Figure 4

Impaired insulin granule formation in a diet-induced model of islet dysfunction. 8–10 week old male C57BL6/J mice were maintained on standard chow (SC) or Western diet (WD; 40% fat/kcal, 43% carbohydrate) for 8 weeks. Body weight (A) and ad lib fed blood glucose (B) were measured weekly (n = 10 mice per group). (C-D) Following 8 weeks of diet, 4–6 h fasted mice (n = 14–15 mice per group) were injected i.p. with glucose (1 mg/g bw). Blood glucose (C) and plasma insulin (D) were measured at the indicated times. (E–F) Isolated mouse islets were treated with AdRIP-proCpepRUSH (n = 6 mice per group; 3–21 cells per mouse). 48 h post-infection, islets were incubated with biotin (200 μM) for 3 h at 37 °C to stimulate proCpepRUSH (green) trafficking. Cells were immunostained for GM130 (magenta) and counterstained with DAPI (blue). (E) Representative images are shown. Scale bar = 5 μm. (F) The distances of proCpepGFP-positive granules from the Golgi were normalized per cell as a frequency distribution. Data represents the mean ± S.E.M. *p < 0.05 by 2 way-ANOVA with repeated measures (A-D) or Sidak post-test analysis (F).