Activation of Sonic hedgehog signaling in ventricular cardiomyocytes exerts DNA protection against hypoxia / 中国药理学通报

ABSTRACT

Aim To investigate the protective roles of sonic hedgehog( Shh) signaling pathway in hypoxia-in-duced DNA damage with the neonatal rat cardiomyo-cytes. Methods The hypoxia model on neonatal car-diomyocytes was established with one to two days old Sprague Dawley rats by deprivation of oxygen and glu-cose ( OGD) . After pretreated with Shh pathway ago-nist SAG1.3 or antagonist GANT61, the survival rates of cardiomyocytes were assayed by MTT after OGD 6 hours or 12 hours. The protein levels of Shh pathway, phosphorylated histone H2AX at serine 139 (γH2AX), phosphorylated ATM (p-ATM), phospho-rylated p53 ( p-p53 ) , cleaved-caspase-3, Bcl-2 and Bax were detected by Western blot. The γH2AX foci was detected by immunofluorescence. Results Com-pared to control group, the protein expression of γH2AX, p-ATM, cleaved-caspase-3, p-p53 in OGD cardiomyocytes significantly increased, and Bcl-2/Bax ratio proportionally decreased. Particularly, the ex-pression of γH2AX, p-ATM was highest at OGD 6 h, and then gradually declined after OGD 12 h. After SAG1.3 pretreatment, the expression of γH2AX, p-ATM, cleaved-caspase-3 and p-p53 dramatically de-creased and the Bcl2/Bax ratio increased in OGD 6 h or OGD 12 h cardiomyocytes. On the contrary, in GANT61 pretreatment group, the expression of γH2AX, p-ATM, cleaved-caspase-3 and p-p53 signifi-cantly increased and the Bcl-2/Bax ratio decreased compared to the OGD 6 h or OGD 12 h cardiomyo-cytes. Conclusion The activation of Shh pathway protects cardiomyocytes against hypoxia-induced apop-tosis through inhibition of DNA damage.