title: Leptin regulates MMP-2, TIMP-1 and collagen synthesis via p38 MAPK in HL-1 murine cardiomyocytes.
abstract: A clear association between obesity and heart failure exists and a significant role for leptin, the product of the obese gene, has been suggested. One aspect of myocardial remodeling which characterizes heart failure is a disruption in the balance of extracellular matrix synthesis and degradation. Here we investigated the effects of leptin on matrix metalloproteinase (MMP) activity, tissue inhibitor of metalloproteinase (TIMP) expression, as well as collagen synthesis in HL-1 cardiac muscle cells. Gelatin zymographic analysis of MMP activity in conditioned media showed that leptin enhanced MMP-2 activity in a dose- and time-dependent manner. Leptin is known to stimulate phosphorylation of p38 MAPK in cardiac cells and utilization of the p38 MAPK inhibitor, SB203580, demonstrated that this kinase also plays a role in regulating several extracellular matrix components, such that inhibition of p38 MAPK signaling prevented the leptin-induced increase in MMP-2 activation. We also observed that leptin enhanced collagen synthesis determined by both proline incorporation and picrosirius red staining of conditioned media. Pro-collagen type-I and pro-collagen type-III expression, measured by real-time PCR and Western blotting were also increased by leptin, effects which were again attenuated by SB203580. In summary, these results demonstrate the potential for leptin to play a role in mediating myocardial ECM remodeling and that the p38 MAPK pathway plays an important role in mediating these effects.
authors.affiliation: Department of Biology, York University, Toronto, Canada.
authors.forename: Kristin
authors.initials: K
authors.lastname: Schram
authors.forename: Sabrina
authors.initials: S
authors.lastname: De Girolamo
authors.forename: Siham
authors.initials: S
authors.lastname: Madani
authors.forename: Diana
authors.initials: D
authors.lastname: Munoz
authors.forename: Farah
authors.initials: F
authors.lastname: Thong
authors.forename: Gary
authors.initials: G
authors.lastname: Sweeney
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis*; D017077:Culture Media, Conditioned; D006801:Humans; D020738:Leptin / Q000494:pharmacology*; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics / Q000378:metabolism*; D020257:Ventricular Remodeling / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D017077:Culture Media, Conditioned; D020738:Leptin; D011498:Protein Precursors; D019715:Tissue Inhibitor of Metalloproteinase-1; D003094:Collagen; D048051:p38 Mitogen-Activated Protein Kinases; D020778:Matrix Metalloproteinase 2