Molecular Pathways Regulated By DUX4, an FSHD-Associated Gene

描述（由申请人提供）：面肩肱型肌营养不良症（FSHD）是一种遗传显性进行性肌营养不良症，影响约1/20，000的个体。虽然这种疾病是由4号染色体上的重复序列缺失引起的，这被认为是不适当地激活附近的基因，但关键致病基因的身份尚不清楚，并且该区域的基因与肌肉病理学相关的机制也不清楚。目前没有有效的治疗FSHD。我们在细胞培养系统中筛选了来自4号染色体FSHD区域的候选基因，并鉴定了对成肌细胞具有极端毒性的基因（双同源结构域转录因子DUX 4，其嵌入在4号染色体上的D4 Z4重复序列内）。使用诱导型基因表达系统，我们表明DUX 4的表达导致先前在微阵列和蛋白质组学研究中鉴定为FHSD中特异性失调的一组基因表达的变化，包括应激反应途径的元件和转录因子MyoD。我们进一步表明，这些反应涉及竞争与Pax 7，一个转录因子在肌源性层次的顶点与高度相关的同源异型域。我们建议研究DUX 4下游的分子途径，并鉴定与DUX 4和Pax 7相反调节的肌肉再生相关的基因（Aim 1），以基于患者来源的D4 Z4/DUX 4序列的表达产生FSHD的新细胞和小鼠模型（Aim 2），并检验肌肉的干细胞或祖细胞区室在FSHD中受DUX 4特异性影响的假设（目的3）。 公共卫生相关性：面肩肱型肌营养不良症（FSHD）是一种与4号染色体上重复序列缺失相关的遗传显性进行性肌营养不良症。这种缺失被认为会解除附近基因的调节，我们已经证明与这种缺失相关的基因之一DUX 4会导致成肌细胞对氧化应激变得敏感，并通过与肌肉干细胞主调节因子Pax 7竞争来干扰肌生成途径。我们建议研究DUX 4下游的分子通路，并鉴定与DUX 4和Pax 7相反调节的肌肉再生相关的基因（Aim 1），基于患者来源的D4 Z4/DUX 4序列的表达产生FSHD的小鼠模型（Aim 2），并测试肌肉的干细胞或祖细胞区室在FSHD中受到DUX 4特异性影响的假设（Aim 3）。

DESCRIPTION (provided by applicant): Facioscapulohumeral muscular dystrophy (FSHD) is a genetically dominant progressive muscular dystrophy affecting approximately 1/20,000 individuals. Although the disease is caused by a deletion of repeated sequence on chromosome 4, which is thought to inappropriately activate nearby genes, the identity of the key causative gene is unknown and mechanisms relating genes in the area to muscle pathology are unknown. There is currently no effective treatment for FSHD. We have screened candidate genes from the FSHD region of chromosome 4 in a cell culture system, and identified a gene (the double-homeodomain transcription factor, DUX4, which is embedded within the D4Z4 repeats on chromosome 4) with extreme toxicity to myoblasts. Using an inducible gene expression system, we show that expression of DUX4 causes changes in expression of a set of genes previously identified in microarray and proteomic studies as specifically misregulated in FHSD, including elements of stress response pathways, and the transcription factor MyoD. We further show that these responses involve competition with Pax7, a transcription factor at the apex of the myogenic hierarchy with a highly related homeodomain. We propose to investigate the molecular pathways downstream of DUX4 and identify genes relevant to muscle regeneration that are oppositely regulated by DUX4 and Pax7 (Aim 1), to generate novel cell and mouse models for FSHD based on expression of patient-derived D4Z4/DUX4 sequences (Aim 2), and to test the hypothesis that the stem or progenitor cell compartments of muscle are specifically affected by DUX4 in FSHD (Aim 3). PUBLIC HEALTH RELEVANCE: Facioscapulohumeral muscular dystrophy (FSHD) a genetically dominant progressive muscular dystrophy associated with a deletion of repetitive sequences on chromosome 4. This deletion is thought to deregulate nearby genes and we have shown that one of the genes associated with this deletion, DUX4, causes myoblasts to become sensitive to oxidative stress, and interferes with myogenic pathways by competing with the muscle stem cell master regulator, Pax7. We propose to investigate the molecular pathways downstream of DUX4 and identify genes relevant to muscle regeneration that are oppositely regulated by DUX4 and Pax7 (Aim 1), to generate a mouse model for FSHD based on expression of patient-derived D4Z4/DUX4 sequences (Aim 2), and to test the hypothesis that the stem or progenitor cell compartments of muscle are specifically affected by DUX4 in FSHD (Aim 3).