DUX4 and Facioscapulohumeral Muscular Dystrophy

描述（由申请人提供）： 面肩肱型肌营养不良症（FSHD）是骨骼肌的第三大常见遗传性疾病，大约每20，000人中就有1人患病。与大多数其他肌营养不良症相比，FSHD的分子机制仍然未知。超过95%的FSHD病例与染色体4 q35端粒区附近串联重复的3.3个DNA单位（D4 Z4重复）阵列中的部分缺失相关;然而，尚未确定导致该疾病的特定遗传异常。我们已经在FSHD基因座的每个重复元件中表征了一个称为DUX 4的基因，并获得了初步证据，证明编码的蛋白质在受影响受试者的肌肉中表达。DUX 4蛋白似乎定位于核膜，与Emery-Dreifuss肌营养不良症中突变的Emerin和核纤层蛋白A和C相同的位置。本探索性/开发性[R21]提案旨在进一步评价FSHD中DUX 4的表达，并获得有关其功能的初步数据。目的1将评估来自FSHD患者的细胞中DUX 4的表达。将使用来自FSHD患者和未受影响的对照的成肌细胞通过免疫印迹、免疫荧光显微镜和质谱法评估蛋白质的表达。在目标2中，将检查DUX 4蛋白靶向核膜及其在整个细胞周期中的分布。将对DUX 4结合蛋白（包括核膜蛋白核纤层蛋白和emerin）进行测序。还将研究DUX 4的潜在结合。由于FSHD中发生程序性细胞死亡，因此还将评估DUX 4诱导细胞凋亡的能力。将DUX 4获得的结果与DUX 1（一种在正常肌肉细胞中表达的非病理性蛋白）进行比较。该探索性/开发性[R21]项目的结果将确定DUX 4是否在FSHD中发生异常表达，并为未来研究其在疾病发病机制中的作用提供必要的试点数据和方向。这项工作可能会导致新的诊断方法的发展，以及确定治疗FSHD的潜在蛋白质靶点。

DESCRIPTION (provided by applicant): Facioscapulohumeral muscular dystrophy (FSHD) is the third most common genetic disease of skeletal muscle, affecting approximately 1 in 20,000 persons. In contrast to most other muscular dystrophies, the molecular mechanisms responsible for FSHD remain unknown. More than 95% of cases of FSHD are associated with a partial deletion in an array of tandemly repeated 3.3 kilobase DNA units (D4Z4 repeat) near the telomeric region of chromosome 4q35; however, a specific genetic abnormality that causes the disease has not been identified. We have characterized a gene called DUX4 within each of the repeat elements at the FSHD locus and have obtained preliminary evidence that the encoded protein is expressed in muscle from affected subjects. The DUX4 protein appears to be localized to the nuclear envelope, the same location as emerin and lamins A and C, which are mutated in Emery-Dreifuss muscular dystrophy. This Exploratory/Developmental [R21] proposal is designed to further evaluate the expression of DUX4 in FSHD and to obtain pilot data on its function. Aim 1 will assess the expression of DUX4 in cells from patients with FSHD. Expression of the protein will be assessed by immuoblotting, immunofluorescence microscopy and mass spectroscopy using myoblasts from patients with FSHD and non-affected controls. In Aim 2, the targeting of the DUX4 protein to the nuclear envelope and its distribution throughout the cell cycle will be examined. Searches for DUX4 binding proteins, including the nuclear envelope proteins lamins and emerin, will be performed. Potential binding of DUX4 will also be investigated. As programmed cell death occurs in FSHD, the ability of DUX4 to induce apotosis will also be evaluated. The results obtained for DUX4 will be compared to DUX1, a non-pathological paralogue expressed in normal muscle cells. The results of this Exploratory/Developmental [R21] project will establish if abnormal expression of DUX4 occurs in FSHD and provide the prerequisite pilot data and direction for future studies on its role in disease pathogenesis. This work could lead to the development of new diagnostic methods as well as the identification of potential protein targets for the treatment of FSHD.