A role for Ca2+/calmodulin-dependent protein kinase II in the mitogen-activated protein kinase signaling cascade of cultured rat aortic vascular smooth muscle cells.
Exposure of cultured rat aortic vascular smooth muscle (VSM) cells to the Ca2+ ionophore ionomycin produced an increase in extracellular signal-regulated kinase 1/2 (ERK1/2) activity that was maximal between 2 and 5 minutes but then declined to basal values within 20 minutes of stimulation. Elevation of [Ca2+]i in VSM cells leads to an even more rapid activation of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II); thus, it was postulated that the Ca(2+)-dependent component of ERK1/2 activation was mediated by CaM kinase II. Transient ERK1/2 activation by ionomycin was almost completely abolished by pretreating cells with 30 mumol/L KN-93, a CaM kinase II inhibitor. Treatment of cells with KN-93 did not antagonize the ability of ionomycin to mobilize intracellular Ca2+ but prevented CaM kinase II and ERK1/2 activation with almost identical potencies. Consistent with a role for Ca2+ and calmodulin in intracellular Ca(2+)-induced activation of ERK, cells pretreated with calmodulin inhibitors (W-7 or calmidazolium) exhibited an attenuated ERK response to ionomycin. ERK1/2 activation in response to phorbol esters and platelet-derived growth factor were not significantly affected by KN-93, whereas the response to angiotensin II and thrombin were attenuated by 60% and 40%, respectively. Transient expression of wild-type delta 2 CaM kinase II in COS-7 cells resulted in increased ERK2 activity, whereas coexpression of wild-type and a kinase-negative mutant resulted in a diminution of this response. These data suggest that regulation of cellular responses by Ca(2+)-dependent pathways in VSM cells may be mediated in part by CaM kinase II-dependent activation of ERK1/2.
Abraham
S T
ST
Weis Center for Research, Geisinger Clinic, Danville, Pa, USA.
Benscoter
H A
HA
Schworer
C M
CM
Singer
H A
HA
D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism*; D001596:Benzylamines / Q000494:pharmacology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism / Q000502:physiology*; D002478:Cells, Cultured; D004789:Enzyme Activation; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D008934:Mitogens / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013449:Sulfonamides / Q000494:pharmacology; D000096926:Benzenesulfonamides
D001596:Benzylamines; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D015759:Ionomycin; D007476:Ionophores; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D008934:Mitogens; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D013449:Sulfonamides; C072105:KN 93; D000096926:Benzenesulfonamides