Fig. 6.

Caspase-dependent proteolytic cleavage of PKCδ in vanadium-induced neurotoxicity. (A) Vanadium-induced caspase-mediated PKCδ cleavage. PKCδ was immunoblotted after 40 μM vanadium treatment in N27 dopaminergic neuronal cells with or without the addition of 100 μM Z-VAD-FMK for 9 h. Proteins were separated from lysates by 12% SDS-PAGE and the immunoblot was probed with PKCδ antibody to observe both native (72–74 kDa) and cleaved (38–41 kDa) PKCδ bands. To confirm equal protein loading in each lane, the membranes were reprobed with β-actin antibody. Data represent results from at least two individual measurements. (B) Vanadium-induced PKCδ cleavage increases the kinase activity. N27 dopaminergic cells were harvested 9 h after treatment with 40 μM vanadium in the presence or absence of 100 μM Z-VAD-FMK. Cell lysates were isolated and PKCδ was immunoprecipitated from treated cell lysates and the enzyme activity was measured by ³²P phosphorylation. The values are expressed as a percentage of untreated control cells. Data represent results from at least three individual measurements and are expressed as mean ± S.E.M. *p<0.05 and **p<0.01.