Jamaluddin Md Saha, Hu Pei-Wen, Jan Yih, Siwak Edward B, Rice Andrew P
Department of Molecular Virology and Microbiology, Baylor College of Medicine , Houston, Texas.
AIDS Res Hum Retroviruses. 2016 Feb;32(2):169-73. doi: 10.1089/AID.2015.0347.
Cessation of highly active antiretroviral therapy (HAART) in HIV-infected individual leads to a rebound of viral replication due to reactivation of a viral reservoir composed largely of latently infected memory CD4(+) T cells. Efforts to deplete this reservoir have focused on reactivation of transcriptionally silent latent proviruses. HIV provirus transcription depends critically on the positive transcription elongation factor b (P-TEFb), whose core components are cyclin-dependent kinase 9 (CDK9) and cyclin T1. In resting CD4(+) cells, the functional levels of P-TEFb are extremely low. Cellular activation upregulates cyclin T1 protein levels and CDK9 T-loop (T186) phosphorylation. The broad-spectrum histone deacetylase inhibitors (HDACis) vorinostat and panobinostat have been shown to reactivate latent virus in vivo in HAART-treated individuals. In this study, we have found that vorinostat and panobinostat activate P-TEFb in resting primary CD4(+) T cells through induction of CDK9 T-loop phosphorylation. In contrast, tacedinaline and romidepsin, HDAC 1 and 2 inhibitors, were unable to activate CDK9 T-loop phosphorylation. We used a CCL19 primary CD4(+) T-cell model HIV latency to assess the correlation between induction of CDK9 T-loop phosphorylation and reactivation of latent HIV virus by HDACis. Vorinostat and panobinostat treatment of cells harboring latent HIV increased CDK9 T-loop phosphorylation and reactivation of latent virus, whereas tacedinaline and romidepsin failed to induce T-loop phosphorylation or reactivate latent virus. We conclude that the ability of vorinostat and panobinostat to induce latent HIV is, in part, likely due to the ability of the broad-spectrum HDACis to upregulate P-TEFb through increased CDK9 T-loop phosphorylation.
在感染HIV的个体中，停止高效抗逆转录病毒疗法（HAART）会导致病毒复制反弹，这是由于主要由潜伏感染的记忆CD4(+) T细胞组成的病毒储存库重新激活所致。耗尽这个储存库的努力主要集中在重新激活转录沉默的潜伏前病毒。HIV前病毒转录关键依赖于正转录延伸因子b（P-TEFb），其核心成分是细胞周期蛋白依赖性激酶9（CDK9）和细胞周期蛋白T1。在静止的CD4(+)细胞中，P-TEFb的功能水平极低。细胞活化会上调细胞周期蛋白T1蛋白水平和CDK9 T环（T186）磷酸化。广谱组蛋白去乙酰化酶抑制剂（HDACis）伏立诺他和帕比司他已被证明能在接受HAART治疗的个体体内重新激活潜伏病毒。在本研究中，我们发现伏立诺他和帕比司他通过诱导CDK9 T环磷酸化，在静止的原代CD4(+) T细胞中激活P-TEFb。相比之下，HDAC 1和2抑制剂他西那林和罗米地辛无法激活CDK9 T环磷酸化。我们使用CCL19原代CD4(+) T细胞模型的HIV潜伏性来评估CDK9 T环磷酸化的诱导与HDACis重新激活潜伏HIV病毒之间的相关性。用伏立诺他和帕比司他处理携带潜伏HIV的细胞会增加CDK9 T环磷酸化和潜伏病毒的重新激活，而他西那林和罗米地辛未能诱导T环磷酸化或重新激活潜伏病毒。我们得出结论，伏立诺他和帕比司他诱导潜伏HIV的能力，部分可能是由于广谱HDACis通过增加CDK9 T环磷酸化来上调P-TEFb的能力。
