Heat shock protein 90 mediates cytoprotection by H₂S against chemical hypoxia‐induced injury in PC12 cells

Abstract

1. Increasing evidence indicates that hydrogen sulphide (H₂S) 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 H₂S against chemical hypoxia-induced injury in PC12 cells is not known. 2. In the present study, CoCl₂ (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 H₂S 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 H₂S donor, for 3 h prior to exposure to 600 μmol/L CoCl₂ provided significant, concentration-dependant protection to PC12 cells against CoCl₂-induced cytotoxicity. Specifically, pretreatment of PC12 cells with 400 μmol/L NaHS decreased apoptosis to 16.77 ± 1.77% and blocked the CoCl₂-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 CoCl₂ 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 H₂S-induced neuroprotection against chemical hypoxia-induced injury via anti-oxidant and anti-apoptotic effects.

Valproic acid synergistically enhances the cytotoxicity of gossypol in DU145 prostate cancer cells: An iTRTAQ-based quantitative proteomic analysis

“…GOS combined with VPA induced activation of glycolysis-related proteins (HKII, LDHA) and HYOU1, and resulted in accumulation of the key oxygen-sensitive transcription factor HIF-1α. Stabilization and nuclear translocation of HIF-1α are associated predominantly with hypoxia; in some cases, disruption of TCA cycle, mitochondrial function and increase of cellular stress can also lead to the stabilization of HIF-1α under normoxic conditions, as have been reported in a variety of cells, including DU145, treated with nitric oxide [43], reactive oxygen species and other ER stress reagents [44][45][46], alltrans retinoid acid [47], iron chelator [48], as well as chemical hypoxia mimetic CoCl 2 [49].…”

Hydrogen sulfide as an oxygen sensor

“…H 2 S has also been shown to protect cells from both hypoxiaand hyperoxia-induced redox imbalance and apoptosis (13,83,85,92,101,189,190). The beneficial effects of H 2 S in treating ischemia/reperfusion injury and in pre-and postconditioning have been well documented, and it has been suggested that the beneficial effects of exogenous H 2 S are due to mimicking transient hypoxia, which is also used in conditioning (128).…”

Hydrogen Sulfide in Biochemistry and Medicine

“…These in vitro findings were mirrored by in vivo observations that H 2 S protects ischemic brain by reinstating GSH levels decreased by oxidative stress. H 2 S has been shown to protect neurons against hypoxic injury by upregulating expression of heat shock protein (HSP) 90 (127,199). HSP90 is a ubiquitous molecule that contributes to cell survival by regulating the folding of various cellular proteins, including survival factors, and by binding to apoptotic protease activating factor-1 (Apaf-1), thereby preventing apoptosis.…”