Dysregulation of BAF chromatin remodeling in cancer

项目摘要/摘要 表观遗传失调是肿瘤发生的主要驱动力。中国最常见的表观遗传修饰物突变 人类癌症是BAF复合体(梵天相关因子)。BAF是一种进化保守的多维生物。 亚基依赖于ATP的染色质重塑复合体，在五分之一的癌症中发生突变。巴夫 动员核小体暴露潜在的DNA，以调节DNA结合部位的访问 转录机制，因此发挥转录的主要调节作用。该酶的活性 复合体由两个相互排斥的催化ATPase中的一个提供，BRG1或BRM，另外 调节复合体的靶向性和酶活性的亚基。尽管生物滤池的频率很高 癌症中的突变，人们对癌症相关的BAF突变如何影响核小体知之甚少 该复合体的重塑活动或有助于肿瘤的发生。确定这些突变的影响是 由于我们对建筑群的正常活动和监管缺乏了解而受到阻碍。这项研究将 通过使用纯化的重组BAF复合体来评估正常调节，来解决这一知识缺口 以及它在癌症中的错误调控。这项研究将利用已知的监管特征 RSC，一种BAF的酵母同源物，并测试它们在人类中是否保守。的功能 肌动蛋白/BAF53模块以及人血清白蛋白后结构域和BRG1和BRM的突起1结构域在 将评估该络合物的催化活性。BRG1和BRM的HSA后结构域和突起1结构域 在癌症中经常发生突变；这些突变对复合体重塑活性的影响 也要接受检查。最明显的致癌BAF改变是SNF5亚单位在 恶性横纹肌样瘤与SS18BAF亚基和SSX蛋白的融合 滑膜肉瘤(SS)，据报道从BAF复合体中驱逐SNF5。捷运和SS是其中之一 大多数基因简单的肿瘤，每个肿瘤通常只带有上面列出的单一基因改变。这种缺失 额外突变的研究表明SNF5缺失和SS18-SSX融合蛋白促进肿瘤形成 通过表观遗传机制。重要的是，SNF5影响BRG1的催化活性，这表明 该复合体异常的酶活性是MRT和SS肿瘤发生的表观遗传学驱动因素。肿瘤 这些突变的特异性表明，SS18-SSX融合和SNF5缺失并不等同。这个 含或不含SNF5和SS18-SSX的重组BAF复合体的核小体重塑活性 将对融合进行评估，以确定这些突变的组织特异性是否可能归因于 催化活性的差异。这项研究的结果将为了解一名专业人士的正常功能提供帮助 表观遗传修饰物及其在癌症中的错误调控，并可能在广泛的领域提供新的治疗策略 各种肿瘤。 好了！

Project Summary/Abstract Epigenetic dysregulation is a major driver of tumorigenesis. The most commonly mutated epigenetic modifier in human cancer is the BAF complex (Brahma Associated Factors). BAF is an evolutionarily-conserved multi- subunit ATP-dependent chromatin remodeling complex that is mutated in one fifth of all cancers. BAF mobilizes nucleosomes to expose the underlying DNA in order to regulate access of DNA binding sites to transcriptional machinery, and thus functions as a major regulator of transcription. The enzymatic activity of the complex is provided by one of two mutually exclusive catalytic ATPases, BRG1 or BRM, with additional subunits regulating the targeting and enzymatic activity of the complex. Despite the frequency of BAF mutations in cancer, little is known about how cancer-associated BAF mutations affect the nucleosome remodeling activity of the complex or contribute to tumorigenesis. Determining the effects of these mutations is hindered by our lack of knowledge regarding the normal activity and regulation of the complex. This study will address this gap in knowledge by using purified recombinant BAF complexes to assess the normal regulation of the complex as well as its misregulation in cancer. This study will leverage the known regulatory features of RSC, a yeast homolog of BAF, and test whether they are conserved in humans. The function of the Actin/BAF53 module as well as the roles of the Post-HSA and Protrusion 1 domains of BRG1 and BRM in the catalytic activity of the complex will be assessed. The Post-HSA and Protrusion 1 domains of BRG1 and BRM are frequently mutated in cancer; the effects of these mutations on the remodeling activity of the complex will be examined as well. The most clearly oncogenic BAF alterations are the uniform loss of the SNF5 subunit in malignant rhabdoid tumor (MRT) and the fusion between the SS18 BAF subunit and the SSX protein in synovial sarcoma (SS), which is reported to evict SNF5 from the BAF complex. MRT and SS are among the most genetically simple tumors, each typically bearing only the single genetic alteration listed above. This lack of additional mutations suggests that SNF5 loss and the SS18-SSX fusion protein promote tumor formation through an epigenetic mechanism. Importantly, SNF5 affects the catalytic activity of BRG1, suggesting that aberrant enzymatic activity of the complex is the epigenetic driver of tumorigenesis in MRT and SS. The tumor specificity of these mutations indicates that SS18-SSX fusions and SNF5 loss are not equivalent. The nucleosome remodeling activities of recombinant BAF complexes containing or lacking SNF5 and SS18-SSX fusions will be assessed to determine whether the tissue specificity of these mutations may be attributed to a difference in catalytic activity. The results of this study will provide insight into the normal function of a major epigenetic modifier as well as its misregulation in cancer, and may inform new therapeutic strategies in a wide variety of tumors. !