Figure 4. EPEC induced mismatch repair protein downregulation was not associated with apoptosis/necrosis.

HT29 cells either uninfected (−) or co-cultured with wild-type EPEC (+wt) for 9–12 hours were stained (red) using an in vitro cell death (TUNEL) detection kit, MLH1 was simultaneously stained (green) and nuclei were counterstained with DAPI (blue) (a). HT29 cells were either uninfected (−) or co-cultured with wild-type (+wt) or mutant (+mut) EPEC; TUNEL positive and negative cells were counted. Fixed HT29 cells treated with DNAase (to induce DNA strand breaks) were used as positive controls, error bars represent standard error of mean (n = 3) (b). HT29 cells were stained for MLH1 (green) and cytochrome c (red) (c) or for cytochrome c (red) and the mitochondrial marker MTCO2 (green) (d). Cells treated with etoposide for 2 h were positive controls for early apoptosis. Scale bar = 10 µm.