ABSTRACT
AIM: To explore the possible mechanism of tert-butyl hydroperoxide (t-BHP)-induced apoptosis in murine MIN6 pancreatic beta-cells. METHODS: MIN6 cells were cultured in vitro. Cell damage was evaluated by epifluorescence microscopy after staining with AO-EB. The percentage of cell apoptosis was determined by flow cytometric assay after Annexin- V-PI staining. Nitric oxide levels were measured by Griess assay. Inducible nitric oxide synthase(iNOS) protein and NF-kappaBp65 fragment were detected by Western blot. RESULTS: Exposure of 25 micromol/L t-BHP to MIN6 cells for 60 min, cell viability was reduced and the percentage of apoptosis was increased significantly. The levels of cytoplasmic iNOS protein and nitrite were elevated. Meanwhile, treatment with t-BHP resulted in nucleus NF-kappaBp65 fragment peaking at 20 min. Both L-NAME and N-Acetyl-l-cysteine (NAC) attenuated the elevated levels of nitrite and percentage of apoptosis due to t-BHP alone. CONCLUSION: NF-kappa-iNOS-nitric oxide signalling pathway can mediated t-BHP induced apoptosis in MIN6 cells .
Subject(s)
Apoptosis , Insulin-Secreting Cells/cytology , NF-kappa B/metabolism , Nitric Oxide Synthase Type II/metabolism , Oxidative Stress/physiology , Animals , Cell Line , Mice , Nitric Oxide/metabolism , Signal Transduction , tert-Butylhydroperoxide/pharmacologyABSTRACT
To explore the effect of glucagon-like peptide-1 receptor agonist--Exendin-4 (Ex-4) on murine MIN6 pancreatic beta-cells apoptosis induced by oxidative stress, the morphological changes of cell damage were evaluated by epifluorescence microscopy after staining with AO-EB. The percentage of cell apoptosis was determined by flow cytometric assay after Annexin-V-FITC-PI staining. Nitric oxide level was measured by Griess reagent assay. Inducible nitric oxide synthase (iNOS) protein and NF-kappaBp65 fragment were detected by Western blotting. Ex-4 inhibited the increase of nitrite level and percentage of apoptosis induced by t-BHP in MIN6 cells. Furthermore, Ex-4 partly reduced the expression of iNOS protein and the ratio of NF-kappaBp65 protein in nucleus:cytosol induced by t-BHP. These results suggest that Ex4 protects MIN6 pancreatic kappa-cells from oxidative stress-induced apoptosis via down-regulation of NF-kappaB-iNOS-nitric oxide pathway.
