Figure 1.
Glucose metabolism in the liver-specific FoxO1/3/4 knockout mice (LTKO) fed chow diet.
(A) Body weight of control and LTKO male mice (n=6) at age of 4 months. (B) Blood glucose levels in 2-month male control and LTKO mice (n=6) after an overnight 16-hour fasting. (C) Non-fasting blood glucose levels in 4-month control and LTKO male mice (n=6). (D, E) Pyruvate tolerance tests (PTT) in 4-month male control and LTKO mice (n=6-7) after an intraperitoneal injection of 2 g pyruvate solution per kg body weight. The areas under the curve (AUC) in the PTT graph were also presented. (F, G) Glucose tolerance tests (GTT) in 3-month male control and LTKO mice (n=6) after an intraperitoneal injection of 2 g glucose solution per kg body weight. The areas under the curve in the GTT graph were also presented. Data represent mean ± SEM. * indicates a significance with P<0.05 in control vs. LTKO mice.
Figure 2.
Insulin sensitivity in LTKO mice fed chow diet.
(A) Insulin tolerance tests (ITT) in 3-month male control and LTKO mice (n=6) after 3-hour fasting and an intraperitoneal injection of 0.75 U human regular insulin (humulin R, Lilly) per kg body weight. (B) The data in Panel A were replotted as percentage of basal blood glucose as a function of injection time. (C) Plasma insulin levels in 4-month male control and LTKO mice (n=12) after an overnight 16-hour fasting. (D) Plasma insulin levels in 4-month male control and LTKO mice (n=6) under ad libitum conditions. Data represent mean ± SEM. * indicates a significance with P<0.05 in control vs. LTKO mice.
Figure 3.
Body composition of LTKO mice fed a high-fat diet.
(A, B) Body weight and length measurements of control and LTKO mice (n=6) after a high-fat diet (HFD) treatment for 5 months, respectively. (C, D) Body fat and bone mineral density (BMD) analyses of the above HFD treated mice by DEXA, respectively. Data represent mean ± SEM.
Figure 4.
LTKO mice maintain euglycemic and glucose tolerant on a high-fat diet.
(A) Fasting glucose levels in 4.5-month male control and LTKO mice (n=8) after the treatment with a high-fat diet for 3.5 months. (B) Non-fasting blood glucose levels in 4-month male control and LTKO mice (n=8) after the treatment with the high-fat diet for 3 months. (C, D) Glucose tolerance tests and the AUC analysis in 4.5-month male control and LTKO mice (n=8) after the treatment with the high-fat diet for 3.5 months, respectively. (E, F) Expression of genes involved in glucose metabolism was analyzed in the liver of control and LTKO mice (n=4) treated with the high-fat diet for 5 months by real-time PCR. Pck1, phosphoenoylpyruvate carboxykinase 1; G6pc, glucose-6-phosphatase, catalytic; Pdk2, pyruvate dehydrogenase kinase 2; Gck, glucokinase; Pklr, pyruvate kinase, liver and red blood cell type. Data represent mean ± SEM. * indicates a significance with P<0.05 in control vs. LTKO mice.
Figure 5.
LTKO mice remain insulin-sensitive on a high-fat diet.
(A) Fasting plasma insulin levels in 6-month male control and LTKO mice (n=8) after the treatment with a high-fat diet for 5 months. (B) HOMA insulin resistance (IR) index was calculated using the fasting blood glucose and insulin data collected from control and LTKO male mice treated with the high-fat diet for 5 months. (C, D) Insulin tolerance tests and the AUC analysis in 4-month male control and LTKO mice (n=8) using a dose of 1 U insulin per kg body weight after the treatment with the high-fat diet for 3 months, respectively. Data represent mean ± SEM. * indicates a significance with P<0.05 in control vs. LTKO mice.
Figure 6.
Sirt6 overexpression has no significant effect on glucose toerance in LTKO mice.
(A) Sirt6 overexpression was assessed by Western blot analysis in liver lysates from control and LTKO mice injected with SIRT6 or GFP adenoviruses (n=6). (B) Glucose tolerance tests in 4-month-old control and LTKO mice injected with SIRT6 or GFP adenoviruses (n=6). (C) Expression of genes involved in glucose metabolism was analyzed in the livers of SIRT6 or GFP adenovirus infected control and LTKO mice (n=6) by real-time PCR. Data represent mean ± SEM. * indicates a significance with P<0.05 between loxp-GFP and loxp-SIRT6 groups.
Figure 7.
Gck knockdown impairs glucose tolerance in both wild-type and LTKO mice.
(A) Gck protein was analyzed in the livers of 3-month-old control and LTKO mice by Western blots. (B) Gck knockdown was assessed by Western blots in liver lysates from control and LTKO mice injected with shGck or shGFP adenoviruses. (C, D) Glucose tolerance tests and insulin tolerance tests in 6-month-old male control and LTKO mice injected with shGck or shGFP adenoviruses (n=5-6), respectively. Data represent mean ± SEM. *, P<0.05 between LTKO-shGFP and LTKO-shGck groups; #, P<0.05 between loxp-shGFP and loxp-shGck groups.