title: [Innate immune responses against viral infection and its suppression by viral proteins].
abstract: Retinoic acid-inducible gene-I(RIG-I) is a cytoplasmic RNA helicase and a viral RNA sensor. RIG-I recognizes 5' triphosphate double-stranded RNA (dsRNA) and activates the IPS-1 adaptor molecule. The association of IPS-1 with RIG-I causes the formation of the prion-like structure of IPS-1. This structure is essential for activation of the signaling required for the induction of type I interferon (IFN), which possesses strong antiviral activity. Recent studies have revealed the novel factors involved in the RIG-I-dependent pathway. DDX3 and DDX60 RNA helicases associate with RIG-I and promote its binding to viral RNA. Riplet and TRIM25 ubiquitin ligase deliver Lys63-linked polyubiquitin moiety to RIG-I and result in signal activation. Several pathogenic viruses have evolved excellent systems to suppress type I IFN production. For example, NS3-4A of hepatitis C virus (HCV) cleaves IPS-1, which is the adaptor molecule of RIG-I, while the HCV core protein abrogates DDX3 function to suppress RIG-I-dependent IPS-1 activation, and the NS-1 of flu inhibits TRIM25 function to suppress RIG-I activation.
authors: Graduate School of Medicine, Hokkaido University, Sapporo, Japan. oshiumi@med.hokudai.ac.jp
authors: Hiroyuki
authors: H
authors: Oshiumi
authors: Misako
authors: M
authors: Matsumoto
authors: Tsukasa
authors: T
authors: Seya
mesh_terms: D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases; D006801:Humans; D007113:Immunity, Innate / Q000502:physiology*; D007370:Interferon Type I / Q000096:biosynthesis; D012367:RNA, Viral / Q000276:immunology; D011971:Receptors, Immunologic; D051196:Toll-Like Receptor 3 / Q000502:physiology; D051193:Toll-Like Receptors / Q000502:physiology; D014764:Viral Proteins / Q000502:physiology*; D014777:Virus Diseases / Q000276:immunology*
chemical_list: D007370:Interferon Type I; D012367:RNA, Viral; D011971:Receptors, Immunologic; D051196:Toll-Like Receptor 3; D051193:Toll-Like Receptors; D014764:Viral Proteins; C452820:RIGI protein, human; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases