Heat-shock proteins participate in H_2O_2 preconditioning-induced and PI3K/Akt signal pathway-mediated anti-apoptosis

AIM: To explore the effects of heat-shock proteins(HSP) on H2O2 preconditioning-induced and PI3K/Akt pathway-mediated anti-apoptosis.METHODS: The experimental model of H2O2 preconditioning against apoptosis(induced by H2O2 at a high concentration) was set up in cultured PC12 cells.The cells were divided into 8 groups as follows:(1) control;(2) H2O2;(3) preconditioning+H2O2;(4) LY294002+preconditioning+H2O2;(5) LY294002;(6) quercetin+preconditioning+ H2O2;(7) 17-AAG+preconditioning+H2O2;(8) vehicle.Hoechst 33258 staining was used to observe the morphology of apoptotic changes.The percentage of apoptotic cells was estimated by flow cytometry with propidium iodide staining.The activity of caspase-3 was assessed by colorimetry.The levels of HSP were detected by Western blotting assay.RESULTS: Preconditioning of H2O2 at the concentration of 100 μmol/L for 90 min significantly protected PC12 cells from 300 μmol/L H2O2-induced apoptosis,reduced the activity of caspase-3,and up-regulated the expression of HSP70 and HSP90.Quercetin and 17-AAG(inhibitor of HSP70 and HSP90) antagonized anti-apoptosis induced by H2O2 preconditioning.LY294002(an inhibitor of PI3K) antagonized not only anti-apoptosis but also up-regulation of HSP70 and HSP90 induced by H2O2 preconditioning.CONCLUSION: The PI3K/Akt pathway,HSP70 and HSP90 involve in the cytoprotection induced by H2O2 preconditioning.Furthermore,HSP70 and HSP90 play a role in H2O2 preconditioning-induced anti-apoptosis mediated by PI3K/Akt pathway.