ARF6 activation by Gαq signaling: Gαq forms molecular complexes with ARNO and ARF6

Patrick Giguère, Moulay Driss Rochdi, Geneviève Laroche, Émilie Dupré, Matthew R. Whorton, Roger K. Sunahara, Audrey Claing, Gilles Dupuis, Jean Luc Parent

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


G protein-coupled receptors (GPCRs) are widely expressed hepta-helical receptors with tightly regulated pleiotropic effects. ADP-Ribosylation Factor 6 (ARF6) plays an important role in GPCR trafficking and is the subject of intense research. However, the mechanisms underlying activation and regulation of ARF6 by GPCRs are poorly characterized. Here we report that Gαq signaling leads to the activation of ARF6. Stimulation of the TPβ receptor triggered ARF6 activation which was completely inhibited by the RGS domain of GRK2 known to specifically bind and sequester Gαq. Co-immunoprecipitation studies revealed that ARNO (a guanine nucleotide exchange factor for ARF6) and ARF6 formed complexes preferentially with activated Gαq compared to non-activated Gαq. Formation of the Gαq complexes with ARNO and ARF6 was detected early and was optimal after 30 min of receptor stimulation corresponding with the profile of ARF6 activation. Interestingly, binding experiments using purified proteins showed that Gαq interacted directly with ARNO. Gαq-dependent TPβ receptor-mediated activation of ARF6 resulted in phosphoinositol-4,5-bisphosphate production which was potently inhibited by dominant negative mutants of ARNO and ARF6. Furthermore, our data show that the expression of ARNO and ARF6 promoted, whereas dominant negative mutants of these proteins inhibited the internalization of the TPβ receptor. This further elucidates our previous data on the PLCβ- and PKC-independent mechanism involved in Gαq-mediated internalization of the TPβ receptor. Taken altogether, our results support a novel model where activated Gαq forms molecular complexes with ARNO and ARF6, possibly through a direct interaction with ARNO, leading to ARF6 activation.

Original languageEnglish (US)
Pages (from-to)1988-1994
Number of pages7
JournalCellular Signalling
Issue number11
StatePublished - Nov 2006


  • ARF6
  • ARF6 activation
  • ARNO
  • G protein-coupled receptor

ASJC Scopus subject areas

  • Cell Biology


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