Figure 1: Glucose homeostasis and islet morphology in mice with constitutive or inducible loss of mTORC1 function.
From: Loss of mTORC1 signalling impairs β-cell homeostasis and insulin processing
(a) Immunoblotting and quantification for Raptor, pS6 (S235 and S240), total S6, p4E-BP1 (T37), total 4E-BP1 and tubulin in islets from raptorf/f and βraKO mice at 30 days of age. A representative image from four independent experiments is included and each lane shows the expression levels from one mouse. (b) Random fed blood glucose levels in raptorf/f, βraptorf/+ and βraKO mice during the first 150 days (n=10). (c) Random fed serum insulin levels in raptorf/f and βraKO mice at 7, 30 and 90 days of age (n=6). (d–f) Assessments of β-cell mass, proliferation by Ki67 and apoptosis by TUNEL in 30-day-old raptorf/f and βraKO mice (n=6). (g) Proliferative responses to glucose in dispersed islets from 30-day-old raptorf/f and βraKO mice cultured independently for 24 h in 5 or 24 mM glucose. Approximately 1,000 β-cells were counted per experiment (n=4). (h,i) Assessment of β-cell mass and cell size analysis in raptorf/f and βraKO mice at 90 days (n=6). (j,k) Random fed blood glucose and insulin levels before and after 4 and 8 weeks post TMX injection (TMX administered at 2 months of age). (l,m) Intraperitoneal glucose tolerance test before and after 8 weeks post TMX injection. MIP-βraKOf/f mice injected with corn oil are shown in these experiments as controls. (n) GSIS (2 versus 24 mM) in islets from raptorf/f and MIP-βraKOf/f mice at 6 weeks after TMX injection (n=5; j–n). (o) GSIS in vitro using isolated islets from 2-month-old raptorf/f, MIP-βraKOf/f and 1-month-old βraKO. MIP-βraKOf/f and controls mice were followed for 4 weeks post TMX injection before islet isolation (TMX injection administered at 1 month of age; n=4). (p–s) Assessments of apoptosis by TUNEL, cell size, β-cell mass and proliferation by Ki67 staining in raptorf/f and MIP-βraKOf/f mice at 8 weeks after TMX injection (120 days of age; TMX administered at 2 months of age; n=5). Measure of cell size expressed as a fold change. Data expressed as means±s.e.m., *P<0.05. Nonparametric U-test (Mann–Whitney).
