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Fig. 3. Modulation of IB1/JIP-1 regulates apoptosis in INS-1 cells. (A) Reduced
IB1/JIP-1 content in INS-1 cells is associated with DNA laddering. DNA
laddering in INS-1 cells producing different levels of IB1/JIP-1 shows a large
increase in nucleosomal band staining in cells exposed to cytokines. Cells
producing lower amounts of IB1 show an increase in the intensity of
nucleosomal bands in the absence and in the presence of cytokines (IL-1ß,
TNF- and IFN- ). (B) Quantitative assessment shows a 400%
increase in the intensity of nucleosomal bands in the presence of cytokines,
whereas no change was observed in cells overproducing IB1. By contrast, cells
decreasing their IB1 content show an increase in the DNA laddering pattern in
the presence (500%) and the absence (400%) of cytokines. (C) Apoptosis rate in
INS-1 cells is dependent on the IB1/JIP-1 content. Cells infected or not with
the different adenovirus constructs were treated with cytokines or not for 2
days. Cells were finally stained with Hoechst 33342 and propidium iodide, and
counted. The ratio between apoptotic and normal cells is indicated. Columns
represent mean ± s.e.m. of three independent experiments performed in
triplicate. **, °° or  P<0.01;
***P<0.001. (D) To confirm the protective effect of IB1 in INS-1
cells, western blots of cleaved caspase were carried out. Cleaved caspase was
increased in cells infected with control adenovirus (Ad-GFP) in the presence
of cytokines. By contrast, overproduction of IB1 decreased the presence of
caspase 3 cleavage.
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