Transient arrestin interaction with the C-terminus of the human vasopressin receptor V1b is associated with its rapid recycling

Life Sciences 2007 (2007) Proc Life Sciences, PC454

Poster Communications: Transient arrestin interaction with the C-terminus of the human vasopressin receptor V1b is associated with its rapid recycling

S. Perkovska1, M. A. Ayoub1, B. Mouillac1, C. Mendre1

1. Dept. of Molecular Pharmacology, IGF, Montpellier, France.

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Many external stimuli are translated into a cellular response through activation of G-protein coupled receptors (GPCRs). Once the ligand is bound, a receptor-desensitization is induced, that is an essential step of the regulation process of the state of cell-responsiveness. For most GPCRs it is initiated by an arrestin-receptor interaction leading further to receptor internalization.The endocytosed GPCR can be then either dephosphorylated and recycled back to the plasma membrane or degraded. Receptor-arrestin interaction and trafficking properties allow GPCRs to be ranked into class A or class B receptors. Among the vasopressin family members, all of them GPCRs, there are representatives of both classes. Contrary to V1a, a typical class A receptor characterized with transient arrestin interaction and rapid recycling, the V2 receptor displays properties innate to class B receptors: continuous interaction and a limited recycling. We investigated the capacity of arrestins to interact with the third vasopressin receptor, the neurohypophyseal V1b receptor, in living cells using the bioluminescence resonance energy transfer (BRET) technique. For this, the C-termini of wild type V1b and V2 were fused to R. luciferase (Rluc) and arrestins to the YFP. Upon agonist stimulation, the two receptors exhibt clearly distinct arrestin interaction patterns:V1b interacts with arrestin in brief and transient manner as opposed to the stable, long-lasting interaction of V2. It has already been shown that arrestin interaction sites on GPCRs are generally settled in the C-terminal region of the receptor. In order to elucidate the role of the V1b C-tail for such interaction, we created chimeric receptors by exchanging the C-tails of V1b and V2, yielding V1b-CterV2-RLuc and V2-CterV1b-RLuc. In terms of functional properties i.e. ligand binding affinities and second messenger production, these chimeric receptors behave as the wild type receptors whose core they possess. Conversely, regarding the arrestin-receptor interaction, it is transient within the set of receptors containing the C-tail of V1b (V1bWT and V2-CterV1b) and stable and continuous within receptors containing the C-tail of V2 (V2WT and V1b-CterV2). Interestingly, in binding experiments after agonist removal, one can distinguish the same two sets of receptors: V1bWT and V2-CterV1b exhibit a high recycling rate compared to V2WT and V1b-CterV2 with a limited recycling. This study highlights that both processes (receptor-arrestin interaction and recycling) involve the receptor C-tail and are strongly related. Morover, it reinforces the importance of GPCR-arrestin interactions for major cellular events such as signaling and trafficking.



Where applicable, experiments conform with Society ethical requirements.

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