scholarly journals C/EBP binding activity to site F of the rat GLUT2 glucose transporter gene promoter is attenuated by c-Jun in vitro

2002 ◽  
Vol 34 (5) ◽  
pp. 379-384 ◽  
Author(s):  
Jae-Woo Kim ◽  
Yong-Ho Ahn
Keyword(s):  
Glucose Transporter ◽  
Gene Promoter ◽  
Binding Activity ◽  
Transporter Gene ◽  
Glut2 Glucose Transporter

scholarly journals CCAAT/enhancer binding protein regulates the promoter activity of the rat GLUT2 glucose transporter gene in liver cells

1998 ◽  
Vol 336 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Jae-woo KIM ◽  
Yong-ho AHN
Keyword(s):  
Transcription Factors ◽  
Primary Culture ◽  
Promoter Activity ◽  
Glucose Transporter ◽  
Liver Cells ◽  
Transporter Gene ◽  
Dnase I Footprinting ◽  
Enhancer Binding Protein ◽  
Glut2 Gene ◽  
Glut2 Glucose Transporter

The liver-specific expression of the GLUT2 glucose transporter gene is suppressed in cultured hepatoma cell lines as well as in hepatocytes in primary culture. To understand the underlying mechanism involved in this process, we analysed the rat GLUT2 promoter region. A DNase I footprinting assay with rat liver nuclear extract revealed eight protected regions within a -500 bp region of the GLUT2 promoter (sites A to H). Three of these sites (B, F and H) were occupied by transcription factors that are considerably enriched in liver cells compared with spleen or kidney. The proteins binding to these sites were investigated by a combination of DNase I footprinting assay and electrophoretic mobility-shift assay with the addition of specific oligonucleotide competitors and specific antibody against known transcription factors. As a result it was revealed that hepatocyte nuclear factor 3 binds to site B (-120 to -70), and CCAAT/enhancer binding protein α (C/EBPα) and C/EBPβ bind to site F (-375 to -356) and site H (-500 to -471). The binding of C/EBP to sites F and H was markedly decreased within 4 h when liver cells were subjected to primary culture, suggesting that C/EBP might be responsible for the decreased expression of GLUT2 in this process. In contrast, Western blot analysis revealed that C/EBPα began to decrease after 1 h of hepatocyte culture, and C/EBPβ was not changed significantly throughout the culture period, suggesting that C/EBP could be regulated at the transcriptional level as well as the post-translational level when hepatocytes were put in culture. To confirm the role of C/EBP in the regulation of GLUT2 promoter activity, sites F and H were ligated to a chloramphenicol acetyltransferase (CAT) reporter gene and co-transfected with a C/EBP expression vector into HepG2 cells. The co-expression of C/EBPα and C/EBPβ resulted in 9.1-fold and 3.8-fold increases of CAT activities in the site F-CAT and site H-CAT constructs respectively. These results indicate that C/EBPα and C/EBPβ regulate the promoter activity of the GLUT2 gene and might be responsible for the down-regulation of the GLUT2 gene when hepatocytes are subjected to primary culture.

scholarly journals Specificity and Regulation of DNA Binding by the Yeast Glucose Transporter Gene Repressor Rgt1

2003 ◽  
Vol 23 (15) ◽  
pp. 5208-5216 ◽  
Author(s):  
Jeong-Ho Kim ◽  
Jeffrey Polish ◽  
Mark Johnston
Keyword(s):  
Dna Binding ◽  
Glucose Transporter ◽  
Binding Activity ◽  
Sequence Motif ◽  
Consensus Binding Site ◽  
Binding Ability ◽  
Dna Binding Activity ◽  
Genes Encoding

ABSTRACT Rgt1 is a glucose-responsive transcription factor that binds to the promoters of several HXT genes encoding glucose transporters in Saccharomyces cerevisiae and regulates their expression in response to glucose. Rgt1 contains a Zn2Cys6 binuclear cluster responsible for DNA binding. Most proteins that contain this sequence motif bind as dimers to regularly spaced pairs of the sequence CGG. However, there are no CGG pairs with regular spacing in promoters of genes regulated by Rgt1, suggesting that Rgt1 binds as a monomer to CGG or to another sequence. We identified the Rgt1 consensus binding site sequence 5′-CGGANNA-3′, multiple copies of which are present in all HXT promoters regulated by Rgt1. Rgt1 binds in vivo to multiple sites in the HXT3 promoter in a nonadditive, synergistic manner, leading to synergistic repression of HXT3 transcription. We show that glucose inhibits the DNA-binding ability of Rgt1, thereby relieving repression of HXT gene expression. This regulation of Rgt1 DNA-binding activity is caused by its glucose-induced phosphorylation: the hyperphosphorylated Rgt1 present in cells growing on high levels of glucose does not bind DNA in vivo or in vitro; dephosphorylation of this form of Rgt1 in vitro restores its DNA-binding ability. Furthermore, an altered Rgt1 that functions as a constitutive repressor remains hypophosphorylated when glucose is added to cells and binds DNA under these conditions. These results suggest that glucose regulates the DNA-binding ability of Rgt1 by inducing its phosphorylation.

scholarly journals A mutation in the Glut2 glucose transporter gene of a diabetic patient abolishes transport activity.

1994 ◽  
Vol 269 (27) ◽  
pp. 17765-17767 ◽  
Author(s):  
M. Mueckler ◽  
M. Kruse ◽  
M. Strube ◽  
A.C. Riggs ◽  
K.C. Chiu ◽  
...  
Keyword(s):  
Diabetic Patient ◽  
Glucose Transporter ◽  
Transporter Gene ◽  
Transport Activity ◽  
Glut2 Glucose Transporter

Polymorphic human glucose transporter gene (GLUT) is on chromosome 1p31.3----p35

Diabetes ◽  
1987 ◽  
Vol 36 (4) ◽  
pp. 546-549 ◽  
Author(s):  
T. B. Shows ◽  
R. L. Eddy ◽  
M. G. Byers ◽  
Y. Fukushima ◽  
C. R. Dehaven ◽  
...  
Keyword(s):  
Glucose Transporter ◽  
Transporter Gene

Recovery of glucose-induced insulin secretion in a rat model of NIDDM is not accompanied by return of the B-cell GLUT2 glucose transporter

Diabetes ◽  
1992 ◽  
Vol 41 (10) ◽  
pp. 1320-1327 ◽  
Author(s):  
C. Chen ◽  
B. Thorens ◽  
S. Bonner-Weir ◽  
G. C. Weir ◽  
J. L. Leahy
Keyword(s):  
Insulin Secretion ◽  
B Cell ◽  
Rat Model ◽  
Glucose Transporter ◽  
Glut2 Glucose Transporter
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