engleski

BpV(phen) induces apoptosis of PC12 cells by activation of MAPKs and caspase-3

Peroxovanadium compounds have been identified as insulinomimetic agents and protein tyrosine phosphatase inhibitors. By altering the net phosphorylation status of the cell, pervanadates can promote cell proliferation, differentiation or death. The mitogen-activated protein kinase (MAPK) superfamily represents an excellent example of signal transduction pathway that proceeds through a phosphorylation cascade. All of MAPK isoforms are activated by phosphorylation of the threonine and tyrosine residues in subdomain VIII. Inactivation or attenuation of MAPK signalling is mediated by a class of dual specificity protein phosphatases (MKP). The balance between the intensity of activation of the MAPK superfamily members appears to play a crucial role in a cell's decision to survive or to commit suicide. The aim of the present study was to explore the possible toxicity of peroxovanadium complex potassium bisperoxo(1, 10-phenantroline)oxovanadate (V)  bpV(phen) on rat pheochromocytoma PC12 cells and the involvement of MAPKs, MKP-1, and caspase-3 in the mechanism underlying bpV(phen) cytotoxicity. PC12 cells were treated with 1, 3, 10 and 100  M bpV(phen) in order to assess bpV(phen) cytotoxicity and to determine the mode of cell death. We tested cell viability by MTT and LDH assays, and by FDA/PI and Hoechst 33258 staining. We examined MAPK expression and activation, MKP-1 expression, and procaspase-3 expression by Western blot analysis. BpV(phen) can exert a bimodal effect on cells: proliferation at lower and cell death at higher micromolar concentrations. Morphological changes of chromatin integrity suggested that cells exposed to bpV(phen) were predominantly undergoing apoptosis. Lower micromolar concentrations of bpV(phen) induced strong and sustained ERK activation, while higher micromolar concentrations induced strong and sustained stress kinases (JNK and p38 MAPK) activation, caspase-3 activation, and suppression of MKP-1 expression. In conclusion, our results suggest that stress kinases, MKP-1 and caspase-3 might have a role in bpV(phen)-induced apoptosis of PC12 cells.

peroxovanadium; MAPK; caspase-3; apoptosis

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