宿主细胞蛋白NPM1在PCV2核酸解超螺旋过程中的作用及机制研究

The pathogenicity of virus is closely related to its replication level in vivo, and the viral genome untwisting is a key step of viral nucleic acid replication initiation. In recent years, nucleophosmin 1 (NPM1) is found to be the key protein that associated with the DNA untwisting of cells. Our previous work found that knockout of the PCV2 interacting protein NPM1 significantly suppressed the replication of PCV2 in cells. And the PCV2 DNA could not be untwist. Further studies found that PCV2 infection did not alter the expression of NPM1 at different times, suggesting that NPM1 may regulate the process of PCV2 DNA untwisting by its post-translational modification. In this project, we will firstly screen the post-translational modification methods and locus for NPM1 during regulating of PCV2 DNA untwisting. Then the role of the confirmed NPM1 post-translational modification in PCV2 DNA untwisting will be clarified. Furthermore, the mechanism of NPM1 recruiting host molecules to regulate the process of PCV2 DNA untwisting will be further determined. The prospective results will help us to clarify the role and mechanism of NPM1 in regulation of PCV2 DNA untwisting, and will laid a theoretical foundation for further study the pathogenic mechanism of PCV2.

病毒的致病性与其在体内的复制水平密切相关，而病毒基因组解超螺旋是病毒核酸复制起始的关键步骤。近年来研究发现，核仁磷酸蛋白1（NPM1）是调控细胞内核酸解超螺旋的关键蛋白。我们前期研究发现，敲除PCV2互作蛋白NPM1能显著抑制PCV2在细胞内的复制，且PCV2核酸不能解超螺旋；进一步研究发现，NPM1表达水平未随着PCV2感染时间发生变化，结果提示NPM1可能是通过翻译后修饰调控PCV2核酸解超螺旋，但NPM1在PCV2核酸解超螺旋过程中的具体作用及机制尚不清楚。本项目拟首先筛选NPM1调控PCV2核酸解超螺旋的翻译后修饰方式及位点，然后明确NPM1翻译后修饰在PCV2核酸解超螺旋过程中的作用，进一步确定NPM1募集宿主分子调控PCV2核酸解超螺旋过程的机制。研究结果将揭示NPM1在PCV2核酸解超螺旋过程中的作用及机制，为进一步研究PCV2复制机制奠定基础。

猪圆环病毒2型（porcine circovirus type 2，PCV2）是危害养猪业的重要病原，其感染导致仔猪病变的严重程度与仔猪体内病毒的量密切相关。近年来研究发现，核仁磷酸蛋白1（NPM1）是调控细胞内核酸复制的关键蛋白。我们前期研究发现，敲除PCV2互作蛋白NPM1能显著抑制PCV2在细胞内的复制，且PCV2核酸不能解超螺旋；进一步研究发现，NPM1表达水平未随着PCV2感染时间发生变化，结果提示NPM1可能是通过翻译后修饰调控PCV2核酸解超螺旋，但NPM1在PCV2核酸解超螺旋过程中的具体作用及机制尚不清楚。本研究发现，PCV2感染PK-15细胞后，通过Cap激活ERK/Ubc9信号通路，使SUMO2/3结合至宿主蛋白NPM1的K263位点，促进NPM1的SUMO化修饰，进而促进其进入细胞核仁，有助于PCV2 DNA的复制。研究结果将揭示NPM1在PCV2核酸解超螺旋过程中的作用及机制，为进一步研究PCV2复制机制奠定基础。

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