[Inhibition of glucose transporter 1 overexpression in mesangial cells by rhein].
OBJECTIVE
To evaluate the effect of rhein on the overexpression of glucose transporter 1(GLUT 1) in mesangial cells transfected with GLUT 1 gene in vitro.


METHODS
Rat mesangial cells were transduced with the human GLUT 1 gene(MCGT 1) by retrovirus vector. Mesangial cells transduced with bacterial beta-galactosidase(MCLacZ) were used as control. Glucose uptake was detected by 2-deoxyglucose(2-DG). Cell volume, RNA/DNA ratio and protein/DNA ratio were evaluated by flow cytometry analysis. The synthesis of collagen IV and fibronectin were measured by 3H-proline incorporation and flow cytometry. The activity of glutamine: fructose-6-phosphate aminotransferase (GFAT) was assayed by spectrophotometry method. The expression of collagen IV, fibronectin and GFAT were analyzed by RT-PCR.


RESULTS
MCGT 1 exhibited a higher 2-DG uptake with increased Vmax value as compared to MCLaZ(741 +/- 60.5) dpm.microgram prot-1 vs (92.2 +/- 9) dpm.microgram prot-1, (P < 0.01), Even cultured in normal glucose concentration, MCGT1 showed cell hypertrophy, including increased cell volume, RNA/DNA and protein/DNA ratios; increased synthesis of extracellular matrix. 3H-proline incorporation significantly enhanced in MCGT1 compared with that in the control(7.0 +/- 0.4) dpm.cell-1 vs (4.6 +/- 0.6) dpm.cell-1, (P < 0.01); and GFAT activity increased to 1.8 fold. Rhein could inhibit 2-DG uptake of MCGT1(560 +/- 64) dpm.microgram prot-1 vs (741 +/- 60.5) dpm.microgram prot-1, (P < 0.05) in a dose-dependent manner, and reverse the cell hypertrophy of MCGT 1. In addition, rhein could diminish the enhanced GFAT activity of MCGT 1 with no influence in mRNA expression.


CONCLUSIONS
It is suggested that glucose transport activity was an important modulator of cellular glucose metabolism in mesangial cells. Rhein could ameliorate the metabolic derangement of MCGT 1 by decreasing glucose uptake. These findings have led us closer to the identification of therapeutic approaches to abort GLUT 1 overexpression in diabetic nephropathy.
Zhu
J
J
Research Institute of Nephropathy, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, China.
Liu
Z
Z
Li
Y
Y
D000818:Animals; D000880:Anthraquinones / Q000494:pharmacology*; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005353:Fibronectins / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D005920:Glomerular Mesangium / Q000187:drug effects* / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1; D006595:Hexosamines / Q000378:metabolism; D006801:Humans; D009004:Monosaccharide Transport Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D011392:Proline / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D014316:Tritium
D000880:Anthraquinones; D004791:Enzyme Inhibitors; D005353:Fibronectins; D051272:Glucose Transporter Type 1; D006595:Hexosamines; D009004:Monosaccharide Transport Proteins; C495677:SLC2A1 protein, human; C495679:Slc2a1 protein, rat; D014316:Tritium; D012313:RNA; D004247:DNA; D011392:Proline; D005947:Glucose; C020491:rhein