Chromatin remodeling and MHC class II gene transcription

染色质重塑和 MHC II 类基因转录

• 批准号: 6558868
• 负责人: JOSEPH D FONTES
• 金额: $ 6.63万
• 依托单位: CLEVELAND STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-15 至 2004-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6558868
• 关键词: MHC class II antigen; chromatin; enzyme activity; genetic transcription; major histocompatibility complex; nuclease; restriction endonucleases; tissue /cell culture; transcription factor

DESCRIPTION (provided by applicant): Expression of major histocompatibility complex (MHC) class II genes is regulated primarily at the level of transcription. Aberrant or absent expression of these genes is associated with autoimmune disease and immunodeficiency, respectively. Characterizing the molecular mechanisms that regulate the transcription of these genes is critical for the development of new therapies and a greater understanding of the etiology of these diseases. The objective of the current application is to illuminate one such regulatory mechanism that has not been addressed: the role of chromatin structure and its remodeling in MHC class II gene transcription. Based upon previous evidence, it is hypothesized that there are two chromatin "barriers"--one on the promoters and the second on the protein coding regions--present on MHC class II genes. The first specific aim will employ restriction endonuclease accessibility and micrococcal nuclease assay to characterize the changes in chromatin structure on MHC class II genes associated with transcriptional activation of these genes. In addition, the role gene-specific trans-acting factors in mediating the changes in chromatin structure will be addressed. Recent observations indicate that one of these trans-acting factors, the class II trans-activator (CIITA) functionally interacts with a subunit of the chromatin remodeling complex SWI/SNF. In the second specific aim, protein interaction assays will be used to characterize the domain of CIITA required for binding to SWI/SNF. Once identified, this domain will be used to determine the functional significance of CIITA-SWI/SNF interaction, in terms of chromatin remodeling and transcriptional activation. CIITA has been found to have endogenous histone acetyltransferase activity, in addition to its ability to recruit at least two histone acetyltransferase enzymes. In the third specific aim, the relationship between CIITA mediated histone acetylation of nucleosomes on MHC class II genes, and SWI/SNF mediated chromatin remodeling will be addressed. Relative changes in transcriptional activation and chromatin remodeling will be determined in cell culture models in which the recruitment of SWI/SNF and CIITA mediated histone acetylation are manipulated. Through these specific aims the importance and mechanistic basis of chromatin remodeling in the transcription of MHC class II genes will be determined.

描述（由申请人提供）：主要组织相容性复合体（MHC） II类基因的表达主要在转录水平上调节。这些基因的异常或缺失表达分别与自身免疫性疾病和免疫缺陷有关。表征调节这些基因转录的分子机制对于开发新疗法和更好地了解这些疾病的病因至关重要。当前应用的目的是阐明一个尚未解决的调控机制：染色质结构及其重塑在MHC II类基因转录中的作用。基于先前的证据，假设在MHC II类基因上存在两个染色质“屏障”——一个在启动子上，第二个在蛋白质编码区域上。第一个具体目标将采用限制性内切酶可及性和微球菌核酸酶测定来表征与这些基因转录激活相关的MHC II类基因的染色质结构变化。此外，还将讨论基因特异性反式作用因子在介导染色质结构变化中的作用。最近的观察表明，这些反式作用因子之一，II类反式激活因子（CIITA）可与染色质重塑复合体SWI/SNF的一个亚基相互作用。在第二个特定目标中，蛋白质相互作用分析将用于表征与SWI/SNF结合所需的CIITA结构域。一旦确定，该结构域将用于确定CIITA-SWI/SNF相互作用在染色质重塑和转录激活方面的功能意义。除了能够招募至少两种组蛋白乙酰转移酶外，还发现CIITA具有内源性组蛋白乙酰转移酶活性。在第三个特定目标中，将讨论CIITA介导的MHC II类基因核小体组蛋白乙酰化与SWI/SNF介导的染色质重塑之间的关系。转录激活和染色质重塑的相关变化将在操纵SWI/SNF募集和CIITA介导的组蛋白乙酰化的细胞培养模型中确定。通过这些具体目标，将确定染色质重塑在MHC II类基因转录中的重要性和机制基础。