RLRs家族中RIG-I和MDA-5的研究进展

非特异性固有免疫是预防病毒感染的第一道防线,Toll样受体(toll-like receptors,TLRs)和维甲酸诱导基因I样受体(RIG-I like receptors,RLRs)是感知病毒RNA的两个主要受体家族。RLRs为存在于胞浆中的RNA解旋酶家族,可识别在病毒感染或复制期间进入到胞浆内的单链或双链RNA。目前研究RLRs家族比较多的成员有维甲酸诱导型基因I(retinoic acid-inducible gene I,RIG-I)、黑色素瘤分化相关基因5(melanoma differentiation associated gene-5,MDA-5)及遗传学和生理学实验室蛋白2(laboratory of genetics and physiology 2,LGP2)。本文分别就RLRs家族中RIG-I和MDA-5结构、生物学作用及其信号传导中关键分子的研究进展作一概述。

Long noncoding RNA 1392 regulates MDA5 by interaction with ELAVL1 to inhibit coxsackievirus B5 infection

Long noncoding RNAs(lncRNAs)modulate many aspects of biological and pathological processes.Recent studies have shown that host lncRNAs participate in the antiviral immune response,but functional lncRNAs in coxsackievirus B5(CVB5)infection remain unknown.Here,we identified a novel cytoplasmic lncRNA,LINC1392,which was highly inducible in CVB5 infected RD cells in a time-and dose-dependent manner,and also can be induced by the viral RNA and IFN-β.Further investigation showed that LINC1392 promoted several important interferon-stimulated genes(ISGs)expression,including IFIT1,IFIT2,and IFITM3 by activating MDA5,thereby inhibiting the replication of CVB5 in vitro.Mechanistically,LINC1392 bound to ELAV like RNA binding protein 1(ELAVL1)and blocked ELAVL1 interaction with MDA5.Functional study revealed that the 245–835 nt locus of LINC1392 exerted the antiviral effect and was also an important site for ELAVL1 binding.In mice,LINC1392 could inhibit CVB5 replication and alleviated the histopathological lesions of intestinal and brain tissues induced by viral infection.Our findings collectively reveal that the novel LINC1392 acts as a positive regulator in the IFN-I signaling pathway against CVB5 infection.Elucidating the underlying mechanisms on how lncRNA regulats the host innate immunity response towards CVB5 infection will lay the foundation for antiviral drug research.

Differential roles of RIG-Ⅰ like receptors in SARS-CoV-2 infection

Retinoic acid-inducible gene Ⅰ (RIG-Ⅰ) and melanoma differentiation-associated protein 5 (MDA5) sense viral RNA and activate antiviral immune responses.Herein we investigate their functions in human epithelial cells,the primary and initial target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).A deficiency in MDA5,RIG-Ⅰ or mitochondrial antiviral signaling protein (MAVS) enhanced viral replication.The expression of the type I/III interferon(IFN) during infection was impaired in MDA5;and MAVS;,but not in RIG-Ⅰ;,when compared to wild type (WT) cells.The mRNA level of full-length angiotensin-converting enzyme 2 (ACE2),the cellular entry receptor for SARS-CoV-2,was approximately 2.5-fold higher in RIG-Ⅰ;than WT cells.These data demonstrate MDA5 as the predominant SARS-CoV-2 sensor,IFN-independent induction of ACE2 and anti-SARS-CoV-2 role of RIG-Ⅰ in epithelial cells.