RESUMO
The helicase RIG-I initiates an antiviral immune response after recognition of pathogenic RNA. TRIM25, an E3 ubiquitin ligase, mediates K63-linked ubiquitination of RIG-I, which is crucial for RIG-I downstream signaling and the antiviral innate immune response. The components and mode of the RIG-I-initiated innate signaling remain to be fully understood. Here we identify a novel long noncoding RNA (Lnczc3h7a) that binds to TRIM25 and promotes RIG-I-mediated antiviral innate immune responses. Depletion of Lnczc3h7a impairs RIG-I signaling and the antiviral innate response to RNA viruses in vitro and in vivo. Mechanistically, Lnczc3h7a binds to both TRIM25 and activated RIG-I, serving as a molecular scaffold for stabilization of the RIG-I-TRIM25 complex at the early stage of viral infection. Lnczc3h7a facilitates TRIM25-mediated K63-linked ubiquitination of RIG-I and thus promotes downstream signaling transduction. Our findings reveal that host RNAs can enhance the response of innate immune sensors to foreign RNAs, ensuring effective antiviral defense.
Assuntos
Proteína DEAD-box 58/genética , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/imunologia , Imunidade Inata/genética , RNA Longo não Codificante/genética , Fatores de Transcrição/genética , Animais , Linhagem Celular , Humanos , Macrófagos Peritoneais/imunologia , Macrófagos Peritoneais/metabolismo , Macrófagos Peritoneais/virologia , Camundongos , Modelos Biológicos , Interferência de RNA , Vírus de RNA/imunologia , Transdução de Sinais , Viroses/genética , Viroses/imunologia , Viroses/metabolismo , Viroses/virologiaRESUMO
The innate RNA sensor RIG-I is critical in the initiation of antiviral type I interferons (IFNs) production upon recognition of "non-self" viral RNAs. Here, we identify a host-derived, IFN-inducible long noncoding RNA, lnc-Lsm3b, that can compete with viral RNAs in the binding of RIG-I monomers and feedback inactivate the RIG-I innate function at late stage of innate response. Mechanistically, binding of lnc-Lsm3b restricts RIG-I protein's conformational shift and prevents downstream signaling, thereby terminating type I IFNs production. Multivalent structural motifs and long-stem structure are critical features of lnc-Lsm3b for RIG-I binding and inhibition. These data reveal a non-canonical self-recognition mode in the regulation of immune response and demonstrate an important role of an inducible "self" lncRNA acting as a potent molecular decoy actively saturating RIG-I binding sites to restrict the duration of "non-self" RNA-induced innate immune response and maintaining immune homeostasis, with potential utility in inflammatory disease management.