title: Matrix metalloproteinase-12 gene expression in human vascular smooth muscle cells.
abstract: BACKGROUND
  Matrix metalloproteinases (MMPs) play an important role in smooth muscle cell (SMC) migration and proliferation during vascular remodelling. To investigate the expression of MMP-12 by SMCs, we examined the protein secretion and mRNA expression of MMP-12 by cultured medial SMCs and intimal SMCs derived from human aortic atherosclerotic lesions. To further elucidate the molecular mechanism for MMP-12 expression in SMCs, we determined the sequence requirements for MMP-12 gene transcriptional activity.
  
  
  RESULTS
  Cultured medial SMCs and intimal SMCs showed substantial MMP-12 expression at both the protein and mRNA levels. A series of 5'-deletion and site-directed mutants of the human MMP-12 promoter demonstrated that an AP-1 site spanning -81 to -75 bp was critical for the MMP-12 promoter activity in SMCs. An electrophoretic mobility shift assay confirmed the AP-1 binding activity in SMCs and showed that the protein bound to the AP-1 site consisted predominantly of c-Jun, JunD and Fra-1. Two structurally different inhibitors of phosphatidylinositol 3-kinase, wortmannin and LY294002, inhibited MMP-12 transcriptional activity and AP-1 binding.
  
  
  CONCLUSIONS
  These results indicated the expression of MMP-12 in vascular SMCs and showed that the MMP-12 gene expression was dependent on the AP-1 binding activity. Phosphatidylinositol 3-kinase signalling may be involved in MMP-12 transcriptional activation through AP-1 binding activity.
authors.affiliation: Department of Pathology, Institute of Basical Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Lihua
authors.initials: L
authors.lastname: Wu
authors.forename: Akihide
authors.initials: A
authors.lastname: Tanimoto
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Murata
authors.forename: Takakazu
authors.initials: T
authors.lastname: Sasaguri
authors.forename: Jianglin
authors.initials: J
authors.lastname: Fan
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Sasaguri
authors.forename: Teruo
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D004586:Electrophoresis; D006801:Humans; D053508:Matrix Metalloproteinase 12; D008666:Metalloendopeptidases / Q000096:biosynthesis / Q000235:genetics*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D012333:RNA, Messenger; D019869:Phosphatidylinositol 3-Kinases; D008666:Metalloendopeptidases; C507122:MMP12 protein, human; D053508:Matrix Metalloproteinase 12