which became more severe with age. A muscle biopsy from one proband was investigated and showed mild fibrosis, targetoid fibers and an neurogenic component with increased abundancy of type one muscle fibers (JJ Martin, Antwerp). Beside muscular features, all affected individuals reported on eye abnormalities such as myopia in early infancy. A detailed investigation of the eye and the eye fundus revealed an atrophy of the optic nerve in all affected individuals, determining progressive blindness. Furthermore, deep investigation of multiple serum and urine parameters showed an increased level of 3-methylglutaconic acid in the urine and in the serum samples analyzed. Additionally, creatine kinase values are also increase in all individuals tested. The affected individuals from this exceptional family suffer from a disease which combines features known for FSHD and optic nerve atrophy. Furthermore, metabolic alterations which might point to mitochondrial dysfunction were identified which could lead to a better understanding of the affected gene product. Since unaffected parents were second-cousins, recurrence in sibship strongly suggested autosomal recessive inheritance. So far, using various molecular genetic techniques we were not able to detect the causative genetic defect in our index family. Due to the fact that no deletions and causative coding mutations as well as alterations in regulatory regions around CCDC67 could be identified, it is very likely that a non-coding mutation is the cause of this disease. To identify the causative alteration ,whole genome sequencing (WGS) is the method of choice. Rawdata analysis and interpretation may be conducted in the Instute of Human Genetics at Charité (University of Berlin) where both the applicant fellow and his supervisor have acquired an international expertise Moreover, they collaborate tightly with strong bioinformatics group which is experienced in evaluation of large scale genetic data [3, 4]. We are planning to analyze whether larger genomic rearrangements such as an inversion or translocations are present which could explain for example the misexpression of CCDC67. Furthermore, mutations in other intergenic and potential regulatory structures will be investigated. After the identification of the causative mutation, we plan to perform functional investigations in in vitro and in vivo models. We are experienced in cells culture driven investigations of genetic disease  and also the generation of mouse models using for example CRISPR/Cas is established in our lab and in the collaboration group at the Max-Planck Institute of Molecular genetics.
“Deciphering the contribution of FAT1-dependent phenotypes to FSHD symptoms and relevance for therapeutic design.” Françoise Helmbacher, PhD, IBDM, CNRS UMR 7288, Marseille, FRANCE. $138,803 for 2 years
Abstract: FSHD is a hereditary human muscular dystrophy affecting groups of muscles in the face and shoulder, characterized by the asymmetry of these muscle symptoms, and additional non-muscular symptoms including hearing loss and retinal vascular abnormalities. FSHD is caused in most cases by chromosomal abnormalities at 4q35, leading to ex cess production of a transcription factor, DUX4, thereby triggering a cascade of gene de-regulations. However, although necessary, DUX4 activation is not sufficient to trigger the symptoms on its own, implying the existence of disease modifiers necessary for the symptoms to appear. My team studies neuromuscular development and the pathologies resulting from alterations of these processes. We have recently started to work on Facioscapulohumeral muscular Dystrophy (FSHD), a hereditary human myopathy characterized by degeneration of muscles in the face and shoulder area, after having found that disruption of the Fat1 cadherin gene in mice caused muscular and non-muscular symptoms resembling those of FSHD, and shown that alterations of the FAT1 locus in humans, located near the FSHD critical region on chromosome 4q35, were associated with FSHD, identifying FAT1 as a modifier gene in FSHD and as a key player of muscular pathologies ( : Caruso, PLoS Genetics, 2013). Fat1 ablation in mice causes abnormalities in shape of selective groups of muscles and leads to regionalized muscle wasting at postnatal stages, the map of affected muscles being highly similar to the map of muscles affected in FSHD . Such a possibility was investigated in collaboration with Pr. N. Levy and M. Bartoli, La Timone, Marseille, and J. Dumonceaux, Myology Institute, Paris. a) We found reduced FAT1 expression levels in muscles of fetal , but also adult (: Mariot et al. submitted) FSHD cases; b) We identified human mutations in the FAT1 locus segregating with FSHD: i) Heterozygous deletions of a putative regulatory enhancer, predicted to cause tissue-specific depletion of FAT1, co-segregate with FSHD ; ii) heterozygous point mutations, either perturbing splicing of FAT1, or leading to deleterious aminoacid changes, were found in FSHD-like patients carrying neither 4q35 alterations nor mutations in SMCHD1 (: Puppo et al., under revision, coll Bartoli/Levy). Thus, FAT1 is a compelling novel FSHD modifier gene, which tissue-specific loss-of-function is sufficient to recapitulate FSHD-like symptoms on its own, and which deregulation was found to co-occur with FSHD. This collaborative work was the objective of a network grant from FSHD Global for which I was the coordinator. In addition, part of this work was also supported by the FSH society through a grant to V. Mariot, working with J. Dumonceaux. My group first initiated work aimed to elucidate in which cell type FAT1 functions were relevant to FSHD-like phenotypes. Through cre/lox-mediated ablation of Fat1 functions in premigratory myoblasts (Pax3-cre), we showed that Fat1 is required in the myogenic lineage to control myoblast migration polarity . We are currently studying the consequences in developing embryos and adult mice of ablating Fat1 in muscle, neurons and mesenchyme. This work has previously received support from the FSH society through a postdoctoral fellowship to Angela Zimmermann in my lab, and is being prepared for publication. The present project aims to extend this work through following approache: We will evaluate the relative frequency of any genetic alteration occurring in the FAT1 locus among classical FSHD1 patients, with particular focus on patients with retinal vascular symptoms, also present in Fat1-deficient mice, to determine whether alteration of FAT1 expression occurs as a result of DUX4 expression, or synergizes with DUX4 expression to cause FSHD symptoms. Results of this project will help understanding to what extent the phenotypes caused by perturbations of FAT1 functions contribute to the appearance of FSHD symptoms, and will be instrumental to elaborate novel therapeutic strategies for FSHD patients.
Awards for the February 2014 Cycle
Novel role for reduced RNA quality control in FSHD pathogenesis. Sujatha Jagannathan, PhD, and Stephen Tapscott, MD, PhD. Fred Hutchinson Cancer Research Center. July 1, 2014 – June 30, 2016. Amount Requested for Project: US$ 116,725 over 2 years. (FSH Society Dotty Lynch Memorial Postdoctoral Fellowship Grant)
Facioscapulohumeral muscular dystrophy (FSHD) is a prevalent and currently untreatable myopathy. FSHD is caused by the misexpression of DUX4, a germline transcription factor, in post-mitotic muscle cells where it activates a germline transcription program and also induces expression of retroelements and repetitive sequences. Ectopic expression of DUX4 triggers cell death in a variety of cells including primary myoblasts and immortalized epithelial cells via an unknown mechanism. We recently discovered that DUX4 reduces the efficiency of a cytoprotective, RNA quality control pathway called the nonsense mediated RNA decay (NMD), thus stabilizing hundreds of aberrant RNAs. It is known that reduced NMD efficiency can affect cellular proteostasis due to expression of malfolded proteins, which can in turn lead to cytotoxicity through the unfolded protein response (UPR). Hence we hypothesized that DUX4-induced reduction in NMD efficiency leads to the stable expression and translation of aberrant RNAs, generating toxic proteins that cause cell death, possibly through UPR-mediated apoptosis. In Aim 1, we will identify the mechanism by which DUX4 expression reduces NMD efficiency. In Aim 2, we will determine the contribution of reduced NMD to DUX4-induced cytotoxicity and elucidate the downstream mechanisms responsible for this phenomenon. These studies will provide valuable insights into the mechanism of DUX4-induced cytotoxicity and uncover potential novel avenues for therapeutic intervention for FSHD.
BET Proteins as Therapeutic Targets in FSHD. Francis M. Sverdrup, PhD. Center for World Health & Medicine, Saint Louis University. August 1, 2014 – July 31, 2015. One year $51,425. (FSH Society William Michael Postdoctoral Fellowship Grant)
Promoting the appropriate epigenetic repression of DUX4 is a therapeutic strategy for FSHD that addresses the underlying mechanism of disease pathology. However, the molecular details of DUX4 de-repression are not completely understood and few specific targets amenable to small molecule drug intervention have been identified. We have used a chemical genetics approach to identify a key role for the bromodomain and extraterminal domain (BET) proteins in the epigenetic switch that activates DUX4. The experiments proposed here will extend these findings by confirming by genetic means the specific BET family member(s) involved in pathogenic DUX4 expression. This will be accomplished by a combination of RNAi technology and overexpression studies. In addition, we will similarly determine the involvement of mediators of the BET pathway of transcriptional activation including the role of protein acetylation. We will aslo determine the functional effects of BET inhibitors (BETi) on FSHD muscle biology in vitro. A 24 h pulse of BETi results in a sustained decrease in expression of DUX4 and its downstream targets in cultured myotubes without long-term interference with muscle differentiation. These data demonstrate that the pharmacodynamics of DUX4 inhibition and undesirable effects on muscle cells are distinct. We propose to perform a more detailed analysis of the effects of BETi on FSHD myoblasts and myotubes by comprehensive gene expression and functional assays. In addition, we will assess protection of FSHD muscle cells from DUX4-induced apoptosis during myotube differentiation.
FSHD Clinical Trials Network Workshop. Rabi Tawil, M.D. – University of Rochester Medical Center (Rochester, NY), May 2015. $25,000
This proposal seeks to establish an FSHD Clinical Trials Network composed of academic research centers working collaboratively in developing, testing and validating clinical outcome measures and biomarkers. Creating this network will significantly increase the likelihood that promising therapeutic interventions in FSHD comes to clinical trials and that those trials will have meaningful outcomes.
Awards for the August 2013 Cycle
Investigating effects of PARP1 inhibitors in DUX4 expression. Yi-Wen Chen, D.V.M., Ph.D. George Washington University & Children’s National Medical Center, Washington DC, USA. $89,267 over 2 years
Summary (Provided by Applicant): Transcriptional de-repression of DUX4 gene due to epigenetic changes of the D4Z4 region is believed to cause FSHD. In our preliminary study, we identified that poly (ADP-ribose) polymerase 1 (PARP1) interacted with the promoter of the DUX4 gene. Interestingly, the interaction was only observed in the FSHD myoblasts but not control cells, suggesting that the interaction may be part of the disease mechanism of FSHD. PARP1 is a nuclear protein, which functions in various cellular processes and has been shown to play critical roles in regulating gene expression. Several studies showed that, at the promoter of a target gene, PARP1 binds to DNA methyltransferase 1 (DNMT1) and suppresses its function by poly-ADP ribosylation. As a consequence, expression of the target gene is de-repressed due to hypomethylation of its promoter region. Interestingly we identified that DNMT1 co-localized at the DUX4 promoter region in our preliminary study. In addition, FSHD myoblasts treated with PARP1 inhibitor showed reduced expression of ZSCAN4, a marker of DUX4 expression. Based on current knowledge and our preliminary data, we hypothesized that the interaction among the PARP1, DNMT1 and the DUX4 promoter contributes to the DNA hypomethylation of the region, and may further influence the expression of DUX4 in FSHD myoblasts. The goal of this study is to test one synthetic and one dietary PARP1 inhibitor for their effects on DUX4 expression and further investigate the involvement of PARP1 and DNMT1 in FSHD. In aim 1, we will determine the effects of PARP1 inhibitors on DUX4 expression and cell phenotypes of FSHD myoblasts. In aim 2, we will determine whether DNMT1 directly interacts with the DUX4 promoter region in FSHD myoblasts. In aim 3, we will determine whether PARP1 is a direct regulatory target of DUX4. The findings of the study will provide insights of the involvement of PARP1 in FSHD and have a direct impact on developing therapeutics for FSHD which does not have an effective treatment currently.
Gene surgery using TALEN technology: a therapy for FSHD. Julie Dumonceaux, Ph.D. Institut de Myologie, University of Paris, U974 – Inserm, Paris, France. $117,500 over 1 year
Summary (Provided by Applicant): FacioScapuloHumeral Dystrophy (FSHD) is one of the most common myopathies and 2 loci of the disease have been characterized. The first one is located in the subtelomeric region of chromosome 4 and is mutated in 95% of FSHD patients (named FSHD1). This region is composed by a 3.3 kb tandemly repeated sequence named D4Z4. In the general population, the number of repeats varies from 11 to 150, whereas FSHD1 patients carry between 1 and 10 repeats. The second one is located in chromosome 18 and is mutated in 5% of the FSHD patients in whom mutations in the SMCHD1 gene have been found. Despite the different genetic origins of the disease, all patients are phenotypically indistinguishable and share common molecular features, among them the expression of a protein named DUX4. DUX4 is a transcription factor encoding a potential homeobox protein which is highly toxic after overexpression by mis-regulating more than 500 genes. DUX4 ORF is present in each D4Z4 unit but only the most telomeric unit might be able to produce a DUX4 mRNA stabilized by the addition of the poly(A) tail induced by 4qA sequences downstream the D4Z4 array. Because DUX4 is the common pathogenic target between FSHD1 and 2 patients, our goal is to perform gene editing using transcription activator-like effector nuclease (TALEN) and CRISPR/Cas9 technology to modify the FSHD locus and permanently inhibit DUX4 expression. We have chosen to develop 2 strategies: (i) to remove the entire D4Z4 array because individuals with such deletions exist and do not present muscular pathology and (ii) to mutate the DUX4 poly(A) signal since it has been shown that a single point mutation in this poly(A) sequence is sufficient to inhibit DUX4 mRNA expression by modifying its stability. Specific aims will include: (i) designing nucleases with the best activity and sequence-specificity and optimizing the genome engineering strategy (ii) select FSHD cells carrying D4Z4 and 4qA sequence modifications for DUX4 inbhibition (iii) testing the therapeutic benefit of D4Z4 genome engineering in appropriate cell culture and animal models by performing several phenotypic measures to assess the consequences of the targeted mutations of the D4Z4 array on FSHD hallmarks. There are a number of advantages to of our proposed approach over other therapeutic strategies currently under investigation for FSHD. There will be no need for repeated long-term administration of treatment since genome editing offers the possibility of permanent correction following transient nuclease activity for the lifetime of the modified cell and its progeny. The benefit of this as a clinical therapy in terms of cost, toxicological and immunological risk is obvious. Moreover, this approach would be useful for all FSHD cases, whatever the precise mutation/contraction involved.
Protein chemistry and protein-protein interactions of DUX4. Jocelyn Eidahl, Ph.D. The Research Institute at Nationwide Children’s Hospital, Columbus, Ohio USA. $70,000 over 1 year
Summary (Provided by Applicant): DUX4 has been identified as an underlying insult in FSHD, but the mechanisms by which DUX4 contributes to FSHD pathologies is unclear. Our central hypothesis is that the DUX4 transcription factor is involved in protein-protein interactions that influence its ability to induce toxicity in muscle cells and ultimately contribute to FSHD. The two DUX4 N-terminal homeodomains are responsible for its ability to bind specific sequences of DNA. C-terminal residues 160-424 of the DUX4 transactivation domain are essential for inducing toxicity in the muscle, however the mechanisms by which the C-terminal domain mediates DUX4 activity are unknown. We propose that the DUX4 C-terminal domain is involved in the recruitment of proteins that influence its ability to transactivate normal and toxic genes. Our preliminary data identified several candidate DUX4-interacting proteins. The goal of our proposed studies is to identify critical interactions between DUX4 and its candidate binding partners that we can therapeutically target to abolish the toxic effects of DUX4 in FSHD muscles. Our proposed aims will define DUX4 protein binding partners and mechanisms, and delineate the influence of protein-protein interactions on the DUX4-associated pathogenic cascade. We plan to pursue the following two specific aims to test our hypothesis: Specific Aim 1: To define the binding partners and protein-protein interaction mechanisms of the DUX4 C-terminal domain. Specific Aim 2: To examine the functional significance of protein-protein interactions of DUX4 that are critical for DUX4 toxicity.
Exploiting genome editing technology to modify and regulate the FSHD disease locus. Michael Kyba, Ph.D. Lillehei Heart Institute, University of Minnesota, Minneapolis, Minnesota USA. $125,000 over 1 year. FSH Society FSHD Canada Foundation research fellowship.
Summary (Provided by Applicant): The recent discovery of DNA-binding factors whose sequence specificity is encoded by modular domains that recognize single bases (TALENs) or by a guide RNA (CRISPRs) have opened up tremendous new possibilities in genome editing. With early support from a 2 year ARRA grant, and now with continuing support of an NIH R01, we have developed a zinc finger nuclease (ZFN) that targets 4q35.2. We have used this tool to introduce a new telomere at this site in FSHD iPS cells, which effectively eliminates the genetic lesion. Individuals who lack 4qter on one allele are normal, and our targeted iPS cells that have lost the contracted D4Z4 element are similarly normal. This modification rids the cells of DUX4 mRNA expression and corrects a differentiation defect that we have identified in FSHD iPS cells. We seek funding from the FSH Society to expand this research program (1) to include FSHD human embryonic stem cells (our NIH grant supports FSHD iPS cells), (2) into the exciting new area of CRISPR technology with more specific genetic reversion of the pathogenic 4qA161 allele, and (3) to test the hypothesis that epigenetic silencing can be introduced by targeting D4Z4 with engineered sequence-specific chromatin nucleators. Aim 1. To correct the FSHD locus in human embryonic stem cells bearing the FSHD mutation. Our work to date has shown that FSHD iPS cells express DUX4 mRNA and suffer from an impaired response to Pax7-induced skeletal muscle differentiation and that these phenotypes are reverted by genetic removal of the contracted D4Z4 array. These iPS cells were derived from myoblasts, therefore there is some question of whether these phenotypes represent an epigenetic memory of the pre-iPS cell type. It will therefore be essential to perform this genetic correction in FSHD human embryonic stem cells. Aim 2. To design CRISPRs that target existing and novel sites at 4q35.2. The efficiency of targeted integration with our ZNF reagent is low, therefore we will test whether our existing genetic repair method can be made more efficient by CRISPER technology. We will also design and test CRISPERs targeting the pathogenic poly A signal, which may allow correction of the locus without elimination of the entire D4Z4 array. Aim 3. To use engineered sequence-specific DNA-binding tools to target a chromatin nucleation complex to D4Z4. While most enthusiasm about TALENs and CRISPRs has been around their ability to target a nuclease to introduce double strand breaks in DNA, they can also be used to target other proteins to DNA. Because FSHD is caused by inappropriate relaxation of D4Z4 chromatin on the contracted allele, we will attempt to reestablish heterochromatin at this site by fusing an engineered D4Z4- specific DNA-binding domain to proteins involved in nucleating heterochromatin. These studies take advantage of and leverage an existing research program in genome editing of FSHD iPS cells, and will provide the field with valuable new tools to study the pathogenesis of FSHD, and to develop cell therapies based on corrected, isogenic, iPS cells. Dr. Kyba’s project is jointly funded through the Society as a result of collaboration and partnership with The FSHD Canada Foundation, Calgary, Alberta.
Microdialysis for the study of inflammatory features in Facioscapulohumeral muscular dystrophy. Giorgio Tasca, M.D. Institute of Neurology Catholic University School of Medicine, Rome, Italy. $70,000 over 1 year
Summary (Provided by Applicant): In the last years, most of the efforts in the research on Facioscapulohumeral Muscular Dystrophy (FSHD), the third most common form of muscular dystrophy, have been focused on the characterization of the non-conventional genetic mechanism activated by pathogenic D4Z4 repeat contractions that underlies the disease. In our study, we will make use of microdialysis with high cut-off membranes, a technique that has never been applied to the study of skeletal muscle, with the aim of elucidating the pathogenetic mechanisms downstream the genetic lesion, with a particular focus on the poorly clarified inflammatory aspects. In the view of a translational research where information coming from clinical imaging is merged with molecular data, we will perform a comparison between the microenvironment of affected muscles in early disease stages (STIR hyperintense and T1-weighted normal signal on muscle MRI, i.e. muscles showing oedema changes but not yet or only partially replaced by fat tissue) and the microenvironment of apparently unaffected muscles (normal T1-weighted and STIR signal on muscle MRI), in FSHD patients. Muscle microdialysates will be analysed using xMAP technology (multi-analyte profiling beads) to compare the levels of inflammatory cytokines, chemokines and growth factors in the two conditions and to characterize the pattern of inflammation and mediators involved. This will allow a better understanding of the role of the inflammatory process in the disease, the identification of biomarkers of disease activity at single muscle level and, finally, the acquisition of information useful for the development of a targeted anti-inflammatory therapy. In the future, the high cut-off muscle microdialysis protocol could be used for molecular monitoring and eventually drug administration in neuromuscular disorders.
Dynamic mapping of perturbed signaling underlying FSHD. Peter S. Zammit, Ph.D. King's College London, London, England. FSH Society Shack Family and Friends research grant, $137,798 over 1 year to 18 months
Summary (Provided by Applicant): Facioscapulohumeral muscular dystrophy (FSHD) is the third most common myopathy worldwide, but its prevalence may have been underestimated, with it being the commonest muscular dystrophy in Europe. FSHD is an adult-onset, autosomal dominant disorder characterised by wasting of facial muscles and upper body musculature. Disease can progress to affect muscles of the lower extremities and can severely impair quality of life. Over 95% of FSHD cases are caused by contraction of the D4Z4 microsatellite repeat on the subtelomeric region of chromosome 4. In unaffected individuals the D4Z4 repeat region comprises 11-100 D4Z4 units, but in FSHD patients the number is reduced to less than 11. At least one D4Z4 unit is required to cause FSHD however, and only when inherited with a specific polymorphism on the distal end of chromosome 4 (4qA161). Each D4Z4 unit contains an open reading frame for the double homeobox 4 (DUX4) gene, with the 4qA161 polymorphism providing a polyadenylation signal for DUX4 transcripts generated by the last D4Z4 unit. This permissive chromosomal configuration generates stable DUX4 transcripts and it is likely that FSHD is caused by a toxic gain-of-function of elevated levels of DUX4. Little is known about the function of DUX4 and the challenge is now to elucidate how elevated levels of DUX4 cause muscular dystrophy. DUX4 is a putative transcription factor; its N-terminus contains two homeodomains with high similarity to the homeodomains of the transcription factor PAX7, and the C-terminus is an activator of transcription. DUX4 induces apoptosis, with lower expression levels decreasing MyoD and affecting myoblast function and differentiation: important as myoblasts and myotube formation are compromised in FSHD. Many gene expression studies have been performed on FSHD, and other muscular dystrophies, but these have not been thoroughly analysed by the latest bioinformatic techniques. To address this, we developed a novel differential network methodology, designed to identify perturbed signaling pathways in disease networks from just such expression data. Using this novel mathematical methodology, we performed a meta-analysis of multiple publicly available gene expression data sets from FSHD muscle biopsies. We then removed changes associated with muscle wasting, aging, atrophy and inflammation following meta-analysis of appropriate data sets. This integrated output is a high-confidence unified network of pathway changes explaining FSHD pathomechanisms. Interrogation of our network has revealed many promising drug targets and candidate therapeutics. Here, we wish to extend and refine this analysis to identify pathways in our FSHD network that lead to compromised muscle repair and regeneration. To address this, we will collect and analyse by RNA-seq, a high-frequency time course of genome wide gene expression during myogenic differentiation in FSHD. Using mathematical methodologies with optimised network theoretic tools on this gene expression dataset, will reveal molecular mechanisms of myogenesis in FSHD. We will also perform high-frequency time-course RNA-seq on myogenic cells ectopically expressing DUX4, with the aim of identifying primary DUX4 transcriptional-mediated gene expression changes. This will order our FSHD network to identify causal signaling events in FSHD, further eliminating non-specific general adaptations to muscle wasting, inflammation, disuse etc. It will also better identify pathways in the network directly linked to DUX4. Together these results will identify key pathway targets, modification of which should help restore muscle regeneration in FSHD, reversing muscle weakness and wasting. Our ultimate aim is to gain knowledge on FSHD myogenesis and inform the design of therapies for FSHD. There are four objectives: 1. Obtain the first high-frequency time course of genome-wide gene expression during myogenic differentiation in FSHD and control human myoblasts. 2. Obtain a high-frequency time course of genome-wide gene expression in myoblasts expressing ectopic DUX4. 3. Apply our mathematical methodologies with optimised network theoretic tools for analysis of time course gene expression datasets generated. 4. Validate a selection of identified targets for rapid translational studies as potential therapeutics for FSHD.
Awards for the February 2013 Cycle
1. Pilot Study of Electrical Impedance Myography in Facioscapulohumeral Muscular Dystrophy. Jeffrey Statland, MD, University of Rochester, Rochester, New York. $48,909 for one year.
The FSH Society has allowed us to expand our focus to include a novel technique to measure muscle structure. Electrical impedance myography (EIM) is a fast, non-invasive way to obtain quantitative information about muscle structure which may correlate with motor strength and function in FSHD. The device, manufactured by Convergence Medical Devices (Figure 1, Boston, MA), uses a low-intensity electrical current to obtain information about underlying muscle structure by taking advantage of the relationship of muscle structure to the impedance of current flow through the muscle. EIM is well suited toward investigation of muscles important to FSHD but not easily testable by traditional strength measures, including facial, abdominal, and paraspinal muscles. The funding from the FSH Society makes projects like this possible. The hardest part of any project is getting money to get the projects off the ground: the FSH Society grant has enabled us to start recruiting participants to test these outcomes, and allowed us to apply for additional funding from organizations like the National Institutes of Health to complete this project. It is of vital importance for the FSHD research community that development of outcome measures parallels advancements in molecular pathophysiology and drug development. At the completion of this project we expect to have three valuable new FSHD-related outcome measures for future clinical trials.
2. Development of a Novel ChIP-Based Diagnostic Assay for FSHD. Kyoko Yokomori, DVM PhD, University of California, Irvine, California and Shohei Koide, PhD, The University of Chicago, Chicago, Illinois. $40,000 for one year.
The goal of the project is to develop an accurate and robust diagnosis for FSHD. Although FSHD is reported to have a one in 20,000 incidence, there is great concern that the actual number of affected individuals is significantly higher due to undiagnosed cases (with a likely incidence of 1/7,000). Most cases of FSHD involve mono-allelic deletion of macrosatellite D4Z4 repeat sequences at the subtelomeric region of chromosome 4q (4qter D4Z4) (FSHD1), while the remaining <5% of cases demonstrate no D4Z4 repeat contraction (FSHD2). Proper diagnosis depends initially on recognizing clinical signs and symptoms, and differentiating FSHD cases from other muscular dystrophies. Molecular studies have been used to reinforce the clinical impression. The primary approach is detection of 4qD4Z4 repeat contraction by pulsed-field gel electrophoresis (PFGE). However, this method cannot identify phenotypic FSHD2, and certain band patterns can prove difficult to interpret. Therefore, we have urgent need for a better diagnostic technology. The Yokomori group previously found a specific change in histone modification (histone H3 lysine 9 trimethylation (H3K9me3)) at the D4Z4 repeat sequences that is detected in both FSHD1 and FSHD2 patient cells. Importantly, this change is highly specific for FSHD, and is seen also in patient cells from blood samples. Thus, in this project, we plan to test the possibility of using detection of the loss of H3K9me3 in patient chromatin as a diagnostic method for FSHD. We plan to use peripheral blood mononucleocytes (PBMCs) from patient blood samples. Detection of H3K9me3 loss will be assessed by a biochemical method (chromatin immunoprecipitation (ChIP)). We will assess the specificity of our protocol by testing blood samples from healthy individuals, from patients of different ages and disease severities, and from individuals with unrelated muscular dystrophies or unrelated diseases. Related previous grant: Epigenetic abnormality in FSHD Investigators. Weihua Zeng, Ph.D. and Kyoko Yokomori, Ph.D., University of California, Irvine, California. From February 2011: $8,875 for three-month extension.
Awards for the August 2012 Cycle
1. Role of Polycomb Group Proteins in Facioscapulohumeral Dystrophy. Valentina Casà, MS, and Davide Gabellini, PhD, Division of Regenerative Medicine, Fondazione Centro San Raffaele, Milan, Italy. $45,000 over 18 months.
Facioscapulohumeral muscular dystrophy (FSHD), the third most common myopathy, is an autosomal dominant neuromuscular disorder characterized by progressive weakness and atrophy affecting specific muscle groups. FSHD is not due to a mutation within a protein-coding gene, but is caused by contraction of the 3.3 kb macrosatellite repeat D4Z4 in the subtelomeric region of chromosome 4q35. While there is general agreement that D4Z4 deletion leads to over-expression of 4q35 genes, the molecular mechanism through which D4Z4 regulates chromatin structure and gene expression is poorly understood. Consequently, no therapeutic tool to control the aberrant 4q35 gene expression in FSHD is currently available. Polycomb (PcG) and Trithorax (TrxG) group proteins act antagonistically in the epigenetic regulation of gene expression and they play crucial roles in many biological aspects such as development, cell proliferation and cancer. In Drosophila, PcG and TrxG proteins bind to specific DNA regions termed Polycomb/Trithorax Response Elements (PREs/TREs), constituting a regulated switchable element that influences chromatin architecture and expression of nearby genes. D4Z4 shares several features with PREs/TREs. Indeed, my previous results (Cell 2012 149:819-31). showed that Polycomb group of epigenetic repressors targets D4Z4 in healthy subjects. Furthermore, I found that Polycomb proteins are required to maintain 4q35 genes repressed and that D4Z4 deletion is associated with reduced Polycomb silencing in FSHD patients (Cell 2012 149:819-31). My preliminary results strongly suggest that D4Z4 could be the first PRE involved in a human genetic disease. An attractive hypothesis would be that a D4Z4 copy number above the threshold of 11 repeats is able to stably substain a Polycomb-mediated repression of 4q35 genes, while few copies of the repeat fail to do this efficiently. Here, I propose to rigorously investigate the PRE activity of D4Z4. These studies will allow a deep understanding of the D4Z4 mechanism of action and will lay the basis to develop therapeutic approaches aimed at normalizing aberrant 4q35 gene expression in FSHD. My specific aims are: 1.) To understand the mechanism through which the deletion of D4Z4 repeats below a threshold copy number is affecting 4q35 gene expression in FSHD; 2.) To identify potential therapeutic targets.
2. Derivation of Human Induced Pluripotent Stem Cells From FSH Patient Fibroblasts. Gabsang Lee, PhD, Johns Hopkins University, Baltimore, Maryland. $49,705 over one year. FSH Society FSHD Canada Foundation research fellowship.
The genetic and biological events that result in Facioscapulohumeral muscular dystrophy (FSHD) pathogenesis are complex and the link between the genetic aberration and manifestation of symptoms is still elusive. We hypothesize that there might be cellular and genetic alteration in the early stage of myogenesis in FSHD patients. The establishment of human induced pluripotent stem cells (hiPSCs) ushered a new era in biomedicine and can be useful for modeling pathogenesis of human genetic diseases, autologous cell therapy after gene correction, and personalized drug screening. Our lab has been studied human genetic disorders by using induced pluripotent stem cells (hiPSCs) that is a new type of stem cells without destruction of any embryonic tissues or embryos. In addition, we already built a novel methodology in highly innovative manner to directly derive and prospectively isolate skeletal muscle from the hiPSCs. Here we propose to establish hiPSC lines from FSHD patient’s somatic cells. Our proposed study will enable us to isolate FSHD-specific skeletal muscle cells for better understanding of FSHD pathogenesis in human system as well as potential autologous cellular therapy accompanying with genetic correction in near future.
3. Autophagy Defects in FSHD. Sachchida Nand Pandey, PhD, Children's Research Institute, Washington, DC. $99,599 over two years.
Our previous study showed that DUX4 was up-regulated in patient’s muscles of FSHD and transcriptionally regulated paired-like homeodomain transcription factor 1 (PITX1). The muscle-specific expression of Pitx1 in transgenic mouse model showed muscular dystrophy phenotype similar to FSHD [Pandey et al., 2012]. Expression profiling data of Pitx1 transgenic mice showed that 16 major autophagy genes, including damage-regulated autophagy modulator (Dram1) were mis-regulated in the muscle over-expressing PITX1. To determine whether the autophagy pathways were also affected in FSHD, we investigated the autophagy state in FSHD myoblasts as well as patients’ muscle biopsies. Our data showed disease-specific up-regulation of a master autophagy regulator, DRAM, in FSHD muscle biopsies but not DMD or controls. To further characterize the autophagy state in FSHD myoblasts we cultured the myoblast in differentiation media and we found that DRAM was up-regulated in FSHD myoblasts compared to the control myoblasts. We then examined two proteins critical to autophagy activities, p62 and LC3B. The p62 protein binds both ubiquitinated substrates and LC3B [Pankiv et al., 2007], and has been used as an indicator of autophagic flux. In addition, the accumulating of p62 has been used as an indicator of defective autophagy [Settembre et al., 2008; Ju et al., 2010]. In our study, instead of down regulation when autophagy is activated, p62 showed up-regulation in FSHD myoblasts suggesting a defect in autophagy activation. We further checked the LC3B-II to LCB3-I ratio (LC3B-II/I) which is a commonly used marker for autophagy activation. Because LC3B-II is formed only when autophagosomes are generated, the LC3B-II/LC3B-I ratio represents the density of autophagosomes in cells. The significantly lower LC3B-II/LC3B-I ratio in the FSHD myoblasts indicated again a suppression of autophagy in the myoblast. The suppression of autophagy is also supported by accumulation of ubiquitinated protein in the FSHD cells. While the activation of DRAM should activate the downstream autophagy pathways, we observed a defect in autophagosome formation. Interestingly, the up-regulation of LAMP1 and 2 at mRNA level in muscle biopsy of patients with FSHD suggests that the lysosomal system is activated and ready for the later steps of forming autophagolysosomes. However, the autophagy process is somehow disrupted in FSHD myoblast.In addition, the aberrant expression of DUX4 is a cause of FSHD so we would like determine whether defect in autophagy process is directly linked with expression of DUX4. On the basis of our preliminary result we hypothesize that defect in autophagy causes differentiation defect in myotubes formation in FSHD. In addition, autophagy defect is directly induced by aberrant expression of DUX4. In proposed study, we will examine the expression changes of the key regulators of autophagy and further investigate the mechanisms involved in autophagy defects in FSHD. In addition, we will knock-down the DUX4 expression in the FSHD myoblasts to determine whether the autophagy defects are directly induced by the aberrant expression of DUX4 in the cells.The goal of this current proposal is to understand the mechanism and to identify molecular pathways for treatment development. The aim for this study as follows: Aim 1: To determine the expression of DRAM, p62, Autophagy related gene 5 (ATG5), Autophagy related gene 4B (ATG4B), LC3B, and LAMP1 in patients with FSHD. We anticipate that DRAM, p62 and LAMP1 will show higher expression whereas LC3B-II/LC3B-I ratio will be low in FSHD. Aim 1A: To determine the expression of DRAM, p62, ATG5, ATG4B, LC3B, and LAMP1 in FSHD myoblasts with and without autophagy induction. Aim 1B: To determine the expression of DRAM, p62, ATG5, ATG4B, LC3B, and LAMP1 in muscle biopsies of patients with FSHD. Aim 2: To determine whether the defects in autophagy are due to inhibition of fusion between the autophagosomes and lysosomes. We anticipate a reduction in fusion of lysosome to autophagosomes will be observed in FSHD myoblasts but not in the control myoblasts. Aim 2A: To determine the inhibition of fusion efficiency between the autophagosomes and lysosomes in immortalized FSHD myoblasts. Aim 2B: To determine the expression of ATG4B, a key regulator of LC3B conversion, in immortalized FSHD myoblasts. Aim 3: To determine whether the defects are induced by DUX4 by knocking down DUX4 in the immortalized human myoblasts using antisense oligonucleotides against DUX4. Aim 3A: To determine the expression of DRAM, p62, ATG5, ATG4B, LC3B in proliferating and differentiating myoblasts after knocking-down DUX4. Aim 3B: To determine whether DUX4 knock-down can correct the inhibition of fusion between the autophagosomes and lysosomes in FSHD myoblasts.
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Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common forms of muscular dystrophy with an estimated prevalence between 1:15,000 and 1:20,000. The clinical spectrum of disease severity is wide, and the regional distribution of muscle weakness, as well as the pattern of progression, is unique. The molecular defect in FSHD on chromosome 4q35 was described in 1992 but the molecular pathophysiology remained unknown until recently. A unifying model has now emerged proposing the aberrant reactivation of the DUX4 gene—resulting in a toxic gain of function- in the pathophysiology of FSHD. This FSHD model has provided, for the first time, therapeutic targets for FSHD, and it is expected that several potential therapeutic interventions will emerge in the coming years. Because of these recent discoveries, there is an urgent need to develop the tools necessary to effectively and efficiently conduct therapeutic trials in FSHD. Existing validated outcome measures in FSHD are neither sensitive to change nor intuitively patient-relevant. More sensitive outcome measures are needed for a more efficient drug development process. The need for patient-relevant outcome measures was emphasized in the proceedings of the 2010 FSHD European Neuromuscular Centre meeting. Moreover, there is increasing emphasis by the FDA on the development of outcome measures that are clinically meaningful and based on the patient’s perspective. There are currently two validated, commonly utilized outcome measures in FSHD (manual muscle testing [MMT] and quantitative myometry) both of which are based on direct strength testing. Although direct measurement of muscle strength makes intuitive sense in a myopathy, what minimum change in such a measure can be considered clinically relevant is not clear. There are, additionally, two FSHD-specific clinical severity scales that have been validated in cross-sectional studies; however, neither the responsiveness to change over time nor the direct relevance to patients has been demonstrated. Moreover, as 10 and 15 point ordinal scales, they are not likely to be highly sensitive to change. Here we plan to test the reliability, validity and responsiveness to change of two FSHD-specific outcomes: the FSHD Health Inventory (FSHDHI) and the FSHD Functional Outcome (FSHD-FO). Both of these instruments were developed based on direct patient input to reflect the most prevalent and important physical limitations of FSHD. We will recruit 35 participants with FSHD for 4 visits over one year of follow up. Outcomes will be compared at baseline and longitudinally to traditional measurements such as the composite MMT score, existing FSHD clinical rating scales, and SF-36 health survey. Additionally an anchoring technique will be used to determine the minimally clinically important change. We expect that this proposal will provide preliminary data on the utility, ease of administration, reliability and validity, and responsiveness to change over one year of two novel and clinically relevant FSHD-specific outcome measures. We have designed our budget so that reliability and convergent validity are tested in year 1; and responsiveness in year 2, months 12-18. It is of vital importance for the FSHD research community that development of outcome measures parallels advancements in molecular pathophysiology and drug development. The scales presented here both represent valuable, patient-relevant tools for the FSHD clinical trial toolkit.
5. Specific Silencing of FAT1: Role in Pathogenesis of FSHD. Angela K. Zimmermann, PhD, Centre National de la Recherche Scientifique, IBDML – Development Biology, Institute of Marseille, Campus de Luminy, Marseille, France. $140,000 over two years.
This proposal outlines a postdoctoral fellowship project, which I (AK Zimmermann) am planning to conduct in the laboratory of Francoise Helmbacher at IBDML in Marseille, France over the next two years. I arrived in the lab 5 months ago and have already initiated the research project described below (see preliminary data). The Helmbacher laboratory studies mechanisms that contribute to assembly of neuromuscular circuits during development and associated pathologies. Recently the lab has begun work on facioscapulohumeral muscular dystrophy (FSHD), a devastating human disease characterized by degeneration of muscles in the face and shoulder area. Mechanisms contributing to FSHD remain elusive although pathogenic deletions within a D4Z4 macrosatellite array on chromosome 4 have been identified in the majority of clinical cases. Several studies investigating how this genetic alteration exerts its pathogenic effect have led to propose a contribution of deregulated expression of genes proximal to the deleted region (FRG1 & 2, ANT1), as well as a toxic effect of DUX4, a transcription factor whose transcription is enabled in the pathogenic context. However, a role for these genes in the selective muscle deficits associated with FSHD has not been irrevocably established and therefore additional candidates remain to be identified. The Helmbacher laboratory has shown that FAT1, a protocadherin gene also located near the D4Z4 locus, regulates muscle development and may play a role in physiology of mature skeletal muscles as well. In two mouse mutant models, FAT1-deficient mice were found to develop an FSHD-like phenotype, including both muscle and non-muscle defects. Notably, the developmental abnormalities of muscle shape appear to prefigure the map of muscles affected in FSHD patients. In addition, analyses of human foetal biopsies suggested that tissue-specific silencing of FAT1 might be a causal mechanism in FSHD. This was supported by the finding that several FSHD patients without the classical D4Z4 abnormality carried a deletion of a cis-regulatory enhancer of the FAT1 gene. Here, I propose to study the role of FAT1 in FSHD pathogenesis, and specifically to answer the following questions: 1. Owing to a conditional allele of FAT1 developed in the Helmbacher lab, I will use a tissue-specific ablation approach to ask in which tissues FAT1 expression is relevant for proper muscle migration (candidates include muscle, nerve, vascular and connective tissues) 2. Using primary culture assays on myoblasts and myotubes isolated from Fat1 mutant embryos, I will ask whether FAT1 also play a role in muscle function, as suggested by its subcellular association to the t-tubule excitation-contraction coupling system. Ultimately, alterations of these functions in FSHD patients might be accessible to preventive therapies. 3. Finally, I will ask how FAT1 silencing contributes to dysregulation of retina vasculature, a symptom of FSHD that may provide clues about the molecular mechanisms associated with both muscle and non-muscle phenotypes of disease? Ultimately we hope these strategies will contribute to the development of therapeutic targets aimed at bypassing FAT1 silencing in FSHD and maintaining functional Fat1 levels in muscle prior to worsening of the muscle degeneration symptom.
Awards for the February 2012 Cycle
1. A Transgenic Mdel of DUX4-Mediated FSHD. Peter Jones, PhD, Boston Biomedical Research Institute, Watertown, Massachusetts. $105,000 over two years; $60,000 year 1, $45,000 year 2.
The most critical need in the FSHD field is a reliable and faithful mouse model of FSHD. This has been inhibited in the past by lack of a consistent and consensus understanding of the gene misregulation in the human condition that leads to FSHD pathology. Now that there is wide spread agreement about the involvement of DUX4-fl in FSHD pathology there are different barriers; the severe cytotoxicity of DUX4 and its lack of conservation in mammals. As such, the field has so far failed to generate a genetic mouse model based on DUX4 expression that recapitulates the DUX4-fl expression profile and FSHD-like pathophysiology. This project proposes to generate a regulable and tunable strain of D4Z4/DUX4 transgenic mice using the Cre/lox system and targeted transgenesis into the Rosa26 locus. Importantly, this model incorporates the downstream cis regulatory elements and DUX4 splicing and polyadenylation of the FSHD-associated 4q35 locus. This is different from any of the mouse models discussed at meetings (none are published) that fail to show any phenotype. The targeting construct has already been generated and shown to function properly in human and mouse myogenic cell culture and myotubes. With this construct we believe we can manipulate DUX4-expression in mice 1) to a range of cells in a population (1:50 down to 1:5000) in the developmental profile of DUX4 expression and/or 2) in any select tissue or spacio-temporal pattern desired. These mice will prove invaluable for therapeutic screening and understanding DUX4 function. As such, once generated and initially characterized we will make these mice available to the FSH community at large in a timely manner for those with therapeutic approaches.
2. Expression of Human DUX4 in Zebrafish Development. Hiroaki Mitsuhashi, PhD, and Louis Kunkel, PhD, Children's Hospital Boston, Boston, Massachusetts. $60,000 over one year.
FSHD is characterized by an asymmetric progressive weakness and wasting of the facial, shoulder and upper arm muscles. Hearing loss and retinal vasculopathy are frequently accompanied. Accumulating evidence supports the hypothesis that derepression of DUX4, a double homeobox gene located within D4Z4 unit in chromosome 4q35, play a role in the pathogenesis of FSHD. However, a major problem with this hypothesis is the extremely low abundance of DUX4 expression in FSHD muscle. It has been shown that approximately one cell per 1000 expresses DUX4 protein in cultured FSHD muscle cells. How this sporadic burst of DUX4 expression can cause a chronic and progressive myopathy is largely unknown. To address this question, generation of DUX4 animal model is essential. However, there is currently no good animal model due to the toxic nature of DUX4 where overexpression of DUX4 induces apoptosis to many types of cells, resulting in embryonic lethality. This has hampered the further understanding of FSHD pathogenesis and the development of therapeutic approaches. To generate DUX4 animal model, we injected extremely small amount of human DUX4 mRNA into zebrafish embryos. Microinjection of 0.2 or 0.1 pg of DUX4 mRNA (≈ 1 x 105 copies) caused asymmetric abnormalities on their eyes and fins. Injected embryos also showed affected muscle birefringence and slow swimming, suggesting muscle degeneration and weakness. These phenotypes are very similar to those observed in FSHD patients. We believe that DUX4 injected in small amounts into zebrafish is a good animal model for investigating the pathogenesis of FSHD and the impact of DUX4 on development. In this proposal, we plan to define the phenotype of the DUX4 mRNA injected zebrafish model to determine how much and where in development expression of DUX4 can cause the human FSHD-like phenotype in zebrafish. Furthermore, we plan to develop a conditional DUX4-transgenic zebrafish to create stable model. These zebrafish models will help us to understand DUX4-mediated pathogenesis in vivo, and provide us a platform to screen a number of small molecules for therapeutic approach.
3. FAT1 Roles in Muscular Physiology and FSHD Onset. Virginie Mariot, PhD; Julie Dumonceaux, PhD; and Gillian Butler-Browne, PhD, Thérapie maladies du muscle strié, Institut de myologie, Paris, France. $68,000 over one year.
FSHD is an autosomal dominant pathology recently ranked to the most prevalent muscular dystrophy. The genetic locus of the FSHD pathology has been identified 20 years ago, but the molecular mechanisms leading from this genotype to FSHD are still not clearly understood. Indeed, despite recent findings which highlighted the notion of permissive chromosome for FSHD, and the fact that Dux4 is always expressed in FSHD biopsies from these permissive chromosomes, the consequence of this expression on muscle development and function is not well established and the link between Dux4 expression and the development of FSHD pathology is not clearly understood. This reinforces the complexity of FSHD and emphasizes the need to identify other genetic elements putatively involved. Recently, in a collaborative effort involving 3 French laboratories (Francoise Helmbacher, Nicolas Levy and ours), we have identified a new gene named FAT1 which, when down-regulated in mice, recapitulates FSHD muscular phenotypes: at early post natal stages, shoulder and face muscles present an asymmetric atrophy, whereas at later stages, a widespread muscular dystrophy is observed. Moreover, the FAT1 mutant mice also present some non muscular FSHD characteristics such as a retinal vasculopathy. In human, FAT1 is located in 4q35 and belongs to the Planar Cell Polarity (PCP) family which is involved in coordinating tissue polarity, morphogenetic movements, and polarized cell flow. Interestingly, we have also observed that FAT1 mRNA is systematically down-regulated in human FSHD fetal muscle biopsies (but not in brain) as compared to age matched control fetuses. Moreover, in several FSHD2 human samples which do not present the typical FSHD contraction, deletions in the FAT1 gene have been found. All together, these observations strongly suggest that FAT1 may play a major role in the FSHD pathology. Since FAT1 has never been described to play a role in muscle physiology in mammals, our goal is now to understand its biological function and to analyze how it may underlie the onset and progression of FSHD disease. We have already demonstrated that different FAT1 isoforms co exist in human muscle cells and that they are differentially expressed in proliferating and differenciating conditions. Moreover we have also observed that the expression of some isoforms can be coregulating each other, thus highlighting the complex regulation of FAT1 expression and the urgent need to decipher its specific expression. Our aim is to specifically up regulate or down regulate each isoform in normal or FSHD fetal myoblasts and to analyse the effects on myotube formation, on the expression of the other isoforms, on the localization of the protein using FAT1 specific antibodies and on the modulation of expression of other factors we have recently identified in biopsies and in cell cultures (proteins, miRNA), which represent putative new biomarkers for FSHD. Finally, different miniFAT1 will be cloned in viral vectors which will be used to transduce the FAT1 mutant mice in order to try to rescue the FSHD phenotype.
4. A Humanized Mouse Model for Investigations of FSHD Pathology and Therapeutic Development. James Windleborn, PhD, and Charles Emerson, PhD, Boston Biomedical Research Institute, Watertown, Massachusetts. $60,000 over one year.
Facioscapulohumeral muscular dystrophy (FSHD) is genetically caused by the contraction of D4Z4 DNA repeats located on chromosome 4 in 4q35. Although the genetic defect was identified 20 years ago, the exact molecular mechanism causing the disease is unknown. Because of the unique nature of human D4Z4 repeats, there is currently no mouse disease model. To provide such a valuable tool, we have developed a humanized mouse model for FSHD. This model was obtained by the engraftment of FSHD patient derived myoblasts into mouse muscle. Because of the dominant nature of the disorder, we hypothesized that the FSHD engrafted fibers will display a disease phenotype and recapitulate pathological molecular mechanisms associated with FSHD that will allow us to study the development of the disease. Our preliminary work has established the feasibility of this project. Our findings demonstrate the successful, high efficiency engraftment of myogenic cells from FSHD and control subjects into injured, regenerating tibialis anterior (TA) muscle of immune-compromised mice. Early passage myoblast cells from cohorts of FSHD probands and their appropriate controls (i.e., a first degree relative) for these studies were provided by the unique cell repository of the Boston Biomedical Research Institute (BBRI) Wellstone Cooperative Research Center for FSHD Research. We have grafted these standardized cultured cells into mouse muscle to obtain the FSHD humanized mouse model, thereby generating a well-controlled in vivo model for the study of FSHD. We here propose to investigate FSHD disease progression in the humanized mouse model, through studies of the expression of DUX4, an FSHD candidate disease gene, and a larger set of 143 putative FSHD disease biomarkers, which includes a number of DUX4 target genes, identified by the BBRI Wellstone Center by microarray analysis of differentiated FSHD and control myogenic cells. Furthermore, in vivo animal imaging technologies will be utilized to investigate the survival, regenerative capacity and maintenance of FSHD myogenic cells engrafted into injured mouse TA muscle as a pathological mechanism for FSHD In summary, this work will contribute to the understanding of the FSHD pathogenesis in vivo by defining the cellular and molecular disease pathology of FSHD using the unique humanized mouse model of FSHD. Research findings will enable identification of new drug targets for FSHD treatment and provide an animal model for preclinical studies of RNA silencing and small molecule FSHD drugs.
5. Tri-dimensional Organization of the FSHD Locus During Proliferation and Differentiation of Muscle Cells in FSHD Patients and Controls. Marie Gaillard, MS, and Frederique Magdinier, PhD, INSERM UMR_S 910, Epigenetics, chromatin & diseases team, Faculté de Médecine de Marseille, France. $30,000 over one year.
FSHD is an autosomal dominant neuromuscular disorder, with an incidence of 7: 100,000 recently ranked as the most common and prevalent rare muscular dystrophy of the adult. The number of D4Z4 is a critical determinant of the age of onset and clinical severity of the disease. A region distal to D4Z4 generates two allelic forms, 4qA and 4qB both equally common in the general population but FSHD is mainly associated with the 4qA allele. In addition, other polymorphisms, qualified as permissive alleles, exist; the pathology being often associated with the 4qA161 allele. In 5-10 % of families with a typical FSHD phenotype, there is no linkage to 4q35 and this type is referred to as type 2. Over the last decade, major advances have occurred in the understanding of the genetics of this disorder however the exact patho-mechanisms secondary to the genetic defect are still not understood. The DUX4 ORF is localized within D4Z4 and since at least one repeat is necessary to generate a pathogenic phenotype it has been hypothesized that DUX4 overexpression contributes to the pathology by leading to the production of a toxic protein in 1 in 1000 muscle nucleus. While several groups are actively seeking targets of the DUX4 protein, a technically challenging approach, our goal is to understand what leads to DUX4 expression. The deletion of repetitive elements and changes in epigenetic marks across the D4Z4 array such as DNA hypomethylation or decrease in H3K9 trimethylation also indicates that FSHD involves chromatin changes and epigenetic alterations. Interestingly, a localization of the 4q telomere at the nuclear periphery has been reported including by our group (Ottaviani et al., 2009; Arnoult et al., 2010), in close proximity to heterochromatin suggesting that subnuclear positioning contributes to this peculiar pathology. However, the links between epigenetic changes, nature of the 4q35 sequences, DUX4 expression and muscle phenotype have never been fully demonstrated. Therefore, based on our current knowledge and expertise, we are deciphering the link between the subnuclear positioning of the D4Z4 array, epigenetic changes and DUX4 expression in the pathology. Thus, we focus on the regulation of the 4q35 region as a whole through the constitution and exploration of a unique cohort of patients’ samples including atypical cases and cellular models. The strategies proposed here, would lay new grounds for the deciphering of this complex disorder. • Within the frame of this project, a cohort of samples from patients is available including accompanying detailed patient histories and genotyping. • Primary myoblasts and fibroblasts for FSHD pathogenesis, • Induced pluripotent cells (iPSCs) from FSHD1 and 2 patients. This cellular model will be a very valuable tool to investigate the role of epigenetic changes in the tri-dimensional organization of the FSHD locus and the regulation of a putative “FSHD gene” during differentiation and investigate how DNA methylation contributes to the pathogenesis. The epigenetic mechanisms regulating the 4q35 locus remain poorly understood, including how DNA methylation is controlled in the pathology and whether hypomethylation is a cause (increased instability) or a consequence of D4Z4 array shortening. We aim at understanding whether D4Z4 hypomethylation is an early event that precedes shortening of the repeated array or simply the consequence of the loss of a certain number of repeats by comparing methylation profiles in normal and diseased cells, and investigate the intergenerational transmission of DNA methylation in FSHD1 and 2 patients and correlate this methylation level with disease penetrance, D4Z4 array compaction and DUX4 expression. We have already shown that is it possible to visualize methylated regions through the detection of methylcytosines on combed DNA molecules using anti-m5C antibodies. We wish to use MC combined with DNA methylation detection with the probes designed for genomic analysis in order to evaluate the DNA methylation pattern of the D4Z4 array and flanking sequences for each individual allele on the slide and all D4Z4 copies. The sensitivity and stringency of the method requires further development and tests of different experimental conditions are in progress. Hypomethylation occurs in FSHD2 suggesting that DNA methylation metabolism is globally altered in FSHD. The de novo methyltransferase (DNMT3b) contributes to D4Z4 methylation suggesting that epigenetic programming of the repeat occurs at early developmental steps. We investigated the expression of catalytical DNMTases and co-regulatory splicing variants in myoblasts. Demethylation and chromatin changes might also be subsequent to differentiation. IPSCs provide a unique platform to dissect the mechanisms of epigenetic reprogramming during differentiation for typical FSHD cases and FSHD2. Using this type of model, we are investigating the timing of production of DUX4, and testing whether repeat’s transcription initiates epigenetic regulation in different genomic contexts and vice versa. Gene localization in the nucleus is not arbitrary, it’s a dynamic process and we have previously identified D4Z4 as the first human sequence able to control the localization of its abutting telomere by tethering this chromosome end toward the nuclear periphery. We hypothesize that the tri-dimensional organization of the 4q35 locus is altered in patients, being responsible for deregulation of disease’s gene expression. Using a large collection of patients’ biopsies, we have shown that the expression of several genes located in the 4q35 region is modulated in patients and we are now trying to describe how the tri-dimensional organization of the D4Z4 array might affect gene expression by comparing 4q35 chromatin conformation in patients and unaffected individuals in order to understand the interactions between sequences, either distant or in close proximity during proliferation of muscle precursors and muscle differentiation. To study the tridimensional distribution of DNA sequences within the nuclear volume, we have developed a FISH technique coupled with immunofluorescence in 3D. Since FSHD is a progressive pathology, we have chosen to focus on three different cell types, fetal and adult primary myoblasts and fibroblasts from patients or controls, as well as induced pluripotent stem cells (IPSc) derived from primary fibroblasts. Our preliminary results show that hybridization patterns differ in patients and controls cells. Signal hybridization volumes display a significant difference between patients and controls which might reflect the degree of chromatin relaxation in the pathology. Moreover, signals corresponding to 4q35 probes are more colocalized in patient cells, suggesting an interaction between sequences undergoing the same regulatory mechanisms. Hence, we will consolidate our data by using iPSCs as a model of the pathology. These approaches should bring further insights into the underlying mechanisms of FSHD in order to identify target genes and to understand by which mechanism, a decrease in the number of D4Z4 leads to this muscular dystrophy. This project is expected to lead to a better understanding of the regulation of the 4q35 at the genomic and epigenomic levels. We believe that the different aspects proposed here are required to get further insights into the patho-mechanism of FSHD, a key step for the future development of specific therapeutic targets.
Awards for the August 2011 Cycle
1. Identification of the Epigenetic Mechanisms That Regulate DUX4 Activity in Skeletal Muscle. Richard J.L.F. Lemmers, PhD, and Silvere van der Maarel, PhD, Leiden University Medical Center (LUMC) Department of Human Genetics, Leiden, Netherlands. $80,000 over two years.
D4Z4 repeat array chromatin relaxation and transcriptional de-repression of the non-polyadenylated double homeobox 4 (DUX4) gene unifies D4Z4 contraction-dependent FSHD1 and contraction-independent FSHD2. Only from FSHD-permissive genetic backgrounds the DUX4 transcript originating from the most telomeric unit of the array can be stabilized by a polyadenylation (polyA) signal outside the array. Non-permissive chromosomes fail to stabilize DUX4 in the absence of this polyA signal. Somatic DUX4 derepression in FSHD1 and FSHD2 leads to bursts of DUX4 protein in sporadic nuclei of cultured FSHD myotubes. DUX4 is highly expressed in the germ line. It is low expressed in embryonic stem cells and it subsequently gets silenced during differentiation. FSHD iPS cells fail to silence DUX4 during differentiation. The regulatory mechanisms that act upon DUX4 in muscle are largely unknown and currently we do not know how a protein that is expressed in minute amounts causes a chronic and progressive muscle wasting. While others have used conventional over-expression vectors to study the effect of DUX4, we have consistently observed that using constructs in which the genomic organization of DUX4 is retained, i.e. within the context of D4Z4, the locus creates sporadic bursts of DUX4 expression: not only in FSHD1 and FSHD2 cultured muscle cells, but also in muscle cells cultured from our transgenic L42 mice and in C2C12 cells stably transfected with a genomic D4Z4 construct. These bursts already occur at low frequency in proliferating cells and increase in frequency during differentiation. I aim to identify the epigenetic mechanisms that regulate the bursts of DUX4 activity. I will develop reporter constructs in which the DUX4 ORF in D4Z4 is replaced by a reporter gene but in which otherwise the genomic integrity of the distal DUX4 gene is preserved. These reporter constructs will be used in the following set of experiments: 1. Fluorescent reporter constructs will be used in life cell imaging studies to precisely characterize the bursts of expression. Although the highest somatic expression of DUX4 is observed in differentiated myotubes, occasional nuclei expressing DUX4 can also be observed during proliferation. Life cell experiments will establish whether bursts of DUX4 are cell-cycle dependent or whether other factors regulate DUX4 expression. It will also establish whether a single nucleus can repeatedly express DUX4, or whether this is a one-time event. 2. Inserting a fluorescent reporter in the construct allows for the separation of expressing muscle cells by FACS sorting and comparison of the chromatin structure of expressing and non-expressing cells by ChIP with a panel of histone modifications that allows for the recognition of the major chromatin states in mammalian cells. These chromatin studies will be validated in our extensive panel of primary muscle cells of FSHD patients and controls. I expect this study yield a comprehensive epigenetic map of the FSHD locus in DUX4 expressing and non-expressing cells. 3. The reporter construct will also be used in dedicated and in large-scale screens for compounds that activate or repress DUX4. I will use an established RNA-interference (RNAi) screen (collaboration with Dr. Agami, NKI, Amsterdam) to identify chromatin modifiers that affect the D4Z4 chromatin structure. I will validate these studies in primary muscle cells of FSHD patients and controls. I expect this study to provide mechanistic insight in the chromatin structuring of the FSHD locus in patients and controls. Currently we have identified a uniform molecular mechanism for FSHD. I expect this study to contribute to the current gap in our model of how a protein that is expressed in minute amounts causes a progressive muscle disease. A FSH Society Marjorie Bronfman research grant FSHS-MGBF-019 FSHS-82011-01
2. Resonance Imaging and Spectroscopy Biomarkers in FSHD. Doris G. Leung, MD, and Kathryn R. Wagner, MD, PhD, Hugo W. Moser Research Institute at Kennedy Krieger, Baltimore, Maryland. $43,650 over one year.
Facioscapulohumeral muscular dystrophy (FSHD) is the most prevalent hereditary progressive muscle disorder in humans. It is an autosomal dominant disease that causes wasting and weakness in multiple muscle groups (face, shoulders, and upper arms initially, and legs later in the disease) as well as significant disability in affected individuals. Recent advances in understanding the pathophysiology of FSHD have led to the identification of therapeutic targets. However, we lack appropriate biomarkers that reflect the degree of muscle degeneration and regeneration in these patients. Such biomarkers will be necessary for the successful completion of clinical trials. The proposed study will test the hypothesis that proton magnetic resonance spectroscopy (MRS) and quantitative magnetic resonance imaging (MRI) can be used to define unique metabolic profiles in the skeletal muscle of patients with FSHD and controls with normal muscles. These profiles can then be used as biomarkers of disease severity and surrogate outcome measures in therapeutic clinical trials in FSHD. The initial aim of the project will be to establish quantitative MRS patterns in the skeletal muscles of patients with FSHD. We will accomplish this by performing a cross-sectional imaging study of 30 subjects with genetically-confirmed FSHD and measurable biceps weakness. Each subject will undergo MRI/MRS imaging of the upper extremity, and we will correlate the metabolic profiles of the biceps muscles to disease severity (as measured with quantitative muscle testing). Further specific aims will be developed to: 1.) compare magnetic resonance spectroscopy profiles of subjects with FSHD to groups of healthy and diseased controls, 2.) identify correlations between MRS biomarkers and molecular biomarkers collected from muscle biopsy samples, and 3.) observe longitudinal changes in muscle spectroscopy on repeat studies. The combined output of the proposed project will be an imaging protocol that can be used in future clinical trials in FSHD. A FSH Society Irene Lai research grant FSHS-SLMM-002 FSHS-82011-02
3. Additional Support for Medicinal Chemistry Developing Anti-DUX4 Therapeutics for FSHD. Michael Kyba, PhD, Lillehei Heart Institute, University of Minnesota, Minneapolis, Minnesota. $25,000 over two years.
This $12,500 per year grant is supplementary support linked to an NIH R21 1R21NS076671-01 (2-year) application directed towards identifying chemical inhibitors of DUX4. We have previously screened 200,000 compounds and identified approximately 600 inhibitors of cell death induced by DUX4, and current work is directed towards identifying the most promising leads within this set of 600. The NIH application was recently selected for funding and the grant was initiated. This support from the FSH Society will be used to supplement the NIH project, principally by providing additional medicinal chemistry support (allowing us to increase the number of compounds that we follow-up by purchase/synthesis. These compounds help us to understand pathways that can indirectly inhibit toxicity associated with DUX4. See 1R21NS076671-01 [ http://projectreporter.nih.gov/project_info_description.cfm?aid=8225734&icde=10980193 ] for more information on the R21.
Awards for the February 2011 Cycle
1. Antisense Strategies Against DUX4 as Therapeutic Approaches for FSHD. Eugénie Ansseau, PhD, and Alexandra Belayew, PhD, Universite de Mons, Mons, Belgium. $70,500 over two years; $25,000 year 1, $45,500 year 2.
FSHD is a muscle degeneration disease genetically linked to contractions of the D4Z4 repeat array on the 4q35 subtelomeric region. Our group has identified the double homeobox 4 (DUX4) gene within each unit of the D4Z4 repeat array and shown that the encoded protein was expressed in primary myoblasts and biopsies of patients with FSHD but not in non-affected individuals. We found that the only stable DUX4 messenger RNAs derive from the last unit and extend to the flanking pLAM sequence that provides a polyA addition signal. This signal is required to develop FSHD as independently confirmed by an eight-laboratory consortium which studied genetic polymorphisms in hundreds of patients and thousands of healthy individuals. In aggregate our collaborative studies with four different groups have shown that the DUX4 protein is a transcription factor that targets a large set of genes, some of which encode other transcription factors that in turn target additional genes. Globally, DUX4 activation at the FSHD locus initiates a transcription cascade leading to muscle atrophy, inflammation, decreased differentiation potential and oxidative stress, the key features of the disease. By differential protein, RNA and gene studies we keep identifying additional FSHD biomarkers and define whether they are direct or indirect DUX4 targets. Strikingly, we found that DUX4 expression in human myoblast induces an atrophic myotube phenotype and atrophy markers. The rationale of our on-going project is that inhibition of DUX4 expression should prevent the global gene deregulation process and allow muscle regeneration in patients. We have first developed small inhibitory RNAs (siRNAs) and conditions to suppress DUX4 protein expression either in primary myoblast cultures transfected with a DUX4 expression vector, or in primary FSHD myoblasts. Addition of DUX4 siRNA to FSHD myoblasts allowed recovery of a normal myotube phenotype with a decrease of atrophy markers. We have started a collaboration with Prof. Steve Wilton (ANRI, Australia) because of his expertise in the exon skipping therapeutic approach with antisense oligonucleotides (AOs) in Duchenne muscular dystrophy. Prof. Wilton provided us with 7 AOs directed against various parts of the DUX4 mRNA characterized in our group: the aim was to either block translation or induce mRNA degradation to prevent DUX4 protein expression. We were able to identify conditions for selective DUX4 inhibition by 3 AOs as done for the siRNAs above in human primary myoblast cultures. Moreover DUX4 mRNA inhibition also affects the expression of several FSHD markers such as μ-crystallin, β-catenin and TP53. These results constitute a proof of concept in myoblast cultures that DUX4 inhibition might reverse the FSHD phenotype. In the present project we want to validate these results by other techniques (RNA and protein expression profiling) and to test the effect of these AOs and siRNA in mouse models in vivo. A FSH Society New York Festive Evening of Music and Song fellowship grant
2. Humanized Mouse Model for the Study of Facioscapulohumeral Dystrophy. Marietta Barro, PhD, and Charles P. Emerson Jr., PhD, Boston Biomedical Research Institute, Watertown, Massachusetts. $40,000 over one year.
FSHD is genetically caused by the contraction of D4Z4 DNA repeats located on chromosome 4 in 4q35. Although the genetic defect was identified 20 years ago, the exact molecular mechanism causing the disease is unknown, and there is currently no mouse disease model. To provide such a valuable tool, we will develop a humanized mouse model for FSHD, obtained by the engraftment of FSHD patient-derived myoblasts into mouse muscle. Engrafted human cells are able to form muscle fibers in the host mouse muscle, thus allowing pioneering studies in an in vivo context. Because of the dominant nature of FSHD, we hypothesize that the engrafted fibers will display a disease phenotype and recapitulate pathological molecular mechanisms associated with FSHD that will allow us to study the development of the disease. Our preliminary studies have already established the feasibility of this project. Through the cell repository of the Boston Biomedical Research Institute (BBRI) Wellstone Center, we have the unique opportunity to access early passage myoblast cells from cohorts of FSHD probands and their appropriate controls, i.e., a first degree relative. We will graft these standardized cultured cells into mouse muscle to obtain the FSHD humanized mouse model, thereby generating a well-controlled in vivo model for the study of FSHD. The very pressing issue in the field today is the verification of the current DUX4 model. The humanized mice produced will be used to investigate the hypothesis that DUX4 gene expression is a major cause of FSHD pathogenesis. In the obtained model, DUX4 expression will be evaluated during in vivo regeneration, and the consequence of its expression on fiber turnover and satellite cell renewal will be assessed. This work will contribute to the understanding of the role of DUX4 in vivo, thus providing a better understanding of FSHD pathogenesis. The proposed project will be completed following 2 specific aims: Specific Aim 1: Optimization of the FSHD humanized mouse model. We will improve results obtained in preliminary experiments by designing more efficient transplantation strategies. In order to fully interpret the disease model, we will seek to increase the amount of muscle formed from implanted human cells, by devising more efficient transplantation strategies. The cell repository of the BBRI Wellstone Center provides access to freshly isolated FSHD and their appropriate control muscle cells sorted for CD56 expression, which are expected to have particularly high engraftment potential. However, the timing between the toxin injection and the cell injection, as well as depletion of endogenous satellite cells by irradiation of the mouse legs, may affect the ability of implanted cells to regenerate the murine muscle and will be optimized during this aim. Upon establishment of an effective mouse model, we will look for disease characteristics, as described in Specific Aim 2. Specific Aim 2: Characterization of the FSHD humanized mouse model to evaluate the role of DUX4 during in vivo muscle regeneration. The model obtained in Specific Aim 1 will be characterized by establishing differences between the fibers generated from FSHD cells and fibers from their appropriate control cells in injected muscles. Recent breakthroughs in the field suggest that DUX4, a gene identified inside D4Z4 repeats, expresses a toxic protein in the muscles of patients with FSHD, thus causing the disease. DUX4 may have a normal role during development and the FSHD pathology might involve incomplete developmental silencing of DUX4. However, the precise molecular and cellular mechanisms involving DUX4 remain to be uncovered. The BBRI Wellstone Center, currently investigating DUX4 expression in muscle samples from its cohort collection, has been able to detect DUX4 transcripts in FSHD samples, and these cohorts will be selected for the generation of the humanized FSHD mouse model. Initially, the expression of DUX4 at the mRNA and/or protein levels will be assessed in FSHD- and control transplanted muscles. This will be followed with experiments designed to compare the biological characteristics of the resulting muscle fibers. Finally, we will develop a dynamic approach to investigate the current DUX4 model in following the evolution of the engrafted fiber over time using in vivo bioluminescence live imaging. Murine models surpass in vitro limitations due to their ability to reproduce complex in vivo environment thereby providing a deeper understanding of disease mechanisms. Our model for creating humanized FSHD fibers in murine muscle will recapitulate the mechanisms of pathological fiber formation in vivo, allowing us to fully characterize the disease progression and test potential therapeutic agents. A FSH Society New York Festive Evening of Music and Song fellowship grant
3. Testing a Therapeutic Approach for FSHD: Evaluation of the Efficacy of AOs Blocking DUX4 in a Mouse Model of Isolated Myofibres. Alexandra Tassin, PhD, and Alexandra Belayew, PhD, Universite de Mons, Mons, Belgium. $15,000 over one year.
FSHD is considered the most frequent hereditary muscle disorder in adults, affecting one individual in 20,000. It is associated with contractions of the D4Z4 repeat array in the 4q35 subtelomeric region. In non-affected individuals, this array comprises 11-100 tandem copies of the 3.3-kb D4Z4 element while in patients, only 1-10 D4Z4 copies are left (Wijmenga et al., 1992). Our group has identified the double homeobox 4 (DUX4) gene within each unit of the D4Z4 repeat array (Gabriels et al., 1999) and several studies have now demonstrated the causative role of DUX4 in FSHD. We have demonstrate that the stable full-length DUX4 messenger RNA (mRNA) is produced from the last D4Z4 unit in FSHD, using a polyadenylation signal in the flanking pLAM region, located telomeric to the distal repeat (Dixit et al., 2007) as recently confirmed by a study of genetic polymorphisms in hundreds of patients and thousands of non-affected individuals (Lemmers et al., 2010). This polyadenylation site is necessary to develop FSHD on a contracted allele therefore called “permissive chromosome” (Lemmers et al., 2010). The mRNA from this distal D4Z4 unit contain the entire DUX4 open reading frame (ORF) and 1 or 2 alternatively spliced introns in the 3’UTR (DUX4-fl). In addition, a short DUX4 mRNA terminates at the previously described polyadenylation site in the pLAM region but uses a cryptic splice donor site within the DUX4 ORF (DUX4-s). DUX4-fl was only detected in FSHD muscle cells and biopsies, whereas DUX4-s is detected both in control and some FSHD samples (Snider et al., 2010). A long DUX4 mRNA was detected in induced pluripotent stem cells (iPS cells) and human testis where the gene contains 4 additional exons and a more distal polyadenylation signal. Expression of this DUX4 mRNA was suppressed during differentiation of control iPS cells to embryoid bodies whereas expression of full length DUX4 mRNA persisted in differentiated FSHD iPS cells (Snider et al., 2010). These data, together with the conservation of the DUX4 ORF through evolution (Clapp et al., 2007) suggests a possible role of DUX4 in human development. Dr. Tassin intends to undertake a post-doc for three months in 2011 at King’s College London, to initiate a collaborative research project between our lab and that of Dr. P. Zammit. In agreement with Dr. Zammit, our collaborative project will consist of testing antisense oligonucleotides (AOs) directed against the 3’UTR of the DUX4 gene that we have developed in our laboratory, in collaboration with Prof. S. Wilton (ANRI, University of Western Australia). These AOs have undergone preliminary screening in cell culture, but require more extensive testing. Dr. Zammit has developed mouse myofibre models that provide an ideal system to further test our AOs. The satellite cells associated with the isolated myofibres will be infected with retroviral vectors encoding DUX4, and the effects on myogenic progression and apoptosis of AO administration analysed. We want specially to focus on the pLAM region responsible for the stabilisation of the DUX4 mRNA leading to FSHD. This system will allow better understanding of the action AOs, for evaluating their potential suitability as a human therapy. We believe that this collaboration will give us new insights into a potential therapy for FSHD. A FSH Society California Walk and Roll fellowship grant
4.Investigating Mouse Models of FSHD. Paraskevi Sakellariou, PhD, and Robert J. Bloch, PhD, University of Maryland School of Medicine, Baltimore, Maryland. $40,000 over one year.
There is a great need for a valid mouse model for FSHD. Such an animal model would provide a valuable tool for exploring the effects of newly cloned genes and novel proteins on the pathophysiology of this disease. It would also greatly facilitate research towards the development and testing of new therapeutic approaches to FSHD. We propose to examine two possible mouse models of FSHD, the FRG1 over-expressor, from Drs. Davide Gabellini and Rossella Tupler, and mu-crystallin over-expressor, developed by Drs. Patrick Reed and Robert Bloch. I will breed these mice and test them for their physiological and morphological characteristics, and their susceptibility to injury and ability to recover from injury. I will also initiate xenografting studies to create mice with humanized normal and FSHD ankle dorsiflexor muscles, combining methods that are routine in the Bloch laboratory with unique reagents provided by collaborators in the Wellstone Muscular Dystrophy Cooperative Research Center (MDCRC), “Biomarkers for Therapy of FSHD.” These experiments should reveal the usefulness of available transgenic models for the study of FSHD, and promote the development of humanized mouse muscles for the study of the pathophysiology of FSHD in situ. A FSH Society New York Festive Evening of Music and Song fellowship grant
5. Epigenetic Abnormality in FSHD. Weihua Zeng, PhD, and Kyoko Yokomori, PhD, University of California, Irvine, California. $8,875 for three-month extension.
Our preliminary findings indicate that D4Z4 repeat regions indeed interact with other genome regions, and that these interactions are indeed disrupted in FSHD. With a three-month extension of my fellowship, I plan to perform a high-throughput identification of potential target genes that interact with D4Z4 using the recently developed “Chromatin Interaction Analysis using a Paired-End Tag” (ChIA-PET) technique. This strategy enables the genome-wide detection of chromatin interactions mediated by specific factors that are normally assembled at D4Z4. Identification of additional FSHD pathogenic genes other than FRG1 and DUX4 is important to explore future therapeutic targets to improve or prevent the clinical symptoms of FSHD. Previously, with the support from the FSH Society in 2010, we found that a set of factors that normally assemble at D4Z4 repeats do not bind to these repeats in FSHD cells. Interestingly, these factors are known to function in gene silencing and long-distance genomic interactions, which appear to be particularly important for coordinated developmental gene regulation in human cells. Two candidate genes, FRG1 in a neighboring region and DUX4 encoded within D4Z4, have been identified whose artificial over expression did cause muscular dystrophy in vivo or a myoblast differentiation defect in vitro, respectively. The loss of chromatin structure associated with gene silencing at D4Z4 may explain the abnormal expression of these genes in the disorder. However, FSHD patient muscle cells do not always over express these genes. Thus, there are likely to be additional unidentified genes and signaling pathways involved in the pathogenesis of FSHD. Our hypothesis is that D4Z4 normally spreads a silencing effect to target genes through genomic interactions mediated by D4Z4-bound factors. This function is lost in FSHD, resulting in the abnormal over expression of a set of target genes that leads to clinical manifestations of the disorder. I am taking two strategies to test this model; (1) screen for any genes that might have lost factors similar to those that are lost from D4Z4 in FSHD by high-throughput genome-wide chromatin immunoprecipitation (ChIP)-sequencing, and (2) directly search for genomic regions that interact with D4Z4 using biochemical chromatin conformation capture (3C)-related methods. Any candidate genes identified by these assays will be tested for their effect on cell viability, proliferation/differentiation, and muscle-related downstream gene expression. I will try to re-create the expression change detected in FSHD cells in normal human myoblasts (by over expression or repression) and compare it to the phenotypes of FSHD myoblasts to determine whether the candidate gene contributes to the FSHD cellular phenotype. My research aims to decipher the epigenetic abnormality mechanism in FSHD, which should provide novel insight into the disease mechanism and thus potentially present new therapeutic strategies. A FSH Society Sanford Batkin & Helen Younger and David Younger research fellowship grant
6. Analysis of DUX4-fl Expression. Peter L. Jones, PhD, Boston Biomedical Research Institute, Watertown, Massachusetts. $7,500 for one year.
We request support from the FSH Society for our pilot project investigating DUX4 expression in unaffected and FSHD subjects. The DUX4-fl expression model for FSHD has not been independently validated, likely due to the lack of quality clinical resources in the field. At this point in FSHD research, validating and expanding upon the DUX4-cytotxicity model for pathogenesis is vital to the entire field and we are best positioned to do the necessary experiments with the unique set of highly controlled reagents being generated by the NIH Wellstone Muscular Dystrophy CRC for FSHD at BBRI. Each Wellstone cohort consists of an FSHD affected subject and an unaffected first-degree relative. Each subject donated two biopsies, one from the biceps and one from the deltoid. A portion of each biopsy was used to derive myogenic cell cultures. Quite surprisingly, in our initial preliminary results using 4 cohorts we found some inconsistencies with the published DUX4 expression results that have warranted further investigation. Therefore we have begun a much larger effort to analyze DUX4-fl mRNA and protein expression in a larger set of Wellstone cohorts using RT-PCR and immunostaining (ICC). However, this project is not funded at all in my lab or in the original Wellstone budget and my lab receives no financial support from the Wellstone Center. The Wellstone has supported us by providing us with cells, which we culture, and RNA which the Louis Kunkel lab purified from biopsies (we do not actually work with the biopsies) and we have been fortunate to receive these Wellstone samples. At this point, to ensure that our results are statistically meaningful, we need to analyze many more cells and biopsy RNAs and it has become cost prohibitive. Therefore I am requesting financial support for consumables and services (DNA sequencing) to conduct these experiments. A FSH Society Cape Cod Walk and Roll fellowship grant
Awards for the August 2010 Cycle
1. Small Molecule Screen to Identify Inhibitors of DUX4-Mediated Toxicity, Therapeutic Approach for FSHD. Darko Bosnakovski, DVM PhD, University Goce Delcev Stip Faculty of Medical Sciences. Krste Misirkov bb, 2000 Stip R. Macedonia. $90,000 over two years.
We and others have shown that DUX4 is toxic to different cell types, and induces FSHD-associated morphological and transcriptional changes in vitro.As a first step towards developing a targeted therapy for FSHD, we have taken advantage of conditional toxicity of DUX4-inducible myoblasts and we developed a small molecule screening platform for identifying inhibitors of DUX4. In our iC2C12-DUX4 inducible myoblasts, we incorporated full length of the last D4Z4 repeat, so prior its induction, we can not exclude that besides DUX4, some other products are not expressed (RNA, spliced proteins). Assay based on rapid cell death within 24 hours induced by high levels of DUX4 was used for high throughput screen of 200,000 chemicals, part of UT Southwestern HTS compound library. We identified more then 586 compounds with significant rescue ability (60 to >100% cell survival). To identify direct inhibitors, we have conducted serial follow up assays, including secondary screens to eliminate compounds which interfere with the rtTA/TRE inducible gene expression system, to distinguish anti oxidants, to confirm reversion of toxicity in other DUX4-expressing cell types. Several classes of compounds reverted toxicity indirectly, including antioxidants. After these secondary screens, we have narrowed down the list to 82 potentially direct DUX4 inhibitors. The goal of this proposal is to discover a chemical compound/s which efficiently inactivates the DUX4 protein and build on that discovery to develop a drug for a therapeutic approach to FSHD. To achieve this we will have to filter our current list (82 compounds) with additional secondary screens. Among them will be an analysis of MyoD expression and stability as well as cellular localization of the DUX4 protein (Aim 1). We reported that DUX4 is a potent inhibitor of MyoD expression. Therefore, a compound that will rescue MyoD expression in DUX4 induced cells is likely to be a therapeutically effective DUX4 inactivator. We assume that compounds which will be able to inactivate DUX4 in our iC2C12-DUX4 system most likely will be able to rescue FSHD myoblast phenotype. FSHD myoblasts were reported to have impaired differentiation, missregulation of myogenic transcription factors and increased susceptibility to oxidative stress. For that reason, as a functional in vitro study, we will test selected compounds for reversion of FSHD myoblast phenotype (Aim 2). Furthermore, we will test whether selected compounds exhibit their effect on inactivation of DUX4 protein or inhibition of DUX4 transcription or translation (Aim 2). At the end the most potent compound /s will be test for pharmacokinetic and pharmacodynamic properties (Aim 3). The aims of our proposed study target the most crucial topic and urgent needs of FSHD patients: specific and direct pharmacological therapy. Aim 1. To narrow our focus to the most promising direct DUX4 inhibitors. Aim 2. To evaluate effectiveness of DUX4 inhibition Aim 3. To analyze pharmacokinetic and pharmacodynamic properties of the selected compounds.
2. Defining the Tissue and Cell Specificity of the Human DUX4 Promoter in Mice. Scott Harper, PhD, Center for Gene Therapy, The Research Institute at Nationwide Children’s Hospital, The Ohio State University Room WA3015, 700 Children’s Drive, Columbus, OH 43205 USA. $50,000 over one year.
FSHD was formally classified in 1954, and the primary genetic defect, D4Z4 contraction, was identified in 1992, but the pathogenic mechanisms underlying the disease have only recently started to come into focus. One reason for the difficulties in understanding FSHD biology is the lack of a relevant animal model expressing FSHD-permissive D4Z4 arrays. Since animal models, particularly mice, are crucial tools for studying disease pathogenesis and developing potential therapeutics, the absence of an FSHD mouse model is a fundamental problem in the FSHD field. A major goal of the Harper lab is to generate an FSHD mouse model expressing a single FSHD-permissive human D4Z4 repeat, and to use this model to understand the role of the D4Z4-resident gene, DUX4, in FSHD pathogenesis, and develop RNAi therapeutics targeting DUX4. In preliminary data, supported by previous FSH Society Fellowships to the Harper Lab, we delivered DUX4 to mouse muscle using adenoassociated viral vectors (AAV). DUX4 over-expression in muscle caused myopathy, but DUX4 is generally toxic to many non-muscle cells as well. Thus, we hypothesized that if DUX4 over-expression is an underlying pathogenic event in FSHD, it must be preferentially expressed only in affected muscles. We therefore developed transgenic mice expressing the green fluorescent protein (GFP) gene from the human DUX4 promoter (DUX4p-GFP mice), to determine the tissue and cell specificity of DUX4. In preliminary studies, we observed gross GFP expression in the face, shoulder girdle, and limbs of three independent DUX4p-GFP mouse lines. In this proposal, we will more carefully define the developmental and cellspecific expression patterns of DUX4p-GFP mice, and develop an AAV vector to determine whether a viral-mediated vascular delivery approach can produce the same expression patterns. Ultimately, these studies will be important first steps toward developing an AAV-mediated D4Z4 mouse model. Specific Aim 1: To define the developmental and cell-specific expression patterns of the human DUX4 promoter in mice. Mounting evidence supports the hypothesis that over-expression of the D4Z4-resident DUX4 gene is an underlying pathogenic event in FSHD. DUX4 is generally toxic to many cell types, and since FSHD is characterized by dystrophy of very specific muscle groups, we hypothesized that DUX4 is preferentially expressed only in affected muscles. Our newly generated DUX4p-GFP reporter mice grossly express GFP in areas that are preferentially affected in FSHD. In this Aim, we will perform a detailed characterization of GFP expression in our DUX4p-GFP mice. These results will help define the expected expression patterns of DUX4, and ultimately increase our understanding about the role of DUX4 FSHD pathogenesis. Specific Aim 2: To develop an AAV vector-mediated DUX4p-GFP mouse model. Previous endeavors to generate D4Z4 or DUX4 FSHD mouse models using traditional transgenic approaches have been unsuccessful. Although the previous attempts are not published in peer-reviewed literature, the difficulties encountered in generating these models were discussed in abstracts and talks at various scientific meetings over the last several years, including at the FSH Society’s 2008 International Research Consortium and Research Planning Meeting held in Philadelphia, Pennsylvania (http://www.fshsociety.org/assets/pdf/FSHD_ASHG_IRC2008_Philadelphia_11Nov_ProgramAndAbstract s_proof.pdf). Vascular delivery of AAV vectors carrying FSHD-permissive D4Z4 repeats to adult mice may circumvent the early embryonic death or developmental defects arising from germline transmission of D4Z4 repeats using traditional methods. In this Aim, we will test the feasibility of using AAV vectors to drive D4Z4-specific expression patterns in mouse muscle using an AAV.DUX4p-GFP reporter vector. +
3. Identification of a Novel FSHD Biomarker (an Unknown 50 kDa Polypeptide Highly Expressed in FSHD Samples). Jessica Sun, PhD, and Peter Jones, PhD, Boston Biomedical Research Institute, 64 Grove Street, Watertown, MA 02472 USA. Partial funding for more preliminary data $10,000 over one year.
Screening FSHD patient-derivedmyoblasts, control myoblast, and muscle samples for expression changes at the proteomic level produced an unknown 50 kDa polypeptide highly expressed in FSHD samples compared to controls. Interestingly, this polypeptide is equally expressed in both normal and FSHD-patient derived myoblasts and early myotubes, however, unlike in control cells where its expression decreases, this unknown polypeptide remains highly expressed in differentiated muscle suggesting it is developmentally regulated and this regulation is disrupted in FSHD. This proposal will utilize standard biochemical techniques including column chromatography and mass spectrometry to purify and identify this 50 kDa putative FSHD biomarker. Subsequently, specific antibodies will be gerneated and characterized for further use to screen FSHD-derived cells to establish the universality of this biomarker. In addition, regardless of what its eventually identification turns out to be, identifying this protein will provide insight into FSHD pathophysiology, will be a useful FSHD biomarker, and may be one of the first proteins consistently and specifically upregulated in viable FSHD muscle. Therefore, generating specific and standardized antibodies to this protein will provide a useful resource for clinicians and basic FSHD researchers. +
4. Toward Therapeutics for FSHD: Understanding mRNA Processing. Thomas A. Rando, MD PhD, and Antoine de Morree, PhD, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford Neurology Clinic, 300 Pasteur Drive, Boswell A-301, Stanford, CA 94305 USA. $100,000 over two years. Project is being matched dollar for dollar by the Stanford Office of Medical Development and Dr. Gary Steinberg, Stanford Institute for Neuro-Innovation and Translational Medicine (SINTN).
The pathogenesis of FSHD has remained a mystery despite remarkable advances in the understanding of the underlying genetics. It was determined in 1992 that patients with FSHD have unusual contractions of a repeat element (so called D4Z4) at position 4q35 in the genome.1 However, what has remained elusive until now is how those contractions, i.e. loss of genomic material, could lead to an autosomal dominant disease. Within each D4Z4 repeat is a sequence termed Dux4 that encodes a putative double homeobox gene. Studies of the protein product have demonstrated that Dux4 overexpression can interfere with muscle differentiation. Thus, much effort has gone into the exploration of how D4Z4 repeats could lead to a “toxic-gain-of-function” related to the Dux4 transcript and protein. To date, no hypothesis has withstood experimental scrutiny. For one thing, there are individuals with D4Z4 contractions that do not develop FSHD. Recently, the group of van der Maarel reported in the journal Science their findings of the high resolution haplotype mapping of patients and unaffected individuals with D4Z4 contractions.2 Their findings provide evidence that the disease develops in individuals who have BOTH a D4Z4 repeat contraction AND a specific sequence in the pLAM domain at the 3’ end of the D4Z4 array (Figure 1). The D4Z4 repeat contraction results in “relaxed chromatin”, and allows the transcription of the Dux4 gene in the final D4Z4 repeat. However, it is the sequence in the pLAM domain that creates a site that is recognized by the cellular machinery allowing cleavage of the mRNA and the addition of a poly(A) tail. Without a poly(A) tail in the 3’ untranslated region (3’ UTR), transcripts are rapidly degraded and never translated into proteins.3 With these tails, transcripts are stabilized and appropriately localized in the cell, allowing for protein translation. In individuals who have D4Z4 contractions but a single base change in the distal sequence, the cell does not recognized it as a “polyadenylation signal” (PAS) site, no poly(A) tail is added to the 3’UTR of the transcript, the Dux4 transcript is unstable, no Dux4 protein is made, and the individuals are protected from getting the disease (Figure 1). Within this cascade are several opportunities, at least theoretically, to treat or even prevent FSHD in susceptible individuals. Any intervention that prevents the addition of the poly(A) tail to the Dux4 transcript is a potential therapeutic approach for FSHD. These findings suggest a direct line to a novel therapeutic approach. The toxicity leading to FSHD depends of effective mRNA processing in which the Dux4 transcript is cleaved and modified by the addition of a poly(A) tail. If one of these processes could be blocked, then the mRNA would be destabilized and the FSHD genotype would yield a normal phenotype. Clearly, it is untenable to interfere with mRNA processing in general because of the toxicity to the cell. Therefore, understanding the mechanisms by which a cell can bypass a specific PAS site would suggest a mechanism for selectively blocking the PAS site in the pLAM domain in the Dux4 gene without generally affecting cellular mRNA processing. This would be an effective treatment for patients with FSHD. +
5. A Multicenter Collaborative Study on the Clinical Features, Expression Profiling, and Quality of Life of Pediatric Facioscapulohumeral Muscular Dystrophy. Jean Mah, MD, Alberta Children’s Hospital, 2888 Shaganappi Trail NW, Calgary, Alberta, CANADA T3B 6A8. $96,669 over two years; $51,434 year 1, $45,235 year 2. Project is being co-funded by the FSHD Fund Muscular Dystrophy Canada FSHD Fund.
Fascioscapulohumeral dystrophy (FSHD) is the third most common type of muscular dystrophy, with an estimated prevalence of 1 in 15,000 to 20,000 (Kissel, 1999) (Flanigan et al., 2001). It is an autosomal dominant disorder due to a deletion within the D4Z4 repeat region located on the subtelomeric region of chromosome 4q35. FSHD causes progressive atrophy and frequently asymmetrical weakness involving the face, shoulder girdle, upper arm, abdominal, and lower limb muscles. Most affected individuals develop symptoms during their second or third decade, with 20% eventually become wheelchair dependent (Padberg, Lunt, Koch & Fardeau, 1991) (Zatz et al., 1998). Early childhood onset of FSHD may be associated with more severe weakness as well as extra-neuromuscular manifestations such as mental retardation, retinal vasculopathy, and sensorineural hearing loss (Jardine et al., 1994) (Klinge et al., 2006). Although the majority of cases of FSHD are inherited, about 20%—30% of sporadic cases may occur as a result of spontaneous mutation or mosaicism (van der Maarel & Frants, 2005). Despite recent advances in the understanding of the molecular genetics of FSHD, the exact mechanism responsible for the disease remains unknown, and presently there is no cure (Tawil & Van Der Maarel, 2006) (van der Maarel, Frants & Padberg, 2007). As well, the prevalence, clinical variability, cross cultural presentation, and the psychosocial impact of FSHD on affected individuals constitute a significant public health concern. Emerging therapeutic trials will benefit from the availability of natural history data and reliable outcome measures (Rose & Tawil, 2004) (Tawil, 2008) for both children and adults with FSHD. Purpose of Study The main objectives of this study are: 1) to establish a standardized muscle testing protocol for use in children and youth with FSHD; 2) to describe the clinical phenotypes of pediatric onset FSHD; 3) to evaluate the impact of FSHD on health-related quality of life and disability across different age groups; and 4) to explore potential genetic modifiers of clinical phenotypes and disease progression in FSHD.