Corepressors for the Orphan Receptor RevErb

核激素受体(NRs)是细胞生长、分化和代谢的关键转录调节因子。NR超家族包括激素、维生素、代谢物和外源生物的受体，以及未知配体的受体，称为孤儿受体，NRs通过招募辅助抑制因子N-COR和SMRT在缺乏配体的情况下抑制转录。激素的作用在很大程度上是协同抑制因子解离的结果，伴随着协同激活剂分子的招募。这个实验室的一个主要目标是了解转录抑制从NRs与辅助抑制物到抑制信号的分子介体的相互作用。孤儿受体混响一直是NRs的极品，它与抑制信号的分子介体共同抑制。孤儿受体混响一直是学习激活螺旋的极好模型，混响同源二聚体将N-COR招募到特定的DNA结合部位。我们假设，DNA结合的混响同源二聚体的每个亚基都与特定的DNA结合位点结合。我们假设DNA结合的混响同源二聚体的每个亚基都与N-COR中不同的CoRNR基序结合。这一假设将在特定的目标1中进行直接测试，该目标将确定混响同源二聚体通过突变、嵌合受体和共抑制物以及蛋白水解图与共抑制物相互作用的分子机制。我们还鉴定了与N-COR/SMRT相互作用的多种组蛋白脱乙酰酶(HDAC)和其他蛋白质，它们是抑制信号的潜在介导者。我们假设不同的共抑制物和共抑制物相关蛋白是以受体和细胞特异性的方式被混响和其他NRs招募的。具体目的2是利用染色质免疫沉淀和RNA干扰技术，在体内确定参与混响和其他NRs抑制的共抑制物和共抑制物相关蛋白。我们还证明了N-COR和SMRT是HDAC3酶的激活辅助因子。具体目标3是确定这种现象的机制，并了解其对其他共抑制物和其他HDAC的适用性。我们推测SMRT和N-COR还有与染色质修饰和转录抑制相关的其他功能。初步数据表明，其中一个功能是组蛋白结合。具体目的4是了解共抑制物的染色质相关功能。组蛋白结合的机制和功能将被阐明。总之，这些研究将阐明NR与共抑制子相互作用的基本调控机制，以及共抑制子对转录的调控。从这项工作中获得的见解将扩大我们对激素作用机制的理解，并有可能导致与NR功能相关的疾病的新方法，包括肥胖症、糖尿病和白血病。

Nuclear hormone receptors (NRs) are key transcriptional regulators of cellular growth, differentiation, and metabolism. The NR superfamily include receptors for hormones, vitamins, metabolites, and xenobiotics, as well as receptors without known ligands, termed orphan receptors, NRs repress transcription in the absence of ligand by recruiting co-repressors N-CoR and SMRT. Hormone action is largely the result of dissociation of co-repressor, accompanied by the recruitment of co-activator molecules. A major goal of this laboratory is to understand transcriptional repression from the interaction of NRs with the co-repressors to the molecular mediators of the repressive signal. The orphan receptor RevErb has been a superb of NRs with co-repressors to the molecular mediators of the repressive signal. The orphan receptor RevErb has been a superb model for learning about activation helix, and that RevErb homodimers recruit N-CoR to specific DNA binding sites. We hypothesize that each subunit of the DNA-bound RevErb homodimer binds to a specific DNA binding sites. We hypothesize that each subunit of the DNA-bound RevErb homodimer binds to a different CoRNR motif in N-CoR. This hypothesis will be directed tested in Specific Aim 1, which will determine the molecular mechanism by which RevErb homodimers interact with co-repressor using mutagenesis, chimeric receptors and co-repressors, and proteolytic mapping. We have also identified multiple histone deacetylases (HDACs) and other proteins that interact with N-CoR/SMRT and are potential mediators of the repressive signal. We hypothesize that different co-repressors and co-repressor associated proteins are recruited by RevErb and other NRs in a receptor- and cell-specific manner. Specific Aim 2 is to determine the co-repressors and co-repressor-associated proteins involved in repression by RevErb and other NRs in vivo, using chromatin immunoprecipitation and RNA interference. We have also shown that N-CoR and SMRT act as activ ating co-factors for the HDAC3 enzyme. Specific Aim 3 is to determine the mechanism of this phenomenon, and to understand its applicability to other co-repressors and other HDACs. We hypothesize that SMRT and N-CoR have others functions related to chromatin modification and transcriptional repression. Preliminary data indicate that one such function is histone binding. Specific Aim 4 is to understand the chromatin-related function of the co-repressors. The mechanism and function of histone binding will be elucidated. Together, these studies will elucidate basic mechanisms underlying the regulation of NR interactions with co-repressors, and co-repressor regulation of transcription. The insights gained from this work will expand our understanding of the mechanisms of hormone action, and has potential to lead to novel approaches to diseases associated with NR function, including obesity, diabetes, and leukemia.