Figure 5.

MPP+ suppresses NF-κB activity. A, NF-κB activity is decreased dose dependently upon MPP+ exposure. SH-SY5Y cells were cotransfected with plasmids NF-κB-luciferase and pSV-β-galactosidase, and treated with MPP+ for 12 h. B, NF-κB activity is decreased following MPP+ treatment in differentiated ReNcell VM cells. Cells were transfected and treated with MPP+ as in A. C, NF-κB activity was not decreased by A23187. Luciferase activity was normalized against β-galactosidase activity. D, Western blot showing that MPP+ treatment in SH-SY5Y cells does not affect RelA expression. E, Immunocytochemistry showing nuclear localization of RelA upon MPP+ treatment for 12 h. As a positive control, nuclear localization of RelA in response to TNF-α treatment for 2 h is shown. F, MPP+ promotes RelA binding to NF-κB DNA element. Binding was measured using the RelA TransAM Kit, which is an ELISA-based assay, with nuclear extracts from cells treated with MPP+ or TNF-α, as indicated in the figure. MPP+ resulted in fourfold increased binding efficiency of RelA to NF-κB DNA, and TNF-α treatment increased binding efficiency >10-fold. *p < 0.05, **p < 0.01.