Foot-and-mouth disease virus infection suppresses autophagy and NF-кB antiviral responses via degradation of ATG5-ATG12 by 3Cpro

Cell Death Dis. 2017 Jan 19;8(1):e2561. doi: 10.1038/cddis.2016.489.

Abstract

Autophagy-related protein ATG5-ATG12 is an essential complex for the autophagophore elongation in autophagy, which has been reported to be involved in foot-and-mouth disease virus (FMDV) replication. Previous reports show that ATG5-ATG12 positively or negatively regulates type I interferon (IFN-α/β) pathway during virus infection. In this study, we found that FMDV infection rapidly induced LC3 lipidation and GFP-LC3 subcellular redistribution at the early infection stage in PK-15 cells. Along with infection time course to 2-5 h.p.i., the levels of LC3II and ATG5-ATG12 were gradually reduced. Further study showed that ATG5-ATG12 was degraded by viral protein 3Cpro, demonstrating that FMDV suppresses autophagy along with viral protein production. Depletion of ATG5-ATG12 by siRNA knock down significantly increased the FMDV yields, whereas overexpression of ATG5-ATG12 had the opposite effects, suggesting that degradation of ATG5-ATG12 benefits virus growth. Further experiment showed that overexpression of ATG5-ATG12 positively regulated NF-кB pathway during FMDV infection, marked with promotion of IKKα/β phosphorylation and IκBα degradation, inhibition of p65 degradation, and facilitation of p65 nuclear translocation. Meanwhile, ATG5-ATG12 also promoted the phosphorylation of TBK1 and activation of IRF3 via preventing TRAF3 degradation. The positive regulation of NF-кB and IRF3 pathway by ATG5-ATG12 resulted in enhanced expression of IFN-β, chemokines/cytokines, and IFN stimulated genes, including anti-viral protein PKR. Altogether, above findings suggest that ATG5-ATG12 positively regulate anti-viral NF-κB and IRF3 signaling during FMDV infection, thereby limiting FMDV proliferation. FMDV has evolved mechanisms to counteract the antiviral function of ATG5-ATG12, via degradation of them by viral protein 3Cpro.

MeSH terms

  • 3C Viral Proteases
  • Animals
  • Autophagy / genetics
  • Autophagy-Related Protein 12 / genetics
  • Autophagy-Related Protein 12 / metabolism*
  • Autophagy-Related Protein 5 / genetics
  • Autophagy-Related Protein 5 / metabolism*
  • Cysteine Endopeptidases / biosynthesis
  • Cysteine Endopeptidases / genetics*
  • Foot-and-Mouth Disease / genetics*
  • Foot-and-Mouth Disease / pathology
  • Foot-and-Mouth Disease / virology
  • Foot-and-Mouth Disease Virus / genetics*
  • Foot-and-Mouth Disease Virus / growth & development
  • Foot-and-Mouth Disease Virus / pathogenicity
  • Gene Expression Regulation, Viral
  • Interferon Regulatory Factor-3 / genetics*
  • Interferon Regulatory Factor-3 / metabolism
  • NF-kappa B / genetics
  • Protein Binding
  • Protein Serine-Threonine Kinases / genetics
  • RNA, Small Interfering / genetics
  • Signal Transduction
  • Viral Proteins / biosynthesis
  • Viral Proteins / genetics*
  • Virus Replication

Substances

  • ATG12 protein, human
  • ATG5 protein, human
  • Autophagy-Related Protein 12
  • Autophagy-Related Protein 5
  • IRF3 protein, human
  • Interferon Regulatory Factor-3
  • NF-kappa B
  • RNA, Small Interfering
  • Viral Proteins
  • Protein Serine-Threonine Kinases
  • TBK1 protein, human
  • Cysteine Endopeptidases
  • 3C Viral Proteases