title: Inhibition of MMP-2 expression with siRNA increases baseline cardiomyocyte contractility and protects against simulated ischemic reperfusion injury.
abstract: Matrix metalloproteinases (MMPs) significantly contribute to ischemia reperfusion (I/R) injury, namely, by the degradation of contractile proteins. However, due to the experimental models adopted and lack of isoform specificity of MMP inhibitors, the cellular source and identity of the MMP(s) involved in I/R injury remain to be elucidated. Using isolated adult rat cardiomyocytes, subjected to chemically induced I/R-like injury, we show that specific inhibition of MMP-2 expression and activity using MMP-2 siRNA significantly protected cardiomyocyte contractility from I/R-like injury. This was also associated with increased expression of myosin light chains 1 and 2 (MLC1/2) in comparison to scramble siRNA transfection. Moreover, the positive effect of MMP-2 siRNA transfection on cardiomyocyte contractility and MLC1/2 expression levels was also observed under control conditions, suggesting an important additional role for MMP-2 in physiological sarcomeric protein turnover. This study clearly demonstrates that intracellular expression of MMP-2 plays a significant role in sarcomeric protein turnover, such as MLC1 and MLC2, under aerobic (physiological) conditions. In addition, this study identifies intracellular/autocrine, cardiomyocyte-produced MMP-2, rather than paracrine/extracellular, as responsible for the degradation of MLC1/2 and consequent contractile dysfunction in cardiomyocytes subjected to I/R injury.
authors.affiliation: Department of Pharmacology, College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5.
authors.forename: Han-Bin
authors.initials: HB
authors.lastname: Lin
authors.affiliation: Department of Pharmacology, College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5 ; Faculté de Pharmacie, Université de Montréal, Montréal, QC, Canada H3T 1J4.
authors.forename: Virgilio J J
authors.initials: VJ
authors.lastname: Cadete
authors.affiliation: Department of Pharmacology, College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5.
authors.forename: Bikramjit
authors.initials: B
authors.lastname: Sra
authors.affiliation: Department of Pharmacology, College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Sawicka
authors.affiliation: Department of Physiology, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E5.
authors.forename: Zhicheng
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Pharmacology, College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5.
authors.forename: Lane K
authors.initials: LK
authors.lastname: Bekar
authors.affiliation: Department of Physiology, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E5.
authors.forename: Francisco
authors.initials: F
authors.lastname: Cayabyab
authors.affiliation: Department of Pharmacology, College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5 ; Department of Clinical Chemistry, Medical University of Wroclaw, 50-556 Wroclaw, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Sawicki
mesh_terms: D000818:Animals; D024722:Cardiac Myosins / Q000378:metabolism; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D009119:Muscle Contraction / Q000502:physiology*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism*; D018994:Myosin Light Chains / Q000378:metabolism; D020011:Protective Agents / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D018994:Myosin Light Chains; D020011:Protective Agents; D034741:RNA, Small Interfering; C107184:myosin light chain 2; C076659:myosin light chain I; D020778:Matrix Metalloproteinase 2; D024722:Cardiac Myosins