Role of calcium/calmodulin-dependent protein kinase II in the regulation of vascular smooth muscle cell migration.
BACKGROUND
The migration of vascular smooth muscle cells (VSMCs) is a key event in the pathogenesis of many vascular diseases. We have previously shown that VSMC migration in response to platelet-derived growth factor (PDGF) is suppressed when cultured cells are growth-arrested and induced to differentiate. The present study was undertaken to elucidate the mechanism of this suppression.


RESULTS
While both proliferating and growth-arrested VSMCs upregulated expression of the immediate early response genes, c-fos and JE (monocyte chemoattractant protein 1), growth-arrested VSMCs exhibited much smaller changes in intracellular calcium in response to PDGF and failed to activate the calcium/calmodulin-dependent protein kinase II (CaM kinase II). Blocking calcium-calmodulin interactions (50 mumol/L W7) or the activation of CaM kinase II (10 mumol/L KN62) in proliferating cells blocked their migration by more than 90%, whereas inhibition of protein kinase C activation had no significant effect on migration. Pretreatment of growth-arrested VSMCs with the calcium ionophore ionomycin resulted in an approximately 2.5-fold activation of CaM kinase II and increased migration of growth-arrested cells to 84 +/- 6% that of proliferating cells. These effects of ionomycin were blocked by inhibitors of CaM kinase II. Constitutively activated (ie, calcium/calmodulin-independent) CaM kinase II introduced by gene transfection into growth-arrested cells significantly increased migration toward PDGF from < 20% to > 70% that of proliferating cells.


CONCLUSIONS
These results demonstrate that activation of CaM kinase II is required for VSMC migration, that its activation in response to PDGF is suppressed in growth-arrested VSMCs, and that this suppression of CaM kinase II activation is responsible, in large part, for the failure of growth-arrested VSMCs to migrate toward PDGF.
Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224.
R R
RR
Pauly
C
C
Bilato
S J
SJ
Sollott
R
R
Monticone
P T
PT
Kelly
E G
EG
Lakatta
M T
MT
Crow
D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002455:Cell Division; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D004789:Enzyme Activation; D006801:Humans; D066298:In Vitro Techniques; D015759:Ionomycin / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000502:physiology*; D010982:Platelet-Derived Growth Factor / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014162:Transfection
D010982:Platelet-Derived Growth Factor; D015759:Ionomycin; D011493:Protein Kinase C; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases