Regulation of RNA polymerase II pausing and directionality by ATP-dependent chromatin remodelers

摘要 目的：研究SWI/SNFATP依赖的染色质重塑复合体在大鼠心肌梗死中的作用。 RNA聚合酶II启动子近端的暂停和转录方向性的确定 转录调控步骤在发育和疾病中起重要作用。在过去的几年里，研究人员 已经发现，在哺乳动物中，大多数基因都有RNA聚合酶(RNAP)II从25-60个核苷酸暂停 转录起始点，一旦提供了适当信号，转录就可以恢复。规管 启动子近端停顿已被发现是基因调控步骤中的关键，甚至更重要。 表达多于形成预引发复合体。目前对连接的了解很少 在RNAPII暂停和依赖于ATP的染色质重构体(如SWI/SNF)之间，即使 已知启动子区域的染色质结构是RNAPII暂停的一个重要决定因素。 聚合酶停顿也与分化转录的发生有关，这是最近在 抄写。大多数非编码RNA来自发散或双向转录，其中转录 以反义方向发生在编码区的上游。类似于RNAP II暂停 转录是一个发育受控的过程。初步数据显示，SWI/SNF参与了 对这两个过程的调控和这项提案的目标是描绘出 SWI/SNF对这些相对较新的转录方面的调控。 SWI/SNF是癌症中最常见的表观遗传突变因子之一，发生在所有癌症中的约20% 癌症和SWI/SNF突变是两种神经疾病的分子驱动因素，Nicolaides-Baraister 和棺材-西里斯综合征。SWI/SNF复合体对于多能性和分化也是至关重要的。作为一名 染色质的主要守门人，它被认为主要参与使DNA可供 转录起始复合体的形成。这项建议的前提是，SWI/SNF在 对RNAPII暂停和方向性的调节对其在发育和人类疾病中的作用至关重要 促进转录起始复合体的形成。此外，我们还将研究这一重要问题 SWI/SNF如何调控eRNAs的合成，eRNAs是在增强子区域转录的短RNA，给定 显著的相似性，增强子和启动子都被转录，通常是双向的，并使用 相同的转录和延伸因子。ERNA促进启动子和启动子之间的远程相互作用 增强子，并在合成其相应的编码RNA之前合成。这份提案审查了 SWI/SNF如何影响RNAPII增强子区的暂停和方向性，这可能是很重要的 用于增强活性。

Summary The objective is to study the function of the SWI/SNF ATP-dependent chromatin remodeling complex in promoter proximal pausing of RNA polymerase II and determination of transcriptional directionality, key regulatory steps in transcription important in development and diseases. In the last several years, researchers have found that in mammals most genes have RNA polymerase (RNAP) II paused 25-60 nts from the transcription start site and that transcription can resume once the appropriate signal is provided. Regulation of promoter proximal pausing has been uncovered to be as crucial, or perhaps more, of a regulatory step in gene expression than formation of the preinitiation complex. There is currently very little known about connections between RNAPII pausing and ATP-dependent chromatin remodelers such as SWI/SNF, even though the chromatin structure at the promoter region is known to be an important determining factor in RNAPII pausing. Polymerase pausing is also connected to the occurrence of divergent transcription, another recent finding in transcription. Most non-coding RNA comes from divergent or bidirectional transcription in which transcription occurs upstream of the coding region in the anti-sense direction. Similar to RNAP II pausing the directionality of transcription is a developmentally controlled process. Preliminary data shows SWI/SNF’s involvement in the regulation of both of these processes and the goals of this proposal are to delineate the molecular means of SWI/SNF regulation of these relatively new aspects of transcription. SWI/SNF is one of the most frequently mutated epigenetic factors in cancer, occurring in ~20% of all cancers, and mutations in SWI/SNF are the molecular drivers for two neurological disorders, Nicolaides-Baraister and Coffin-Siris syndromes. The SWI/SNF complex is also crucial for both pluripotency and differentiation. As a master gatekeeper of chromatin, it has been assumed to be primarily involved in making DNA accessible for formation of the transcription initiation complex. The premise of this proposal is that the functions of SWI/SNF in regulation of RNAPII pausing and directionality is as vital for its role in development and human disease as promoting formation of the transcription initiation complex. In addition, we will examine the important question of how SWI/SNF regulates the synthesis of eRNAs, short RNAs transcribed at enhancer regions, given the remarkable similarity with which both enhancers and promoters are transcribed, often bi-directionally, and using the same transcription and elongation factors. eRNAs facilitate long-range interactions between promoters and enhancers, and are synthesized prior to the synthesis of its corresponding coding RNAs. This proposal examines how SWI/SNF influences RNAPII pausing and directionality at enhancer regions, which is likely to be important for enhancer activity.