951 PROTECTIVE ROLE OF APURINIC/APYRIMIDINIC ENDONUCLEASE 1 ON THE OXLDL-INDUCED P66SHC PHOSPHORYLATION IN VASCULAR ENDOTHELIAL CELLS

Abstract

Background: Activation of endothelial cell by oxidized low-density lipoprotein (oxLDL) is an early key event in hyperlipidemia-induced endothelial dysfunction and atherosclerosis. However, role of apurinic/apyrimidinic endonuclease1 (APE1) on oxLDL-induced endothelial activation has been unknown. Methods: We investigated the role of APE1 in modulating oxLDL-mediated p66shc phosphorylation using Western blotting, adenoviral gene transfer, and gene silencing with siRNA in MS-1 endothelial cells. Results: Oxidized LDL (oxLDL) induced p66shc phosphorylation at serine 36 residue and PKCβII phosphorylation in mouse endothelial cells. Adenoviral overexpression of APE1 resulted in reduction of oxLDL-induced p66shc and PKCβII phosphorylation. Phorbol 12-myristate 13-acetate (PMA) which stimulates PKCs induced p66shc phosphorylation and this was inhibited by a selective PKCβII inhibitor. Adenoviral overexpression of PKCβII also increased p66shc phosphorylation. Overexpression of APE1 suppressed PMA-induced p66shc phosphorylation. Moreover, PMA-induced p66shc phosphorylation was augmented in cells in which APE1 was knocked down. PMA increased cytoplasmic APE1 expression, compared with basal condition, suggesting the role of cytoplasmic APE1 against p66shc phosphorylation. Conclusions: APE1 suppresses oxLDL-induced endothelial activations by inhibiting of PKCβII-mediated serine phosphorylation of p66shc in vascular endothelial cells. Reference Jeon BH, Irani K. APE1/Ref-1: versatility in progress. Antioxid Redox Signal 2009;11:571-574. Lee SK, Chung JI, Park MS et al. Apurinic/apyrimidinic endonuclease 1 inhibits protein kinase C-mediated p66shc phosphorylation and vasoconstriction. Cardiovasc Res. 2011;91(3):502-509