Placenta growth factor is regulated by hydrogen peroxide at the post‐transcriptional, but not the transcriptional, level in vascular smooth muscle

Abstract

When supply arteries are occluded, arteriogenesis occurs resulting in the expansion of collateral arteries. Placenta growth factor (PLGF), a VEGF‐family protein, is a mediator of arteriogenesis, but little is known about its regulation. We previously showed that hydrogen peroxide (H2O2) is a key paracrine regulator of PLGF mRNA in vascular smooth muscle cells. We also determined that H2O2 regulates PLGF at the post‐transcriptional level in human coronary artery smooth muscle cells (CASMC) by significantly extending the half‐life of PLGF mRNA and this regulation requires p38 MAPK, JNK and ERK1/2 pathways. Pro‐inflammatory stimuli have been shown to increase PLGF promoter activity in other cell types and the PLGF promoter contains binding sites for transcription factors responsive to oxidative stress. Therefore, we hypothesized that H2O2 exerts transcriptional control of PLGF mRNA in CASMC in addition to post‐transcriptional regulation. To test our hypothesis, CASMC were co‐transfected via electroporation with a vector containing the PLGF promoter sequence linked to a firefly luciferase reporter gene and the Renilla luciferase vector as an internal control for transfection efficiency. Co‐transfected CASMC treated with a single dose of H2O2 (50 μM) showed no significant difference from basal PLGF promoter activity observed in untreated co‐transfected CASMC (n=3). We conclude that H2O2 does not regulate PLGF at the transcriptional level in CASMC.