Transfection of AtT-20(ins) cells with GLUT-2 but not GLUT-1 confers glucose-stimulated insulin secretion. Relationship to glucose metabolism

S. D. Hughes, C. Quaade, J. H. Johnson, S. Ferber, C. B. Newgard

Research output: Contribution to journalArticlepeer-review

Abstract

Glucose is thought to stimulate insulin release from islet β-cells through generation of metabolic signals. In the current study we have introduced the genes encoding the facilitated glucose transporters known as GLUT-1 and GLUT-2 into AtT-20(ins) cells to assess their impact on glucose- stimulated insulin release and glucose metabolism. We find that transfection of AtT-20(ins) cells with GLUT-2, but not GLUT-1, confers glucose-stimulated insulin release in both static incubation and perifusion studies. Cells transfected with GLUT-1 have a K(m) for 3-O-methyl glucose uptake of 4 mM and a V(max) of 5-6 mmol/min/liter cell space. These values are increased compared to untransfected AtT-20(ins) cells (K(m) = 2 mM; V(max) = 0.5 mmol/min/liter cell space), but are less than observed in GLUT-2-transfected lines (K(m) = 16-17 mM; V(max) = 17-25 mmol/min/liter cell space). Despite these dramatic differences in glucose transport affinity and capacity, the rates of [5-3H]glucose usage are not different in the control and transfected lines over a range of glucose concentrations from 10 μM to 20 mM. We conclude that the specific effect of GLUT-2 on glucose-stimulated insulin release in AtT-20(ins) cells is not related to changes in the overall rate of glucose metabolism and may instead involve physical coupling of GLUT- 2 with cellular proteins and/or structures involved in glucose signaling.

Original languageEnglish
Pages (from-to)15205-15212
Number of pages8
JournalJournal of Biological Chemistry
Volume268
Issue number20
StatePublished - 1993
Externally publishedYes

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