TSC1-mTOR signaling determines the differentiation of islet cells

1. View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Figure 1

   Deletion of TSC1 and activation of mTOR signaling in the pancreas of Ngn3-Tsc1−/− transgenic mice. (A) Representative Western blot TSC1 and phospho-S6 (pS6) in pancreatic tissue were examined using specific antibodies. n = 3. (B) TSC1 immunoreactivity and (C) pS6 immunoreactivity. Shown are the representative of pancreas from wild-type (WT) and Ngn3-Tsc1−/− (TN) mice, respectively. (D) Co-localization of pS6 and insulin or glucagon. Double-labeling of the pancreatic sections from WT and TN mice were performed with pS6 (green) and insulin (red, upper panel) or glucagon (red, lower panel) antibodies. Nuclei were counter-stained with Hoechst 33342 fluorescent stain (blue).
2. View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Figure 2

   Islet hypertrophy in Ngn3-Tsc1−/− mice. Mean size of islets, average area and diameter of individual islet cell and total number of islet cells were measured in pancreatic sections stained with chromogranin A antibody (CgA) using the ImageJ software. Five tissue sections, each 75 μm apart, and five low magnification (10× objective) views of each section were analyzed for each animal using the Leica microscope DMLFS/A. Results were expressed as mean ± s.e.m. * denotes P < 0.05. n = 7.
3. View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Figure 3

   Changes in insulin, glucagon and somatostatin in Ngn3-Tsc1−/− mice. Pancreatic sections of wild-type littermates (WT) and Ngn3-Tsc1−/− (TN) mice were stained with antibodies against insulin (A), glucagon (B) and somatostatin (C), respectively. Real-time PCR quantification of pancreatic insulin (D), glucagon (E) and somatostatin (F) from neonate and adult WT and TN mice were examined. Serum levels of insulin (G), glucagon (H) and somatostatin (I) from WT and TN mice were measured and expressed as mean ± s.e.m. * denotes P < 0.05 vs WT mice. n = 5.
4. View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Figure 4

   Alteration in glucose tolerance and insulin sensitivity in Ngn3-Tsc1−/− mice. (A) Blood glucose levels of wild-type littermates (WT) and Ngn3-Tsc1−/− (TN) mice fed NCD after oral administration of glucose (2 g/kg body weight). (B) Blood glucose levels of WT and TN mice fed NCD after intraperitoneal injection of insulin (1 IU/kg body weight). (C) Glucose infusion rate (GIR) was examined by hyperglycemic clamps in WT and TN mice. (D) Blood glucose levels of WT and TN mice fed HFD after oral administration of glucose (2 g/kg body weight). (E) Blood glucose levels of WT and TN mice fed HFD after intraperitoneal injection of insulin (1 IU/kg body weight). (F) Serum levels of insulin in WT and TN mice fed HFD. Results were expressed as mean ± s.e.m. *denotes P < 0.05 vs wild-type mice. n = 6.
5. View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Figure 5

   Rescue effect of rapamycin on β cell hypertrophy, OGTT and ITT. (A) Representative Western blot pancreatic pS6 in wild-type (WT) and Ngn3-Tsc1−/− (TN) mice with or without rapamycin treatment were examined. S6 and β-actin were used as loading control. n = 5 mice. (B) Co-localization of pS6 and insulin. Double-labeling of the pancreatic sections from WT and TN mice with or without rapamycin treatment were performed using pS6 (red) and insulin (green) antibodies. Nuclei were counter-stained with Hoechst 33342 fluorescent stain (blue). (C) Levels of insulin mRNA. Real-time PCR quantification of insulin mRNA from WT and TN mice after rapamycin treatment was examined and expressed as mean ± s.e.m. (D) Oral glucose tolerance test (OGTT). Shown are the blood glucose levels of WT and TN mice treated with and without rapamycin after oral administration of glucose (2 g/kg body weight). (E) Insulin sensitivity test (ITT). Shown are the blood glucose levels of WT and TN mice treated with or without rapamycin after intraperitoneal injection of insulin (1 IU/kg body weight).

• © 2017 Society for Endocrinology