title: Cardiac ischemia-reperfusion injury induces matrix metalloproteinase-2 expression through the AP-1 components FosB and JunB.
abstract: Matrix metalloproteinase-2 (MMP-2) is a central component of the response to injury in the heart. During ischemia, MMP-2 influences ventricular performance and is a determinant of postinfarction remodeling. Elevation of MMP-2 during reperfusion after ischemia suggests that new protein is synthesized, but the molecular regulation of MMP-2 generation during ischemia-reperfusion (I/R) injury has not been studied. Using the MMP-2 promoter linked to a beta-galactosidase reporter in transgenic mice, we investigated the transcriptional regulation and cellular sources of MMP-2 in isolated, perfused mouse hearts subjected to acute global I/R injury. I/R injury induced a rapid activation of MMP-2 promoter activity with the appearance of beta-galactosidase antigen in cardiomyocytes, fibroblasts, and endothelial cells. Activation of intrinsic MMP-2 transcription and translation was confirmed by real-time PCR and quantitative Western blot analyses. MMP-2 transcription and translation were inhibited by perfusion with 1.0 mM hydroxyl radical scavenger N-(-2-mercaptopropionyl)-glycine. Nuclear extracts demonstrated increased abundance of two activator proteins-1 (AP-1) components JunB and FosB following I/R injury. Immunohistochemical staining localized JunB and FosB proteins to the nuclei of all three cardiac cell types following I/R injury, consistent with enhanced nuclear transport of these transcription factors. Chromatin immunoprecipitation (ChIP) of the AP-1 binding site in the intrinsic murine MMP-2 promoter yielded only JunB under control conditions, whereas ChIP following I/R injury recovered both JunB and FosB, consistent with a change in occupancy from JunB homodimers in controls to JunB/FosB heterodimers following I/R injury. We conclude that enhanced MMP-2 transcription and translation following I/R injury are mediated by induction, via oxidant stress, of discrete AP-1 transcription factor components.
authors.affiliation: Dept. of Medicine, 111J, San Francisco Veterans Affairs Medical Center/Univ. of California San Francisco, 4150 Clement St., San Francisco, CA 94121, USA.
authors.forename: Maria Alejandra
authors.initials: MA
authors.lastname: Alfonso-Jaume
authors.forename: Marina R
authors.initials: MR
authors.lastname: Bergman
authors.forename: Rajeev
authors.initials: R
authors.lastname: Mahimkar
authors.forename: Sunfa
authors.initials: S
authors.lastname: Cheng
authors.forename: Zhu Q
authors.initials: ZQ
authors.lastname: Jin
authors.forename: Joel S
authors.initials: JS
authors.lastname: Karliner
authors.forename: David H
authors.initials: DH
authors.lastname: Lovett
mesh_terms: D000818:Animals; D005786:Gene Expression Regulation / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis / Q000187:drug effects; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism*; D015427:Reperfusion Injury / Q000235:genetics / Q000378:metabolism*; D008625:Tiopronin / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D008625:Tiopronin; D020778:Matrix Metalloproteinase 2