The Pathogenesis of Facioscapulohumeral Muscular Dystrophy

描述(由申请人提供)：面肩肩周型肌营养不良症(FSHD)是最常见的成人肌营养不良症之一。亚端粒大卫星重复序列(D4Z4重复)的缺失会导致大多数FSHD病例，并导致一种显性遗传性疾病。我们团队最近的工作表明，缺失的等位基因上的抑制性表观遗传标记减少，调节因子与缺失的等位基因的结合增加，以及由D4Z4重复产生的一组复杂的编码和非编码RNA。这些发现有力地支持了FSHD病理生理学的广泛假说：D4Z4重复中表观遗传沉默的缺失会导致导致疾病的RNA物种表达增加，这可能是通过RNA或蛋白质介导的机制。我们的研究小组将致力于具体和互补的目标，共同检验广泛的假说并确定FSHD的特定机制(S)，这对未来的治疗开发至关重要。项目1的目标(van der Maarel博士)将确定4qA161特有的DNA序列和表观遗传学变化，这是授予FSHD病理学所必需的。项目2(Tapscott博士)的目标将确定D4Z4产生的编码和非编码RNA是否在FSHD病理中发挥作用，并确定一般抑制D4Z4重复区域转录的机制。项目3(Dr.Filippova)的目标将是确定CTCF与疾病相关等位基因的结合是否调节区域染色质结构、RNA转录或核定位。项目4(Miller博士)的目标将是使用FSHD来源的IPS细胞来识别FSHD的转录和表观遗传决定因素，以及D4Z4区域的调节区。Tawil博士(核心A)建立了FSHD生物资源核心，从FSHD和对照个体统一收集并具有良好特征的生物样本。核心A的目标将是从血液样本中收集DNA用于遗传分析，从皮肤和肌肉中收集成纤维细胞和成肌细胞用于生物学研究，并收集肌肉活组织用于组织化学和原位生物学分析。行政核心(核心B)将协调赠款的管理、参与者之间的沟通和报告责任。总之，这些研究结合了遗传、表观遗传学、转录和发育方法来确定导致FSHD的分子缺陷，并将为开发治疗方法提供新的基础。 与公共卫生相关：FSHD的病理生理学目前尚不清楚，也没有经过验证的靶点或机制可以为治疗开发提供基础。这项拟议的研究的意义在于，它将识别和验证FSHD的病理生理学的具体机制。这项工作与人类健康的相关性在于，它将为FSHD的合理治疗开发提供新的基础。 项目1 主要研究员：Silvere van der Maarel，博士 FSHD的遗传学和表观遗传学基础 描述(申请人提供)：我们已经证明，FSHD是由D4Z4染色质结构的收缩-cfepencfenf(FSHD1)或收缩非收缩(FSHD2)变化引起的，这种收缩发生在特定的遗传背景(4qA161)上。这导致了一种假设，即4qA161单倍型上D4Z4染色质结构的变化是FSHD病理所必需的。因此，长期目标是识别共同赋予4qA161致病性的特定DNA序列和表观遗传修饰。目的1鉴定疾病单倍型特异序列变异的末端重复单位和侧翼PLAM序列，并对其进行功能鉴定。最近的研究确定了FSHD基因座的这一部分是最小必需区域；目标2将鉴定并功能鉴定这个最小必需区域的染色质结构；目标3将确定D4Z4重复调控DUX4表达并在早期胚胎发育中具有生物学作用的假设；以及目标3将确定D4Z4在人类ES细胞中的遗传和表观遗传学特征，以确定D4Z4与FSHD临床特征的发育作用。 公共卫生相关性：这些研究的意义在于，确定FSHD所需的遗传和表观遗传学条件将为FSHD的病理生理学提供基本见解，并为介入治疗提供新的途径。

DESCRIPTION (provided by applicant): Facioscapulohumeral muscular dystrophy (FSHD) Is one of the most common adult muscular dystrophies. Deletion of a subset of subtelomeric macrosatellite repeats (D4Z4 repeats) causes most cases of FSHD and results in a dominantly inherited disease. Recent work from our groups have shown a decrease of repressive epigenetic markings on the deleted allele, increased binding of regulatory factors to the deleted allele, and a complex set of coding and non-coding RNAs generated from the D4Z4 repeats. These findings strongly support a broad hypothesis for the pathophysiology of FSHD: loss of epigenetic silencing in the D4Z4 repeat leads to increased expression of an RNA species that causes the disease, either through an RNA or protein mediated mechanism. Our research groups will address specific and complementary aims that together will both test the broad hypothesis and identify the specific mechanism(s) of FSHD, which is critical for future therapy development. The aims of Project 1 (Dr. van der Maarel) will identify the DNA sequences and epigenetic changes specific to 4qA161 that are necessary to confer FSHD pathology. The aims of Project 2 (Dr. Tapscott) will determine whether the D4Z4-generated coding and non-coding RNAs have a role in FSHD pathology and identify mechanisms of generally suppressing transcription from the D4Z4 repeat region. The aims of Project 3 (Dr. Filippova) will be to determine whether CTCF binding on the disease associated allele regulates regional chromatin structure, RNA transcription, or nuclear localization. The aims of Project 4 (Dr. Miller) will be to use FSHD-derived IPS cells to identify the transcriptional an epigenetic determinants of FSHD, and the regulatory regions in the D4Z4 region. Dr. Tawil (Core A) has established an FSHD Bioresources Core with uniformly collected and well-characterized biological samples from FSHD and control individuals. The aims of Core A will be to collect DNA from blood samples for genetic analysis, fibroblast and myoblasts from skin and muscle for biological studies, and muscle biopsies for histochemical and in situ biological analyses. The Administrative Core (Core B) will coordinate the administration of the grant, communications among the participants, and reporting responsibilities. Together, these studies combine genetic, epigenetic, transcriptional and developmental approaches to defining the molecular deficits that cause FSHD and will provide a new basis for developing therapies. PUBLIC HEALTH RELEVANCE: The pathophsiology of FSHD is currently unknown and there are no validated targets or mechanisms that can provide the basis for therapeutic development. The significance of this proposed study is that it will identify and validate specific mechanisms for the pathophysiology of FSHD. The human health relevance of this work is that it will provide a new basis for rational therapeutic development for FSHD. PROJECT 1 Principal Investigator: Silvere van der Maarel, PhD Title: The Genetic and Epigenetic Basis for FSHD Description (provided by applicant): We have demonstrated that FSHD is caused by a contraction-cfepencfenf (FSHD1) or contractionindependent (FSHD2) change in chromatin structure of D4Z4 only when this contraction occurs on a specific genetic background (4qA161). This leads to the hypothesis that a change in D4Z4 chromatin structure on the 4qA161 haplotype is essential for FSHD pathology. Therefore, the long-term goal is to identify the specific DNA sequences and the epigenetic modifications that together confer pathogenicity to 4qA161. Aim 1 will identify and functionally characterize the disease haplotype-specific sequence variants of the distal repeat unit and flanking pLAM sequence. Recent studies identified this part of the FSHD locus as the minimal essential region; Aim 2 will identify and functionally characterize the chromatin structure of this minimal essential region test the hypothesis that the D4Z4 repeats regulate DUX4 expression and have a biological role in early embryonic development; and Aim 3 will determine the genetic and epigenetic characteristics of D4Z4 in human ES cells to establish the developmental role of D4Z4 in relation to the clinical features of FSHD. Public Health Relevance: The significance of these studies is that identifying the genetic and epigenetic conditions required for FSHD will provide fundamental insight into the pathophysiology of FSHD as well as providing new avenues for interventional therapies.