The newly synthesized selective Ca2+/calmodulin dependent protein kinase II inhibitor KN-93 reduces dopamine contents in PC12h cells.
We reported that one of the isoquinolinesulfonamide derivatives, KN-62, is a potent and specific inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMKII) (Tokumitsu, H., Chijiwa, T., Hagiwara, M., Mizutani, A., Terasawa, M. and Hidaka, H. (1990) J. Biol. Chem. 265, 4315-4320). We have now investigated the inhibitory property of a newly synthesized methoxybenzenesulfonamide, KN-93, on CaMKII activity in situ and in vitro. KN-93 elicited potent inhibitory effects on CaMKII phosphorylating activity with an inhibition constant of 0.37 microM but this compound had no significant effects on the catalytic activity of cAMP-dependent protein kinase, Ca2+/phospholipid dependent protein kinase, myosin light chain kinase and Ca(2+)-phosphodiesterase. KN-93 also inhibited the autophosphorylation of both the alpha- and beta-subunits of CaMKII. Kinetic analysis indicated that KN-93 inhibits CaMKII, in a competitive fashion against calmodulin. To evaluate the regulatory role of CaMKII on catecholamine metabolism, we examined the effect of KN-93 on dopamine (DA) levels in PC12h cells. The DA levels decreased in the presence of KN-93. Further, the tyrosine hydroxylase (TH) phosphorylation induced by KCl or acetylcholine was significantly suppressed by KN-93 in PC12h cells while events induced by forskolin or 8-Br-cAMP were not affected. These results suggest that KN-93 inhibits DA formation by modulating the reaction rate of TH to reduce the Ca(2+)-mediated phosphorylation levels of the TH molecule.
Sumi
M
M
Department of Pharmacology, Nagoya University School of Medicine, Japan.
Kiuchi
K
K
Ishikawa
T
T
Ishii
A
A
Hagiwara
M
M
Nagatsu
T
T
Hidaka
H
H
D000818:Animals; D001596:Benzylamines / Q000494:pharmacology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002417:Cattle; D002645:Chickens; D004298:Dopamine / Q000378:metabolism*; D007700:Kinetics; D009130:Muscle, Smooth / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D016716:PC12 Cells; D010766:Phosphorylation; D016548:Prosencephalon / Q000201:enzymology; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000302:isolation & purification; D011817:Rabbits; D051381:Rats; D013449:Sulfonamides / Q000494:pharmacology*; D000096926:Benzenesulfonamides
D001596:Benzylamines; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004298:Dopamine; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D013449:Sulfonamides; C072105:KN 93; D000096926:Benzenesulfonamides