- The Role of Akt-1/PKBalpha on Insulin Action in 3T3-L1 Adipocyte.
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Jung Min Lee, Hyun Shik Son, Hyuk Sang Kwon, Seung Ki Kwack, Seung Hyun Ko, Sang Ah Chang, Kun Ho Yoon, Bong Yun Cha, Kwang Woo Lee, Ho Young Son, Sung Koo Kang, Prem Sharma
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Korean Diabetes J. 2002;26(4):274-285. Published online August 1, 2002
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 Abstract
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- BACKGROUND
S: 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.
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