The stimulation of MAP kinase by 1,25(OH)(2)-vitamin D(3) in skeletal muscle cells is mediated by protein kinase C and calcium.
In previous work we have demonstrated that the steroid hormone 1,25(OH)(2)-vitamin D(3) [1,25(OH)(2)D(3)] stimulates in skeletal muscle cells the phosphorylation and activity of the extracellular signal-regulated mitogen-activated protein (MAP) kinase isoforms ERK1 and ERK2. In the present study we evaluated the involvement of Ca(2+) and protein kinase C (PKC) on 1,25(OH)(2)D(3)-induced activation of MAP kinase. The hormone response was found to depend on PKC stimulation since it was attenuated by the PKC inhibitors calphostin C (100 nM) and bisindolylmaleimide I (30 nM) and PKC downregulation by prolonged treatment with the phorbol ester TPA (1 microM). Removal of external Ca(2+), chelation of intracellular Ca(2+) with BAPTA (5 microM), inhibition of phosphoinositide-phospholipase C (PLC) by neomycin, the calmodulin antagonist fluphenazine (50 microM) and the specific inhibitor of calmodulin kinase II, KN-62 (10 microM), significantly decreased 1,25(OH)(2)D(3)-activation of MAP kinase. In addition, the Ca(2+)-channel blocker verapamil (5 microM) suppressed hormone-induced MAP kinase activity in these cells. Furthermore, the Ca(2+)-mobilizing agent thapsigargin and the Ca(2+)-inophore A23187 paralleled the phosphorylation of MAP kinase observed with 1,25(OH)(2)D(3). Taken together, these results indicate that PKC and Ca(2+) are two upstream activators mediating the effects of 1,25(OH)(2)D(3) on MAP kinase in skeletal muscle cells.
Morelli
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S
Departamento de Biologia, Bioquímica and Farmacia, Universidad Nacional del Sur, San Juan 670, 8000, Bahia Blanca, Argentina.
Buitrago
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C
Boland
R
R
de Boland
A R
AR
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002642:Chick Embryo; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005476:Fluphenazine / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008301:Maleimides / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D009281:Naphthalenes / Q000494:pharmacology; D009355:Neomycin / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology
D002147:Calmodulin; D007211:Indoles; D008301:Maleimides; D009281:Naphthalenes; D000001:Calcimycin; D004533:Egtazic Acid; C063302:KN 62; D019284:Thapsigargin; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D014700:Verapamil; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D002117:Calcitriol; D009355:Neomycin; C058819:calphostin C; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; C070515:bisindolylmaleimide I; D013755:Tetradecanoylphorbol Acetate; D005476:Fluphenazine; D002118:Calcium