The E3 Ubiquitin Ligase Triad3A Negatively Regulates the RIG-I/MAVS Signaling Pathway by Targeting TRAF3 for Degradation

PLoS Pathogens

John Hiscott¹  Qiang Sun²  Thibault Mesplede³  Long Yang³  Carl F. Ware⁴  Peyman Nakhaei⁴  Tsung-Hsien Chuang⁴  Mayra Solis⁴  Rongtuan Lin⁴  Tiejun Zhao⁴ 

[1] Department of Immunology, The Scripps Research Institute, La Jolla, California, United States of America;Department of Medicine, McGill University, Montreal, Quebec, Canada;Department of Microbiology & Immunology, McGill University, Montreal, Quebec, Canada;The Terry Fox Molecular Oncology Group, Lady Davis Institute for Medical Research, Montreal, Quebec, Canada

关键词: Plasmid construction;    Transcription factors;    Ubiquitination;    Immune receptor signaling;    Sendai virus;    293T cells;    Interferons;    Immune response;   

DOI  :  10.1371/journal.ppat.1000650

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The primary role of the innate immune response is to limit the spread of infectious pathogens, with activation of Toll-like receptor (TLR) and RIG-like receptor (RLR) pathways resulting in a pro-inflammatory response required to combat infection. Limiting the activation of these signaling pathways is likewise essential to prevent tissue injury in the host. Triad3A is an E3 ubiquitin ligase that interacts with several components of TLR signaling and modulates TLR activity. In the present study, we demonstrate that Triad3A negatively regulates the RIG-I RNA sensing pathway through Lys48-linked, ubiquitin-mediated degradation of the tumor necrosis factor receptor-associated factor 3 (TRAF3) adapter. Triad3A was induced following dsRNA exposure or virus infection and decreased TRAF3 levels in a dose-dependent manner; moreover, Triad3A expression blocked IRF-3 activation by Ser-396 phosphorylation and inhibited the expression of type 1 interferon and antiviral genes. Lys48-linked ubiquitination of TRAF3 by Triad3A increased TRAF3 turnover, whereas reduction of Triad3A expression by stable shRNA expression correlated with an increase in TRAF3 protein expression and enhancement of the antiviral response following VSV or Sendai virus infection. Triad3A and TRAF3 physically interacted together, and TRAF3 residues Y440 and Q442—previously shown to be important for association with the MAVS adapter—were also critical for Triad3A. Point mutation of the TRAF-Interacting-Motif (TIM) of Triad3A abrogated its ability to interact with TRAF3 and modulate RIG-I signaling. TRAF3 appears to undergo sequential ubiquitin “immuno-editing” following virus infection that is crucial for regulation of RIG-I-dependent signaling to the antiviral response. Thus, Triad3A represents a versatile E3 ubiquitin ligase that negatively regulates RIG-like receptor signaling by targeting TRAF3 for degradation following RNA virus infection.

【 授权许可】

CC BY