Sendai virus V protein decreases nitric oxide production by inhibiting RIG-I signaling in infected RAW264.7 macrophages

Microbes Infect. 2020 Sep;22(8):322-330. doi: 10.1016/j.micinf.2020.01.005. Epub 2020 Feb 5.

Abstract

Sendai virus V protein is a known antagonist of RIG-I-like receptors (RLRs) RIG-I and MDA5, which activate transcription factors IRF3, leading to activation of ISGF3 and NF-κB. These transcription factors are known activators of inducible NO synthase (iNOS) and increase the production of nitric oxide (NO). By inhibiting ISGF3 and NF-κB, the V protein acts as an indirect negative regulator of iNOS and NO. Here we report that the V gene knockout Sendai virus [SeV V(-)] markedly enhanced iNOS expression and subsequent NO production in infected macrophages compared to wild-type SeV. The knockout of RIG-I in cells inhibited SeV V(-)-induced iNOS expression and subsequent NO production. To understand the underlying mechanism of the V protein-mediated negative regulation of iNOS activation, we transfected HEK293T cells with RIG-I and the RIG-I regulatory protein TRIM25. Our results demonstrated that the V protein inhibited iNOS activation via the RIG-I/TRIM25 pathway. Moreover, the V protein inhibited TRIM25-mediated K63-linked ubiquitination of RIG-I, as well as its CARD-dependent interaction with mitochondrial antiviral signaling (MAVS) molecules. These results suggest that the V protein downregulates iNOS activation and inhibits NO production by preventing the RIG-I-MAVS interaction, possibly through its effect on the ubiquitination status of RIG-I.

Keywords: Macrophages; Nitric oxide; RIG-I; Sendai virus; TRIM25; V protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Animals
  • DEAD Box Protein 58 / genetics
  • DEAD Box Protein 58 / metabolism*
  • DNA-Binding Proteins / metabolism
  • HEK293 Cells
  • Humans
  • Macrophages / metabolism*
  • Macrophages / virology
  • Mice
  • Nitric Oxide / metabolism*
  • Nitric Oxide Synthase Type II / metabolism
  • Protein Binding
  • RAW 264.7 Cells
  • Sendai virus / genetics
  • Sendai virus / metabolism*
  • Signal Transduction*
  • Transcription Factors / metabolism
  • Ubiquitination
  • Viral Proteins / genetics
  • Viral Proteins / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • DNA-Binding Proteins
  • IPS-1 protein, mouse
  • Transcription Factors
  • Trim25 protein, mouse
  • V protein, Sendai virus
  • Viral Proteins
  • Nitric Oxide
  • Nitric Oxide Synthase Type II
  • Nos2 protein, mouse
  • Ddx58 protein, mouse
  • DEAD Box Protein 58