Cluster Analysis of Insulin Action in Adipocytes Reveals a Key Role for Akt at the Plasma Membrane |
| |
| Authors: | Yvonne Ng Georg Ramm James G Burchfield Adelle C F Coster Jacqueline St?ckli David E James |
| |
| Institution: | From the ‡Diabetes and Obesity Research Program, The Garvan Institute of Medical Research, Sydney, New South Wales 2010, ;the §School of Biotechnology and Biomolecular Sciences, ;‖School of Mathematics and Statistics, and ;**Faculty of Medicine, University of New South Wales, Sydney, New South Wales 2052, and ;the ¶School of Biomedical Sciences, Monash University, Melbourne, Victoria 3800, Australia |
| |
| Abstract: | The phosphatidylinositol 3-kinase/Akt pathway regulates many biological processes, including insulin-regulated GLUT4 insertion into the plasma membrane. However, Akt operates well below its capacity to facilitate maximal GLUT4 translocation. Thus, reconciling modest changes in Akt expression or activity as a cause of metabolic dysfunction is complex. To resolve this, we examined insulin regulation of components within the signaling cascade in a quantitative kinetic and dose-response study combined with hierarchical cluster analysis. This revealed a strong relationship between phosphorylation of Akt substrates and GLUT4 translocation but not whole cell Akt phosphorylation. In contrast, Akt activity at the plasma membrane strongly correlated with GLUT4 translocation and Akt substrate phosphorylation. Additionally, two of the phosphorylated sites in the Akt substrate AS160 clustered separately, with Thr(P)-642 grouped with other Akt substrates. Further experiments suggested that atypical protein kinase Cζ phosphorylates AS160 at Ser-588 and that these two sites are mutually exclusive. These data indicate the utility of hierarchical cluster analysis for identifying functionally related biological nodes and highlight the importance of subcellular partitioning of key signaling components for biological specificity. |
| |
| Keywords: | |
|
|
