Effect of GSK-3α liver KO on insulin signaling.

<p>(A) liver, (B) muscle from eight week old Alb Cre − (−) and Alb Cre + (+) littermate control animals were extracted following either an overnight (16–18 h) fast alone or an overnight fast followed by i.p. administration of 150 mU/g insulin for 15 min. Twenty µg of the protein lysates was resolved by SDS-PAGE. Proteins were detected by immunoblotting with antibodies against phospho-PKB, PKB, phospho-GSK-3β, GSK-3β, phospho-GS and GS. Even loading was determined by blotting for either β-actin or GAPDH. Blots are representative from 4 separate experiments. (C) GSK-3 kinase activity was determined from liver tissue extracted from male Alb Cre − control (open bars) and Alb Cre + (filled bars) mice as described in experimental procedures. GSK-3 kinase activity was determined using a quantitative peptide phosphorylation assay. GSK-3 kinase activity is expressed relative to the Cre− control (which is set at 100%) and is the mean ± SEM of four different liver samples with each assayed in triplicate. Genetic background was C57BL/6/129.