Degradation of cardiac myosin light chain kinase by matrix metalloproteinase-2 contributes to myocardial contractile dysfunction during ischemia/reperfusion

• Published in: Journal of molecular and cellular cardiology Vol. 77; pp. 102 - 112
• Main Authors: Gao, Ling, Zheng, Yan-Jun, Gu, Shan-Shan, Tan, Ji-Liang, Paul, Christian, Wang, Yi-Gang, Yang, Huang-Tian
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.12.2014
• Subjects: Animals; Cardiac myosin light chain kinase; Cardiovascular; Cells, Cultured; Contraction; Ischemia/reperfusion injury; Male; Matrix Metalloproteinase 2 - metabolism; Matrix metalloproteinase-2; Myocardial Contraction; Myocardial Ischemia - enzymology; Myocardial Reperfusion Injury - enzymology; Myocardial Reperfusion Injury - physiopathology; Myocardium - enzymology; Myocardium - pathology; Myocytes, Cardiac - enzymology; Myosin-Light-Chain Kinase - metabolism; Protein Processing, Post-Translational; Proteolysis; Rats, Sprague-Dawley; Ventricular myosin regulatory light chain; Cardiac myosin light chain kinase; Ischemia/reperfusion injury; Ventricular myosin regulatory light chain; Contraction; Matrix metalloproteinase-2
• ISSN: 0022-2828; 1095-8584
• DOI: 10.1016/j.yjmcc.2014.10.004

Abstract Although ischemia/reperfusion (I/R)-induced myocardial contractile dysfunction is associated with a prominent decrease in myofilament Ca 2 + sensitivity, the underlying mechanisms have not yet been fully clarified. Phosphorylation of ventricular myosin light chain 2 (MLC-2v) facilitates actin–myosin interactions and enhances contractility, however, its level and regulation by cardiac MLC kinase (cMLCK) and cMLC phosphatase (cMLCP) in I/R hearts are debatable. In this study, the levels and/or effects of MLC-2v phosphorylation, cMLCK, cMLCP, and proteases during I/R were determined. Global myocardial I/R-suppressed cardiac performance in isolated rat hearts was concomitant with decreases of MLC-2v phosphorylation, myofibrillar Ca 2 + -stimulated ATPase activity, and cMLCK content, but not cMLCP proteins. Consistently, simulated I/R in isolated cardiomyocytes inhibited cell shortening, Ca 2 + transients, MLC-2v phosphorylation, and myofilament sensitivity to Ca 2 + . These observations were reversed by cMLCK overexpression, while the specific cMLCK knockdown by short hairpin RNA (shRNA) had the opposite effect. Moreover, the inhibition of matrix metalloproteinase-2 (MMP-2, a zinc-dependent endopeptidase) reversed IR-decreased cMLCK, MLC-2v phosphorylation, myofibrillar Ca 2 + -stimulated ATPase activity, myocardial contractile function, and myofilament sensitivity to Ca 2 + , while the inhibition or knockdown of cMLCK by ML-9 or specific shRNA abolished MMP-2 inhibition-induced cardioprotection. Finally, the co-localization in cardiomyocytes and interaction in vivo of MMP-2 and cMLCK were observed. Purified recombinant rat cMLCK was concentration- and time-dependently degraded by rat MMP-2 in vitro, and this was prevented by the inhibition of MMP-2. These findings reveal that the I/R-activated MMP-2 leads to the degradation of cMLCK, resulting in a reduction of MLC-2v phosphorylation, and myofibrillar Ca 2 + -stimulated ATPase activity, which subsequently suppresses myocardial contractile function through a decrease of myofilament Ca 2 + sensitivity.