Submitted on December 22, 2008
Revised on April 7, 2009
Accepted on April 21, 2009
Involvements of NADPH Oxidase in Oxidized LDL-Induced Upregulation of Heat Shock Factor-1 and Plasminogen Activator Inhibitor-1 in Vascular Endothelial Cells
Ruozhi Zhao1, Xiuli Ma1, Xueping Xie1, and Garry X Shen1*
1 University of Manitoba
* To whom correspondence should be addressed. E-mail: gshen{at}ms.umanitoba.ca.
Plasminogen activator inhibitor-1 (PAI-1) is implicated in thrombogenesis, inflammation and extracellular matrix remodeling. Previous studies indicated that oxidized low density lipoprotein (LDL) stimulated the generation of PAI-1 in vascular endothelial cells (EC). The present study demonstrated that LDL oxidized by copper, iron or 3-morpholinosydnonimine increased the expression of NADPH oxidase (NOX)2, PAI-1 and heat shock factor-1 (HSF1) in human umbilical vein EC (HUVEC) or coronary artery EC (HCAEC) compared to LDL or vehicle. Diphenyleneiodonium, a NOX inhibitor, prevented the increases of the expression of HSF1 and PAI-1 in EC induced by oxidized LDLs. Small interference RNA (siRNA) for p22phox, an essential subunit of NOX, prevented oxidized LDL-induced expression of NOX2, HSF1 and PAI-1 in EC. HSF1 siRNA inhibited oxidized LDL-induced expression of PAI-1 and HSF1, but not NOX2, in EC. The binding of HSF1 to PAI-1 promoter and the activity of PAI-1 promoter in EC were enhanced by oxidized LDL. Butylated hydroxytulene, a potent antioxidant, inhibited oxidized LDL-induced release of hydrogen peroxide (H2O2) and the expression of NOX2, HSF1 and PAI-1 in EC. Treatment with H2O2 increased the abundance of NOX2, HSF1 and PAI-1 in EC. The results of the present study indicate that oxidized LDL-induced expression of NOX may lead to the elevated release of reactive oxygen species, the activation of HSF1 and the enhancement of the transcription of PAI-1 gene in cultured vascular EC.
