ROLE OF CHROMATIN REMODELING IN GROWTH CONTROL

任何给定基因的染色质状态都是其调控的关键方面。染色质建立了一个抑制转录的抑制环境，从阻止初始因子结合到抑制伸长。这种抑制作用似乎被atp依赖性染色质重塑复合物和组蛋白尾部乙酰化酶所缓解，并被抑制蛋白复合物、组蛋白去乙酰化酶和其他因素所增强。最近的证据表明，两种染色质重塑复合物hSWI/SNF和NRD可能是视网膜母细胞瘤肿瘤抑制蛋白家族募集生长控制机制所必需的。尽管这一证据表明了这些复合物的重要作用，但它对它们的作用机制知之甚少。目前的证据，从我和其他人的工作，表明潜在的机制，重塑复合体可以激活，以及抑制，转录。本研究的目的是分析两种人类染色质重塑复合物hSWI/SNF和NRD的机制，以更好地了解它们对转录控制的潜在影响。我们将分析这些复合物对核小体流动性和高阶结构的影响，以及它们受转录因子和染色质相关蛋白影响的作用。染色质重塑在促进NRD的第二个功能，组蛋白去乙酰化中的作用也将被研究。视网膜母细胞瘤蛋白与这些复合物相互作用并将其招募到启动子的能力将在体外和体内进行研究，目的是建立一个强大的模型系统来研究染色质重塑在生长控制决策和一般转录调控中的作用。

The state of chromatin at any given gene is a critical aspect of its regulation. Chromatin establishes a repressive environment that is inhibitory to transcription, from prevention of initial factor binding to inhibition of elongation. This repressive effect appears to be relieved by ATP-dependent chromatin remodeling complexes and enzymes that acetylate the histone tails, and enhanced by complexes of repressor proteins, histone deacetylases, and other factors. Recent evidence suggests that two chromatin remodeling complexes, hSWI/SNF and NRD, might be essential for growth control mechanisms through recruitment by the retinoblastoma family of tumor suppressor proteins. Although this evidence indicates an important role for these complexes, it tells us very little about their mechanism of action. Current evidence, from my work and others', suggest potential mechanisms by which remodeling complexes could activate, as well as repress, transcription. The purpose of the research described here is to analyze the mechanisms of the two human chromatin remodeling complexes, hSWI/SNF and NRD, to better understand their potential effects on transcriptional control. These complexes will be assayed for their ability to affect nucleosome mobility and higher-order structures, and for their effects to be influenced by transcription factors and chromatinassociated proteins. The role of chromatin remodeling in facilitating the second function of NRD, histone deacetylation will also be examined. The ability of the retinoblastoma protein to interact with these complexes to recruit them to promoters will be examined in vitro and in vivo, with the aim of establishing a strong model system for examining the role of chromatin remodeling in growth control decisions and general transcriptional regulation.