J Korean Diabetes Assoc.  2002 Aug;26(4):274-285.

The Role of Akt-1/PKBalpha on Insulin Action in 3T3-L1 Adipocyte

• Lee JM
• Son HS
• Kwon HS
• Kwack SK
• Ko SH
• Chang SA
• Yoon KH
• Cha BY
• Lee KW
• Son HY
• Kang SK
• Sharma P

Abstract

BACKGROUNDS: Akt/PKB as a serine/threonine kinase is stimulated by insulin and other growth factors. And insulin stimulates glucose uptake by promoting the translocation of glucose transporter 4 (GLUT4) to the cell membrane. But, it is not clear that Akt/PKB, a downstream target of PI 3-kinase, is involved in glucose uptake pathway. In this study, we investigated the role of Akt/PKB, especially Akt-1, on insulin action in 3T3-L1 adipocyte.
METHODS
We made recombinant Ad5.Akt-1 vector by the insertion of Akt-1 gene to adenoviral vector. And then, we overexpressed Akt-1 proteins(wild type and kinase inactive type) in 3T3-L1 adipocytes by using a adenoviral transfection method. We observed the changes of glucose uptake, glycogen synthesis, activities of mitogen-activated protein kinase (MAPK, also called extracellular signal-regulated kinase), p70 ribosomal s6 protein kinase (p70s6k), and glycogen synthase kinase 3 (GSK3) according to Akt-1 activity and insulin treatment.
RESULTS
First, overexpression of Akt-1 did not affect to glucose uptake, whether insulin stimulates or not. Second, overexpression of Akt-1 did not affect the phosphorylation of p44/42-MAPK, either. Third, the glycogen synthesis was increased by overexpression of Akt-1.
CONCLUSION
Akt-1 activation is necessary for glycogen synthesis, but is not essential for glucose transport in 3T3-L1 adipocytes.

Keyword

Adenovirus; Transfection; Insulin; Akt; PKB; MAPK; p70s6k; Glucose uptake; Glycogen synthesis

MeSH Terms

Adenoviridae
Adipocytes*
Cell Membrane
Glucose
Glucose Transport Proteins, Facilitative
Glycogen
Glycogen Synthase Kinase 3
Insulin*
Intercellular Signaling Peptides and Proteins
Phosphatidylinositol 3-Kinases
Phosphorylation
Phosphotransferases
Protein Kinases
Ribosomal Protein S6 Kinases, 70-kDa
Transfection
Glucose
Glucose Transport Proteins, Facilitative
Glycogen
Glycogen Synthase Kinase 3
Insulin
Intercellular Signaling Peptides and Proteins
Phosphatidylinositol 3-Kinases
Phosphotransferases
Protein Kinases
Ribosomal Protein S6 Kinases, 70-kDa