Heterodimerization of V1a and V2 vasopressin receptors determines the interaction with β-arrestin and their trafficking patterns

doi:10.1073/pnas.0305322101

Heterodimerization of V1a and V2 vasopressin receptors determines the interaction with β-arrestin and their trafficking patterns

^*Département de Biochimie, Université de Montréal, Montréal, QC, Canada H3C 3J7; and ^†U469 Institut National de la Santé et de la Recherche Médicale, 141 Rue de la Cardonille, 34094 Montpellier Cedex 5, France

Edited by Henry R. Bourne, University of California, San Francisco, CA (received for review August 19, 2003)

Abstract

V1a vasopressin receptor (V1aR) and V2 vasopressin receptor (V2R) present distinct mechanisms of agonist-promoted trafficking. Although both receptors are endocytosed by way of β-arrestin-dependent processes, β-arrestin dissociates rapidly from V1aR, allowing its rapid recycling to the plasma membrane while β-arrestin remains associated with V2R in the endosomes, leading to their intracellular accumulation. Here, we demonstrate that, when coexpressed, the two receptors can be endocytosed as stable heterodimers. On activation with a nonselective agonist, both receptors cotrafficked with β-arrestin in endosomes where the stable interaction inhibited the recycling of V1aR to the plasma membrane, thus conferring a V2R-like endocytotic/recycling pattern to the V1aR/V2R heterodimer. Coexpression of the constitutively internalized R137HV2R mutant with V1aR was sufficient to promote cointernalization of V1aR in β-arrestin-positive vesicles even in the absence of agonist stimulation. This finding indicates that internalization of the heterodimer does not require activation of each of the protomers. Consistent with this notion, a V1aR-selective agonist led to the coendocytosis of V2R. In that case, however, the V1aR/V2R heterodimer was not stably associated with β-arrestin, and both receptors were recycled back to the cell surface, indicating that the complex followed the V1aR endocytotic/recycling path. Taken together, these results suggest that heterodimerization regulates the endocytotic processing of G protein-coupled receptors and that the identity of the activated protomer within the heterodimer determines the fate of the internalized receptors.

Footnotes

↵ ‡ To whom correspondence should be addressed at: Département de Biochimie, Faculté de Médecine, P.O. Box 6128, Succursale Centre-Ville, Montréal, QC, Canada H3C 3J7. E-mail: michel.bouvier{at}umontreal.ca.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: AVP, arginine-vasopressin; β2AR, β2 adrenergic receptor; GPCR, G protein-coupled receptor; V1aR, V1a vasopressin receptor; V2R, V2 vasopressin receptor; HA, hemagglutinin; HEK, human embryonic kidney; YFP, yellow fluorescent protein.