Secreted APE1/Ref-1 inhibits TNF-?-stimulated endothelial inflammation via thiol-disulfide exchange in TNF receptor.

ABSTRACT: Apurinic apyrimidinic endonuclease 1/Redox factor-1 (APE1/Ref-1) is a multifunctional protein with redox activity and is proved to be secreted from stimulated cells. The aim of this study was to evaluate the functions of extracellular APE1/Ref-1 with respect to leading anti-inflammatory signaling in TNF-?-stimulated endothelial cells in response to acetylation. Treatment of TNF-?-stimulated endothelial cells with an inhibitor of deacetylase that causes intracellular acetylation, considerably suppressed vascular cell adhesion molecule-1 (VCAM-1). During TSA-mediated acetylation in culture, a time-dependent increase in secreted APE1/Ref-1 was confirmed. The acetyl moiety of acetylated-APE1/Ref-1 was rapidly removed based on the removal kinetics. Additionally, recombinant human (rh) APE1/Ref-1 with reducing activity induced a conformational change in rh TNF-? receptor 1 (TNFR1) by thiol-disulfide exchange. Following treatment with the neutralizing anti-APE1/Ref-1 antibody, inflammatory signals via the binding of TNF-? to TNFR1 were remarkably recovered, leading to up-regulation of reactive oxygen species generation and VCAM-1, in accordance with the activation of p66(shc) and p38 MAPK. These results strongly indicate that anti-inflammatory effects in TNF-?-stimulated endothelial cells by acetylation are tightly linked to secreted APE1/Ref-1, which inhibits TNF-? binding to TNFR1 by reductive conformational change, with suggestion as an endogenous inhibitor of vascular inflammation.

SUBMITTER: Park MS 

PROVIDER: S-EPMC4786854 | biostudies-other | 2016 Mar

REPOSITORIES: biostudies-other