Probing the Activity of DUX4 in FSHD

 描述（由申请人提供）：FSHD影响美国超过25，000人。按发病率计算，它是第三常见的肌营养不良症，但按患病率计算，它可能是最常见的（Orphanet，2008）。与这种疾病相关的DNA损伤是在4q端粒附近的一系列3.3kb重复序列（D4Z4重复序列）内的收缩。这种收缩改变了4q35.2的染色质构型，导致每个D4Z4重复序列中编码的基因DUX4的错误表达。我们已经证明，DUX4在各种细胞模型系统中以高水平表达时具有细胞毒性，并且在卫星细胞和成肌细胞中以低水平表达时干扰肌原性基因表达。然而，从机制上讲，DUX4还没有得到很好的理解，我们对肌肉中哪些细胞类型表达DUX4以及这种表达的后果是什么没有一个清晰的了解，并且病理机制仍然没有得到解决。本申请中提出的研究通过以下方式解决这些问题：（1）探测DUX4的辅因子在转录中的活性，（2）研究FSHD患者骨骼肌的ste细胞区室，以及（3）对小鼠中的DUX4表达和D4Z4调节进行建模。这项研究将解决FSHD中的关键突出问题，将在分子，细胞和组织水平上推进对FSHD中DUX4的机制理解，并可能导致改进的动物模型和新的治疗方向。

 DESCRIPTION (provided by applicant): FSHD affects over 25,000 individuals in the United States. It is the third most common muscular dystrophy by incidence but may be the most common by prevalence (Orphanet, 2008). The DNA lesion associated with this disease is a contraction within a series of 3.3 kb repeats (D4Z4 repeats) near the telomere of 4q. The contraction modifies the chromatin configuration of 4q35.2 which results in misexpression of a gene encoded within each D4Z4 repeat, DUX4. We have shown that DUX4 is cytotoxic when expressed at high levels in various cellular model systems, and interferes with myogenic gene expression when expressed at low levels in satellite cells and myoblasts. However mechanistically, DUX4 is not well understood, we do not have a clear picture of which cell types in muscle express DUX4 and what the consequence of that expression is, and a pathological mechanism still eludes the field. The research proposed in this application addresses these issues by (1) probing the activity of cofactors of DUX4 in transcription, (2) investigating the ste cell compartment of skeletal muscle of FSHD patients, and (3) modeling DUX4 expression and D4Z4 regulation in mouse. This research will address key outstanding questions in FSHD, will advance a mechanistic understanding of DUX4 in FSHD at the molecular, cellular, and tissue levels, and may lead to both an improved animal model and new therapeutic directions.