Enterovirus 71 protease 2Apro and 3Cpro differentially inhibit the cellular endoplasmic reticulum-associated degradation (ERAD) pathway via distinct mechanisms, and enterovirus 71 hijacks ERAD component p97 to promote its replication

PLoS Pathog. 2017 Oct 6;13(10):e1006674. doi: 10.1371/journal.ppat.1006674. eCollection 2017 Oct.

Abstract

Endoplasmic reticulum-associated degradation (ERAD) is an important function for cellular homeostasis. The mechanism of how picornavirus infection interferes with ERAD remains unclear. In this study, we demonstrated that enterovirus 71 (EV71) infection significantly inhibits cellular ERAD by targeting multiple key ERAD molecules with its proteases 2Apro and 3Cpro using different mechanisms. Ubc6e was identified as the key E2 ubiquitin-conjugating enzyme in EV71 disturbed ERAD. EV71 3Cpro cleaves Ubc6e at Q219G, Q260S, and Q273G. EV71 2Apro mainly inhibits the de novo synthesis of key ERAD molecules Herp and VIMP at the protein translational level. Herp differentially participates in the degradation of different glycosylated ERAD substrates α-1 antitrypsin Null Hong Kong (NHK) and the C-terminus of sonic hedgehog (SHH-C) via unknown mechanisms. p97 was identified as a host factor in EV71 replication; it redistributed and co-exists with the viral protein and other known replication-related molecules in EV71-induced replication organelles. Electron microscopy and multiple-color confocal assays also showed that EV71-induced membranous vesicles were closely associated with the endoplasmic reticulum (ER), and the ER membrane molecule RTN3 was redistributed to the viral replication complex during EV71 infection. Therefore, we propose that EV71 rearranges ER membranes and hijacks p97 from cellular ERAD to benefit its replication. These findings add to our understanding of how viruses disturb ERAD and provide potential anti-viral targets for EV71 infection.

MeSH terms

  • Endopeptidases / metabolism*
  • Endoplasmic Reticulum / enzymology*
  • Endoplasmic Reticulum-Associated Degradation / physiology*
  • Enterovirus A, Human / physiology*
  • Humans
  • Membrane Proteins / metabolism
  • Protein Transport / physiology
  • Ubiquitin-Protein Ligases / metabolism*
  • Viral Proteins / metabolism*
  • Virus Replication*

Substances

  • Membrane Proteins
  • Viral Proteins
  • Ubiquitin-Protein Ligases
  • Endopeptidases

Grants and funding

This work was supported by the CAMS Innovation Fund for Medical Science (CIFMS 2016-12M-1-014), the National Key Plan for Scientific Research and Development of China (2016YFD0500300), the Innovative Research Team in University (IRT13007), the National Foundation for Distinguished Young Scientists (81225014), and the National Natural Science Foundation of China (NSFC 81572008 and NSFC 31400159). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.