Heterologous inhibition of G protein-coupled receptor endocytosis mediatedby receptor-specific trafficking of beta-arrestins

We have observed an unexpected type of nonreciprocal "cross-regulation" of the agonist-induced endocytosis of G protein-coupled receptors by clathrin- coated pits, Isoproterenol-dependent internalization of beta (2)-adrenergic receptors in stably transfected HEK293 cells was specifically blocked (> 6 5% inhibition) by vasopressin-induced activation of V2 vasopressin receptor s co-expressed at similar levels. In contrast, activation of beta (2) recep tors caused no detectable effect on V2 receptor internalization in the same cells. Several pieces of evidence suggest that this nonreciprocal inhibiti on of endocytosis is mediated by receptor-specific intracellular traffickin g of beta -arrestins. First, previous studies showed that the activation of V2 but not beta (2) receptors caused pronounced recruitment of beta -arres tins to endocytic membranes (Oakley, R. H,, Laporte, S, A., Holt, J, A., Ba rak, L, S,, and Caron, M, G, (1999) J, Biol. Chem. 274, 32248-32257), Secon d, overexpression of arrestin 2 or 3 (beta -arrestin 1 or 2) abolished the V2 receptor-mediated inhibition of beta (2) receptor internalization. Third , mutations of the V2 receptor that block endomembrane recruitment of beta -arrestins eliminated the V2 receptor-dependent blockade of beta (2) recept or internalization. These results identify a novel type of heterologous reg ulation of G protein-coupled receptors, define a new functional role of rec eptor-specific intracellular trafficking of beta -arrestins, and suggest an experimental method to rapidly modulate the functional activity of beta -a rrestins in intact cells.