Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, China.
Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China.
Front Immunol. 2021 Mar 9;12:636806. doi: 10.3389/fimmu.2021.636806. eCollection 2021.
Interferon-induced transmembrane proteins (IFITMs) are novel viral restriction factors which inhibit numerous virus infections by impeding viral entry into target cells. To investigate the roles of IFITMs during fish virus infection, we cloned and characterized an IFITM1 homolog from orange spotted grouper () (EcIFITM1) in this study. EcIFITM1 encodes a 131-amino-acid polypeptide, which shares 64 and 43% identity with and , respectively. The multiple sequence alignment showed that EcIFITM1 contained five domains, including NTD (aa 1-45), IMD (aa 46-67), CIL (aa 68-93), TMD (aa 94-119), and CTD (aa 120-131). , the level of EcIFITM1 mRNA expression was significantly up-regulated in response to Singapore grouper iridovirus (SGIV), or red-spotted grouper nervous necrosis virus (RGNNV) infection. EcIFITM1 encoded a cytoplasmic protein, which was partly colocalized with early endosomes, late endosomes, and lysosomes. The ectopic expression of EcIFITM1 significantly inhibited the replication of SGIV or RGNNV, which was demonstrated by the reduced virus production, as well as the levels of viral gene transcription and protein expression. In contrast, knockdown of EcIFITM1 using small interfering RNAs (siRNAs) promoted the replication of both viruses. Notably, EcIFITM1 exerted its antiviral activity in the step of viral entry into the host cells. Furthermore, the results of non-targeted lipometabolomics showed that EcIFITM1 overexpression induced lipid metabolism remodeling . All of the detected ceramides were significantly increased following EcIFITM1 overexpression, suggesting that EcIFITM1 may suppress SGIV entry by regulating the level of ceramide in the lysosomal system. In addition, EcIFITM1 overexpression positively regulated both interferon-related molecules and ceramide synthesis-related genes. Taken together, our results demonstrated that EcIFITM1 exerted a bi-functional role, including immune regulation and lipid metabolism in response to fish virus infections.
干扰素诱导跨膜蛋白（IFITMs）是新型的病毒限制因子，通过阻碍病毒进入靶细胞来抑制多种病毒感染。为了研究 IFITMs 在鱼类病毒感染过程中的作用，本研究从斜带石斑鱼（Epinephelus coioides）中克隆和鉴定了一个 IFITM1 同源物（EcIFITM1）。EcIFITM1 编码一个 131 个氨基酸的多肽，与 和 的同源性分别为 64%和 43%。多重序列比对显示，EcIFITM1 包含五个结构域，包括 NTD（aa1-45）、IMD（aa46-67）、CIL（aa68-93）、TMD（aa94-119）和 CTD（aa120-131）。EcIFITM1 的 mRNA 表达水平在感染新加坡石斑鱼虹彩病毒（SGIV）或红鳍东方鲀神经坏死病毒（RGNNV）后显著上调。EcIFITM1 编码一个细胞质蛋白，部分与早期内体、晚期内体和溶酶体共定位。EcIFITM1 的异位表达显著抑制了 SGIV 或 RGNNV 的复制，这表现在病毒产量的降低，以及病毒基因转录和蛋白表达水平的降低。相比之下，使用小干扰 RNA（siRNA）敲低 EcIFITM1 则促进了两种病毒的复制。值得注意的是，EcIFITM1 在病毒进入宿主细胞的步骤发挥了其抗病毒活性。此外，非靶向脂质组学的结果表明，EcIFITM1 过表达诱导了脂质代谢重塑。EcIFITM1 过表达后，所有检测到的神经酰胺都显著增加，这表明 EcIFITM1 可能通过调节溶酶体系统中的神经酰胺水平来抑制 SGIV 的进入。此外，EcIFITM1 过表达正向调节干扰素相关分子和神经酰胺合成相关基因。总之，我们的研究结果表明，EcIFITM1 在鱼类病毒感染中发挥了双重功能，包括免疫调节和脂质代谢。
