ER egress of invariant chain isoform p35 requires direct binding to MHCII molecules and is inhibited by the NleA virulence factor of enterohaemorrhagic Escherichia coli

Maryse Cloutier, Catherine Gauthier, Jean Simon Fortin, Laetitia Genève, Kyungho Kim, Samantha Gruenheid, Jinoh Kim, Jacques Thibodeau

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Four invariant chain (Ii) isoforms assist the folding and trafficking of human MHC class II (MHCIIs). The main isoforms, Iip33 and Iip35, assemble in the ER into homo- and/or hetero-trimers. The sequential binding of up to three MHCII αβ heterodimers to Ii trimers results in the formation of pentamers, heptamers and nonamers. MHCIIs are required to overcome the p35-encoded di-arginine (RxR) ER retention motif and to allow anterograde trafficking of the complex. Here, we show that inactivation of the RxR motif requires a direct cis interaction between p35 and the MHCII, precluding ER egress of some unsaturated Ii trimers. Interestingly, as opposed to MHCII/p33 complexes, those including p35 remained in the ER when co-expressed with the NleA protein of enterohaemorrhagic Escherichia coli. Taken together, our results demonstrate that p35 influences distinctively MHCII/Ii assembly and trafficking.

Original languageEnglish (US)
Pages (from-to)292-296
Number of pages5
JournalHuman Immunology
Volume76
Issue number4
DOIs
StatePublished - 2015

Keywords

  • Antigen presentation
  • COPII
  • Di-arginine
  • Invariant chain
  • MHC class II
  • NleA

ASJC Scopus subject areas

  • Immunology
  • Immunology and Allergy

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