Dexamethasone causes translocation of glucose transporters from the plasma membrane to an intracellular site in human fibroblasts

• Published in: The Journal of biological chemistry Vol. 262; no. 36; pp. 17696 - 17702
• Main Authors: Horner, H C, Munck, A, Lienhard, G E
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 25-12-1987; American Society for Biochemistry and Molecular Biology
• Subjects: 5'-Nucleotidase; Biological and medical sciences; Cell Membrane - metabolism; Cell physiology; Cells, Cultured; Deoxyglucose - metabolism; dexamethasone; Dexamethasone - pharmacology; Dose-Response Relationship, Drug; fibroblasts; Fibroblasts - cytology; Fibroblasts - drug effects; Fundamental and applied biological sciences. Psychology; glucose transporter; Humans; Insulin - pharmacology; man; Membrane and intracellular transports; Molecular and cellular biology; Monosaccharide Transport Proteins - metabolism; Nucleotidases - metabolism; Time Factors; Human; Translocation; Cell culture; Dexamethasone; Transportation system; Monoclonal antibody; Glucose; Glucocorticoid; Insulin; Plasma membrane; Kinetics; Inhibition; Transport; Fibroblast
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)45435-X

To investigate the mechanism by which glucocorticoids inhibit glucose transport in peripheral tissues, we have used a monoclonal antibody directed against the human glucose transporter to measure the relative amounts of glucose transporter polypeptide in various cell fractions of human foreskin fibroblasts after treatment with and without dexamethasone. In cells treated for 4 h with 100 nM dexamethasone, a decrease of 48% in glucose transport was accompanied by a decrease of 40% in the amount of glucose transporter polypeptide in a plasma membrane fraction enriched 10-fold in 5′-nucleotidase activity and a 78% increase in the amount of transporter polypeptide in a fraction of putative intracellular membranes, designated P2. There was no significant change in the amount of transporter polypeptide in whole cell lysates. Insulin (200 nM) stimulated glucose transport in basal fibroblasts by only 9%. However, addition of insulin for 30 min to cells that had been treated for 4 h with dexamethasone completely reversed the dexamethasone-induced decrease in glucose transport and also reversed the dexamethasone-induced changes in glucose transporter polypeptide content of the plasma membrane and P2 fractions. From these observations we conclude that dexamethasone decreases glucose transport by causing translocation of glucose transporters from the plasma membrane to an internal location and that insulin reverses the dexamethasone effect by reversing the translocation.