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High Mobility Group Protein HMG I(Y) in Transcription

转录中的高迁移率组蛋白 HMG I(Y)

基本信息

批准号：
6525704
负责人：
Dimitris Thanos
金额：
$ 30.22万
依托单位：
COLUMBIA UNIVERSITY HEALTH SCIENCES
依托单位国家：
美国
项目类别：
财政年份：
1996
资助国家：
美国
起止时间：
1996-08-01 至 2003-07-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Eukaryotic organisms employ a variety of important but poorly understood mechanisms to control the expression of their genes. A full understanding of these mechanisms is an important issue since regulation of gene expression plays an important role in the development and differentiation of functionally distinct cell types in a precise spatial manner. The genomic regulatory network that controls gene expression ultimately determines form and function in each species. In addition, regulation of transcription reflects the ability of cells to respond to extracellular signals and environmental stresses. The operational nature of the regulatory programming specified by the interplay between cis-regulatory DNA sequences, the cognate transcription factors and the coactivators of transcription has been determined for the human IFN-beta gene, whose transcription is activated in response to virus infection. Activation of the IFN-beta gene is a transient phenomenon requiring three distinct sets of transcription factors, which with the help of the HMG I(Y) protein bind to enhancer DNA cooperatively to assemble the enhanceosome. The enhanceosome activates transcription by instructing an ordered recruitment of chromatin modifying activities such as Histone Acetyl Transferases (CBP and GCN5) and ATP-dependent remodeling machines (SWI/SNF), which alter the local chromatin structure in a way that allows subsequent assembly of the basal transcriptional complex and initiation of transcription. In parallel, GCN5 and CBP acetylate HMG I at distinct lysine residues conferring opposite effects on enhanceosome stability. The overall goals of this proposal are to elucidate the mechanisms of enhanceosome assembly/disassembly in vivo and the molecular basis by which histone acetylation acts to form a "histone code" read by other proteins to bring about chromatin remodeling and transcriptional activation. Our approach will use cells lacking the HMG I(Y) gene. We will transduce several HMG I(Y) derivatives deficient in distinct functions of the protein and we will investigate enhanceosome assembly in vivo by chromatin immunoprecipitation experiments. Furthermore, we will decode the "histone acetylation code" by identifying the histones and the specific residues acetylated in vivo in response to virus infection and their role in gene activation. Finally, we will carry out in vivo and in vitro experiments to understand the nature of chromatin remodeling at the IFN-beta promoter and how the general transcriptional machinery is instructed by the enhanceosome to assemble on the remodeled IFN-beta promoter.

描述（由申请人提供）：真核生物使用多种重要但知之甚少的机制，以控制其表达，基因.充分了解这些机制是一个重要问题，因为基因表达的调控在发育中起重要作用，功能不同的细胞类型的分化在一个精确的空间方式最终控制基因表达的基因组调控网络决定了每个物种的形态和功能此外，监管转录反映了细胞对细胞外信号的反应能力和环境压力。监管的业务性质由顺式调节DNA序列之间的相互作用指定的编程，同源转录因子和转录辅激活因子具有已经确定了人IFN-β基因，其转录被激活以应对病毒感染。IFN-β基因的激活是一种短暂的这种现象需要三组不同的转录因子， HMG I（Y）蛋白与增强子DNA协同结合，增强体增强体通过指示一个转录因子激活转录。有序募集染色质修饰活性，如组蛋白乙酰基转移酶（CBP和GCN 5）和ATP依赖性重塑机器（SWI/SNF），从而改变局部染色质结构，基础转录复合物的组装和转录的起始。平行地，GCN 5和CBP在不同的赖氨酸残基处乙酰化HMG I 从而对增强体稳定性产生相反的作用。的总目标本文旨在阐明增强体的作用机制，组装/拆卸在体内和分子基础，乙酰化作用形成一个“组蛋白密码”，由其他蛋白质读取，染色质重塑和转录激活。我们的方法将使用缺乏HMG I（Y）基因的细胞。我们将研究几种HMG I（Y）衍生物，缺乏蛋白质的独特功能，我们将研究通过染色质免疫沉淀实验增强体内的小体组装。此外，我们将通过识别组蛋白乙酰化密码来解码“组蛋白乙酰化密码”。组蛋白和体内应答病毒的乙酰化特异性残基感染及其在基因激活中作用。最后，我们将在体内进行和体外实验，以了解染色质重塑的性质， IFN-β启动子以及一般的转录机制是如何在增强体的指导下在重塑的IFN-β启动子上组装。