Effect of mmLDL on plasminogen activator inhibitor-1 expression and regulation in human umbilical vein endothelial cells / 中国病理生理杂志

ABSTRACT

AIM: To study the influence of minimal modified low density lipoprotein (mmLDL) on plasminogen activator inhibitor-1 (PAI-1) activity, gene expression and regulation in human vascular endothelial cells. METHODS: The PAI-1 activity in human umbilical vein endothelial cells (HUVEC) culture medium was measured by chromogenic assay. The PAI-1 mRNA expression were determined by Northern blot. Using gene recombination techniques, four luciferase reporter gene plasmids containing different length of human PAI-1 gene promoter were constructed. Through the transient transfection analysis, the roles of AP-1 element(from -823 bp to -553 bp) in PAI-1 promoter have been determined. In order to further verify the role of AP-1 element, the three site-directed mutants were received using PCR and sequencing assay. RESULTS: The PAI-1 activity and mRNA level were increased when HUVECs were exposed to 50 mg/L mmLDL. At the same time, the AP-1 protein level was increased in nuclear. The induction by mmLDL were decreased markedly when the three AP-1 elements in PAI-1 promoter had been mutated, respectively. CONCLUSION: (1) mmLDL increased PAI-1 activity and mRNA expression in HUVEC. (2) Increase in PAI-1 activity induced by mmLDL was related to its mRNA expression. (3) Three AP-1 element in PAI-1 promoter may have an important role in PAI-1 gene transcription in endothelial cells induced by mmLDL.