Cardiac tissue inhibitor of matrix metalloprotease 4 dictates cardiomyocyte contractility and differentiation of embryonic stem cells into cardiomyocytes: Road to therapy.
BACKGROUND
TIMP4 (Tissue Inhibitors of Matrix Metalloprotease 4), goes down in failing hearts and mice lacking TIMP4 show poor regeneration capacity after myocardial infarction (MI). This study is based on our previous observation that administration of cardiac inhibitor of metalloproteinase (~TIMP4) attenuates oxidative stress and remodeling in failing hearts. Therefore, we hypothesize that TIMP4 helps in cardiac regeneration by augmenting contractility and inducing the differentiation of cardiac progenitor cells into cardiomyocytes.


METHODS
To validate this hypothesis, we transfected mouse cardiomyocytes with TIMP4 and TIMP4-siRNA and performed contractility studies in the TIMP4 transfected cardiomyocytes as compared to siRNA-TIMP4 transfected cardiomyocytes. We evaluated the calcium channel gene serca2a (sarcoplasmic reticulum calcium ATPase2a) and mir122a which tightly regulates serca2a to explain the changes in contractility. We treated mouse embryonic stem cells with cardiac extract and cardiac extract minus TIMP4 (using TIMP4 monoclonal antibody) to examine the effect of TIMP4 on differentiation of cardiac progenitor cells.


RESULTS
Contractility was augmented in the TIMP4 transfected cardiomyocytes as compared to siRNA-TIMP4 transfected cardiomyocytes. There was elevated expression of serca2a in the TIMP4 transformed myocytes and down regulation of mir122a. The cells treated with cardiac extract containing TIMP4 showed cardiac phenotype in terms of Ckit+, GATA4+ and Nkx2.5 expression.


CONCLUSIONS
This is a novel report suggesting that TIMP4 augments contractility and induces differentiation of progenitor cells into cardiac phenotype. In view of the failure of MMP9 inhibitors for cardiac therapy, TIMP4 provides an alternative approach, being an indigenous molecule and a natural inhibitor of MMP9.
Department of Physiology and Biophysics, School of Medicine, University of Louisville, KY, USA. Electronic address: p0chat03@louisville.edu.
Pankaj
P
Chaturvedi
Department of Physiology and Biophysics, School of Medicine, University of Louisville, KY, USA.
Anuradha
A
Kalani
Department of Physiology and Biophysics, School of Medicine, University of Louisville, KY, USA.
Anastasia
A
Familtseva
Department of Physiology and Biophysics, School of Medicine, University of Louisville, KY, USA.
Pradip Kumar
PK
Kamat
Department of Physiology and Biophysics, School of Medicine, University of Louisville, KY, USA.
Naira
N
Metreveli
Department of Physiology and Biophysics, School of Medicine, University of Louisville, KY, USA.
Suresh C
SC
Tyagi
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009119:Muscle Contraction / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000502:physiology*; D019714:Tissue Inhibitor of Metalloproteinases / Q000235:genetics* / Q000378:metabolism; D014162:Transfection / Q000379:methods; D000097792:Tissue Inhibitor of Metalloproteinase-4
D019714:Tissue Inhibitor of Metalloproteinases; D000097792:Tissue Inhibitor of Metalloproteinase-4
Cardiomyocytes; Contractility; MicroRNA; Stem cells; Tissue inhibitor of matrix metalloprotease (TIMP)