ATP-Dependent Chromatin Remodeling in Human Malignancy

项目摘要 肿瘤中ATP依赖的染色质重塑 染色质和表观遗传调节剂已成为人类癌症的重要贡献者。亚基 的mSWI/SNF或BAF ATP依赖性染色质重塑复合物在超过20%的人中突变， 癌的此外，其他几种ATP依赖性重塑因子也对细胞凋亡有重要贡献。 特定癌症的发病机制。这些复合物通常作为遗传上显性的肿瘤抑制剂发挥作用， 然而，BAF复合物也在滑膜肉瘤和鳞状细胞癌中起致癌作用。 尽管它们在人类癌症中的普遍作用，但它们的致癌机制仍不清楚，并且详细的研究还没有被证实。 对于治疗发展所必需的分子理解是难以捉摸的。一个最好的 BAF复合物的记录作用是它们对Polycomb抑制复合物（PRC）的反对 配合物事实上，BAF亚基在果蝇中被发现是PRC 1突变的抑制因子。此外，本发明还提供了一种方法， PRC的抑制在BAF复合物中具有功能缺失突变的某些癌症中是治疗性的。 然而，BAF染色质重塑复合物和 Polycomb复合体仍不清楚。我们将获得物理相互作用的详细了解 并探索它们的致癌作用，目的是确定潜在的位点， 治疗干预BAF-中国反对的一个可能机制是BAF的潜力 复合物交换或驱逐由PRC 1和2修饰的核小体。核小体测量率 通过几种技术和几个小组的交换表明，核小体交换几次， 细胞周期这一观察结果似乎与广泛持有的概念不一致，即组蛋白和/或核小体 修饰是表观遗传和表型稳定性的基础。另一种说法是“为什么32岁的人 哺乳动物基因组中编码的SNF 2样ATP依赖性重塑蛋白不能快速清除所有组蛋白 通过核小体交换进行修饰？如果通过ATP进行核小体交换， 依赖性重塑剂对特定重塑剂和特定核小体修饰具有选择性。因此，在本发明中， 我们正在开发两种新技术，通过测量 特异性修饰的核小体，并将其归因于特定的重塑，包括其翻译后 或致癌修饰。这些技术应该允许理解的悖论， 核小体交换的速率似乎远远快于组蛋白修饰的变化速率。我们将使用 这些技术将表观遗传景观中的变化分配给特定的ATP依赖性染色质 调节因子，并了解正常和恶性细胞中表观遗传组蛋白修饰的稳定性。在 在我们研究的结论中，我们希望能对正常的 以及与mSWI/SNF或BAF染色质重塑的突变或功能障碍相关的致癌机制 复杂.

Project Summary ATP-Dependent Chromatin Remodeling in Cancer Chromatin and epigenetic regulators have emerged as important contributors to human cancer. The subunits of the mSWI/SNF or BAF ATP-dependent chromatin remodeling complex are mutated in over 20% of human cancers. In addition, several other ATP-dependent remodelers make important contributions to the pathogenesis of specific cancers. These complexes often function as genetically dominant tumor suppressors, however the BAF complex also plays oncogenic roles in synovial sarcoma and squamous cell carcinoma. Despite their prevalent roles in human cancer their oncogenic mechanism(s) remain unclear and a detailed molecular understanding, necessary for therapeutic development, has been elusive. One of the most well documented roles of BAF complexes is their opposition to Polycomb Repressive Complexes (PRC) complexes. Indeed, BAF subunits were discovered in flies as suppressors of PRC1 mutations. In addition, inhibition of PRC is therapeutic in some cancers having loss of function mutations in the BAF complex. However, the mechanisms underlying the opposition between BAF chromatin remodeling complexes and Polycomb complexes is still unclear. We will obtain a detailed understanding of the physical interaction between these complexes and explore their oncogenic roles with the goal of identifying potential sites of therapeutic intervention. One possible mechanism underlying the BAF-PRC opposition is the potential of BAF complexes to exchange or evict nucleosomes modified by PRC1 and 2. Measured rates of nucleosome exchange by several techniques and by several groups show that nucleosomes exchange several times per cell cycle. This observation seems inconsistent with the widely held concept that histone and/or nucleosome modifications are the basis of epigenetic and phenotypic stability. Another way of stating this is “why do the 32 SNF2-like ATP-dependent remodelers encoded in the mammalian genome not quickly erase all histone modifications by nucleosome exchange? This conflict would be resolved if nucleosome exchange by ATP- dependent remodelers was selective to a specific remodeler and a specific nucleosomal modification. Thus, we are developing two new techniques that will fill this gap in our knowledge by measuring exchange of specifically modified nucleosomes and attributing them to specific remodelers, including their post translational or oncogenic modifications. These techniques should allow the understanding of the paradox that rates of nucleosome exchange appear to be far faster than the rate of change of histone modifications. We will use these techniques to assign changes in the epigenetic landscape to specific ATP-dependent chromatin regulators and to understand the stability of epigenetic histone modifications in normal and malignant cells. At the conclusion of our studies, we hope to have a deeper and more detailed understanding of both the normal and oncogenic mechanisms related to mutation or dysfunction of the mSWI/SNF or BAF chromatin remodeling complex.