The Changes Of Expression And Transcription Activity Of PPARβ In Hydrogen Peroxide-induced Apoptosis In Human Umbilical Vein Endothelial Cells

Peroxisome proliferator-activated receptor beta (PPARβ) is a ligand activated transcription factor belonging to the nuclear receptor superfamily. PPARs are expressed in various organizations, such as cardiovascular, liver, kidney, skeletal muscle and fat tissues, the central nervous system (CNS),etc.Activated PPARs can adjust the expression of target gene,affecting the lipid metabolism and inflammation.Recent evidence suggests that the activated PPARβpromotes cell growth in epidermal cells and inhibits NF-κB in myocardial cells.However, little is known about the role of the activated PPARβin oxidative stress (H2O2)-induced apoptosis in human umbilical vein endothelial cells (HUVECs).Therefore,we studied the changes of expression and activation of PPARβduring H2O2-induced apoptosis in HUVECsIn this study,flow cytometry and measurement of the activity of caspase-3 were used to assay apoptosis.PPARβprotein levels were analyzed by Western-blot analysis.DNA-binding and transcriptional activities of PPARβwere observed by EMSA and luciferase reporter assays.The main results are as follows:①The percentage of apoptotic cells was increased significantly at 12hr (p<0.05 VS Oh),24hr and 36hr after treatment with H2O2 (0.5mmol/L)(p<0.01 VS Oh).The activity of caspase-3 reached the peak at 12hr after treatment with H2O2 (0.5mmol/L)(p<0.05 VS Ctrl)and go down at 24hr.②estern-blot showed that PPARβwas decreased at 6hr and decreased to a minimum at 24hr after the treatment with H2O2 (p<0.01 VS Oh).③The EMSA results showed that:a shift band was visible in the normal condition; and the shift band was weakened by the treatment with H2O2(0.5mmol/L) for 6h and 24h or disappeared by the competition of 200 times of cold probe;also the band was supershifted by the specific antibody to PPARβbut not by the antibody to PPAR a or PPAR④Luciferase reporter assay demonstrated that the transcriptional activity of PPARβwas decreased after H2O2 treatment for different time (6hr, 12hr,24hr) (p<0.01),or at different concentrations (0.25,0.5, 1.0mmol/L)in HUVECs.These data demonstrated that the expression and activation of PPARβwas down-regulated during H2O2-induced apoptosis in HUVECs, which might play important roles in oxidative stress related diseases including atherosclerosis.