Title

Insulin signaling through Akt/protein kinase B analyzed by small interfering RNA-mediated gene silencing

UMMS Affiliation

Program in Molecular Medicine

Publication Date

6-17-2003

Document Type

Article

Subjects

1-Phosphatidylinositol 3-Kinase; 3T3 Cells; Adipocytes; Animals; Biological Transport; Blotting, Western; Cells, Cultured; Deoxyglucose; Electroporation; Fibroblasts; *Gene Silencing; Glucose; Humans; Insulin; Mice; Microscopy, Fluorescence; Phosphorylation; Plasmids; Protein-Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; RNA, Small Interfering; *Signal Transduction; Time Factors

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

Glucose homeostasis is controlled by insulin in part through the translocation of intracellular glucose transporter 4 to the plasma membrane in muscle and fat cells. Akt/protein kinase B downstream of phosphatidylinositol 3-kinase has been implicated in this insulin-signaling pathway, but results with a variety of reagents including Akt1-/- and Akt2-/- mice have been equivocal. Here we report the application of small interfering RNA-directed gene silencing to deplete both Akt1 and Akt2 in cultured 3T3-L1 adipocytes. Loss of Akt1 alone slightly impaired insulin-mediated hexose transport activity but had no detectable effect on glycogen synthase kinase (GSK)-3 phosphorylation. In contrast, depletion of Akt2 alone by 70% inhibited approximately half of the insulin responsiveness. Combined depletions of Akt1 plus Akt2 in these cells even more markedly attenuated insulin action on glucose transporter 4 movements, hexose transport activity, and GSK-3 phosphorylation. These data demonstrate a primary role of Akt2 in insulin signaling, significant functional redundancy of Akt1 and Akt2 isoforms in this pathway, and an absolute requirement of Akt protein kinases for regulation of glucose transport and GSK-3 in cultured adipocytes.

Rights and Permissions

Citation: Proc Natl Acad Sci U S A. 2003 Jun 24;100(13):7569-74. Epub 2003 Jun 13. Link to article on publisher's site

DOI of Published Version

10.1073/pnas.1332633100

Related Resources

Link to Article in PubMed

Journal/Book/Conference Title

Proceedings of the National Academy of Sciences of the United States of America

PubMed ID

12808134