ASH1L在HIV-1潜伏储存库形成和再激活中的作用及机制研究

HIV-1 reactivation with latency revering agents (LRAs) is the key step of “shock and kill” strategy. Due to the limitation of the existing LRAs in clinical application, the explorations of new LRAs with high efficacy and safety are urgent for HIV-1 cure. Histone methylated modifications likely play key roles in HIV-1 latency and reactivation by regulating chromatin-remodeling complexes. As a key factor involved in post-translational histone modifications, ASH1L was mainly focused on immune response and tumorigenesis, and the relationship between ASH1L and HIV-1 latency has not been fully elucidated. In our preliminary study, we found long term non-progressors (LTNP) possess significantly high ASH1L expression in CD4+ and resting CD4+ T cells, compared with HIV-1 acute and chronic infected individuals. In addition, knockdown of ASH1L reactivated latent HIV-1 replication in T cell line (J-Lat 5A8), which indicated that ASH1L could participate in HIV-1 latency and reactivation. In the proposed studies, we aim to investigate the mechanisms of ASH1L mediated HIV-1 latent reactivation and identify the active motif of the ASH1L. All these results shall provide new targets and approaches for clinical explorations of LRAs in HIV-1 eradication.

HIV-1潜伏储存库的再激活是“激活再清除”治疗策略的关键环节。鉴于现有潜伏激活剂的不足，寻找新的安全高效的激活剂对于艾滋病的彻底治愈至关重要。研究表明，组蛋白甲基化修饰通过调控染色质的致密和疏松状态，进而影响HIV-1潜伏储存库的形成和再激活。甲基转移酶ASH1L是参与组蛋白翻译后修饰的关键分子，与机体的免疫应答、肿瘤发生等密切相关，但目前尚无ASH1L与HIV-1潜伏感染的相关报道。我们前期研究发现，与HIV-1急性、慢性感染患者相比，ASH1L在长期无进展者体内的表达显著升高，而干扰ASH1L后，潜伏的HIV-1重新复制，提示ASH1L可能参与HIV-1潜伏储存库的形成和再激活。本研究在此基础上，拟利用各种细胞与分子生物学技术，深入探讨ASH1L介导的甲基化修饰在HIV-1潜伏储存库再激活中的作用机制，明确ASH1L的活性结构域，最终为HIV-1潜伏激活剂的研发提供新靶点和新策略。

HIV的转录潜伏期是根除病毒的最后一个屏障。染色质重塑复合体和翻译后组蛋白修饰在HIV-1重新激活中起关键作用，但其潜在机制尚不完全清楚。我们确定ASH1L是一种调节HIV-1潜伏病毒库的赖氨酸甲基转移酶。在T细胞系和原代CD4+T细胞中，ASH1L基因的敲降重新激活了潜伏的HIV-1。ASH1L与潜伏的HIV-1启动子染色质有关，并在组蛋白H3第4位赖氨酸三甲基化位点富集(H3K4me3)。L3MBTL1，一种具有染色质压缩特性的识别H3K4me3的阅读器蛋白，以ASH1L依赖的方式被招募到潜在的HIV-1启动子上。我们认为ASH1L-H3K4me3-L3MBTL1轴与HIV-1潜伏期有关，可作为小分子ASH1L抑制剂的靶点。