Regulatory Mechanisms in Transcriptional Signaling

描述（由申请人提供）：转录调控在指定细胞和组织分化、细胞生长、发育和对疾病的易感性中起着重要作用。真核基因表达的高度调节过程是由涉及染色质、转录因子如核激素受体和具有组蛋白/染色质修饰活性的关键辅助/调节蛋白的多种机制的相互作用协调的。组蛋白经历翻译后修饰，例如乙酰化、磷酸化和甲基化。这些修饰的组蛋白随后导致了转录的“组蛋白密码”的建立。例如，未修饰的组蛋白抑制转录，而乙酰化的历史促进基因激活。在高等真核生物中，未修饰的组蛋白“编码”转录抑制的机制在很大程度上是未知的。辅调节因子的翻译后修饰也影响基因转录。我们研究的长期目标是识别和分子表征调节激素信号传导和转录的新机制。我们最近的研究表明，一种称为INHAT的人类细胞复合物至少部分地通过与组蛋白结合并调节辅激活因子的组蛋白乙酰转移酶活性来调节核受体的功能和转录，pp 32是INHAT复合物的亚基和核磷蛋白。我们假设pp 32是转录抑制的关键成分，pp 32的磷酸化在其体内功能中起着关键作用。为了验证这些假设，我们将（1）确定pp 32在翻译转录的抑制性“组蛋白密码”中的作用;（2）描述pp 32转录抑制的分子机制;（3）分析磷酸化在pp 32体内功能中的作用。我们将使用涉及生物化学、分子和细胞生物学方法的体外和体内分析的组合来解决上述具体目标。调节组蛋白修饰和蛋白磷酸化的蛋白质的改变的活性已经与改变的激素信号传导和人类疾病（包括癌症和发育异常）相关联。来自拟议研究的信息不仅可以更好地理解转录和激素信号传导，而且可能有助于靶向药物开发以治疗人类疾病。

DESCRIPTION (provided by applicant): Transcriptional regulation plays a fundamental role in specifying cellular and tissue differentiation, cell growth, development and susceptibility to diseases. The highly regulated process of eukaryotic gene expression is coordinated by the interplay of multiple mechanisms involving chromatin, transcription factors such as nuclear hormone receptors and critical accessory/regulatory proteins with histone/chromatin modifying activities. Histones undergo posttranslational modifications such as acetylation, phosphorylation and methylation. These modified histones subsequently led to the establishment of a "histone code" of transcription. For example, unmodified histones repress transcription while acetylated histories promote gene activation. The mechanisms by which unmodified histones "code" for transcriptional repression in higher eukaryotes are largely unknown. Post-translational modification of coregulators also influence gene transcription. The long-term goal of our research is to identify and molecularly characterize novel mechanisms regulating hormonal signaling and transcription. We have recently shown that a human cellular complex termed INHAT regulates nuclear receptor function and transcription at least in part by binding to histones and modulating histone acetyltransferase activity of coactivators, pp32 is a subunit of the INHAT complex and a nuclear phosphoprotein. We hypothesize that pp32 is a critical component in transcriptional repression and that phosphorylation of pp32 plays a critical role in its in vivo function. To test the hypotheses we will (1) determine the role ofpp32 in translating the repressive "histone code" of transcription; (2) characterize molecular mechanisms of transcriptional repression by pp32; and (3) analyze the role of phosphorylation in pp32 function in vivo. We will address the above specific aims using a combination of in vitro and in vivo analyses involving biochemical, molecular, and cell biological methodologies. Altered activities of proteins regulating histone modifications and protein phosphorylation have been linked to altered hormone signaling and human diseases including cancer, and developmental abnormalities. The information stemming from the proposed studies should not only provide a better understanding of transcription and hormone signaling but may also be useful in targeted drug development to treat human diseases.