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Enhanced contractility and myosin phosphorylation induced by Ca(2+)-independent MLCK activity in hypertensive rats.

 Young-Eun Cho  ;  Duck-Sun Ahn  ;  Kathleen G. Morgan  ;  Young-Ho Lee 
 CARDIOVASCULAR RESEARCH, Vol.91(1) : 162-170, 2011 
Journal Title
Issue Date
Analysis of Variance ; Animals ; Apoptosis Regulatory Proteins/metabolism ; Calcium-Calmodulin-Dependent Protein Kinases/metabolism ; Death-Associated Protein Kinases ; Disease Models, Animal ; Dose-Response Relationship, Drug ; Enzyme Inhibitors/pharmacology ; Hypertension/enzymology* ; Hypertension/physiopathology ; Male ; Mesenteric Arteries/enzymology ; Mesenteric Arteries/physiopathology ; Muscle Proteins/metabolism ; Muscle, Smooth, Vascular/drug effects ; Muscle, Smooth, Vascular/enzymology* ; Muscle, Smooth, Vascular/physiopathology ; MyosinLight Chains/metabolism* ; Myosin-Light-Chain Kinase/antagonists & inhibitors ; Myosin-Light-Chain Kinase/metabolism* ; Oxazoles/pharmacology ; Phosphoprotein Phosphatases/antagonists & inhibitors ; Phosphoprotein Phosphatases/metabolism ; Phosphoproteins/metabolism ; Phosphorylation ; Protein Kinase C/antagonists & inhibitors ; Protein Kinase C/metabolism ; Protein Phosphatase 1/metabolism ; Rats ; Rats, Inbred SHR ; Rats, Inbred WKY ; Up-Regulation ; Vasoconstriction*/drug effects ; Vasoconstrictor Agents/pharmacology
ZIPK ; Hypertension ; Phosphorylation of MLC ; Phosphorylation of MYPT1 ; Calyculin A
AIMS: The role of Ca(2+) sensitization induced by a Ca(2+)-independent myosin light chain kinase (MLCK) in hypertension has not been determined. The aim of this study was to clarify the role of possible Ca(2+)-independent MLCK activity in hypertension.

METHODS AND RESULTS: We compared increases in contractile force and phosphorylation of myosin light chain (MLC) evoked by calyculin A, a phosphatase inhibitor, in β-escin-permeabilized mesenteric arteries at pCa 9.0 between spontaneously hypertensive rat (SHR) and Wistar Kyoto rat (WKY). We found that there was no detectable phosphorylation of MLC at pCa 9.0, but that the administration of 1 μM calyculin A gradually increased force and mono- and di-phosphorylation of MLC. This contraction was inhibited by staurosporine but not by wortmannin, Y-27632, or calphostin-C. The calyculin A-induced contraction was significantly greater in the SHR than in the WKY and was associated with an increase in mono- and di-phosphorylation of MLC. SM-1, a zipper-interacting protein kinase (ZIPK)-inhibiting peptide, significantly inhibited the amplitude of the calyculin A-induced contraction and di-phosphorylation. Total ZIPK expression (54 + 32 kDa) was greater in the SHR than in the WKY. Phosphorylation of myosin phosphatase target subunit at Thr(697), but not at Thr(855), was consistently stronger in the SHR than in the WKY in calyculin A-treated tissues at pCa 9.0.

CONCLUSIONS: Our results suggest that Ca(2+)-independent MLCK activity is enhanced in the SHR, and that ZIPK plays, at least in part, an important role as a candidate for this kinase in rat mesenteric arteries.
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1. College of Medicine (의과대학) > Dept. of Physiology (생리학교실) > 1. Journal Papers
Yonsei Authors
Ahn, Duk Sun(안덕선) ORCID logo https://orcid.org/0000-0001-9351-6951
Lee, Young Ho(이영호) ORCID logo https://orcid.org/0000-0002-5749-1045
Cho, Young Eun(조영은)
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