A selective Ca2+/calmodulin-dependent protein kinase II inhibitor, KN-62, inhibits the enhanced phosphorylation and the activation of tyrosine hydroxylase by 56 mM K+ in rat pheochromocytoma PC12h cells.
Involvement of Ca2+/calmodulin-dependent protein kinase II (Ca2+/CaM-kinase II) on the phosphorylation of tyrosine hydroxylase (TH, EC.1.14.16.2) in rat pheochromocytoma, PC12h cells was examined using KN-62, 1-[N,O-Bis(5-isoquinolinsulfonyl)-N-methyl-L-tyrosyl]-4-phenylpipe razine, a selective inhibitor of Ca2+/CaM-kinase II. Both the enhanced phosphorylation of TH and the activated L-3,4-dihydroxyphenylalanine (DOPA) formation in the high K+ depolarization were inhibited by 10 microM KN-62. After incubation of PC12h cells with 10 microM KN-62 for 1 hr, the activation of TH with 3 min incubation of 56 mM K+ was reduced to the basal activity. However, KN-62 did not directly affect the activity of purified rat TH at pH 6.0 or 7.0. These results indicate that Ca2+/CaM-kinase II phosphorylates and activates TH of PC12h cells in the high K+ depolarization.
Department of Biochemistry, Nagoya University School of Medicine, Japan.
A
A
Ishii
K
K
Kiuchi
R
R
Kobayashi
M
M
Sumi
H
H
Hidaka
T
T
Nagatsu
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives*; D000310:Adrenal Gland Neoplasms; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002460:Cell Line; D004295:Dihydroxyphenylalanine / Q000378:metabolism; D004789:Enzyme Activation; D007546:Isoquinolines / Q000494:pharmacology*; D007700:Kinetics; D008970:Molecular Weight; D010673:Pheochromocytoma; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors; D051381:Rats; D014446:Tyrosine 3-Monooxygenase / Q000302:isolation & purification / Q000378:metabolism*
D007546:Isoquinolines; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D004295:Dihydroxyphenylalanine; C063302:KN 62; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D014446:Tyrosine 3-Monooxygenase; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D011188:Potassium