SMCHD1 Pathways as Candidate Targets for FSHD

项目总结 面肩肱骨营养不良症(FSHD)影响约1/10,000人，由 DUX4逆转录基因在骨骼中的表观遗传抑制及随后的错误表达 肌肉。AS增强Smchd1介导的D4Z4基因座的表观遗传抑制使DUX4沉默 在FSHD1和FSHD2肌肉细胞中，这一应用将采取直接的分子生物学方法来 确定Smchd1复合体的多样性以及每个组件在建立和 维持D4Z4的抑制性染色质结构并阻止DUX4在骨骼中的表达 肌肉。广泛和长期的目标是确定SMCHD1的功能组件 D4Z4基因上的复合体作为未来针对增加表观遗传学的治疗的基础 压抑。主要假设是Smchd1根据POST的不同而形成不同的相互作用。 翻译修饰、染色质结合和细胞的发育状态，以及 了解不同络合物的功能作用将为以下方面提供简单的还原模型 测试候选干预措施。目标1将确定与Smchd1络合的蛋白质 D4Z4基因座及其功能意义、染色质关联和相扑依赖。目标2将 测定基因组中常染色体单拷贝基因座上Smchd1复合体的组成 与D4Z4的重复区和亚区进行比较。目标3将确定以下各项的相对角色 Smchd1复合组分在表观遗传修饰的建立和维持中的作用 在干细胞重新编程和分化过程中。这些目标加在一起，将使 Smchd1复合体的组成及其在D4Z4表观遗传抑制中的功能作用 提供新的机会来设计干预措施以抑制DUX4的表达作为治疗 FSHD。

PROJECT SUMMARY Facioscapulohumeral dystrophy (FSHD) affects ~1/10,000 people and is caused by decreased epigenetic repression of the DUX4 retrogene with subsequent mis-expression of DUX4 in skeletal muscle. As increasing the SMCHD1-mediated epigenetic repression at the D4Z4 locus silences DUX4 in FSHD1 and FSHD2 muscle cells, this application will take a direct molecular biology approach to identify the diversity of SMCHD1 complexes and the role of each component in establishing and maintaining repressive chromatin structure at the D4Z4 and preventing DUX4 expression in skeletal muscle. The broad and long-term goal is to determine the functional components of the SMCHD1 complexes at the D4Z4 locus as a basis for future therapies directed at increasing epigenetic repression. The major hypothesis is that SMCHD1 forms different interactions depending on post- translational modification, chromatin association, and developmental state of the cell, and that understanding the functional roles of the different complexes will provide simple reductionist models for testing candidate interventions. Aim 1 will determine the proteins complexed with SMCHD1 at the D4Z4 locus and their functional significance, chromatin association, and SUMO dependence. Aim 2 will determine the composition of SMCHD1 complexes at autosomal single copy loci in the genome compared to repetitive regions and to subdomains of the D4Z4. Aim 3 will identify the relative roles of SMCHD1 complex components in the establishment and maintenance of epigenetic modifications during stem cell reprogramming and differentiation. Together, these aims will add clarity to the components of SMCHD1 complexes and their functional roles in D4Z4 epigenetic repression, and provide new opportunities to design interventions to suppress DUX4 expression as a treatment for FSHD.