Abstract
Glucagon-like peptide-1 (7–36) amide (GLP-1) is an insulin secretagogue. Recently, many studies have shown GLP-1 can improve insulin resistance in peripheral tissues. In the present study, we investigated glucose uptake in 3T3-L1 adipocytes in either basal or insulin resistant state and dissected insulin signaling pathway in order to elucidate the molecular mechanisms of GLP-1 mediated improvement of insulin resistance. We found GLP-1 and its long lasting analogue, exendin 4 up-regulated basal IR, IRS-1 and Glut 4 expressions although they did not increase basal glucose uptake alone. However, GLP-1 and exendin-4 increased insulin mediated glucose uptake in intact and TNF-α treated 3T3-L1 adipocytes by up-regulation of phophorylated IRβ, IRS-1, Akt and GSK-3β. These results indicate that GLP-1 and its analogue exendin-4 can amplify insulin signaling in 3T3-L1 adipocytes by up-regulation of some crucial insulin signaling molecules.
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Acknowledgements
This study was supported by the grant from Shanghai Committee for Science and Technology (No. 04DZ19502 and No.05PJ14060) and from E-Institute of Shanghai Universities, Shanghai Municipal Education Commission (No. E03007).
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Hong Gao and Xinjun Wang equally contributed to this work.
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Gao, H., Wang, X., Zhang, Z. et al. GLP-1 amplifies insulin signaling by up-regulation of IRβ, IRS-1 and Glut4 in 3T3-L1 adipocytes. Endocr 32, 90–95 (2007). https://doi.org/10.1007/s12020-007-9011-4
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DOI: https://doi.org/10.1007/s12020-007-9011-4