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

描述（由申请人提供）：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。艾滋病的特点是CD4+ T淋巴细胞耗竭。Tat是由HIV-1基因组编码的病毒反式激活因子，通过结合反式激活反应区（TAR）并招募cdk9/cyclin T1、p300/CBP、SWI/SNF和RNA聚合酶II，在HIV-1感染细胞的转录水平上负责HIV-1复制。持续的HIV-1复制使受感染的T细胞进一步向艾滋病发展。我们研究的长期目标是了解染色质环境，Tat和染色质重塑物/修饰物如何合作影响HIV-1转录。在其未修饰的形式下，与组蛋白乙酰转移酶p300/CBP相关。然而，我们最近发现乙酰化的Tat结合BRG1，这是SWI/SNF染色质重塑复合体的一个组成部分。SWI/SNF复合体参与激活转录的进一步测试指向PBAF复合体的特异性使用。这种Tat-SWI/SNF复合物足以从HIV-1启动子中移除/改造nuc1，从而允许tar特异性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在激活HIV-1转录中起作用。我们的假设是未经修饰的Tat复合物与p300/CBP和cdk9/cyclin T1启动HIV-1转录，而乙酰化的Tat复合物与SWI/SNF和p300/CBP相关因子（p/CAF）促进转录延伸。然而，p300/CBP也可能参与了tat介导的转录延伸。我们进行这些研究的基本原理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表达中至关重要。因此，现在有更多的强调鉴定染色质因子/修饰，通过抑制性染色质复合体帮助过渡。以下具体目标解决了我们的假设：(I)在细胞系和PBMC感染细胞中，Tat-p300/CBP和Tat-p/CAF复合物在HIV-1启动子和开放阅读框上的染色质标记和转录延伸中的意义是什么？（II） Tat- SWI/SNF （Tat- pbaf）复合物在感染细胞系和PBMC感染细胞中HIV-1 LTR染色质重塑中的作用是什么？从这些研究中获得的数据将揭示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（艾滋病）的病原体。HIV-1基因组（Tat）编码的一种病毒蛋白在DNA水平上负责HIV-1的复制。我们的研究旨在了解存在于HIV-1 DNA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对调节HIV-1表达至关重要，现在染色质相关蛋白作为新的治疗靶点得到了进一步的重视。这项工作将揭示染色质在tat介导的HIV-1表达中的作用。

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.