ATP-Dependent Chromatin Remodeling in Human Malignancy

项目摘要 肿瘤中依赖于ATP的染色质重塑 染色质和表观遗传调节器已经成为人类癌症的重要贡献者。亚单位 在超过20%的人类中，mSWI/SNF或BAFATP依赖的染色质重塑复合体发生突变 癌症。此外，其他几个依赖于ATP的重建器对 特定癌症的发病机制。这些复合体通常作为基因优势的肿瘤抑制因子发挥作用， 然而，BAF复合体也在滑膜肉瘤和鳞癌中发挥致癌作用。 尽管它们在人类癌症中的普遍作用，它们的致癌机制仍然不清楚(S)和详细的 治疗发展所必需的分子理解一直难以捉摸。最好的井之一 有文献记载的BAF复合体的作用是它们与多梳抑制复合体(PRC)的对立 复合体。事实上，在果蝇中发现了BAF亚单位，作为Prc1突变的抑制因子。此外, 抑制PRC对某些BAF复合体功能突变丧失的癌症具有治疗作用。 然而，BAF染色质重塑复合体和BAF染色质重塑复合体之间对立的机制 多梳复合体仍不清楚。我们将对物理相互作用有一个详细的了解 并探索它们的致癌作用，目的是确定潜在的 治疗性干预。BAF-PRC对立的一个可能的机制是BAF的潜力 用来交换或驱逐经PrC_1和2修饰的核小体的复合体。测量核小体的速率 通过几种技术和几个基团的交换表明，核小体在每一次 细胞周期。这一观察结果似乎与普遍认为的组蛋白和/或核小体的概念不一致 修饰是表观遗传和表型稳定性的基础。另一种表述方式是“为什么32 哺乳动物基因组中编码的类SNF2-ATP依赖重构体不会很快消除所有组蛋白 通过核小体交换进行修饰？如果通过ATP进行核小体交换，这一冲突就会得到解决- 依赖重构体对特定的重构体和特定的核小体修饰具有选择性。因此， 我们正在开发两种新技术，它们将通过测量 特定修饰的核小体，并将其归因于特定的重构体，包括它们的翻译后 或致癌基因修饰。这些技术应该允许理解速度的矛盾 核小体交换似乎比组蛋白修饰的改变速度快得多。我们将使用 这些技术将表观遗传格局中的变化分配给特定的ATP依赖的染色质 并了解表观遗传组蛋白修饰在正常细胞和恶性细胞中的稳定性。在… 总结我们的研究，我们希望对这两个常态有一个更深入、更详细的了解 与mSWI/SNF或BAF染色质重构突变或功能障碍相关的致癌机制 很复杂。

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.