Chronic exposure of human glomerular epithelial cells to high glucose concentration results in modulation of high-affinity glucose transporters expression.
BACKGROUND
GLUTs are specific membrane proteins that transport glucose down a concentration gradient. There have been few studies on their expression in the kidney. The aim of this study was to identify the expression of GLUTs 1, 3, and 4 in HGEC and their regulation under diabetic milieu.


METHODS
An immortalized cell line of HGEC was used. Cells were cultured in medium containing 5 or 25 mM D-glucose. Western blotting and flow cytometry were used to examine the presence of GLUTs (1, 3, 4) and alterations in expression.


RESULTS
Western blotting analysis revealed that GLUT-1 levels were increased by 53% in HGEC cultured under experimental diabetes compared to cells grown in 5mM glucose. GLUT-3 levels were also increased by 15% under diabetic conditions. GLUT-4 levels were decreased by 20% in diabetes. Fluorescence Activated Cell Sorting (FACS) analysis demonstrated that cell surface expression of GLUT-1 was increased by 28% in cells grown in 25mM glucose. High glucose concentration did not affect cell surface expression of GLUT-3 and GLUT-4.


CONCLUSIONS
These findings suggest that depressed GLUT4 expression in glomerulus and overexpression of GLUT-1 and in a lesser extent of GLUT-3 may alter the glucose uptake in these cells. It has been suggested that the overexpression of GLUT-1 in glomerulus, being the major isoform, may lead to the initial pathologic hallmarks of diabetic nephropathy.
Moutzouris
Dimitrios-Anestis D
DA
First Department of Propaedeutic Medicine, University of Athens Medical School, Laiko University Hospital, Athens, Greece. moutzouris@hotmail.com
Kitsiou
Paraskevi V
PV
Talamagas
Argiris A
AA
Drossopoulou
Garyfallia I
GI
Kassimatis
Theodore I
TI
Katsilambros
Nikolaos K
NK
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002469:Cell Separation; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology*; D051246:Glucose Transport Proteins, Facilitative / Q000096:biosynthesis* / Q000187:drug effects*; D051272:Glucose Transporter Type 1 / Q000096:biosynthesis / Q000187:drug effects; D051274:Glucose Transporter Type 3 / Q000096:biosynthesis / Q000187:drug effects; D051275:Glucose Transporter Type 4 / Q000096:biosynthesis / Q000187:drug effects; D006801:Humans; D050199:Podocytes / Q000187:drug effects* / Q000378:metabolism*; D011817:Rabbits; D013549:Sweetening Agents / Q000494:pharmacology*; D013997:Time Factors
D051246:Glucose Transport Proteins, Facilitative; D051272:Glucose Transporter Type 1; D051274:Glucose Transporter Type 3; D051275:Glucose Transporter Type 4; D013549:Sweetening Agents; D005947:Glucose