Molecular determinants of bHLH-PAS transcription factor function

响应于特定刺激的基因表达是由称为转录因子的一大组蛋白质进行的。 为了以适当的空间和时间方式指导转录，这些蛋白质必须指导染色质上的大型蛋白质机器的协调组装和拆卸。 我的研究计划的目的是了解蛋白质是如何穿梭和基因表达机制在转录过程中的基本-HALPH-Loop-HALPH-PAS（bHLH-PAS）家族的转录因子。我的目标是了解这些变化如何改变蛋白质功能以响应不同的信号。这些信息将有助于合理设计利用转录因子功能并直接靶向其活性的疗法。 我选择研究两个严格调控的模型系统：芳香烃受体（AHR）调控的CYP 1A 1活性;以及低氧诱导因子-1a（HIF-1a）调控的VEGF和EPO表达。 我已经确定，雌激素，通过雌激素受体α（ER），抑制AHR功能，通过直接的蛋白质-蛋白质相互作用。 此外，ER通过促进组蛋白脱乙酰酶HDAC 4与辅阻遏蛋白RIP 140在AHR靶基因的调节元件处的交换来实现。在本研究的第一部分，我建议阐明ER介导的AHR调节转录抑制的分子决定因素。我设计了一系列的实验，以了解如何雌激素反应性募集的阻遏物RIP 140调节AHR活性，并确定HDAC 4在维持RIP 140在一个有利于AHR介导的基因转录的状态中发挥的作用。 本提案的第二部分概述了我阐明视网膜母细胞瘤蛋白（Rb）对HIF-1a调控转录的作用的计划。我已经证明了共激活因子TRIP 230对于HIF-1a的转录激活是必不可少的。 此外，我有证据表明介导的HIF-1a依赖的转录活性是负调控Rb。总之，这些研究将增加我们对正常AHR生理学、血管发生和转录因子功能的理解。

The expression of genes in response to specific stimuli is carried out by a large group of proteins known as transcription factors. In order to direct transcription in an appropriate spatial and temporal fashion, these proteins must direct the coordinated assembly and disassembly of large protein machines on chromatin. The objective of my research program is to understand how proteins are shuttled to and from gene expression machinery during transcription by the basic-Helix-Loop-Helix-PAS (bHLH-PAS) family of transcription factors. It is my goal to understand how these changes alter protein function in response to different signals. This information will aid in the rational design of therapies that exploit transcription factor function and are directly targeted at their activities. I have chosen to study two tightly regulated model systems; aryl hydrocarbon receptor (AHR)-regulated CYP1A1 activity; and, hypoxia-inducible factor-1a (HIF-1a)-regulated VEGF and EPO expression. I have established that estrogens, through the estrogen receptor-alpha (ER), repress AHR function via direct protein-protein interactions. Furthermore, ER does so by facilitating an exchange for the histone deacetylase, HDAC4 for the co-repressor protein, RIP140 at the regulatory elements of AHR target genes. In part 1 of this study, I propose to elucidate the molecular determinants of ER-mediated repression of AHR-regulated transcription. I have designed a series of experiments to understand how estrogen-responsive recruitment of the repressor RIP140 modulates AHR activity and to determine the role HDAC4 plays in maintaining RIP140 in a state conducive to AHR-mediated gene transcription. The second part of this proposal outlines my plans to elucidate the role of the retinoblastoma protein (Rb) on HIF-1a regulated transcription. I have demonstrated that the co-activator TRIP230 is essential for transcriptional activation by HIF-1a. In addition, I have evidence that mediated HIF-1a-dependent transcriptional activity is negatively regulated by Rb. Together, these studies will increase our understanding of normal AHR physiology, vasculogenesis, and transcription factor function in general.