Activation of a novel PKC isoform synergistically enhances D2L dopamine receptor-mediated sensitization of adenylate cyclase type 6.
Despite acutely inhibiting adenylate cyclase, prolonged activation of Galpha(i/o)-coupled receptors leads to a subsequent heterologous sensitization of adenylate cyclase responsiveness. Recently, protein kinase signaling and phosphorylation have been implicated in the sensitization of adenylate cyclase type 6 (AC6). To examine the sensitization specifically of AC6, we constructed human embryonic kidney cells (HEK293) cells stably expressing AC6 and the Galpha(i/o)-coupled D2L dopamine receptor. In contrast to observations in delta-opioid-expressing Chinese hamster ovary (CHO) cells that express endogenous AC6 and AC7, neither protein kinase C (PKC) nor tyrosine kinase inhibitors attenuated D2L receptor-mediated sensitization of AC6. Inhibition of Raf1 modestly inhibited the magnitude of D2L receptor-induced sensitization of AC6; however, activation of PKC robustly enhanced D2L receptor-mediated AC6 sensitization in a Raf1-dependent manner. These data indicate that, although PKC and Raf1 are not required for sensitization, activation of the PKC-Raf1 pathway robustly potentiated D2L receptor-mediated sensitization of AC6.
Beazely
Michael A
MA
Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907-2091, USA.
Watts
Val J
VJ
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D002147:Calmodulin / Q000502:physiology; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D004789:Enzyme Activation; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism* / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D019908:Proto-Oncogene Proteins c-raf / Q000502:physiology; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D002147:Calmodulin; D007527:Isoenzymes; D017448:Receptors, Dopamine D2; C113776:dopamine D2L receptor; D011505:Protein-Tyrosine Kinases; D019908:Proto-Oncogene Proteins c-raf; D011493:Protein Kinase C; D000262:Adenylyl Cyclases; D013755:Tetradecanoylphorbol Acetate