Control of HIV-1 Gene Transcription in Brain Cells

脑细胞中 HIV-1 基因转录的控制

• 批准号: 6919797
• 负责人: SHOHREH AMINI
• 金额: $ 29.53万
• 依托单位: TEMPLE UNIV OF THE COMMONWEALTH
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-12-01 至 2009-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6919797
• 关键词: DNA repair; astrocytes; cell growth regulation; chromatin immunoprecipitation; cytokine; fluorescence microscopy; gene interaction; host organism interaction; human immunodeficiency virus 1; human tissue; interferon gamma; neurotropic virus; nuclear factor kappa beta; pathologic process; small interfering RNA; tissue /cell culture; transcription factor; transforming growth factors; tumor necrosis factor alpha; virus genetics; virus protein; virus replication; western blottings

Control of HIV-1 gene transcription at different stages during the course of infection requires a delicate balance of interaction among various host factors and viral proteins. In the central nervous system (CNS), cells of neural origin such as astrocytes and peripheral cells of macrophage/monocytic lineage are the primary sites for the expression of the HIV-1 genome. However, the mechanism which modulates expression of the viral genome during the infection cycle in CNS cells, i.e. the immediate early stage when basal transcription of the viral genome is initiated by host factors; at the early stage when host factors cooperate with the viral transactivator, Tat; and at the late stage when other viral regulatory proteins such as Vpr participate in viral gene transcription, remains unknown. HIV-1 infection of CNS cells is accompanied by induction/dysregulation of several critical pathways required for the maintenance of host function. One of the viral proteins that has an established role in affecting host function is Tat, which has the ability to communicate with several regulatory factors to augment transcription of the HIV-1 LTR and alters the level of expression from the host genome. Our recent results demonstrate upregulation of Rad51, a cellular gene which is implicated in homologous recombination, in brain cells of patients with HIV-1 encephalopathy (HIVE). Further, in vitro studies revealed the ability of Tat to elevate Rad51 expression in astrocytes and neuronal culture. As the elevation in Rad51 may affect, directly or indirectly, HIV-1 gene expression and replication, we examined transcription of the viral promoter in the presence of an elevated level of Rad51 and demonstrated the ability of Rad51 to increase basal-and Tat-induced expression of the HIV-1 genome. Preliminary observations from our deletion mutants revealed the importance of the LTR sequence spanning -120 to -80 in Rad51 activation of the LTR in human astrocytes suggesting the involvement of a series of transcription factors such as C/EBP family and NF-kappaB, whose activities are mediated, at least in part, through their interaction with the DNA sequence. Thus, we hypothesize that cross-communication of Rad51 with transcription activators such as C/EBPbeta and NF-kappaB families and Tat results in a positive feedback regulatory event that leads to stimulation of the HIV-1 gene expression in CNS cells. To test our hypothesis we will employ a comprehensive approach using state of the art techniques of molecular biology to decipher the cooperative interaction of Rad51 with various cellular proteins such as C/EBPbeta, CHOP, NF-kappaB, and p53, and viral proteins such as Tat and Vpr and assess their impact on the HIV-1 genome at the immediate early, early, and late phases of viral gene expression. The outcome of these studies will provide important information which can be utilized in the current treatment of AIDS patients and in devising more effective molecular strategies toward inhibition of viral gene expression in the CNS.

在感染过程中，在不同阶段对HIV-1基因转录的控制需要各种宿主因素和病毒蛋白之间的相互作用平衡。在中枢神经系统（CNS）中，神经来源的细胞，例如星形胶质细胞和巨噬细胞/单核细胞谱系的外周细胞是HIV-1基因组表达的主要部位。但是，在CNS细胞中感染周期中调节病毒基因组表达的机制，即，宿主因子启动病毒基因组基础转录的早期阶段。在早期宿主因素与病毒式反式激活因子TAT合作时；在晚期，当其他病毒调节蛋白（例如VPR）参与病毒基因转录时，仍然未知。 CNS细胞的HIV-1感染伴随着维持宿主功能所需的几种关键途径的诱导/失调。 TAT是在影响宿主功能方面具有确定作用的病毒蛋白之一，它具有与几个调节因素进行通信以增强HIV-1 LTR转录并改变宿主基因组的表达水平。 我们最近的结果表明，在HIV-1脑病（HIVE）患者的脑细胞中，Rad51（一种与同源重组有关的细胞基因）上调。此外，体外研究揭示了TAT升高星形胶质细胞和神经元培养中Rad51表达的能力。由于RAD51中的升高可能直接或间接影响HIV-1基因的表达和复制，因此我们在RAD51升高的情况下检查了病毒启动子的转录。 TAT诱导的HIV-1基因组的表达。从我们的缺失突变体中的初步观察结果揭示了LTR序列在人类星形胶质细胞中LTR激活的LTR序列跨越-120至-80的重要性，这表明C/EBP家族和NF -KAPPAB等一系列转录因子的参与表明，至少通过与DNA序列进行了介导的活动，其活性是介导的。因此，我们假设Rad51与C/EBPBETA和NF-KAPPAB家族等转录激活剂的跨沟道以及TAT结果 在一个积极的反馈调节事件中，导致CNS细胞中HIV-1基因表达的刺激。 To test our hypothesis we will employ a comprehensive approach using state of the art techniques of molecular biology to decipher the cooperative interaction of Rad51 with various cellular proteins such as C/EBPbeta, CHOP, NF-kappaB, and p53, and viral proteins such as Tat and Vpr and assess their impact on the HIV-1 genome at the immediate early, early, and late phases of viral gene expression.这些研究的结果将提供重要的信息，这些信息可用于当前对艾滋病患者的治疗，并设计出更有效的分子策略来抑制中枢神经系统中病毒基因的表达。