Figure 3.

Downregulation or loss of Chop inhibits ER stress-induced apoptosis. (a) Quantitative RT-PCR of wild-type C57BL/6 islets cultured for 3 days in a control medium or in a medium containing 50 mM ribose, 0.5 mM TUDCA or 1.0 mM NAC for 3 days. Relative mRNA expression levels for Chop were calculated by normalizing to the signal for β-Actin mRNA in each sample and comparison with islets cultured in a control medium. Treatment with thapsigargin (5 μM for 1 day) was used as a positive control. Results represent mean±s.e.m. of n=5 independent experiments. *P<0.05, ***P<0.001 (one-way ANOVA). (b and c) The frequency of cells undergoing DNA fragmentation was measured by flow cytometry in islets from wild-type and Chop^−/− mice that had been cultured in a control medium containing 5.5 mM glucose or a medium containing 50 mM ribose for 4 days (b) or 33.3 mM glucose for 6 days (c). Results represent mean±s.e.m. of n=3 independent experiments. *P<0.05, ***P<0.001 when comparing islets from Chop^−/− mice with those from wild-type mice (two-way ANOVA)