Open AccessSustained Activation of Interferon Regulatory Factor 3 during Infection by Paramyxoviruses Requires MDA5
Author(s) -
Nathalie Grandvaux,
Xiaochun Guan,
Fabrice Yoboua,
Nicolas Zucchini,
Karin Fink,
Priscilla Doyon,
Lydie Martin,
Marc J. Servant,
Stéfany Chartier
Publication year - 2014
Publication title -
journal of innate immunity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.078
H-Index - 64
eISSN - 1662-8128
pISSN - 1662-811X
DOI - 10.1159/000360764
Subject(s) - mda5 , rig i , gene knockdown , interferon regulatory factors , biology , interferon , innate immune system , microbiology and biotechnology , sendai virus , transcription factor , virology , virus , gene , rna , rna interference , immunology , immune system , genetics
Retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5) are the main cytosolic sensors of single-stranded RNA viruses, including paramyxoviruses, and are required to initiate a quick and robust innate antiviral response. Despite different ligand-binding properties, the consensus view is that RIG-I and MDA5 trigger common signal(s) to activate interferon regulatory factor 3 (IRF-3) and NF-κB, and downstream antiviral and proinflammatory cytokine expression. Here, we performed a thorough analysis of the temporal involvement of RIG-I and MDA5 in the regulation of IRF-3 during respiratory syncytial virus (RSV) infection. Based on specific RNA interference-mediated knockdown of RIG-I and MDA5 in A549 cells, we confirmed that RIG-I is critical for the initiation of IRF-3 phosphorylation, dimerization and downstream gene expression. On the other hand, our experiments yielded the first evidence that knockdown of MDA5 leads to early ubiquitination and proteasomal degradation of active IRF-3. Conversely, ectopic expression of MDA5 prolonged RIG-I-induced IRF-3 activation. Altogether, we provide novel mechanistic insight into the temporal involvement of RIG-I and MDA5 in the innate antiviral response. While RIG-I is essential for initial IRF-3 activation, engagement of induced MDA5 is essential to prevent early degradation of IRF-3, thereby sustaining IRF-3-dependent antiviral gene expression. MDA5 plays a similar role during Sendai virus infection suggesting that this model is not restricted to RSV amongst paramyxoviruses.