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Negative role of RIG-I serine 8 phosphorylation in the regulation of interferon-beta production.

RIG-I (retinoic acid-inducible gene I) and TRIM25 (tripartite motif protein 25) have emerged as key regulatory factors to induce interferon (IFN)-mediated innate immune responses to limit viral replication. Upon recognition of viral RNA, TRIM25 E3 ligase binds the first caspase recruitment domain (CARD) of RIG-I and subsequently induces lysine 172 ubiquitination of the second CARD of RIG-I, which is essential for the interaction with downstream MAVS/IPS-1/CARDIF/VISA and, thereby, IFN-beta mRNA production. Although ubiquitination has emerged as a major factor involved in RIG-I activation, the potential contribution of other post-translational modifications, such as phosphorylation, to the regulation of RIG-I activity has not been addressed. Here, we report the identification of serine 8 phosphorylation at the first CARD of RIG-I as a negative regulatory mechanism of RIG-I-mediated IFN-beta production. Immunoblot analysis with a phosphospecific antibody showed that RIG-I serine 8 phosphorylation steady-state levels were decreased upon stimulation of cells with IFN-beta or virus infection. Substitution of serine 8 in the CARD RIG-I functional domain with phosphomimetic aspartate or glutamate results in decreased TRIM25 binding, RIG-I ubiquitination, MAVS binding, and downstream signaling. Finally, sequence comparison reveals that only primate species carry serine 8, whereas other animal species carry an asparagine, indicating that serine 8 phosphorylation may represent a primate-specific regulation of RIG-I activation. Collectively, these data suggest that the phosphorylation of RIG-I serine 8 operates as a negative switch of RIG-I activation by suppressing TRIM25 interaction, further underscoring the importance of RIG-I and TRIM25 connection in type I IFN signal transduction.

Pubmed ID: 20406818


  • Nistal-Villán E
  • Gack MU
  • Martínez-Delgado G
  • Maharaj NP
  • Inn KS
  • Yang H
  • Wang R
  • Aggarwal AK
  • Jung JU
  • García-Sastre A


The Journal of biological chemistry

Publication Data

June 25, 2010

Associated Grants

  • Agency: PHS HHS, Id: 266200700010C
  • Agency: NIAID NIH HHS, Id: AI041706
  • Agency: NIAID NIH HHS, Id: AI083355
  • Agency: NCI NIH HHS, Id: CA082057
  • Agency: NIAID NIH HHS, Id: R01 AI087846
  • Agency: NIAID NIH HHS, Id: R01AI46954
  • Agency: NCRR NIH HHS, Id: RR00168
  • Agency: NIAID NIH HHS, Id: U19AI083025

Mesh Terms

  • Adaptor Proteins, Signal Transducing
  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Blotting, Western
  • Cell Line
  • Cell Line, Tumor
  • Cercopithecus aethiops
  • DEAD-box RNA Helicases
  • Green Fluorescent Proteins
  • Humans
  • Interferon Regulatory Factor-3
  • Interferon-beta
  • Microscopy, Confocal
  • Models, Molecular
  • Mutation
  • Phosphorylation
  • Promoter Regions, Genetic
  • Protein Binding
  • Protein Structure, Tertiary
  • Serine
  • Transcription Factors
  • Transcriptional Activation
  • Transfection
  • Ubiquitin-Protein Ligases
  • Vero Cells