Modulation of Apoptosis Pathways by Oxidative Stress and Autophagy in β Cells
Figure 6
Activation of JNK by cytokines. (a) MIN6 cells were incubated in the absence and presence of 20 μM JNK inhibitor, SP600125 and/or a combination of cytokines, IL-1β (2 ng/mL) TNF-α (10 ng/mL) and IFN-γ (10 ng/mL) for the indicated time periods. The treated cells were processed for the Western blot analysis of phosphorylated (Phos) c-jun, total c-jun, phosphorylated (Phos) JNK and total JNK. ((b) and (c)) MIN6 cells were transfected with a CRE site-containing bcl-2 promoter linked to a firefly luciferase reporter and a constitutively active renilla luciferase. A combination of plasmid mixture encoding the JNK isozymes or their vector was also included for one experiment (b). Transfected cells were incubated in the absence and presence of a combination of cytokines and JNK inhibitor (SP600125) as indicated for 24 h followed by the assay for luciferases. Bcl-2 promoter activity was inhibited by cytokines and JNK isozymes. Cytokine action on bcl-2 promoter activity was blocked by the JNK inhibitor. The results are M ± SE of 4 independent experiments. *; ** versus untreated control.
