Combinatorial regulation of the enhancer codes in senescence

摘要 基于定义细胞衰老新见解的重要性，我们发起了研究来调查 是否可能存在一个特定的增强子激活“代码”，是细胞衰老的基础 鉴定负责的 DNA 结合转录因子。虽然正在迅速兴起，但现在 无可辩驳的证据，证明每种细胞类型中 40-70,000 个增强子在发育、体内平衡中的作用 通常，病理事件，它们在细胞衰老中的作用仍然不明确。此外，虽然蜂窝 衰老代表衰老的基本过程和已知的病理驱动因素，即衰老的致病作用 新激活的增强子群体在衰老过程中的作用仍知之甚少。因此， 在广泛的初步数据的支持下，该提案的目标是测试一个新的假设，即 de 两个特定增强子群的新出现启动了渐进的、功能性的- 重要的是，基因转录程序的改变。基于我们对改变的增强子的研究和 复制衰老期间的染色体景观，我们已经开始确定老年保护性 mTOR 抑制剂雷帕霉素可显着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子程序的功能重要性 细胞衰老的基础，并确定细胞衰老背后的关键 DNA 结合转录因子 基于互补的专业知识的转录程序是复制衰老的决定因素 Suh 和 Rosenfeld 实验室。具体来说： i) 我们将使用公正的屏幕来记录至少 两个不同的激活增强子网络独立调节增殖抑制和 SASP 方面 分别是复制衰老。 ii) 我们将确定与 以前未被识别的转录因子，NFI-A，NFI-C，来调节所获得的增强子 增殖抑制，以及与 SMAD2/3 和 NFkB 一起调节 SASP 程序的那些。与此同时，我们 可能涉及潜在的信号通路。 iii) 我们将鉴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。 iv) 我们将确定 激活素和 Tgf2 分别作为增殖和 SASP 增强程序的抑制剂。我们的建议 有望为启动和延续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 SASP 程序的潜在新治疗方式。

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.