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

J Mol Cell Cardiol. 2014 Dec:77:102-12. doi: 10.1016/j.yjmcc.2014.10.004. Epub 2014 Oct 18.

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.

Keywords: Cardiac myosin light chain kinase; Contraction; Ischemia/reperfusion injury; Matrix metalloproteinase-2; Ventricular myosin regulatory light chain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Male
  • Matrix Metalloproteinase 2 / metabolism*
  • 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

Substances

  • Myosin-Light-Chain Kinase
  • Matrix Metalloproteinase 2
  • Mmp2 protein, rat