Activation of extracellular-regulated kinase by 5-hydroxytryptamine(2A) receptors in PC12 cells is protein kinase C-independent and requires calmodulin and tyrosine kinases.
5-Hydroxytryptamine (5-HT)(2A) receptors have been implicated to play a role in both the treatment and pathophysiology of a number of psychiatric disorders. Therefore, the coupling of this receptor to signals, such as extracellular signal-regulated kinase (ERK), that elicit long-term neuronal changes may be relevant. In the present study we examined the coupling of the G(q)-coupled receptor to ERK in PC12 cells, a cell line commonly used as a neuronal model system. Activation of ERK occurred through a pathway different than the protein kinase C-dependent pathways described previously in studies of non-neuronal cells. Activation of ERK, in PC12 cells, was inhibited by both chelation of extracellular Ca(2+) and by depletion of intracellular Ca(2+) stores. Surprisingly, activation was not inhibited, but actually potentiated, by a variety of protein kinase C inhibitors covering all known protein kinase C isoforms. In contrast, the coupling of receptor to activation of ERK was found to be sensitive to N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W7) and N-(4-aminobutyl)-5-chloro-1-naphthalenesulfonamide (W13), inhibitors of calmodulin, but not to 1-(N,O-bis[5-isoquinolinesulfonyl]-N-methyl-L-tyrosyl)-4-phenylpiperazine (KN62) and 2-[N-(2-hydroxyethyl)]-N-4-methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylamine) (KN93), inhibitors of calmodulin-dependent protein kinase. Additionally, the general tyrosine kinase inhibitor genistein, as well as the Src inhibitor PP1 and the epidermal growth factor receptor kinase inhibitor 4-(3-chloroanilino)-6,7-dimethoxyquinazoline (AG 1478), inhibited receptor-mediated activation of ERK, suggesting a role for tyrosine kinases. In fact, 5-HT was found to stimulate tyrosine phosphorylation of a number of proteins, and this phosphorylation was inhibited by W7. 5-HT(2A) receptor-activation of ERK through a protein kinase C-independent pathway requiring Ca(2+)/calmodulin/tyrosine kinases represents a pathway distinct from those described in studies of non-neuronal cells.
Quinn
John C
JC
Department of Psychiatry, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, 125 Paterson Street, New Brunswick, NJ 08901, USA.
Johnson-Farley
Nadine N
NN
Yoon
JiYoung
J
Cowen
Daniel S
DS
D000818:Animals; D000911:Antibodies, Monoclonal; D001596:Benzylamines / Q000494:pharmacology; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016716:PC12 Cells; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011799:Quinazolines; D051381:Rats; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000187:drug effects*; D013449:Sulfonamides / Q000494:pharmacology; D020032:Tyrphostins / Q000494:pharmacology; D000096926:Benzenesulfonamides
D000911:Antibodies, Monoclonal; D001596:Benzylamines; D002147:Calmodulin; D017868:Cyclic AMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D020928:Mitogen-Activated Protein Kinases; D011493:Protein Kinase C; D011505:Protein-Tyrosine Kinases; D011799:Quinazolines; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; D013449:Sulfonamides; D020032:Tyrphostins; C072105:KN 93; D000096926:Benzenesulfonamides; C101044:RTKI cpd; C017967:W 7; C033772:N-(4-aminobutyl)-5-chloro-2-naphthalenesulfonamide