MHC Ⅱ类分子HLA-DM在HTLV-1复制过程中的功能和机制研究

The major histocompatibility complex(MHC) molecules have important functions in many aspects such as antigen presentation,induction of immune response and so on.HTLV-1,as a kind of endogenous antigen,is presented to T lymphocytes by MHC classⅠ molecules and induces immune response.So MHC classⅠmolecules are very important in HTLV-1 infection. However, the role of MHC classⅡ molecules play in this course is not clear now. We have found that the expression of HLA-DM,the non-classic MHC classⅡmolecules,is upregulated and co-localized with autophagy-associated protein LC3 in HTLV-1 infected cells.Based on above,we propose the hypothesis that HLA-DM has effect on the replication of HTLV-1 through antophagy.We will investigate the relationship between HLA-DM and the replication of HTLV-1, and explore whether autophagy plays a role in this course by the methods of immune fluorescence staining, co-immunoprecipitation, RNAi silence and western blot etc., and using the instruments of confocal micros cope and flow cytometry etc. It will be firstly revealed that mechanism of HLA-DM action to HTLV-1 replication.The result will contribute to understand HTLV-1 infection and provide new treatment target for HTLV-1 associated illnesses.

主要组织相容性复合体（MHC）在抗原递呈、诱导免疫应答等方面具有重要功能。HTLV-1作为内源性抗原，主要由MHCⅠ类分子递呈给T淋巴细胞而诱导免疫反应，因此MHCⅠ类分子在HTLV-1的感染过程中具有重要作用。而MHCⅡ类分子在此过程中发挥的作用尚不清楚。我们研究发现，在HTLV-1感染的细胞中，非经典MHCⅡ类分子HLA-DM表达升高，并与自噬蛋白LC3存在共定位现象。据此我们提出假说，HLA-DM能够通过自噬来影响HTLV-1的复制。我们拟利用共聚焦显微镜、流式细胞仪等仪器，采用免疫荧光染色、免疫共沉淀、RNAi沉默、western-blot等方法，研究HLA-DM与HTLV-1复制的关系，并探索自噬是否参与此过程。本项目将首次阐述MHCⅡ类分子HLA-DM在HTLV-1复制过程中的作用机制，不仅有利于深入理解HTLV-1的感染机理，也将为HTLV-1相关疾病的治疗提供新靶点。

自噬在病毒感染中的作用很复杂。虽然已经证明自噬可以通过消除细胞内的病毒和调节适应性免疫而在宿主抗病毒防御中起作用，但是一些病毒已经进化出了从自噬中获益的分子机制。有文献报道，自噬体积累过程对于1型人类T细胞白血病病毒（HTLV-1）的复制是有利的。在本项目中，我们研究了HLA-DMB（我们称为DMB），即非经典MHC-II蛋白HLA-DM的β链，在HTLV-1转化的T细胞系中具有高表达；并且HTLV-1感染后，在Hela，PMA分化的THP1（PMA-THP1）或原代人单核细胞也有诱导表达。WB和qPCR分析表明DMB的过表达降低了HTLV-1蛋白的表达，而沉默DMB后HTLV-1蛋白表达升高。免疫印迹和共聚焦检测表明，DMB的过表达可降低HTLV-1诱导的自噬体积累，而沉默DMB后产生相反的结果。进一步研究发现，DMB可以与自噬相关基因（ATG）7相互作用并增加了ATG7的乙酰化修饰。总之，这些结果表明DMB通过调节自噬体的积聚来调节HTLV-1蛋白的表达，提示了宿主细胞抵御HTLV-1感染的新机制。