摘要
BACKGROUND: Retinoid X receptor(RXR) plays a central role in the regulation of intracellular receptor signaling pathways. The activation of RXR has protective effect on H2O2-induced apoptosis of H9c2 ventricular cells in rats. But the protective effect and mechanism of activating RXR in cardiomyocytes against hypoxia/reoxygenation(H/R)-induced oxidative iniury are still unclear.METHODS: The model of H/R injury was established through hypoxia for 2 hours and reoxygenation for 4 hours in H9c2 cardiomyocytes of rats. 9-cis-retinoic acid(9-cis RA) was obtained as an RXR agonist, and HX531 as an RXR antagonist. Cultured cardiomyocytes were randomly divided into four groups: sham group, H/R group, H/R+9-cis RA-pretreated group(100 nmol/L 9-cis RA), and H/R+9-cis RA+HX531-pretreated group(2.5 μmol/L HX531). The cell viability was measured by MTT, apoptosis rate of cardiomyocytes by flow cytometry analysis, and mitochondrial membrane potential(ΔΨm) by JC-1 fluorescent probe, and protein expressions of Bcl-2, Bax and cleaved caspase-9 with Western blotting. All measurement data were expressed as mean±standard deviation, and analyzed using one-way ANOVA and the Dunnett test. Differences were considered signif icant when P was <0.05.RESULTS: Pretreatment with RXR agonist enhanced cell viability, reduced apoptosis ratio, and stabled ΔΨm. Dot blotting experiments showed that under H/R stress conditions, Bcl-2 protein level decreased, while Bax and cleaved caspase-9 were increased. 9-cis RA administration before H/R stress prevented these effects, but the protective effects of activating RXR on cardiomyocytes against H/R induced oxidative injury were abolished when pretreated with RXR pan-antagonist HX531.CONCLUSION: The activation of RXR has protective effects against H/R injury in H9c2 cardiomyocytes of rats through attenuating signaling pathway of mitochondria apoptosis.
BACKGROUND： Retinoid X receptor （RXR） plays a central role in the regulation of intracellular receptor signaling pathways. The activation of RXR has protective effect on H2O2-induced apoptosis of H9c2 ventricular cells in rats. But the protective effect and mechanism of activating RXR in cardiomyocytes against hypoxia/reoxygenation （H/R）-induced oxidative iniury are still unclear. METHODS： The model of H/R injury was established through hypoxia for 2 hours and reoxygenation for 4 hours in H9c2 cardiomyocytes of rats. 9-cis-retinoic acid （9-cis IRA） was obtained as an RXR agonist, and HX531 as an RXR antagonist. Cultured cardiomyocytes were randomly divided into four groups： sham group, H/R group, H/R＋9-cis IRA-pretreated group （100 nmol/L 9-cis IRA）, and H/R＋9-cis RA＋HX531-pretreated group （2.5 pmol/L HX531）. The cell viability was measured by MTT, apoptosis rate of cardiomyocytes by flow cytometry analysis, and mitochondrial membrane potential （AU;m） by JC-1 fluorescent probe, and protein expressions of Bcl-2, Bax and cleaved caspase-9 with Western blotting. All measurement data were expressed as mean＋standard deviation, and analyzed using one-way ANOVA and the Dunnett test. Differences were considered significant when P was 〈0.05. RESULTS： Pretreatment with RXR agonist enhanced cell viability, reduced apoptosis ratio, and stabled △ψm. Dot blotting experiments showed that under H/R stress conditions, Bcl-2 protein level decreased, while Bax and cleaved caspase-9 were increased. 9-cis RA administration before H/R stress prevented these effects, but the protective effects of activating RXR on cardiomyocytes against H/R induced oxidative injury were abolished when pretreated with RXR pan-antagonist HX531. CONCLUSION： The activation of RXR has cardiomyocytes of rats through attenuating signaling protective effects against H/R injury in H9c2 pathway of mitochondria apoptosis.
基金
supported by grants from the National Natural Science Foundation of China(81270282,81070176,30600242,81170192,81200163)
Wenzhou Science Technology Bureau Foundation(Y20100010)
Education Foundation of Zhejiang Province(Y200906376)
