Effect of heme oxygenase-1 on CDK5-ATM-P53 signal transduction pathway in rat hippocampal neurons subjected to oxygen-glucose deprivation injury

Abstract

Objective To investigate the effect of heme oxygenase-1 (HO-1) on cyclin-dependent kinase 5 (CDK5)-ataxia telangiectasia mutated (ATM)-P53 signal transduction pathway in rat hippocampal neurons subjected to oxygen-glucose deprivation (OGD) injury.Methods Hippocampal neurons of newborn Wistar rats ( ＜ 48 h) were cultured for 7 days in vitro.The primary cultured neurons were randomly divided into 4 groups with 10 wells in each group:control group (group C),OGD (group D),OGD + hemin (HO-1 inducer) group (group D + H ) and OGD + hemin + zinc protoporphyrin ( HO-1 inhibitor) group ( group D + H + T).For OGD experiments,cultures were washed three times in a glucose-free balanced salt solution (BSS).They were then placed in deoxygenated glucose-free medium and sealed under 95％ N2-5％ CO2 in an anaerobic chamber equilibrated to 37°C and 100％ humidity for 45 min.OGD was terminated by replacement of stored medium and by returning the cultures to a standard incubator maintained at 37 ℃ in 95％ air-5％ CO2.The OGD model was established after the neurons were preconditioned with hemin 10 μmol/L for 24 h in group D + H.The OGD model was established after the neurons were preconditioned with hemin 10 μmol/L and zinc protoporphyrin 10 μmol/L for 24 h in group D + H + T.After 24 h of culture,the neuronal viability,apoptosis rate,and expression of HO-1 mRNA and protein,and CDK5,ATM and P53 protein were detected.Results Compared with group C,the expression of HO-1 mRNA,and HO-1,CDK5,ATM and P53 protein was up-regulated,the neuronal viability was significantly decreased,and the apoptosis rate was significantly increased in group D (P ＜ 0.01 ).Compared with group D,the expression of HO-1 mRNA and protein was up-regulated,the expression of CDK5,ATM and P53 protein was down-regulated,the neuronal viability was significantly increased,and the apoptosis rate was significanlly decreased in group D + H ( P ＜ 0.01 ).Compared with group D + H,the expression of HO-1 mRNA and protein was down-regulated,the expression of CDK5,ATM and P53 protein was up-regulated,the neuronal viability was significantly decreased,and the apoptosis rate was significantly increased in group D + H + T ( P ＜ 0.01 ).Conclusion HO-1 can inhibit neuronal apoptosis through blocking CDK5-ATM-P53 signal transduction pathway in rat hippocampal neurons subjected to OGD injury. Key words: Heme oxygenase-1; Anoxia; Hippocampus; Neurons; Cyclin-dependent kinase 5; Ataxia telangiectasia; Genes; Genes,p53