Combinatorial regulation of the enhancer codes in senescence

摘要 基于定义对细胞衰老的新见解的重要性，我们发起了研究 是否可能存在一种特定的增强子激活“密码”，它是细胞衰老的基础 确定负责的DNA结合转录因子。虽然有快速崛起的，现在 无懈可击的证据，关于每种细胞类型中40-70,000个增强子在发育、动态平衡中的作用 而且，通常是病理事件，它们在细胞衰老中的作用仍然不确定。此外，虽然蜂窝 衰老是衰老的一个基本过程，也是已知的病理驱动因素，其致病作用 新激活的增强子队列在衰老进程中的作用仍然知之甚少。因此， 这项建议的目标，在大量初步数据的支持下，是为了测试一个新的假设，即 Novo的两个特定的增强剂队列的出现启动了一种进步的，功能上的- 重要的是，基因转录程序的改变。基于我们对修饰的增强子和 染色体版图在复制衰老过程中，我们已经开始建立起对染色体的保护作用 MTOR抑制剂雷帕霉素显著延缓细胞衰老的各个方面，包括外观 新的、功能性的增强剂。我们的重点是阐明获得的增强剂计划的功能重要性 细胞衰老的基础上，并确定关键的DNA结合转录因子 转录程序是复制衰老的决定因素，基于互补的专业知识 苏氏实验室和罗森菲尔德实验室。具体地说：i)我们将使用无偏见的屏幕记录至少 两个不同的激活增强子网络独立地调节增殖抑制和SASP方面 分别是复制衰老的。Ii)我们将确定与 以前未知的转录因子，NFI-A，NFI-C，来调控获得的增强子 抑制扩散，以及与Smad2/3和NFkB一起规范SASP计划的那些。同时，我们 可能牵涉到潜在的信号通路。三)我们将确定以前未被识别的组蛋白 的修饰特征及其在复制衰老中的功能重要性。四)我们将确定 激活素和转化生长因子-2分别作为增殖和SASP增强子程序的抑制物。我们的建议 承诺为启动和维持衰老细胞的分子事件提供变革性的见解 表型，并有助于阐明针对有害的SASP计划的潜在新治疗方式。

Abstract Based on the importance of defining new insights into cellular senescence, we initiated studies to investigate whether there might be a specific enhancer activation “code” that underlies cellular senescence for identifying the responsible DNA binding transcription factors. While there is rapidly-emerging, and now unassailable evidence, on the role of the 40-70,000 enhancers in each cell type in development, homeostasis and, often, pathological events, their role in cellular senescence remains undefined. Furthermore, while cellular senescence represents a fundamental process of aging and a known driver of pathologies, the causative role of newly activated enhancer cohorts underlying progression of senescence remain poorly understood. Therefore, the goal of this proposal, supported by extensive preliminary data, is to test a novel hypothesis that the de novo appearance of two specific cohorts of enhancers sets into motion a progressive, functionally- important, alteration in gene transcription programs. Based on our study of the altered enhancer and chromosomal landscape during replicative senescence, we have begun to establish that the geroprotective mTOR inhibitor, Rapamycin, markedly delays all aspects of cellular senescence, including the appearance of new, functional, enhancers. Our focus is to elucidate the functional importance of a gained enhancer program underlying cellular senescence, and identify the critical DNA binding transcription factors underlying the transcriptional programs that are determinants of replicative senescence, based on the complementary expertise of the Suh and Rosenfeld laboratories. Specifically: i) We will use unbiased screens to document that at least two distinct activated enhancer networks independently regulate the proliferation arrest and SASP aspects of replicative senescence, respectively. ii) We will identify combinatorial factors synergizing with the previously-unrecognized transcription factors, NFI-A, NFI-C, to regulate the gained enhancers underling proliferation arrest, and those that, with SMAD2/3 and NFkB, to regulate the SASP program. In parallel, we can implicate the underlying signaling pathways. iii) We will identify previously unrecognized histone modification signatures of, and their functional importance in replicative senescence . iv) We will Identify Activin and Tgf2 as inhibitors of the proliferation and SASP enhancer programs, respectively. Our proposal promises to provide transformative insights into molecular events that initiate and perpetuate the senescent cell phenotypes, and help elucidate potential novel therapeutic modalities against the deleterious SASP program.