Hepatocyte-specific deletion of Tsc1 leads to mild insulin resistance.

<p>A. Liver-specific ablation of <i>Tsc1</i>. <i>Tsc1^fl/fl</i> mice were crossed to <i>Cre^Alb</i> mice resulting in <i>Tsc1^fl/fl</i>; <i>Cre^+/+</i> (a.k.a. <i>Tsc1</i>+/+) and <i>Tsc1^fl/fl</i>; <i>Cre^Alb</i> (a.k.a. <i>Tsc1</i>−/−) littermates. Tissues from eight-week old <i>Tsc1</i>−/− and <i>Tsc1</i>+/+ animals were analyzed for the expression of Tsc1, Tsc2 and S6K by immunoblot analyses using the indicated antibodies. WAT, white adipose tissues. Note the reduced Tsc2 expression secondary to its diminished stability in the absence of Tsc1 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0018075#pone.0018075-Nellist1" target="_blank">[30]</a>. B. The loss of <i>Tsc1</i> in hepatocytes resulted in increased mTORC1 activity (based on the expression of phospho-S6K and phospho-S6) that was sensitive to rapamycin. <i>Tsc1</i>−/− mice were fasted and treated with or without rapamycin (2 mg/kg IP, 6 hrs). Liver lysates were analyzed by SDS-PAGE and blotted with the indicated antibodies. Note the effect of rapamycin on Akt phosphorylation in the <i>Tsc1</i>−/− liver. Actin, loading control. C. Systemic glucose tolerance (left) and insulin sensitivity (right) tests in 8-week old female (top) and male (bottom) mice. Following a 16-hr fast, glucose (1 mg/g) was given IP followed by serial blood glucose monitoring at indicated times. For insulin sensitivity test, 0.5 mU/g of insulin was injected IP after a 4-hr fast. *, p<0.05 between the <i>Tsc1</i>+/+ and <i>Tsc1</i>−/− groups. D. Fasting blood glucose and insulin levels in wild-type and mutant mice. Plasma insulin levels 30 minutes after glucose administration are also shown (filled boxes).