Specific galpha11beta3gamma5 protein involvement in endothelin receptor-induced phosphatidylinositol hydrolysis and Ca2+ release in rat portal vein myocytes.
In this study, we identified the receptor subtype activated by endothelin-1 (ET-1) and the subunit composition of the G protein coupling this receptor to increase in cytosolic Ca2+ concentration in rat portal vein myocytes. We used intranuclear antisense oligonucleotide injection to selectively inhibit the expression of G protein subunits. We show here that the endothelin receptor subtype A (ETA)-mediated increase in cytosolic Ca2+ concentration was mainly dependent on Ca2+ release from the intracellular store. ETA receptor-mediated Ca2+ release was selectively inhibited by antisense oligonucleotides that inhibited the expression of alpha11, beta3, and gamma5 subunits, as checked by immunocytochemistry. Intracellular dialysis of a carboxyl terminal anti-betacom antibody and a peptide corresponding to the Gbetagamma binding region of the beta-adrenergic receptor kinase-1 had no effect on the ETA receptor-mediated Ca2+ release. In contrast, a synthetic peptide corresponding to the carboxyl terminus of the alphaq/alpha11 subunit, heparin (an inhibitor of inositol 1,4,5-trisphosphate receptors), and U73122 (an inhibitor of phosphatidylinositol-phospholipase C) inhibited, in a concentration-dependent manner, the ETA receptor-mediated Ca2+ responses. Accumulation of [3H]inositol trisphosphate evoked by norepinephrine peaked at approximately 15 s, whereas that evoked by ET-1 progressively increased within 2 min. In myocytes injected with anti-alphaq antisense oligonucleotides, both amplitude and time course of the norepinephrine-induced Ca2+ release became similar to those of the ET-1-induced Ca2+ response. We conclude that the ETA receptor-mediated Ca2+ release is selectively transduced by the heterotrimeric G11 protein composed of alpha11, beta3, and gamma5 subunits, and that a delayed stimulation of phospholipase C occurs via the alpha11 subunit.
Macrez
N
N
Laboratoire de Physiologie Cellulaire et Pharmacologie Moléculaire, Centre National de la Recherche Scientifique, Enseignement Supérieur Associé 5017, Université de Bordeaux II, 33076 Bordeaux Cedex, France.
Morel
J L
JL
Mironneau
J
J
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D019332:Endothelin-1 / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006493:Heparin / Q000494:pharmacology; D006868:Hydrolysis; D007295:Inositol Phosphates / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism*; D011169:Portal Vein / Q000166:cytology / Q000378:metabolism; D051381:Rats; D017466:Receptors, Endothelin / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D019332:Endothelin-1; D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D017466:Receptors, Endothelin; D006493:Heparin; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D002118:Calcium; D009638:Norepinephrine