Effects of oxidized and glycated low-density lipoproteins on transcription and secretion of plasminogen activator inhibitor-1 in vascular endothelial cells

Plasminogen activator inhibitor-1 (PAI-1) is the major physiological inhibitor of fibrinolysis. Elevated levels of PAI-1 were frequently detected in patients with coronary artery disease (CAD) or diabetes. Low-density lipoprotein (LDL) is a classical risk factor of CAD. Oxidation and glycation increase the atherogenecity of LDL. Previous studies demonstrated that oxidized LDL (oxLDL) or glycated LDL (gly-LDL) increased the release of PAI-1 from endothelial cells (ECs). The present study examined the effects of oxLDL and gly-LDL on the transcription, expression, secretion, and subcellular distribution of PAI-1 in cultured human ECs. Treatment with LDL significantly increased the promoter activity, mRNA level, and the release of PAI-1 from ECs by two- to threefold compared to controls. Oxidation or glycation significantly enhanced the effects of LDL on PAI-1 production in ECs compared to LDL (four- to fivefold vs. controls). No significant differences were detected between the effects of oxLDL and gly-LDL. Abundant PAI-1 antigens were detected in the perinuclear region of ECs and overlapped with giantin, a marker of Golgi apparatus. Treatment with brefeldin A disturbed the stack structure of Golgi apparatus and almost completely inhibited the release of PAI-1 from ECs induced by the lipoproteins and at basal conditions. The results suggest that oxidation and glycation enhanced the effects of LDL on the production of PAI-1 in ECs through increasing the transcription of PAI-1. Intact Golgi apparatus is required for PAI-1 generation from ECs induced by LDL or its modified forms.