Matrix metalloproteinase-12 gene expression in human vascular smooth muscle cells.
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.
Wu
Lihua
L
Department of Pathology, Institute of Basical Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
Tanimoto
Akihide
A
Murata
Yoshitaka
Y
Sasaguri
Takakazu
T
Fan
Jianglin
J
Sasaguri
Yasuyuki
Y
Watanabe
Teruo
T
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
D012333:RNA, Messenger; D019869:Phosphatidylinositol 3-Kinases; D008666:Metalloendopeptidases; C507122:MMP12 protein, human; D053508:Matrix Metalloproteinase 12