title: Regulation of homocysteine-induced MMP-9 by ERK1/2 pathway.
abstract: Homocysteine (Hcy) induces matrix metalloproteinase (MMP)-9 in microvascular endothelial cells (MVECs). We hypothesized that the ERK1/2 signaling pathway is involved in Hcy-mediated MMP-9 expression. In cultured MVECs, Hcy induced activation of ERK, which was blocked by PD-98059 and U0126 (MEK inhibitors). Pretreatment with BAPTA-AM, staurosporine (PKC inhibitor), or Gö6976 (specific inhibitor for Ca(2+)-dependent PKC) abrogated ERK phosphorylation, suggesting the role of Ca(2+) and Ca(2+)-dependent PKC in Hcy-induced ERK activation. ERK phosphorylation was suppressed by pertussis toxin (PTX), suggesting the involvement of G protein-coupled receptors (GPCRs) in initiating signal transduction by Hcy and leading to ERK activation. Pretreatment of MVECs with genistein, BAPTA-AM, or thapsigargin abrogated Hcy-induced ERK activation, suggesting the involvement of the PTK pathway in Hcy-induced ERK activation, which was mediated by intracellular Ca(2+) pool depletion. ERK activation was attenuated by preincubation with N-acetylcysteine (NAC) and SOD, suggesting the role of oxidation in Hcy-induced ERK activation. Pretreatment with an ERK1/2 blocker (PD-98059), staurosporine, folate, or NAC modulated Hcy-induced MMP-9 activation as measured using zymography. Our results provide evidence that Hcy triggers the PTX-sensitive ERK1/2 signaling pathway, which is involved in the regulation of MMP-9 in MVECs.
authors.affiliation: Department of Physiology and Biophysics, University of Louisville School of Medicine, A-1115, 500 S. Preston St., Louisville, KY 40202, USA.
authors.forename: Karni S
authors.initials: KS
authors.lastname: Moshal
authors.forename: Utpal
authors.initials: U
authors.lastname: Sen
authors.forename: Neetu
authors.initials: N
authors.lastname: Tyagi
authors.forename: Brooke
authors.initials: B
authors.lastname: Henderson
authors.forename: Mesia
authors.initials: M
authors.lastname: Steed
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Ovechkin
authors.forename: Suresh C
authors.initials: SC
authors.lastname: Tyagi
mesh_terms: D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation; D004790:Enzyme Induction / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005492:Folic Acid / Q000494:pharmacology; D006710:Homocysteine / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D020935:MAP Kinase Signaling System; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D018384:Oxidative Stress; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism
chemical_list: D043562:Receptors, G-Protein-Coupled; D006710:Homocysteine; D005492:Folic Acid; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D020780:Matrix Metalloproteinase 9; D002118:Calcium