Effect of chromatin remodelers/modifiers on HIV-1 Tat activated transcription

描述(申请人提供)：人类免疫缺陷病毒(HIV)是获得性免疫缺陷综合征(AIDS)的病原体。艾滋病的特征是CD4T淋巴细胞耗尽。TAT是HIV-1基因组编码的病毒反式激活剂，通过结合反式激活反应区(TAR)和募集CDK9/Cyclin T1、p300/CBP、SWI/SNF和RNA聚合酶II，在转录水平上负责HIV-1在HIV-1感染细胞中的复制。持续的HIV-1复制使感染的T细胞进一步向AIDS发展。我们研究的长期目标是了解染色质环境、TAT和染色质重构体/修饰物如何合作影响HIV-1转录。未修饰的TAT与组蛋白乙酰转移酶p300/CBP结合。然而，我们最近发现，乙酰化的TAT与BRG1结合，BRG1是SWI/SNF染色质重塑复合体的一个组成部分。对SWI/SNF复合体参与激活转录的进一步测试指向PBAF复合体的特定用途。这种TAT-SWI/SNF复合体足以从HIV-1启动子中移除/重塑nuc-1，从而允许TAR特异性的HIV-1转录。我们还发现BRG1和Baf200在HIV-1复制中起关键作用。因此，这些结果使我们推测TAT-SWI/SNF在TAT激活HIV-1转录中起作用。我们的假设是，未修饰的TAT与p300/CBP和CDK9/Cyclin T1形成的复合物启动HIV-1的转录，而与SWI/SNF和p300/CBP相关因子(p/CAF)的乙酰化的TAT则促进转录延长。然而，p300/CBP也可能参与TAT介导的转录延长。我们进行这些研究的理论基础是基于越来越多的数据，这些数据表明染色质环境和染色质相关因子在调节HIV-1表达方面至关重要。因此，现在更加强调识别有助于通过抑制性染色质复合体过渡的染色质因子/修饰。。以下特定目的针对我们的假设：(I)TAT-p300/CBP和TAT-p/CAF复合体在细胞株和PBMC感染细胞中对HIV-1启动子和开放阅读框上的染色质标记和转录延长有什么意义？(Ii)TAT-SWI/SNF(TAT-PBAF)复合体在感染细胞系和PBMC感染细胞中HIV-1 LTR染色质重塑中起什么作用？从这些研究中获得的数据将阐明染色质环境如何调节TAT激活的HIV-1转录。公共卫生相关性：叙述人类免疫缺陷病毒(HIV)是获得性免疫缺陷综合征(AIDS)的病原体。一种由HIV-1基因组(TAT)编码的病毒蛋白，负责在DNA水平上复制HIV-1。我们的研究试图了解存在于HIV-1DNA上的蛋白质和因子(染色质)如何通过Tat的作用影响病毒的表达。基于越来越多的数据表明染色质环境在调节HIV-1表达方面是关键的，现在人们更加重视染色质相关蛋白作为新的治疗靶点。这项工作将为染色质在TAT介导的HIV-1表达中的作用提供新的线索。

DESCRIPTION (provided by applicant): Human immunodeficiency virus (HIV) is the etiological agent of acquired immunodeficiency syndrome (AIDS). AIDS is characterized by CD4+ T lymphocyte depletion. Tat, the viral trans-activator encoded by the HIV-1 genome, is responsible for HIV-1 replication at the transcriptional level in HIV-1 infected cells by binding the trans-activation response region (TAR) and recruiting cdk9/cyclin T1, p300/CBP, SWI/SNF, and RNA Polymerase II. Sustained HIV-1 replication further progresses infected T cells towards AIDS. The long-term goal of our research is to understand how the chromatin environment, Tat, and chromatin remodelers/modifiers cooperate to influence HIV-1 transcription. Tat, in its unmodified form, associates with the histone acetyltransfersase p300/CBP. However, we have recently found that acetylated Tat binds BRG1, a component of the SWI/SNF chromatin remodeling complex. A further test of which SWI/SNF complex is involved in activated transcription points to specific use of PBAF complex. This Tat-SWI/SNF complex is sufficient to remove/remodel nuc-1 from the HIV-1 promoter to allow for TAR-specific HIV-1 transcription. We also show that BRG1 and Baf200 play critical role in HIV-1 replication. Therefore, these results led us to speculate that Tat-SWI/SNF plays a role Tat activated HIV-1 transcription. Our hypothesis is that unmodified Tat complexes with p300/CBP and cdk9/cyclin T1 to initiate HIV-1 transcription while acetylated Tat complexes with SWI/SNF and p300/CBP- associated factor (p/CAF) to promote transcriptional elongation. However, p300/CBP may also be involved in Tat-mediated transcriptional elongation. Our rationale for these studies is based on mounting data demonstrating that the chromatin environment and chromatin-associated factors are critical in regulating HIV-1 expression. Hence, there is now added emphasis on identifying chromatin factors/modifications that aid in transition through the inhibitory chromatin complex. . The following specific aims address our hypothesis: (I) What is the significance of the Tat-p300/CBP and Tat-p/CAF complexes in chromatin marking and transcription elongation on the HIV-1 promoter and open reading frames in cell lines and PBMC infected cells? (II) What is the role of the Tat- SWI/SNF (Tat-PBAF) complex in chromatin remodeling at the HIV-1 LTR in infected cell lines and PBMC infected cells? Data obtained from these studies will shed light on how the chromatin environment regulates Tat activated HIV-1 transcription. PUBLIC HEALTH RELEVANCE: Narrative Human immunodeficiency virus (HIV) is the causative agent of acquired immunodeficiency syndrome (AIDS). A viral protein encoded by the HIV-1 genome (Tat), is responsible for HIV-1 replication at the level of DNA. Our research seeks to understand how the proteins and factors (chromatin) present on HIV-1 DNA influence viral expression when acting through the actions of Tat. Based on the mounting data demonstrating that the chromatin environment is critical in regulating HIV-1 expression, there is now an added emphasis on chromatin-associated proteins as novel therapeutic targets. This work will shed new light on the role of chromatin in Tat-mediated HIV-1 expression.