Poddar Darshana, Sharma Nikhil, Ogino Tomoaki, Qi Xu, Kessler Patricia M, Mendries Hiran, Dutta Ranjan, Sen Ganes C
Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.
Department of Medical Microbiology and Immunology, College of Medicine and Life Sciences, The University of Toledo, Toledo, Ohio, USA.
mBio. 2024 Jul 17;15(7):e0056824. doi: 10.1128/mbio.00568-24. Epub 2024 Jun 18.
The interferon (IFN) system protects mammals from diseases caused by virus infections. IFN synthesis is induced by pattern recognition receptor signaling pathways activated by virus infection. IFN is secreted from the infected cells and acts upon neighboring cells by binding cell surface receptors and triggering induction of hundreds of IFN-stimulated genes and proteins, many of which block different steps of virus replication. The IFN-induced tetratricopeptide repeat proteins (IFIT) are a family of RNA-binding proteins. We and others have previously reported that IFIT2 protects mice from many neurotropic RNA viruses; indeed, Ifit2-/- mice are very susceptible to intranasal or subcutaneous infections with vesicular stomatitis virus (VSV). Here, using a newly generated conditional knockout mouse, we report that ablation of Ifit2 expression only in neuronal cells was sufficient to render mice susceptible to neuropathogenesis caused by intranasal, but not subcutaneous, infection of VSV. Another genetically modified mouse line, expressing a mutant IFIT2 that cannot bind RNA, was as susceptible to VSV infection as -/- mice. These results demonstrated that IFIT2 RNA-binding activity is essential for protecting mice against neurological diseases caused by intranasal infection of VSV.IMPORTANCEInterferon's (IFN's) antiviral effects are mediated by the proteins encoded by the interferon-stimulated genes. IFN-stimulated genes (IFIT2) is one such protein, which inhibits replication of many RNA viruses in the mouse brain and the resultant neuropathology. Our study sheds light on how IFIT2 works. By ablating Ifit2 expression only in neuronal cells, using a newly generated conditional knockout mouse line, we showed that Ifit2 induction in the neurons of the infected mouse was necessary for antiviral function of interferon. IFIT2 has no known enzyme activity; instead, it functions by binding to cellular or viral proteins or RNAs. We engineered a new mouse line that expressed a mutant IFIT2 that cannot bind RNA. These mice were very susceptible to infection with vesicular stomatitis virus indicating that the RNA-binding property of IFIT2 was essential for its antiviral function .
干扰素（IFN）系统保护哺乳动物免受病毒感染引起的疾病。IFN的合成由病毒感染激活的模式识别受体信号通路诱导。IFN从受感染细胞分泌，通过结合细胞表面受体作用于邻近细胞，并触发数百种IFN刺激基因和蛋白质的诱导，其中许多可阻断病毒复制的不同步骤。IFN诱导的四肽重复蛋白（IFIT）是一类RNA结合蛋白。我们和其他人之前曾报道，IFIT2可保护小鼠免受多种嗜神经性RNA病毒的侵害；事实上，Ifit2-/-小鼠对水泡性口炎病毒（VSV）的鼻内或皮下感染非常敏感。在此，我们使用新生成的条件性敲除小鼠，报告仅在神经元细胞中敲除Ifit2表达就足以使小鼠易受鼻内（而非皮下）VSV感染引起的神经病变。另一种基因改造的小鼠品系表达一种无法结合RNA的突变型IFIT2，其对VSV感染的易感性与Ifit2-/-小鼠相同。这些结果表明，IFIT2的RNA结合活性对于保护小鼠免受鼻内VSV感染引起的神经疾病至关重要。重要性干扰素的抗病毒作用由干扰素刺激基因编码的蛋白质介导。干扰素刺激基因（IFIT2）就是这样一种蛋白质，它可抑制许多RNA病毒在小鼠脑中的复制以及由此产生的神经病理学变化。我们的研究揭示了IFIT2的作用机制。通过使用新生成的条件性敲除小鼠品系仅在神经元细胞中敲除Ifit2表达，我们表明受感染小鼠神经元中Ifit2的诱导对于干扰素的抗病毒功能是必要的。IFIT2没有已知的酶活性；相反，它通过与细胞或病毒蛋白或RNA结合发挥作用。我们构建了一个新的小鼠品系，该品系表达一种无法结合RNA的突变型IFIT2。这些小鼠对水泡性口炎病毒感染非常敏感，表明IFIT2的RNA结合特性对其抗病毒功能至关重要。
