School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230026, China; Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650204, China.
Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650204, China; KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650204, China; National Resource Center for Non-Human Primates, National Research Facility for Phenotypic & Genetic Analysis of Model Animals (Primate Facility), Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650107, China.
Dev Comp Immunol. 2022 Feb;127:104307. doi: 10.1016/j.dci.2021.104307. Epub 2021 Nov 5.
DNA damage inducible transcript 3 (DDIT3, also known as CHOP) belongs to the CCAAT/enhancer-binding protein (C/EBP) family and plays an essential role in endoplasmic reticulum stress. Here, we characterized the potential role of the Chinese tree shrew (Tupaia belangeri chinensis) DDIT3 (tDDIT3) in viral infections. The tDDIT3 protein is highly conserved and has a species-specific insertion of the SQSS repeat upstream of the C-terminal basic-leucine zipper (bZIP) domain. Phylogenetic analysis of DDIT3 protein sequences of tree shrew and related mammals indicated a closer genetic affinity between tree shrew and primates than between tree shrew and rodents. Three positively selected sites (PSSs: Glu83, Pro93, and Ser172) were identified in tDDIT3 based on the branch-site model. Expression analysis of tDDIT3 showed a constitutively expressed level in different tissues and a significantly increased level in tree shrew cells upon herpes simplex virus type 1 (HSV-1) and Newcastle disease virus (NDV) infections. Overexpression of tDDIT3 significantly increased the production of HSV-1 and vesicular stomatitis virus (VSV) in tree shrew primary renal cells (TSPRCs), whereas tDDIT3 knockout in tree shrew stable cell line (TSR6 cells) had an inhibitory effect on virus production. The enhanced effect on viral infection by tDDIT3 was not associated with the three PSSs. Mechanistically, tDDIT3 overexpression inhibited type I IFN signaling. tDDIT3 interacted with tMAVS through CARD and PRR domains, but not with other immune-related factors such as tMDA5, tSTING and tTBK1. Collectively, our results revealed tDDIT3 as a negative regulator for virus infection.
DNA 损伤诱导转录因子 3（DDIT3，也称为 CHOP）属于 CCAAT/增强子结合蛋白（C/EBP）家族，在内质网应激中发挥重要作用。在这里，我们研究了中国树鼩（Tupaia belangeri chinensis）DDIT3（tDDIT3）在病毒感染中的潜在作用。tDDIT3 蛋白高度保守，在 C 端碱性亮氨酸拉链（bZIP）结构域上游有一个物种特异性的 SQSS 重复插入。树鼩和相关哺乳动物的 DDIT3 蛋白序列的系统发育分析表明，树鼩与灵长类动物的遗传亲和力比树鼩与啮齿类动物更密切。基于分支位点模型，在 tDDIT3 中鉴定出 3 个正选择位点（PSS：Glu83、Pro93 和 Ser172）。tDDIT3 的表达分析表明，它在不同组织中呈组成型表达，在树鼩细胞中感染单纯疱疹病毒 1（HSV-1）和新城疫病毒（NDV）后表达水平显著增加。tDDIT3 的过表达显著增加了 HSV-1 和水疱性口炎病毒（VSV）在树鼩原代肾细胞（TSPRCs）中的产量，而 tDDIT3 在树鼩稳定细胞系（TSR6 细胞）中的敲除对病毒产量有抑制作用。tDDIT3 对病毒感染的增强作用与 3 个 PSS 无关。在机制上，tDDIT3 过表达抑制了 I 型 IFN 信号通路。tDDIT3 通过 CARD 和 PRR 结构域与 tMAVS 相互作用，但不与其他免疫相关因子如 tMDA5、tSTING 和 tTBK1 相互作用。总之，我们的研究结果揭示了 tDDIT3 作为病毒感染的负调控因子。
