Host factors regulating HIV latency and reactivation

摘要 我们的中心前提是，HIV转录抑制剂可以用作潜伏期促进剂（LPAs）， 阻断和锁定功能性治愈方法，旨在减少抗逆转录病毒治疗（ART）期间的残留病毒血症 以及限制治疗中断（TI）时的病毒反弹。这一假说是随着 达特抑制剂，双脱氢皮质抑素A（dCA）。在HIV潜伏期的体外和体内模型中，ART与 dCA加速HIV-1抑制至检测限以下，并阻断TI后的病毒反弹，或 用潜伏期逆转剂（LRA）刺激。通过dCA的转录关闭导致 HIV启动子处的异染色质化和RNAPII的丢失。我们最近报道了另一个LPA， 非专利药螺内酯（SP）。有趣的是，这种药物降解宿主XPB亚单位的一般 转录因子TFIIH抑制来自感染个体的原代细胞中的HIV转录并阻断病毒 从潜伏期重新激活而不影响细胞转录组学7.这项研究很重要，因为它强调了 宿主因子可以靶向沉默HIV而不影响细胞活力。总之，知识越多 我们了解了达特、转录因子调节机制之间的相互联系以及它们如何影响 核小体定位在HIV启动子周围，我们就越能利用转录调控因子， 抗病毒靶点 为了鉴定调节HIV转录的新宿主因子，我们使用染色质亲和纯化方法 与质谱法（ChAP-MS）一起。我们鉴定了p32（ASF/SF 2剪接因子相关蛋白） 和FUBP 3（远上游元件结合蛋白3）在生产性感染的ART处理的启动子中，但在 dCA处理的启动子中，HIV被沉默; PHB 2（抑制素-2）在dCA处理的启动子中富集， 只接受抗逆转录病毒治疗的人减少。这些结果表明，p32和FUBP 3是HIV转录因子。 激活因子，而PHB 2是HIV沉默因子。初步研究证实了它们在 艾滋病。在这里，我们提出了一个详细的分子机制研究如何p32和FUBP 3增强和如何PHB 2 抑制HIV转录。了解它们在前起始复合物（PIC）形成、起始、延伸中的作用 和核小体组织在潜伏的艾滋病毒启动子将是关键的发展成功的战略， 持久的艾滋病毒沉默。这些因素中的一个或多个的强烈影响将促进对小分子的搜索。 调制器。我们的首要目标是通过将潜伏的HIV前病毒驱动到稳定的 在异染色质中它们将保持“锁定”。我们提出以下目标： 目的1：明确p32、FUBP 3和PHB 2在HIV转录和染色质结构中的作用。 目的2：鉴定与p32、FUBP 3和PHB 2相关的蛋白复合物，并研究与达特的相互作用。 目标3：使用单个或多个因素及其相关性来研究“封锁”方法 在达特/TAR电路上。

Abstract Our central premise is that HIV transcriptional inhibitors can be used as latency promoting agents (LPAs) in block-and-lock functional cure approaches, aimed at reducing residual viremia during antiretroviral therapy (ART) and limiting viral rebound upon treatment interruption (TI). This hypothesis came about with the discovery of the Tat inhibitor, didehydro-Cortistatin A (dCA). In in vitro and in vivo models of HIV latency combining ART with dCA accelerated HIV-1 suppression to below the limit of detection and blocked viral rebound upon TI or stimulation with latency reversing agents (LRAs). The transcriptional shutdown by dCA resulted in the heterochromatinization and loss of RNAPII at the HIV promoter. We recently reported on another LPA, the generic drug Spironolactone (SP). Interestingly this drug degrades the host XPB subunit of the general transcription factor TFIIH inhibiting HIV transcription in primary cells from infected individuals and blocking viral reactivation from latency without affecting cellular transcriptomics7. This study is important because it highlights that a host factor can be targeted to silence HIV without affecting cellular viability. In sum, the more knowledge we gain on the interconnectivity between Tat, transcription factors regulatory mechanisms and how these affect nucleosomes positioning around the HIV promoter, the more we can leverage transcriptional regulators as antiviral targets. To identify novel host factors regulating HIV transcription we used a chromatin affinity purification approach together with mass spectrometry (ChAP-MS). We identified p32 (ASF/SF2 splicing factor-associated protein) and FUBP3 (Far upstream element binding protein 3) in productively infected ART treated promoters but not in dCA-treated where HIV was silenced; and PHB2 (prohibitin-2) was enriched in dCA treated promoters but reduced in ART only treated ones. These results suggest that p32 and FUBP3 are HIV transcriptional activators while PHB2 is a HIV silencing factor. Preliminary studies confirmed their transcriptional activity on HIV. Here we propose a detailed molecular mechanistic study on how p32 and FUBP3 enhance and how PHB2 inhibits HIV transcription. Understanding their role in pre-initiation complex (PIC) formation, initiation, elongation and nucleosome organization at the latent HIV promoter will be key for developing successful strategies for durable HIV silencing. Strong effects of one or more of these factors will prompt the search for small-molecule modulators. Our overarching goal is to durably silence latent HIV proviruses by driving each into stable heterochromatin where they will remain “locked.” We propose the following aims: Aim 1: Define the roles of p32, FUBP3 and PHB2 in HIV transcription and chromatin structure. Aim 2: Identify protein complexes associated with p32, FUBP3 and PHB2 and study interaction with Tat. Aim 3: Investigate the “block-and-lock” approach using single or combinations of factors and their dependence on Tat/TAR circuitry.