Involvement of intracellular Ca2+ elevation but not cyclic AMP in PACAP-induced p38 MAP kinase activation in PC12 cells.
We have recently shown that in PC12 cells, pituitary adenylate cyclase-activating polypeptide (PACAP) and NGF synergistically stimulate PACAP mRNA expression primarily via a mechanism involving a p38 mitogen-activated protein kinase (MAPK)-dependent pathway. Here we have analyzed p38 MAPK activation by PACAP and the mechanism underlying this action of PACAP in PC12 cells. PACAP increased phosphorylation of p38 MAPK with a bell-shaped dose-response relationship and a maximal effect was obtained at 10(-8) M. PACAP (10(-8) M)-induced p38 MAPK phosphorylation was already evident at 2.5 min, maximal at 5 min, and rapidly declined thereafter. PACAP-induced p38 MAPK phosphorylation was potently inhibited by depletion of Ca(2+) stores with thapsigargin and partially inhibited by the phospholipase C inhibitor U-73122, L-type voltage-dependent calcium channel inhibitors nifedipine and nimodipine, and the Ca(2+) chelator EGTA, whereas the protein kinase C inhibitor calphostin C, the protein kinase A inhibitor H-89, the cAMP antagonist Rp-cAMP, and the nonselective cation channel blocker SKF96365 had no effect. These results indicate that PACAP activates p38 MAPK in PC12 cells through activation of a phospholipase C, mobilization of intracellular Ca(2+) stores, and Ca(2+) influx through voltage-dependent Ca(2+) channels, but not cyclic AMP-dependent mechanisms.
Sakai
Yoshiyuki
Y
Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Japan.
Hashimoto
Hitoshi
H
Shintani
Norihito
N
Ichibori
Ayako
A
Tomimoto
Shuhei
S
Tanaka
Kazuhiro
K
Hirose
Megumi
M
Baba
Akemichi
A
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D007424:Intracellular Fluid / Q000187:drug effects* / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009281:Naphthalenes / Q000494:pharmacology; D009479:Neuropeptides / Q000494:pharmacology*; D016716:PC12 Cells; D010766:Phosphorylation / Q000187:drug effects; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051381:Rats; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
C495403:Adcyap1 protein, rat; D002121:Calcium Channel Blockers; D009281:Naphthalenes; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; C058819:calphostin C; D002118:Calcium