脂代谢相关因子促进新冠病毒复制的分子机理研究

新冠病毒已成为目前全球关注的重大公共卫生问题。解析脂代谢因子在新冠病毒复制中的作用机理利于人们获得新的抗病毒靶标。我们的前期研究表明：脂代谢相关因子DGAT2/IRE1α/SCD1的沉默可显著抑制新冠病毒的复制；进一步发现DGAT2通过与病毒蛋白Nsp8结合介导脂滴与病毒复制复合物的互作；IRE1α经UPR通路上调SCD1表达，从而调控脂代谢发挥促病毒作用；此外，SCD1蛋白的稳定性依赖于DGAT2。在此基础上，本项目拟在多种细胞模型中，明确DGAT2/IRE1α/SCD1的促病毒效应及作用环节；解析它们促病毒所需的结构域和酶活性位点；探索这三个宿主因子、脂代谢和病毒复制之间的内在联系；评估DGAT2/IRE1α/SCD1抑制剂的抗病毒效应。本项目研究结果对于阐明新冠病毒与宿主互作的分子机制具有重要的理论意义，也为DGAT2/IRE1α/SCD1的特异靶向药物的研发提供前瞻性数据。

SARS-CoV-2 has become a major global public health problem. Thus, identifying lipid metabolism associated host factors and clarifying their molecular mechanisms will benefit the development of novel anti-SARS-CoV-2 targets. Our preliminary work demonstrated that knockdown of lipid metabolism associated factor diacylglycerol O-acyltransferase 2 (DGAT2)/inositol-requiring enzyme-1α (IRE1α)/stearoyl-CoA desaturase-1 (SCD1) significantly inhibited SARS-CoV-2 replication. Further studies showed that DGAT2 mediated the interaction between lipid droplet and SARS-CoV-2 replication complex through binding viral protein Nsp8. We also showed that IRE1α up-regulated the expression of SCD1 through UPR signaling pathway, then enhancing the lipid metabolism and ultimately promoting viral replication. In addition, the protein stability of SCD1 relies on DGAT2. Based on these results, our goal is to elucidate the above mechanisms by intensive research. The specific aims of the proposed studies are: 1) To demonstrate the functions of DGAT2/IRE1α/SCD1 promoting SARS-CoV-2 replication in a variety of cell models and to identify which step of SARS-CoV-2 life cycle they act on; 2) To explore the key domains and enzyme active site(s) mediating their pro-viral functions; 3) To verify the relationship between DGAT2/IRE1α/SCD1, lipid metabolism, and SARS-CoV-2 replication; 4) To test the anti-viral effects of DGAT2/IRE1α/SCD1 inhibitors in SARS-CoV-2-infected cell models. The studies of the project will provide theoretical evidence for the molecular mechanisms of the interaction between SARS-CoV-2 and host, and will contribute prospective data to the development of DGAT2/IRE1α/SCD1-specific targeted drugs.