Characterization of DUX4-induced histone H3 variants

项目总结 组蛋白在整个动物界的转录调控中起着重要作用，不同的变种 在各种特定的组织和过程中发挥重要作用。最近发现的两个组蛋白H3.X和H3.X H3.Y是灵长类特有的基因，在人类的睾丸和大脑以及一些肿瘤和癌症中都有表达 细胞系。我的初步研究已经确定这些基因是DUX4的靶基因，DUX4是一个双同源盒 通常在睾丸生殖细胞中表达的转录因子。当在肌肉中错误表达时， DUX4会引起面部肩周型肌营养不良症(FSHD)，这是一种进行性疾病，目前还没有治疗方法 治疗，并可能导致一些癌症。DUX4的表达显著改变转录并导致DUX4的缺失 抑制整个基因组中的许多基因和序列，这些基因和序列通常被抑制在 异染色质。H3.X/Y已被证实为组蛋白，并被证明有助于更开放的染色质 它们在体外的构象优于H3.3，但在FSHD中的体内作用尚不清楚。目标1号将识别基因 从关到开，染色质不可达，进入开放的染色质状态，表达DUX4。会的 然后确定H3.X/Y是否优先整合在这些基因座上，并检查它们的影响 在表达上。这将决定H3.X/Y在FSHD中的全基因组整合及其对 DUX4靶基因的表达。目标2将确定H3.X/Y在DUX4表观遗传记忆中的作用 转录组。它将扩展H3.X/Y增加DUX4耐力的初步研究 以及检测H3.X/Y对染色质结构和特性的影响 异染色质。此外，这一目标将检查DUX4累积毒性、H3.X/Y、 和细胞周期，因为成熟的肌肉是有丝分裂后的。通过组蛋白变体介导的表观遗传记忆可能 解释为什么FSHD的病理通常局限于肌肉，并提出了一种靶向治疗的机制。 此外，数据集将独立地用于确定由DUX4引起的染色质变化 可应用于FSHD的研究。该提案将检验合并了H3.X/Y的假设 进入并促进由DUX4转录激活的通常被抑制的基因的表达 通过异染色质，并提供表观遗传记忆的DUX4转录程序。

PROJECT SUMMARY Histones play a major role in the regulation of transcription across the animal kingdom, and different variants play important roles in a variety of specific tissues and processes. Two recently-described histones, H3.X and H3.Y, are primate-specific and are expressed in human testis and brain, as well as some tumors and cancer cell lines. My preliminary studies have identified these genes as targets of DUX4, a double-homeobox transcription factor that is normally expressed in the germ cells of the testis. When mis-expressed in muscle, DUX4 causes facioscapulohumeral muscular dystrophy (FSHD), a progressive disease for which there are no treatments, and may drive some cancers. Expression of DUX4 drastically alters transcription and leads to de- repression of many genes and sequences throughout the genome that are normally repressed in heterochromatin. H3.X/Y have been validated as histones and shown to facilitate a more open chromatin conformation than H3.3 in vitro, but their in vivo effects in FSHD are as yet unknown. Aim 1 will identify genes that go from off to on and inaccessible chromatin to an open chromatin state with expression of DUX4. It will then determine whether H3.X/Y are preferentially incorporated at these loci as well as examining their effects on expression. This will determine the genome-wide incorporation of H3.X/Y in FSHD and effects on expression of DUX4 targets. Aim 2 will determine the role of H3.X/Y in epigenetic memory of the DUX4 transcriptome. It will extend preliminary studies suggesting that H3.X/Y increase the perdurance of DUX4 target expression as well as examine the effects over time of H3.X/Y on chromatin structure and features of heterochromatin. Additionally, this aim will examine the relationship between cumulative DUX4 toxicity, H3.X/Y, and cell cycle, as mature muscle is postmitotic. Epigenetic memory mediated through histone variants could explain why FSHD pathology is typically restricted to muscle and suggest a mechanism to target for therapy. Additionally, the datasets will be independently useful to determine chromatin changes induced by DUX4 that can be applied to the study of FSHD. This proposal will test the hypotheses that H3.X/Y are incorporated into and facilitate expression of genes transcriptionally activated by DUX4 that are normally repressed by heterochromatin, and provide an epigenetic memory of the DUX4 transcriptional program.