RNA polymerase II Elongation Complex: Structure and Function

描述（由申请人提供）： RNA聚合酶II的转录延长和终止是决定初级转录物命运从而调节基因表达的复杂过程。一幅画面正在出现，其中有一个以上的转录终止模式。这在酿酒酵母中得到了最好的检验。在这两种情况下，根据RNA序列信号和初级转录物的长度，涉及不同的蛋白质组。在一个突出的例子中，IMD2基因上游的非编码RNA的条件性转录终止调节IMP脱氢酶（IMD2的蛋白质产物）的表达。RNA聚合酶II对起始位点的选择和TFIIB参与了这一过程。本项目的目标是阐明这种监管策略的细节，并剖析RNA聚合酶II选择终止机制的要求。IMD2作为一个有用的模型来理解和解开终止的不同机制。在从酵母到人类的生物体中可以看到核苷酸对该基因的调节，IMP脱氢酶是生物医学上重要的酶。人类IMPDH的突变与视网膜色素变性有关。抑制它的小分子是广泛用作器官移植受者的有价值的免疫抑制剂的有效药物。这项建议将调查的基本机制，转录起始和终止的RNA聚合酶II，允许鸟嘌呤调节酵母IMD 2。这包括通过pol II滑动搜索起始位点，染色质的起始和终止区域的相互作用，终止与非编码RNA的外泌体降解的偶联，以及酵母中推定的解旋酶Sen1和人类中Setx的活性。SEN1的人类直系同源物SETX具有生物医学重要性，因为其功能障碍导致神经退行性疾病共济失调和眼用不能（AOA）2型和肌萎缩侧索硬化（ALS）4型。揭示这种蛋白质的生物化学和生物学功能对于理解这些疾病的病理生理基础将是重要的。 公共卫生相关性： 解码（转录）遗传信息的细胞机制是复杂的，它的功能不正常会导致许多人类疾病。该项目使用一种模式生物，在这种模式生物中，基因和这种所谓的转录机制可以通过实验进行操纵，并将揭示遗传信息表达的细节。这里研究的转录机制的部分涉及神经，视觉和免疫疾病。

DESCRIPTION (provided by applicant): Transcription elongation and termination by RNA polymerase II are complex processes that determine the fate of the primary transcript thereby regulate gene expression. A picture is emerging in which there is more than one mode of transcription termination. This has been best examined in the yeast Saccharomyces cerevisiae. In the two conditions, different sets of proteins are involved depending upon RNA sequence signals and the primary transcript's length. In one striking example, conditional transcription termination of a non-coding RNA upstream of the IMD2 gene regulates the expression of IMP dehydrogenase, IMD2's protein product. RNA polymerase II's selection of an initiation site and TFIIB, are implicated in this process. The goal of this project is to elucidate the details of this regulatory strategy and to dissect the requirements by which RNA polymerase II chooses a termination mechanism. IMD2 serves as a useful model to understand and unravel the different mechanisms of termination. Regulation of this gene by nucleotides is seen in organisms from yeast to humans and IMP dehydrogenase is a biomedically important enzyme. Mutations in human IMPDH are linked to retinitis pigmentosa. Small molecules that inhibit it are effective drugs in wide use as valuable immunosuppressants in organ transplant recipients. This proposal will investigate the basic mechanisms of transcription initiation and termination by RNA polymerase II that allow guanine regulation of yeast IMD2. This includes the sliding search for initiation sites by pol II, the interaction of initiator and terminator regions of chromatin, the coupling of termination to exosome degradation of non-coding RNAs, and the activity of the putative helicase Sen1 in yeast and Setx in humans. The human ortholog of SEN1, SETX, is of biomedical importance since its dysfunction results in the neurodegenerative diseases Ataxia and Ocular Apraxia (AOA) type 2 and Amyotrophic Lateral Sclerosis (ALS) type 4. Unraveling this protein's biochemical and biological function will be important for understanding the pathophysiological basis of these diseases. PUBLIC HEALTH RELEVANCE: Project Narrative The cellular machinery that decodes (transcribes) genetic information is complex and its failure to function properly leads to a number of human diseases. This project uses a model organism in which genes, and this so-called transcription machinery, can be experimentally manipulated and will unravel the details by which genetic information is expressed. The parts of the transcription machinery studied here are involved in neurological, visual, and immunological diseases.