Stimulation of GLUT-1 glucose transporter expression in response to hyperosmolarity.
Glucose transporter isoform-1 (GLUT-1) expression is stimulated in response to stressful conditions. Here we examined the mechanisms mediating the enhanced expression of GLUT-1 by hyperosmolarity. GLUT-1 mRNA, GLUT-1 protein, and glucose transport increased after exposure of Clone 9 cells to 600 mosmol/l (produced by addition of mannitol). The stimulation of glucose transport was biphasic: in the early phase (0-6 h) a approximately 2.5-fold stimulation of glucose uptake was associated with no change in the content of GLUT-1 mRNA, GLUT-1 protein, or GLUT-1 in the plasma membrane, whereas the approximately 17-fold stimulation of glucose transport during the late phase (12-24 h) was associated with increases in both GLUT-1 mRNA (approximately 7.5-fold) and GLUT-1 protein content. Cell sorbitol increased after 3 h of exposure to hyperosmolarity. The increase in GLUT-1 mRNA content was associated with an increase in the half-life of the mRNA from 2 to 8 h. A 44-bp region in the proximal GLUT-1 promoter was necessary for basal activity and for the two- to threefold increases in expression by hyperosmolarity. It is concluded that the increase in GLUT-1 mRNA content is mediated by both enhanced transcription and stabilization of GLUT-1 mRNA and is associated with increases in GLUT-1 content and glucose transport activity.
Hwang
D Y
DY
Department of Physiology, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Ismail-Beigi
F
F
D019325:3-O-Methylglucose / Q000493:pharmacokinetics; D000449:Aldehyde Reductase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D004234:Diuretics, Osmotic / Q000494:pharmacology; D015870:Gene Expression / Q000502:physiology; D051272:Glucose Transporter Type 1; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D009997:Osmotic Pressure; D011401:Promoter Regions, Genetic / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D013012:Sorbitol / Q000494:pharmacology; D014316:Tritium; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology*
D004234:Diuretics, Osmotic; D051272:Glucose Transporter Type 1; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; C495679:Slc2a1 protein, rat; D014316:Tritium; D019325:3-O-Methylglucose; D013012:Sorbitol; D000449:Aldehyde Reductase