SUN-KASH跨核膜复合物的组装调控与抗病毒功能机制

Nuclear envelope (NE) functions as a selective barrier to maintain the integrity of genetic material. The NE consists of two lipid bilayers, the inner and the outer nuclear membrane (INM and ONM), which are connected at nuclear pores. NE is closely related to infectious diseases.. However, the specific function and mechanism of NE relevant to virus infection and host antiviral immune responses have not been clearly defined to date. Our recent structural and biochemical studies of the NE-spanning complex formed by INM protein SUN and ONM protein KASH revealed that SUN domain associates as a homo-trimer, which function as a primary binding unit to recruit three independent "hook"-like KASH peptide. Based on these work, the applicant will continue focusing on the SUN-KASH complex, in order to define the assembly features of the whole complex, as well as its regulatory machinery relevant to virus infection and antiviral immune response of host cell. Our preliminary studies have shown that SUN2 significantly inhibits HIV replication, and that its mutation that abrogates the interaction between SUN and KASH could block this inhibitory effect on HIV replication. These results indicate that the correct assembly of SUN-KASH complex is important for antiviral immune regulation. The applicant will extend her study along this line and further investigates the specific function and mechanism of the SUN-KASH complex during virus infection, aiming to resolve the regulatory nature of antiviral signaling and find possible targets for efficient antiviral therapy.

核膜功能异常与病毒性疾病的发生密切相关。然而目前对于核膜在病毒侵染与宿主免疫应答过程中的功能和作用机制仍未明晰。申请人所在实验室在跨核膜复合物SUN-KASH的结构生物学研究方面已取得并发表了重要研究成果。本项目拟继续围绕SUN-KASH复合物，深入探索其动态组装与功能调控，着重研究其抗病毒功能作用及信号转导机理。我们初步研究证实SUN2在病毒侵染与宿主免疫应答过程中发挥重要功能，并且进一步发现靶向SUN-KASH复合物组装的SUN2突变体破坏了其与KASH相互作用，同时丧失了对HIV病毒复制的抑制作用，提示该复合物的组装调控与其抗病毒功能存在紧密联系。在此基础上，申请者将从复合物整体组装以及相互作用调控，病毒识别受体的活化、抗病毒信号转导、炎症因子及干扰素分泌等多个角度出发，进一步阐释SUN-KASH复合物在病毒侵染与宿主应答过程中的功能与机制，为新型抗病毒策略的研发提供理论依据和靶点。

核膜功能异常与病毒性疾病的发生密切相关。然而目前对于核膜在病毒侵染与宿主免疫应答过程中的功能和作用机制仍未明晰。本项目围绕SUN-KASH复合物，深入探索其动态组装与功能调控，着重研究其抗病毒功能作用及信号转导机理。我们通过对SUN2蛋白进行质谱分析，发现了β-TrCP1/2可以调控SUN2的蛋白水平，进一步的机制研究发现CK2-β-TrCP1/2通过泛素化及蛋白酶体降解的途径影响SUN2的蛋白水平，并进一步影响SUN-KASH复合物在细胞核膜上的机械支持作用。同时，采用荧光原位杂交（FISH）的实验方法，该复合物对HIV病毒的转录抑制作用很可能与SUN2参与HIV转录中染色质构象变化的相关过程。进一步地，我们还探究了该复合物在巨噬细胞激活及功能可塑性方面的功能与机制。这些研究成果为进一步阐释SUN-KASH 复合物在病毒侵染与宿主应答过程中的功能与机制，为新型抗病毒策略的研发提供理论依据和靶点。