Insulin-Like Growth Factor (IGF) Binding Protein-2, Independently of IGF-1, Induces GLUT-4 Translocation and Glucose Uptake in 3T3-L1 Adipocytes

Figure 4

IGFBP-2 stimulates Akt and AMPK activation and thus increased GLUT-4 translocation. (a) Insulin, IGF-1, and IGFBP-2 significantly increase Akt Ser473 phosphorylation. (b) IGF-1 and IGFBP-2 but not insulin increase AMPK Thr172 phosphorylation. , , and versus control. (c) The AMPK inhibitor, Compound C, abolishes IGFBP-2-induced glucose uptake in 3T3-L1 adipocytes. Differentiated 3T3-L1 adipocytes were incubated with 200 μM Compound C for 20 min before treatment with IGFBP-2 for 30 min. and . Insulin, IGF-1, and IGFBP-2 significantly increase TBC1D1 Ser237 phosphorylation (d) and GLUT-4 translocation (e). , , and versus control. Each experiment was performed with three technical replicates and total number of experiments was three. The glucose uptake values are percentage of the controls. The results are presented as mean ± SEM.

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