Resveratrol strongly enhances the retinoic acid-induced superoxide generating activity via up-regulation of gp91-phox gene expression in U937?cells

摘要

Abstract The membrane bound cytochrome b 558 composed of gp91-phox and p22-phox proteins, and cytosolic proteins p40-, p47-and p67-phox are important components of superoxide (O 2 ? )-generating system in phagocytes. Here, we describe that resveratrol, a pleiotropic phytochemical belonging to the stilbenoids, dramatically activates the O 2 ? -generating system during retinoic acid (RA)-induced differentiation of human monoblastic leukemia U937?cells to macrophage-like cells. When U937?cells were cultured in the presence of RA and resveratrol, the O 2 ? -generating activity increased more than 5-fold compared with that in the absence of the latter. Semiquantitative RT-PCR showed that co-treatment with RA and resveratrol strongly enhanced transcription of the gp91-phox compared with those of the RA-treatment only. On the other hand, immunoblot analysis revealed that co-treatment with RA and resveratrol caused remarkable accumulation of protein levels of gp91-phox (to 4-fold), p22-phox (to 5-fold) and p47-phox (to 4-fold) compared with those of the RA-treatment alone. In addition, ChIP assay suggested that resveratrol participates in enhancing the gene expression of gp91-phox via promoting acetylation of Lys-9 residues and Lys-14 residues of histone H3 within chromatin around the promoter regions of the gene. These results suggested that resveratrol strongly enhances the RA-induced O 2 ? -generating activity via up-regulation of gp91-phox gene expression in U937?cells. Highlights ? Resveratrol effectively enhanced the RA-induced O 2 ? -generating activity. ? Resveratrol strongly enhanced gene expression of gp91-phox. ? Resveratrol caused remarkable accumulation of cytochrome b 558 and p47-phox proteins. ? Resveratrol promoted histone acetylation around the promoter of gp91-phox gene. ? Resveratrol enhances the O 2 ? -generating activity via transactivation of gp91-phox.