Heat shock protein 90 mediates cytoprotection by H.

1. Increasing evidence indicates that hydrogen sulphide (HS) may serve as an important biological cytoprotective agent. Heat shock protein (Hsp) 90 can attenuate stress-induced injury. However, whether Hsp90 mediates the cytoprotective effect of HS against chemical hypoxia-induced injury in PC12 cells is not known. 2. In the present study, CoCl (a chemical hypoxia mimetic) was used to treat PC12 cells to create a model of chemical hypoxia. To explore the role of Hsp90 in the cytoprotection afforded by HS against chemical hypoxia-induced injury, 2 μmol/L 17-allylaminogeldanamycin (17-AAG), a selective inhibitor of Hsp90, was administered for 30 min prior to preconditioning with 400 μmol/L NaHS, followed by chemical hypoxia. 3. Cobalt chloride reduced cell viability (by 52.7 ± 1.5%), increased PC12 cell apoptosis (by 42.1 ± 1.5%), induced reactive oxygen species (ROS) by 3.79% compared with control and induced the dissipation of mitochondrial membrane potential (MMP) by 2.56% compared with control. 4. Pretreatment of PC12 cells with 100-400 μmol/L sodium hydrosulphide (NaHS), an HS donor, for 3 h prior to exposure to 600 μmol/L CoCl provided significant, concentration-dependant protection to PC12 cells against CoCl-induced cytotoxicity. Specifically, pretreatment of PC12 cells with 400 μmol/L NaHS decreased apoptosis to 16.77 ± 1.77% and blocked the CoCl-induced increase in ROS production and loss of MMP. 5. At 400 μmol/L, NaHS upregulated Hsp90 in a time-dependant manner (over the period 0-180 min). In addition to its effects on Hsp90 expression, NaHS pretreatment of PC12 cells augmented the overexpression of Hsp90 induced by 600 μmol/L CoCl by 1.38-fold ( P < 0.01). 6. Treatment of PC12 cells with 2 μmol/L 17-AAG for 30 min prior to NaHS pretreatment blocked the overexpression of Hsp90 induced by NaHS preconditioning, as evidenced by decreased cell viability (by 54.2 + 1.2%; P < 0.01), increased PC12 cell apoptosis (by 36.6 ± 1.2%; P < 0.01) and increasing ROS production. 7. The findings of the present study provide novel evidence that Hsp90 mediates HS-induced neuroprotection against chemical hypoxia-induced injury via anti-oxidant and anti-apoptotic effects. [ABSTRACT FROM AUTHOR]