GSK-3ß-mediated regulation of cadmium-induced cell death and survival.

BACKGROUND: Previous studies indicated that cadmium (Cd) increases PI3-kinase/Akt phosphorylation, resulting in an alteration in GSK-3ß activity. However, the mechanism of Cd-induced endoplasmic reticulum (ER) stress in neuronal cells has yet to be studied in needs further elucidation. We examined the role of GSK-3ß in Cd-induced neuronal cell death and the related downstream signaling pathways. METHODS: SH-SY5Y human neuroblastoma cells were treated with 10 or 20 µM BAPTA-AM and 1 µM wortmannin for 30 min and then incubated with 25 µM Cd for 12 h. Apoptotic cells were visualized via DAPI and PI staining. Data were evaluated with one-way analysis of variance (ANOVA) followed by Student's t-test. Data are expressed as the means ± SD of experiments performed at least three times. RESULTS: Treatment of human neuronal SH-SY5Y cells with Cd induced ER, stress as evidenced by the increased expression of GRP78, which is a marker of ER stress. Cd exposure significantly increased the phosphorylation of Akt at thr308 and ser473 and that of GSK-3ß at ser9 in a time-dependent manner, while the total protein levels of GSK-3ß and Akt did not change. Cd-induced apoptosis was higher in GSK-3ß-knockdown cells than in normal cells. CONCLUSIONS: Our data suggest that Akt/GSK-3ß signaling activated by Cd is involved in neuronal cell survival.