The V2 vasopressin receptor stimulates ERK1/2 activity independently of heterotrimeric G protein signalling.
The V2 vasopressin receptor (V2R) activates the mitogen activated protein kinases (MAPK) ERK1/2 through a mechanism involving the scaffolding protein beta arrestin. Here we report that this activating pathway is independent of G alpha s, G alpha i, G alpha q or G betagamma and that the V2R-mediated activation of G alpha s inhibits ERK1/2 activity in a cAMP/PKA-dependent manner. In the HEK293 cells studied, the beta arrestin-promoted activation was found to dominate over the PKA-mediated inhibition of the pathway, leading to a strong vasopressin-stimulated ERK1/2 activation. Despite the strong MAPK activation and in contrast with other GPCR, V2R did not induce any significant increase in DNA synthesis, consistent with the notion that the stable interaction between V2R and beta arrestin prevents signal propagation to the nucleus. Beta arrestin was found to be essential for the ERK1/2 activation, indicating that the recruitment of the scaffolding protein is necessary and sufficient to initiate the signal in the absence of any other stimulatory cues. Based on the use of selective pharmacological inhibitors, dominant negative mutants and siRNA, we conclude that the beta arrestin-dependent activation of ERK1/2 by the V2R involves c-Src and a metalloproteinase-dependent trans-activation event. These findings demonstrate that beta arrestin is a genuine signalling initiator that can, on its own, engage a MAPK activation machinery upon stimulation of a GPCR by its natural ligand.
Charest
Pascale G
PG
Department of Biochemistry and Groupe de Recherche Universitaire sur le Médicament, Institute for Research in Immunology and Cancer, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montréal (Québec) Canada H3C 3J7.
Oligny-Longpré
Geneviève
G
Bonin
Hélène
H
Azzi
Mounia
M
Bouvier
Michel
M
D000818:Animals; D019390:Arrestins / Q000378:metabolism; D000081247:CSK Tyrosine-Protein Kinase; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D020962:Heterotrimeric GTP-Binding Proteins / Q000502:physiology*; D006801:Humans; D020782:Matrix Metalloproteinases / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000502:physiology*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D017483:Receptors, Vasopressin / Q000502:physiology*; D015398:Signal Transduction; D015533:Transcriptional Activation; D000071557:beta-Arrestins; D019061:src-Family Kinases
D019390:Arrestins; D000081247:CSK Tyrosine-Protein Kinase; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D020962:Heterotrimeric GTP-Binding Proteins; D020782:Matrix Metalloproteinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D017483:Receptors, Vasopressin; D000071557:beta-Arrestins; D019061:src-Family Kinases; C000631346:CSK protein, human