Modulation of Apoptosis Pathways by Oxidative Stress and Autophagy in β Cells
Figure 4
Antiapoptotic actions of MnSOD and exendin-4 in MIN6 cells: MIN6 cells cultured on chamber slides were transfected with cDNA encoding MnSOD-GFP chimeric protein. The transfected cells were exposed to a mixture of cytokines (2 ng of IL-1β, 10 ng of TNF-α and 10 ng of IFN-γ) for 24 h. The cells were fixed, permeabilized and probed with antibodies specific for the active cleaved fragment of caspase-9 (a) and caspase-3 (b). This was followed by probing with secondary antibodies linked to Cy3. The images were analyzed by digital deconvolution microscopy. The cells expressing MnSOD (green) are protected from cytokine-induced apoptosis. Images from three independent experiments are presented. (c) MIN6 cells were cultured in the absence and presence of exendin-4 (50 nM). ER stress was induced by exposing the cells to thapsigargin (Th; 100 nM) or tunicamycin (Tu; 1 μg/mL) for 24 h. Lysates of the treated cells were analyzed by Western blotting for active caspase-3 and β actin. Band intensities were quantitated by scanning. Results are M ± SE of three independent experiments. ** when compared to untreated control. * versus respective ER stress control in the absence of exendin-4.
