Diabetes, Vol 41, Issue 11 1436-1445, Copyright © 1992 by American Diabetes Association
Human GLUT4/muscle-fat glucose-transporter gene. Characterization and genetic variation
JB Buse, K Yasuda, TP Lay, TS Seo, AL Olson, JE Pessin, JH Karam, S Seino and GI Bell
Department of Medicine, University of Chicago, IL 60637.
Four overlapping DNA fragments spanning 32 kb containing the human GLUT4
facilitative glucose-transporter gene were isolated and characterized. The
sequence of the GLUT4 gene (approximately 6.3 kb) and 2.0 kb of the
promoter region was determined. The sequence of the promoter revealed
potential binding sites for transcription factors known to regulate gene
expression in muscle cells and adipocytes. However, transfection of
constructs including 2 kb of the GLUT4 promoter fused to the bacterial CAT
gene into 3T3-L1 adipocytes displayed only weak promoter activity. Because
insulin resistance plays a prominent role in the development of NIDDM,
genetic variation in the sequence of GLUT4 also was evaluated.
Oligonucleotide primer pairs were selected that allowed the protein-coding
region of the human GLUT4 gene to be amplified by PCR. The sequence of the
protein-coding region of the GLUT4 gene and all intron-exon junctions was
determined for a single diabetic Pima Indian and was identical to that of
the cloned gene and cDNA. SSCP analysis was used to screen patients with
diabetes mellitus and normal, healthy nondiabetic individuals for mutations
at the GLUT4 locus. In addition to the silent substitution in the codon for
Asn130 (AAC or AAT) and a Val383 (GTC)-->Ile(ATC) replacement described
previously, two new variants were identified. One was a T-->A
substitution in intron 1 that was found in 1 of 36 NIDDM patients who were
typed for this variant. The second was a Ile385(ATT)-->Thr(ACT)
replacement that occurred in 1 normal individual and was not found in any
of 676 other normal and diabetic subjects. A large and racially diverse
group of normal and diabetic individuals also was screened for the Ile383
polymorphism. It occurred in both diabetic and nondiabetic subjects. There
is no indication from our data that these polymorphisms are associated with
NIDDM.