Facilitative glucose uptake transport systems are ubiquitous in animal cells and are responsible for transporting glucose across cell surface membranes. Evaluation of glucose uptake is crucial in the study of numerous diseases and metabolic disorders such as myocardial ischemia, diabetes mellitus, and cancer. Detailed in this unit are laboratory methods for assessing glucose uptake into mammalian cells. The unit is divided into five sections: (1) a brief overview of glucose uptake assays in cultured cells; (2) a method for measuring glucose uptake using radiolabeled 3-O-methylglucose; (3) a method for measuring glucose uptake using radiolabeled 2-deoxyglucose (2DG); (4) a microplate method for measuring 2DG-uptake using an enzymatic, fluorometric assay; and (5) a microplate-based method using a fluorescent analog of 2DG.

Our previous report demonstrated that epigallocatechin gallate (EGCg) promotes translocation of glucose transporter 4 (GLUT4) in skeletal muscle. In this study, we investigated the molecular mechanism of GLUT4 translocation by EGCg at the physiological concentration range. In L6 cells, EGCg induced phosphorylation of phosphatidylinositide 3'-kinase (PI3K) and downstream protein kinase C (PKC) λ/ξ without affecting the phosphorylation of insulin receptor and Akt. EGCg-induced GLUT4 translocation was suppressed by RNA interference-mediated knockdown of PI3K and treatment with PKC inhibitor Go6983. Moreover, EGCg increased Rac1 activity and actin remodelling as downstream events of PKCλ/ξ. These results indicate that EGCg induced GLUT4 translocation through a PI3K-dependent pathway, but its mode of action differed from that of insulin. EGCg also induced GLUT4 translocation through a 5'-adenosine monophosphate-activated protein kinase (AMPK)-dependent pathway. 67 kDa laminin receptor, which is a target molecule of EGCg, was not involved in EGCg-induced glucose uptake in L6 cells. The oral administration of EGCg suppressed postprandial hyperglycaemia accompanied by GLUT4 translocation through both PI3K- and AMPK-dependent pathways, and promoted glycogen accumulation in skeletal muscle of ICR mice. EGCg promotes GLUT4 translocation through both PI3K- and AMPK-dependent pathways and glycogen accumulation in skeletal muscle.

Facilitative glucose uptake transport systems are ubiquitous in animal cells and responsible for transporting glucose across the cell surface membrane. Evaluation of glucose uptake is crucial in the study of numerous diseases and metabolic disorders, such as myocardial ischemia, diabetes mellitus, and cancer. Methods for assessing glucose uptake into mammalian cells are detailed in this unit. The work is divided into four sections: (1) a brief overview of glucose uptake assays in cultured cells; (2) a method for measuring glucose uptake using radiolabeled 3-O-methylglucose; (3) a method for measuring glucose uptake using radiolabeled 2-deoxyglucose (2DG); and (4) an improved method for measuring 2DG-uptake using an enzymatic, fluorometric assay, eliminating the need for radiolabeled glucose analogs.