P-TEFb and HIV Latency

描述(由申请人提供)：当前抗HIV-1药物的组合在许多患者中将病毒复制抑制到无法检测的水平。然而，这些患者拥有一个含有潜伏的HIV-1前病毒的细胞储存库，一旦停止抗病毒药物，这些细胞就会自动重新激活，从而排除了治愈感染的可能性。描述得最好的潜在储集层是 长寿记忆的CD4+T淋巴细胞，它含有转录沉默但复制能力强的前病毒。尽管目前对CD4+T淋巴细胞潜伏期的机制还不完全清楚，但人们相信，多种机制协同作用来建立和维持潜伏期。细胞基因在整合部位的转录干扰可能会导致潜伏期。抑制染色质是针对潜伏期前病毒而建立的。细胞转录因子的限制水平也对潜伏期有重要影响，特别是P-TEFb，一种参与病毒TAT蛋白功能的转录延伸因子核心P-TEFb由Cyclin T1(CCNT1)和CDK9组成。最近在HIV-1潜伏期的原代CD4+T淋巴细胞系统中的研究结果表明，随着潜伏期的建立，CCNT1蛋白和CDK9 T环磷酸化水平下调。相反，当潜伏病毒被T细胞激活诱导时，CCNT1和T-loop磷酸化在该系统中上调。这些发现表明，CCNT1的下调在潜伏期的建立中是一个重要的、或许是必不可少的事件。这里提出的这项研究将检验P-TEFb下调可以驱动CD4+T淋巴细胞中HIV-1潜伏期的假设。这项研究还将探讨CCNT1下调的机制，以及调节静止和激活的CD4+T淋巴细胞中CDK9 T环磷酸化的机制。最后，这项研究将确定选择性上调P-TEFb是否有助于潜伏的原代细胞系统中潜伏的HIV-1重新激活。研究的完成将确定P-TEFb是否是建立和维持HIV-1潜伏期的关键细胞因素。这项研究有可能将P-TEFb确立为重新激活潜伏病毒从而治愈HIV-1感染的重要治疗靶点。

DESCRIPTION (provided by applicant): Combinations of current anti-HIV-1 drugs suppress virus replication to undetectable levels in many patients. However, these patients possess a reservoir of cells harboring latent HIV-1 proviruses that spontaneously reactivate upon cessation of anti-viral drugs, thereby precluding a cure of infection. The best described latent reservoir is that of long-lived memory CD4+ T lymphocytes which contain a transcriptionally silent but replication competent provirus. Although mechanisms involved in latency in CD4+ T lymphocytes are incompletely understood, it is believed that multiple mechanisms act in concert to establish and maintain latency. Transcriptional interference by cellular genes at the site of integration can contribute to latency. Repressive chromatin is established for latent proviruses. Limiting levels of cellular transcription factors also make important contributions to latency, especially P-TEFb, a transcriptional elongation factor involved in the viral Tat protein's function Core P-TEFb is composed of Cyclin T1 (CCNT1) and CDK9. Recent results in a primary CD4+ T lymphocyte system of HIV-1 latency have shown that CCNT1 protein and CDK9 T-loop phosphorylation levels are down-regulated as latency is established. Conversely, CCNT1 and T-loop phosphorylation are up- regulated in this system when latent viruses are induced by T cell activation. These findings suggest that down-regulation of CCNT1 is an important and perhaps essential event in the establishment of latency. The research proposed here will test the hypothesis that down-regulation of P-TEFb can drive HIV-1 latency in CD4+ T lymphocytes. The research will also investigate mechanisms involved in the down-regulation of CCNT1 and mechanisms that regulate CDK9 T-loop phosphorylation in resting and activated CD4+ T lymphocytes. Finally, the research will determine if selective up-regulation of P-TEFb can contribute to reactivation of latent HIV-1 in a primary cell system of latency. Completion of the research will determine if P- TEFb is a key cellular factor for establishment and maintenance of HIV-1 latency. The research has the potential to establish P-TEFb as an important therapeutic target to reactivate latent viruses and thereby cure HIV-1 infection.