CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
Front Immunol. 2020 Jul 14;11:1247. doi: 10.3389/fimmu.2020.01247. eCollection 2020.
Ostreid herpesvirus-1 microvariant (OsHV-1 μVar) is considered a major infectious microbe that can reduce the survival of natural or cultured oysters in summer. Because they lack an adaptive immune system, oysters are dependent on their innate immune systems to fight pathogens. The duplication and functional divergence of innate immune genes in the oyster have been studied, but the contribution of molecular mechanisms underlying innate immunity remains to be defined. Here, we identified the interacting proteins associated with Toll-like receptors (CgTLR) using a yeast two-hybrid (Y2H) screening system. A total of eight proteins were identified that could interact with CgTLR. Three of these appeared at least four times in the screening and were related to MyD88. Two genes encoding these MyD88-like proteins, CgMyD88-1 and CgMyD88-2, possessed typical death and TIR domains. The third gene encoding an MyD88-like protein possessed only a TIR domain, and we named it CgMyD88s. CgMyD88s interacted only with CgTLR, but not CgMyD88-1 or CgMyD88-2. Both CgMyD88-1 and CgMyD88-2 mRNAs were upregulated after OsHV-1 μVar infection, whereas the expression of CgMyD88s decreased. When overexpressed in HEK293T cells, CgMyD88-1 and CgMyD88-2 activated an NF-κB reporter, whereas CgMyD88s impaired activation induced by CgMyD88-1 or CgMyD88-2. Intriguingly, the silencing of CgMyD88s using double-stranded RNA (dsRNA)-mediated RNA interference increased the expression of CgMyD88-1 and CgMyD88-2. Taken together, our results revealed that CgMyD88-1, CgMyD88-2, and CgMyD88s may all participate in the TLR-mediated innate immune pathway and that CgMyD88s served as a plug to avoid oysters from excessive inflammatory response during OsHV-1 μVar infections.
牡蛎疱疹病毒 1 微变体（OsHV-1 μVar）被认为是一种主要的传染性微生物，它会降低夏季天然或养殖牡蛎的存活率。由于牡蛎缺乏适应性免疫系统，因此它们依赖于先天免疫系统来抵御病原体。牡蛎中先天免疫基因的复制和功能分化已经得到研究，但先天免疫的分子机制的贡献仍有待确定。在这里，我们使用酵母双杂交（Y2H）筛选系统鉴定了与 Toll 样受体（CgTLR）相互作用的蛋白。总共鉴定出 8 种可以与 CgTLR 相互作用的蛋白。其中三种在筛选中至少出现了四次，与 MyD88 有关。编码这两种 MyD88 样蛋白的两个基因，CgMyD88-1 和 CgMyD88-2，具有典型的死亡和 TIR 结构域。第三个编码 MyD88 样蛋白的基因仅具有一个 TIR 结构域，我们将其命名为 CgMyD88s。CgMyD88s 仅与 CgTLR 相互作用，而不与 CgMyD88-1 或 CgMyD88-2 相互作用。在 OsHV-1 μVar 感染后，CgMyD88-1 和 CgMyD88-2 的 mRNA 均上调，而 CgMyD88s 的表达则下调。当在 HEK293T 细胞中过表达时，CgMyD88-1 和 CgMyD88-2 激活了 NF-κB 报告基因，而 CgMyD88s 则削弱了由 CgMyD88-1 或 CgMyD88-2 诱导的激活。有趣的是，用双链 RNA（dsRNA）介导的 RNA 干扰沉默 CgMyD88s 会增加 CgMyD88-1 和 CgMyD88-2 的表达。总之，我们的结果表明，CgMyD88-1、CgMyD88-2 和 CgMyD88s 可能都参与了 TLR 介导的先天免疫途径，而 CgMyD88s 则作为一种塞子，避免牡蛎在 OsHV-1 μVar 感染期间发生过度炎症反应。
