College of Life Science, Nanchang University, Nanchang, China.
Human Aging Research Institute, Nanchang University, Nanchang, China.
Front Immunol. 2021 Nov 22;12:762162. doi: 10.3389/fimmu.2021.762162. eCollection 2021.
Type I interferon and apoptosis elicit multifaceted effects on host defense and various diseases, such as viral infections and cancers. However, the gene/protein network regulating type I interferon and apoptosis has not been elucidated completely. In this study, we selected grass carp () as an experimental model to investigate the modulation of RNASEK on the secretion of type I interferon and apoptosis. We first cloned two paralogs RNASEK-a and -b in grass carp, defined three exons in each gene, and found the length of both coding regions is 306 bp with 73.27% of protein homology. The protein sequences of the two paralogs are highly conserved across species. Two proteins were mainly localized in early and late endosomes and endoplasmic reticulum. Further, quantitative real-time PCR demonstrated that dsRNA poly I:C and grass carp reovirus upregulated RNASEK-a and -b in grass carp cells and tissues. Overexpression of RNASEK-a and -b individually induced type I interferon expression and the phosphorylation of IRF3/IRF7 shown by Western blot and immunofluorescent staining, increased / mRNA ratio, DNA fragmentations, TUNEL-positive cells, and the proportion of Annexin V-positive signals in flow cytometry, and activated eIF2α, opposite to that observed when RNASEK-a and -b were knocked down in multiple cell types. Taken together, we claim for the first time that fish paralog proteins RNASEK-a and -b enhance type I interferon secretion and promote apoptosis, which may be involved in the phosphorylation of IRF3/IRF7 and eIF2α, respectively. Our study reveals a previously unrecognized role of RNASEK as a new positive regulator of type I interferon and apoptosis.
I 型干扰素和细胞凋亡对宿主防御和各种疾病（如病毒感染和癌症）产生多方面的影响。然而，调节 I 型干扰素和细胞凋亡的基因/蛋白质网络尚未完全阐明。在这项研究中，我们选择草鱼（）作为实验模型，研究 RNASEK 对 I 型干扰素和细胞凋亡分泌的调节作用。我们首先在草鱼中克隆了两个 RNASEK-a 和 -b 的同源基因，定义了每个基因的三个外显子，并发现两个编码区的长度均为 306bp，蛋白质同源性为 73.27%。两个同源基因的蛋白质序列在物种间高度保守。两种蛋白质主要定位于早期和晚期内体和内质网。进一步的定量实时 PCR 表明双链 RNA 聚 I:C 和草鱼呼肠孤病毒上调了草鱼细胞和组织中的 RNASEK-a 和 -b。单独过表达 RNASEK-a 和 -b 分别通过 Western blot 和免疫荧光染色诱导 I 型干扰素表达和 IRF3/IRF7 的磷酸化，增加 /mRNA 比值、DNA 片段化、TUNEL 阳性细胞和流式细胞术检测到的 Annexin V 阳性信号的比例，并激活 eIF2α，与在多种细胞类型中敲低 RNASEK-a 和 -b 时观察到的结果相反。总之，我们首次声称鱼类同源蛋白 RNASEK-a 和 -b 增强 I 型干扰素的分泌并促进细胞凋亡，这可能分别涉及 IRF3/IRF7 和 eIF2α 的磷酸化。我们的研究揭示了 RNASEK 作为 I 型干扰素和细胞凋亡的新的正调控因子的以前未被认识的作用。
