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Human GLUT-2 overexpression does not affect glucose-stimulated insulin secretion in MIN6 cells
H Ishihara1, T Asano, K Tsukuda
1Institute for Adult Diseases, Asahi Life Foundation, Tokyo, Japan.
The American Journal of Physiology
|November 1, 1995
Summary
Glucose transporter 2 (GLUT-2) overexpression in MIN6 cells did not enhance glucose-stimulated insulin secretion. GLUT-2's role appears limited to glucose transport, not glucose sensing in these cells.
Area of Science:
- Cell biology
- Molecular biology
- Endocrinology
Background:
- Glucose transporter 2 (GLUT-2) is implicated in glucose transport and potentially glucose-stimulated insulin secretion.
- The precise role of GLUT-2 beyond glucose transport in cellular glucose sensing remains incompletely understood.
Purpose of the Study:
- To investigate whether overexpressing human GLUT-2 in MIN6 cells affects glucose utilization and insulin secretion.
- To determine if GLUT-2 has functions beyond glucose transport in glucose sensing.
Main Methods:
- Engineered MIN6 cells to overexpress human GLUT-2 via transfection with human GLUT-2 cDNA.
- Measured 3-O-methyl-D-glucose uptake to assess transporter activity.
- Assessed glucokinase activity and glucose utilization via [5-3H]glucose conversion to [3H]H2O.
- Evaluated glucose-stimulated insulin secretion in response to varying glucose concentrations.
Main Results:
- MIN6 cells overexpressing human GLUT-2 showed a twofold increase in 3-O-methyl-D-glucose uptake.
- Glucokinase activity and glucose utilization remained unchanged in GLUT-2 overexpressing cells.
- Glucose-stimulated insulin secretion was not significantly affected by GLUT-2 overexpression.
Conclusions:
- Increased GLUT-2 abundance does not correlate with enhanced glucose responsiveness when glycolysis is regulated by glucose phosphorylation.
- These findings suggest GLUT-2's primary function in MIN6 cells is glucose transport, with limited direct role in glucose sensing.