title: Homocysteine-mediated activation and mitochondrial translocation of calpain regulates MMP-9 in MVEC.
abstract: Hyperhomocysteinemia (HHcy) is associated with atherosclerosis, stroke, and dementia. Hcy causes extracellular matrix remodeling by the activation of matrix metalloproteinase-9 (MMP-9), in part, by inducing redox signaling and modulating the intracellular calcium dynamics. Calpains are the calcium-dependent cysteine proteases that are implicated in mitochondrial damage via oxidative burst. Mitochondrial abnormalities have been identified in HHcy. The mechanism of Hcy-induced extracellular matrix remodeling by MMP-9 activation via mitochondrial pathway is largely unknown. We report a novel role of calpains in mitochondrial-mediated MMP-9 activation by Hcy in cultured rat heart microvascular endothelial cells. Our observations suggested that calpain regulates Hcy-induced MMP-9 expression and activity. We showed that Hcy activates calpain-1, but not calpain-2, in a calcium-dependent manner. Interestingly, the enhanced calpain activity was not mirrored by the decreased levels of its endogenous inhibitor calpastatin. We presented evidence that Hcy induces the translocation of active calpain from cytosol to mitochondria, leading to MMP-9 activation, in part, by causing intramitochondrial oxidative burst. Furthermore, studies with pharmacological inhibitors of calpain (calpeptin and calpain-1 inhibitor), ERK (PD-98059) and the mitochondrial uncoupler FCCP suggested that calpain and ERK-1/2 are the major events within the Hcy/MMP-9 signal axis and that intramitochondrial oxidative stress regulates MMP-9 via ERK-1/2 signal cascade. Taken together, these findings determine the novel role of mitochondrial translocation of calpain-1 in MMP-9 activation during HHcy, in part, by increasing mitochondrial oxidative stress.
authors.affiliation: Dept. of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, KY 40202, USA.
authors.forename: Karni S
authors.initials: KS
authors.lastname: Moshal
authors.forename: Mahavir
authors.initials: M
authors.lastname: Singh
authors.forename: Utpal
authors.initials: U
authors.lastname: Sen
authors.forename: Dorothea Susanne E
authors.initials: DS
authors.lastname: Rosenberger
authors.forename: Brooke
authors.initials: B
authors.lastname: Henderson
authors.forename: Neetu
authors.initials: N
authors.lastname: Tyagi
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Suresh C
authors.initials: SC
authors.lastname: Tyagi
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002154:Calpain / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000378:metabolism / Q000473:pathology; D003600:Cytosol / Q000378:metabolism; D004151:Dipeptides / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000473:pathology; D005419:Flavonoids / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006710:Homocysteine / Q000502:physiology*; D020138:Hyperhomocysteinemia / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D018384:Oxidative Stress; D051381:Rats; D017208:Rats, Wistar; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D002135:Calcium-Binding Proteins; D004151:Dipeptides; D005419:Flavonoids; D014475:Uncoupling Agents; D006710:Homocysteine; C071482:calpeptin; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; C033668:calpastatin; D048052:Mitogen-Activated Protein Kinase 3; D002154:Calpain; D020780:Matrix Metalloproteinase 9; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one