title: RIG-I self-oligomerization is either dispensable or very transient for signal transduction.
abstract: Effective host defence against viruses depends on the rapid triggering of innate immunity through the induction of a type I interferon (IFN) response. To this end, microbe-associated molecular patterns are detected by dedicated receptors. Among them, the RIG-I-like receptors RIG-I and MDA5 activate IFN gene expression upon sensing viral RNA in the cytoplasm. While MDA5 forms long filaments in vitro upon activation, RIG-I is believed to oligomerize after RNA binding in order to transduce a signal. Here, we show that in vitro binding of synthetic RNA mimicking that of Mononegavirales (Ebola, rabies and measles viruses) leader sequences to purified RIG-I does not induce RIG-I oligomerization. Furthermore, in cells devoid of endogenous functional RIG-I-like receptors, after activation of exogenous Flag-RIG-I by a 62-mer-5'ppp-dsRNA or by polyinosinic:polycytidylic acid, a dsRNA analogue, or by measles virus infection, anti-Flag immunoprecipitation and specific elution with Flag peptide indicated a monomeric form of RIG-I. Accordingly, when using the Gaussia Luciferase-Based Protein Complementation Assay (PCA), a more sensitive in cellula assay, no RIG-I oligomerization could be detected upon RNA stimulation. Altogether our data indicate that the need for self-oligomerization of RIG-I for signal transduction is either dispensable or very transient.
authors.affiliation: Centre International de Recherche en Infectiologie, INSERM, U1111, CNRS, UMR5308, Université Lyon 1, ENS Lyon, Lyon, France.
authors.forename: Jade
authors.initials: J
authors.lastname: Louber
authors.affiliation: European Molecular Biology Laboratory, Grenoble Outstation, Grenoble Cedex 9, France; Unit of Virus Host-Cell Interactions, UJF-EMBL-CNRS, UMI 3265, Grenoble Cedex 9, France.
authors.forename: Eva
authors.initials: E
authors.lastname: Kowalinski
authors.affiliation: Centre International de Recherche en Infectiologie, INSERM, U1111, CNRS, UMR5308, Université Lyon 1, ENS Lyon, Lyon, France.
authors.forename: Louis-Marie
authors.initials: LM
authors.lastname: Bloyet
authors.affiliation: Centre International de Recherche en Infectiologie, INSERM, U1111, CNRS, UMR5308, Université Lyon 1, ENS Lyon, Lyon, France.
authors.forename: Joanna
authors.initials: J
authors.lastname: Brunel
authors.affiliation: European Molecular Biology Laboratory, Grenoble Outstation, Grenoble Cedex 9, France; Unit of Virus Host-Cell Interactions, UJF-EMBL-CNRS, UMI 3265, Grenoble Cedex 9, France.
authors.forename: Stephen
authors.initials: S
authors.lastname: Cusack
authors.affiliation: Centre International de Recherche en Infectiologie, INSERM, U1111, CNRS, UMR5308, Université Lyon 1, ENS Lyon, Lyon, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Gerlier
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007113:Immunity, Innate / Q000502:physiology*; D016899:Interferon-beta / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012367:RNA, Viral / Q000235:genetics; D011971:Receptors, Immunologic; D015398:Signal Transduction / Q000502:physiology*; D014709:Vero Cells
chemical_list: D012367:RNA, Viral; D011971:Receptors, Immunologic; D016899:Interferon-beta; C452820:RIGI protein, human; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases