Carbon Monoxide Inhibits the Nuclear-cytoplasmic Translocation of HMGB1 in an In Vitro Oxidative Stress Injury Model of Mouse Renal Tubular Epithelial Cells

Carbon monoxide(CO),as a vital small molecule in signaling pathways,is found to be involved in ischemia-reperfusion injury(IRI) in renal transplantation.CO-releasing molecule-2(CORM-2),a CO-releasing molecule,is a type of metal carbonyl complexes which can quickly release CO in vivo.In this study,an in vitro oxidative stress injury model was established to examine the effect of CORM-2 pretreatment on the nuclear-cytoplasmic translocation of high mobility group box 1 protein(HMGB1) in mouse primary renal proximal tubular epithelial cells(RPTECs).Immunofluorescence staining showed that HMGB1 in the medium-and CORM-2-treated groups was predominantly localized in the nucleus of the cells,whereas higher amounts of HMGB1 translocated to the cytoplasm in the H2O2-and inactive CORM-2(i CORM-2)-treated groups.Western blotting of HMGB1 showed that the total amounts of cytoplasmic HMGB1 in the H2O2-treated(0.59±0.27) and i CORM-2-treated(0.57±0.22) groups were markedly higher than those in the medium-treated(0.19±0.05) and CORM-2-treated(0.21±0.10) groups(P<0.05).Co-immunoprecipitation showed that the levels of acetylated HMGB1 in the H2O2-treated(642.98±57.25) and i CORM-2-treated(342.11±131.25) groups were markedly increased as compared with the medium-treated(78.72±74.17) and CORM-2-treated(71.42±53.35) groups(P<0.05),and no significant difference was observed between the medium-treated and CORM-2-treated groups(P>0.05).In conclusion,our study demonstrated that in the in vitro oxidative stress injury model of primary RPTECs,CORM-2 can significantly inhibit the nuclear-cytoplasmic translocation of HMGB1,which is probably associated with the prevention of HMGB1 acetylation.