TY - JOUR T1 - Using Molecular Tools to Dissect the Role of Gα<sub>s</sub> in Sensitization of AC1 JF - Molecular Pharmacology JO - Mol Pharmacol SP - 1617 LP - 1624 DO - 10.1124/mol.104.000166 VL - 66 IS - 6 AU - Timothy A. Vortherms AU - Chau H. Nguyen AU - Catherine H. Berlot AU - Val J. Watts Y1 - 2004/12/01 UR - http://molpharm.aspetjournals.org/content/66/6/1617.abstract N2 - Short-term activation of Gαi/o-coupled receptors inhibits adenylyl cyclase, whereas persistent activation of Gαi/o-coupled receptors results in a compensatory sensitization of adenylyl cyclase activity after subsequent activation by Gαs or forskolin. Several indirect observations have suggested the involvement of increased Gαs-adenylyl cyclase interactions in the expression of sensitization; however, evidence supporting a direct role for Gαs has not been well established. In the present report, we used two genetic approaches to further examine the role of Gαs in heterologous sensitization of Ca2+-sensitive type 1 adenylyl cyclase (AC1). In the first approach, we constructed Gαs-insensitive mutants of AC1 (F293L and Y973S) that retained sensitivity to Ca2+ and forskolin activation. Persistent (2 h) activation of the D2 dopamine receptor resulted in a significant augmentation of basal or Ca2+- and forskolin-stimulated AC1 activity; however, sensitization of Gαs-insensitive mutants of AC1 was markedly reduced compared with wild-type AC1. In the second strategy, we examined the requirement of an intact receptor-Gαs signaling pathway for the expression of sensitization using dominant-negative Gαs mutants (α3β5 G226A/A366S or α3β5 G226A/E268A/A366S) to disrupt D1 dopamine receptor activation of recombinant AC1. D1 dopamine receptor-Gαs signaling was attenuated in the presence of α3β5 G226A/A366S or α3β5 G226A/E268A/A366S, but D2 agonist-induced sensitization of Ca2+-stimulated AC1 activity was not altered. Together, the present findings directly support the hypothesis that the expression of sensitization of AC1 involves Gαs-adenylyl cyclase interactions. ER -