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Cardiac specific TIMP‐4 dictates cardiomyocyte contractility through Serca‐2a in cardiac dysfunction: a novel mechanism (868.7)
Author(s) -
Chaturvedi Pankaj,
Metreveli Naira,
Tyagi Suresh
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.868.7
Subject(s) - serca , contractility , microbiology and biotechnology , biology , transfection , downregulation and upregulation , phospholamban , myocyte , microrna , medicine , endocrinology , endoplasmic reticulum , cell culture , atpase , gene , genetics , biochemistry , enzyme
Although previous studies show MMP9 (Matrix Metalloprotease 9) dysregulation in cardiac disorders, the mechanisms how an MMP9 modulator (TIMP4‐Tissue Inhibitor of Matrix Metalloprotease 4) regulates contractility and regeneration remain elusive. Providing an insight into this mechanism, we hypothesize that TIMP4 regulates cardiomyocyte contractility by regulating the expression of Serca‐2a (Sarcoplasmic Reticulum Calcium ATPase) through microRNAs. To check this hypothesis, we overexpressed TIMP4 in cardiomyocytes along with its inhibition through siRNA, to elucidate the contractility profiles and establish regulatory effects of TIMP4. We checked the expression of serca‐2a and microRNA 122 with Western, RT‐PCR, qRT‐PCR. DesRed2 plasmid carrying the TIMP4 gene was used to overexpress TIMP4 in mouse cardiomyocytes while GFP plasmid was used as control to standardize transfections. Contractility measurements were executed by ION OPTIX instrument and transfection studies were done by confocal microscopy. The expression studies of TIMP4 were performed by Western, RT‐PCR, qRT‐PCR and additionally confirmed in HL‐1 cardiomyocyte cell line. We found increased contractility with increase in the amplitude and peak height with TIMP4 overexpression while with siRNA, the results were reversed. Intrestingly, we found increased expression of serca‐2a along with downregulation of microRNA 122. The data suggested a novel regulatory effect of TIMP4 on contractile function by regulating serca‐2a through microRNA 122. Grant Funding Source : NIH grant HL‐74185 and HL‐108621