Virus-inducible IGFALS facilitates innate immune responses by mediating IRAK1 and TRAF6 activation
Virus-inducible IGFALS facilitates innate immune responses by mediating IRAK1 and TRAF6 activation
复制标题
DOI：
10.1038/s41423-021-00649-0
复制
发表时间：
2021-03
影响因子：
24.1
通讯作者：
Gang Xu;Feiyan Deng;Qi Zuo;Lin Liu;Kaiwen Dou;Zhikui Cheng;W. Cao;Chuanjin Luo;Chen Yu;Shi Liu;Ying Zhu
中科院分区：
文献类型：
--
作者：
Gang Xu;Feiyan Deng;Qi Zuo;Lin Liu;Kaiwen Dou;Zhikui Cheng;W. Cao;Chuanjin Luo;Chen Yu;Shi Liu;Ying Zhu
TLR信号的激活是宿主防御系统清除入侵病原体的第一道防线。1胰岛素样生长因子结合蛋白，酸不稳定亚基(IGFALS)是一种富含亮氨酸的糖蛋白。通过延长IGF-I在血管系统中的半衰期，2IGFALS调节IGF的生物利用度，这对正常生长发育和代谢调节至关重要。3、4然而，IGFALS在抗病毒先天免疫反应中的作用尚未确定。在这项研究中，我们发现IGFALS是病毒诱导的，而它反过来又抑制病毒的复制。在机制上，IGFALS直接与IRAK1和TRAF6结合，促进IRAK1/TRAF6复合体的形成，并促进这两种蛋白的K63连接的多泛素化以充分激活，从而促进抗病毒信号转导。首先，我们评估了病毒和IGFALS之间的相互作用。IGFALS蛋白的表达随着IAV或SeV感染而显著增强(图1A)。此外，在IGFALS过表达的A549细胞中，IAV的复制受到抑制(图1B)。此外，IGFALS的异常表达降低了SeV的复制(图1C)。然后，我们构建了针对IGFALS的特异性shRNA。与上述发现一致的是，IGFALS基因敲除增强了EV71感染的RD细胞中VP1mRNA的水平(图1D)。接下来，我们制备了小鼠胚胎成纤维细胞(MEF)，以证实IGFALS的抗病毒活性。我们发现，在IGFALS缺陷的MEF中，EV71 VP1的mRNA和蛋白水平都升高(图1E)。抗病毒信号级联的激活导致I型和III型干扰素(IFN)的产生。5定量聚合酶链式反应实验结果表明，IGFALS的过表达增强了VSV诱导的干扰素的产生(图1F)。此外，我们还产生了IGFALS缺陷的脾细胞；qPCR分析结果表明
Activation of TLR signaling is a first line of the host defense system in the elimination of invading pathogens. 1 Insulin-like growth factor binding protein, acid-labile subunit (IGFALS) is a leucine-rich glycoprotein. By prolonging the half-life of IGF-I in the vascular system, 2 IGFALS regulates the bioavailability of IGF, which is crucial for normal growth and development and metabolic regulation. 3, 4 However, the role of IGFALS in antiviral innate immune responses has not been established. In this study, we found that IGFALS is virus inducible, while it in turn inhibits viral replication. Mechanistically, IGFALS directly associates with IRAK1 and TRAF6, facilitating IRAK1/TRAF6 complex formation and enhancing K63-linked polyubiquitination of both proteins for full activation, thereby facilitating antiviral signaling. First, we assessed the interplay of viruses and IGFALS. IGFALS protein expression was significantly enhanced with IAV or SeV infection (Fig. 1 A). In addition, IAV replication was inhibited in A549 cells with IGFALS overexpression (Fig. 1 B). Moreover, aberrant expression of IGFALS diminished SeV replication (Fig. 1 C). Then, we constructed specific shRNAs targeting IGFALS. Consistent with the above findings, IGFALS knockdown enhanced VP1 mRNA levels in EV71-infected RD cells (Fig. 1 D). Next, we generated mouse embryonic fibroblasts (MEFs) to confirm the antiviral activity of IGFALS. We found that both the mRNA and protein levels of EV71 VP1 were elevated in IGFALS-deficient MEFs (Fig. 1 E).Activation of antiviral signaling cascades leads to the production of type I and III interferons (IFNs). 5 The results of qPCR experiments indicated that overexpression of IGFALS potentiated VSV-induced IFN production (Fig. 1 F). Furthermore, we generated IGFALS-deficient splenocytes; the qPCR analysis results demonstrated that