Effects Of TNFα-induced Oxidative Stress On Transcriptional Regulation Of PDGF-B Gene And Its Signal Transduction In Endothelial Cell

Atherosclerosis (AS) is a principal cause of many cardiovascular diseases. However, its mechanisms have not been fully elucidated. AS has been regarded as a chronic inflammatory process, in which the central events are the dysfunction of arterial wall endothelial cells (EC) and the later proliferation of smooth muscle cells. Several growth factors released from the dysfunctional ECs and the surrounding tissues have been implicated in promoting the migration of smooth muscle cells into the intima and its proliferation. Among them is the platlet-deived growth factor (PDGF). The PDGF, a 28-35kD dimmer composed of a A- and/or B-chain, is a potent mitogen and chemotactant for the VSMCs. It is also chemotactic for monocytes and neutrophils. Although VSMCs secrete PDGF-A, endothelial cells are the major source of PDGF-B in vascular tissues. Expression of PDGF-B in endothelial cells is induced by a diversity of stimuli such as thrombin, shear stress and inflammatory cytokines including tumour necrosis factor a (TNFa).The implication of TNFa in the development of atherosclerosis has been suggested by a number of animal and human studies. It was reported that TNFα could induce PDGF-B expression in endothelium. Yet, the signal transduction and the role of PDGF-B gene promoter in PDGF-B expression are not fully elucidated. The aim of this study is to investigate the effect of TNF α on PDGF-B expression in endothelium and the molecular mechanism involved. The following aspects were studied:1. The roles of oxidative stress in PDGF-B expression induced by TNFα in HUVECs(1)The role of NAC in PDGF-B protein expression induced by TNFα was determined with ELISA assays.(2)The role of NAC in PDGF-B transcription induced by TNFα was investigated using RT-PCR technique.(3)Measurement of Cellular oxidation with 2,7-Dichlorofluorescein (DCF) fluorescence probe.(4)The effect of NAC on activity of PDGF-B promoter induced by TNFα was investigated with transient transfection and luciferase assays.(5)The effect of NAC on transcription factor NF-κB and SP-1 induced by TNFα was...