Fig. 2: Impaired proinsulin synthesis and ATP levels for GSIS.

a Schematic of insulin pump implantation. b Random blood glucose levels were monitored every other day in WT, diabetic βRapKO^GFP, and euglycemic βRapKO^GFP mice from 4 weeks to 8 weeks old (n = 6 for WT, n = 7 for diabetic KO, n = 13 for euglycemic KO). c Representative pancreatic sections immunostained for insulin (green) and glucagon (red). The ratio of Gcg⁺ cells to Ins⁺ cells was calculated (n = 3). At least 50 islets or 2000 insulin-positive cells were used for quantifications. Scale bars, 20 μm. d Images of islets labeled with insulin (green) and UCN3 (red). MFI of UCN3 in these three groups (n = 3). At least 10 islets from three sections were used for MFI. Yellow boxes showed the expression of UCN3. Scale bars, 20 μm. e In vitro glucose-stimulated C-peptide secretion in islets at 2.8 and 16.7 mM glucose levels for 1 h (reported as percent of C-peptide content) (n = 7 for WT, n = 6 for diabetic KO, n = 6 for euglycemic KO). White, black, and gray circles represented the WT, diabetic βRapKO^GFP, and euglycemic βRapKO^GFP groups, respectively. Stimulation index of C-peptide secretion in diabetic βRapKO^GFP and euglycemic βRapKO^GFP mice as compared with controls (n = 7 for WT, n = 6 for diabetic KO, n = 6 for euglycemic KO). f ATP content at 2.8 mM glucose and 16.7 mM glucose (n = 3). g Pancreatic C-peptide content (n = 3 independent samples) and h pancreatic proinsulin content normalized by protein concentration were shown (n = 3 independent samples). i The ratio of pancreatic proinsulin to C-peptide content was determined (n = 3 independent samples). j The ratio of islet proinsulin to C-peptide content per 10 size-matched islets at 2.8 mM and high 16.7 mM glucose levels was determined (n = 6 for WT, n = 5 for diabetic KO, n = 5 for euglycemic KO). k INS-1 cells were transfected with SiRaptor or SiNC for 72 h. Immunoblotting and quantification of insulin and proinsulin in INS-1 cells transfected with SiNC or SiRaptor (n = 4 independent cell experiments). Data represent means ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001 by two-sided Student’s t-test and one-way ANOVA adjusted by LSD multiple comparison, p values included in source data.