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Identification of transacting factors responsible for the tissue-specific expression of human glucose transporter type 2 isoform gene. Cooperative role of hepatocyte nuclear factors 1alpha and 3beta.

 Ji-Young Cha  ;  Ha-il Kim  ;  Kyung-Sup Kim  ;  Man-Wook Hur  ;  Yong-ho Ahn 
 Journal of Biological Chemistry, Vol.275(24) : 18358-18365, 2000 
Journal Title
Issue Date
Base Sequence ; CCAAT-Enhancer-Binding Proteins ; Cells, Cultured ; Consensus Sequence ; DNA-Binding Proteins/metabolism ; DNA-Binding Proteins/physiology* ; Diabetes Mellitus, Type 1/genetics ; Gene Expression Regulation* ; Glucose Transporter Type 2 ; Hepatocyte Nuclear Factor 1 ; Hepatocyte Nuclear Factor 1-alpha ; Hepatocyte Nuclear Factor 1-beta ; Hepatocyte Nuclear Factor 3-beta ; Humans ; Molecular Sequence Data ; Monosaccharide Transport Proteins/biosynthesis ; Monosaccharide Transport Proteins/genetics* ; Nuclear Proteins/physiology* ; Promoter Regions, Genetic ; Transcription Factors/physiology* ; Transcriptional Activation*
We investigated transacting factors binding to the cis-element important in tissue-specific expression of the human glucose transporter type 2 isoform (GLUT2) gene. By transient transfection assay, we determined that the 227-base pair fragment upstream of the ATG start site contained promoter activity and that the region from +87 to +132 (site C) was responsible for tissue-specific expression. DNase I footprinting and electrophoretic mobility shift assay indicated that site C contained one binding site for hepatocyte nuclear factor 1 (HNF1) and two binding sites for HNF3. The mutations at positions +101 and +103, which are considered to be critical in binding HNF1 and HNF3, resulted in a 53% decrease in promoter activity, whereas the mutation of the proximal HNF3 binding site (+115 and +117) reduced promoter activity by 28%. The mutations of these four sites resulted in marked decrease (70%) in promoter activity as well as diminished bindings of HNF1 and HNF3. A to G mutation, which causes conversion of the HNF1 and HNF3 binding sequence to the NF-Y binding site, resulted in a 22% decrease in promoter activity. We identified that both HNF1 and HNF3 function as transcriptional activators in GLUT2 gene expression. Coexpression of the pGL+74 (+74 to +301) construct with the HNF1alpha and HNF3beta expression vectors in NIH 3T3 cells showed the synergistic effect on GLUT2 promoter activity compared with the expression of HNF1alpha, HNF3beta, or a combination of HNF1beta and HNF3beta. These data suggest that HNF1alpha and HNF3beta may be the most important players in the tissue-specific expression of the human GLUT2 gene.
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1. College of Medicine (의과대학) > Dept. of Biochemistry and Molecular Biology (생화학-분자생물학교실) > 1. Journal Papers
Yonsei Authors
Kim, Ha Il(김하일)
Ahn, Yong Ho(안용호) ORCID logo https://orcid.org/0000-0002-4133-0757
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