[Regulation of the expression and function of glucose transporter-1 by TGF-beta 1 and high glucose in mesangial cells].
OBJECTIVE
To study the effects of high glucose and transforming growth factor-beta 1 (TGF-beta 1) on the expression and function of glucose transporter-1 (GLUT1) in mouse mesangial cells.


METHODS
Cultured mouse mesangial cells were used. The expression of GLUT1 mRNA was detected by Northern Blot; glucose uptake and its kinetics were determined with a 2-Deoxy-[3H]-D-glucose uptake assay.


RESULTS
Mesangial cells exposed to enriched glucose medium (20 mmol/L) for 72 hours demonstrated a decrease in both GLUT1 mRNA and Vmax for uptake of the glucose analog, 2-deoxy-D-glucose (2DOG), as compared to mesangial cells cultured in physiologic glucose concentrations (5.5 mmol/L). In contrast, hypertonic mannitol had no effect on GLUT1 mRNA levels. TGF-beta 1 treatment for 10 hours stimulated 2DOG uptake, both in 5.5 mmol/L and 20 mmol/L glucose medium, by approximately 4.28-fold in a dose-dependent manner (2 ng/ml maximum). Kinetic analysis of 2DOG uptake revealed an increase in Vmax and a decrease in Km in the presence of TGF-beta 1. TGF-beta 1 also up-regulated the expression of GLUT1 mRNA in mesangial cells. The addition of anti-TGF-beta neutralizing antibody (30 micrograms/ml) in mesangial cells cultured in enriched glucose medium (20 mmol/L) led to a 40% decrease in 2DOG uptake.


CONCLUSIONS
The expression of GLUT1 can be suppressed by exposure of mesangial cells to high glucose medium, which may serve as a protective mechanism against possible adverse effects of excessive glucose flux into cells. TGF-beta 1 stimulates glucose uptake by enhancing the expression and function of GLUT1 in mesangial cells. This effect is independent of the glucose milieu in the cultured medium.
Zhang
J
J
Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, Nanjing 210002, China.
Liu
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Liu
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Li
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D000818:Animals; D002460:Cell Line; D003847:Deoxyglucose / Q000378:metabolism; D003928:Diabetic Nephropathies / Q000209:etiology*; D005920:Glomerular Mesangium / Q000166:cytology / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology*; D051272:Glucose Transporter Type 1; D051379:Mice; D008810:Mice, Inbred C57BL; D009004:Monosaccharide Transport Proteins / Q000235:genetics* / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D051272:Glucose Transporter Type 1; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; C495678:Slc2a1 protein, mouse; D016212:Transforming Growth Factor beta; D003847:Deoxyglucose; D005947:Glucose