Diabetes, Vol 44, Issue 12 1369-1374, Copyright © 1995 by American Diabetes Association
Pancreatic islet GLUT2 glucose transporter mRNA and protein expression in humans with and without NIDDM
J Ferrer, C Benito and R Gomis
Endocrinology and Nutrition Service, University of Barcelona School of Medicine, Hospital Clinic, Spain.
GLUT2 glucose transporter mRNA has been shown to be underexpressed in
pancreatic islets of numerous animal models of non-insulin-dependent
diabetes mellitus (NIDDM). It has been proposed that this molecular defect
contributes to the pathogenesis of diabetes, although information
concerning the expression of GLUT2 in human pancreatic islet tissue is
lacking. In contrast to the high abundance of GLUT2 in rat islets, human
islets were found to express distinctly low levels of this glucose
transporter mRNA and protein. Thus, a sensitive competitive reverse
transcription-polymerase chain reaction assay was developed to quantify
human GLUT2 mRNA. We obtained pancreases from 4 human organ donors with
previously diagnosed NIDDM and 11 nondiabetic donors and found no
significant differences in GLUT2 mRNA between the two groups. GLUT2 mRNA
was 0.24 +/- 0.08 amol/micrograms RNA (mean +/- SE) in pancreases from
humans with diabetes and 0.27 +/- 0.06 amol/microgram RNA in those without
this diagnosis. Similarly, human pancreatic islet GLUT2 protein was
measured by immunoblot and found to be present at similar levels in two
individuals with diabetes relative to six control samples. These results
thus demonstrate the existence of species differences in the abundance of
islet GLUT2 mRNA and protein. Furthermore, the analysis of islet GLUT2 in a
small sample of human organ donors with and without diabetes raises the
possibility that decreased beta-cell GLUT2 may not represent a widespread
feature of humans with NIDDM.