Rottlerin protected dopaminergic cell line from cytotoxicity of 6-hydroxydopamine by inhibiting PKCδ phosphorylation

Objective The present study aims to investigate the role of protein kinase C delta subtype (PKC delta) phosphorylation in the process of 6-hydroxydopamine (6-OHDA)-induced dopaminergic cell death, and demonstrate the molecular basis of neurological disorders, such as Parkinson's disease. Methods The pheochromocytoma (PC12) cell line was employed in the present study. Cells were treated with 2 mu mol/L PKC delta inhibitor Rottlerin, 10 nmol/L protein kinase C alpha subtype (PKC alpha) inhibitor bisindolylmaleimide I, or 5 nmol/L Go6976 that could specifically inhibit the calcium-dependent PKC isoforms, respectively. PKC delta activator phorbol-12-myristate-13-acetate (PMA, 100 nmol/L) was also used in this study. All these agents were added to the medium before cells were incubated with 6-OHDA. Cells with no treatment served as control. The cytotoxicity of 6-OHDA was determined by methyl thiazolyl tetrazolium (MTT) reduction assay and PKC delta phosphorylation levels in various groups were measured by western blotting. Results Bisindolylmaleimide I and Go6976 exerted no significant attenuation on the cytotoxicity of 6-OHDA, nor any effects on PKCd phosphorylation in PC12 cells. However, Rottlerin could inhibit the phosphorylation of PKC delta and attenuate 6-OHDA-induced cell death, and the cell viability was raised to 69.6 +/- 2.63% of that in control group (P < 0.05). In contrast, PMA induced a significant increase in PKC delta phosphorylation and also strengthened the cytotoxic effects of 6-OHDA. The cell viability of PMA-treated PC12 cells decreased to 49.8 +/- 5.06% of that in control group (P < 0.001). Conclusion Rottlerin can protect PC12 cells from cytotoxicity of 6-OHDA probably by inhibiting PKCd phosphorylation. The results suggest that PKCd may be a key regulator of neuron loss in Parkinson's disease.