Hepatocyte nuclear factor-1alpha recruits the transcriptional co-activator p300 on the GLUT2 gene promoter.
Mutations in the hepatocyte nuclear factor (HNF)-1alpha gene have been linked to subtype 3 of maturity-onset diabetes of the young (MODY), a disease characterized by a primary defect in insulin secretion. Here we show that the human GLUT2 gene is closely regulated by HNF-1alpha via sequences downstream of the transcriptional start site by interaction with transcriptional co-activator p300. The promoter region of the human GLUT2 gene was subcloned into luciferase expression plasmids that were transfected together with HNF-1alpha expression plasmid into a pancreatic beta-cell line, HIT-T15, to evaluate transcriptional activities. HNF-1alpha enhanced human GLUT2 promoter activity sixfold. Site-direct mutagenesis and footprint analyses showed that the HNF-1alpha binding site (+200 to +218) is critical in human GLUT2 gene expression. Furthermore, mammalian two-hybrid and immunoprecipitation studies revealed the transactivation domain of HNF-1alpha (amino acids 391-540) to interact with both the NH(2)-terminal region (amino acids 180-662) and the COOH-terminal region (amino acids 1,818-2,079) of p300. These findings demonstrated that HNF-1alpha binds to the 5'-untranslated region of GLUT2 and that p300 acts as a transcriptional co-activator for HNF-1alpha. In addition, these results provided new insight into the regulatory function of HNF-1alpha by suggesting a molecular basis for human GLUT2 gene expression.
Ban
Nobuhiro
N
Department of Metabolism and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Japan.
Yamada
Yuichiro
Y
Someya
Yoshimichi
Y
Miyawaki
Kazumasa
K
Ihara
Yu
Y
Hosokawa
Masaya
M
Toyokuni
Shinya
S
Tsuda
Kinsuke
K
Seino
Yutaka
Y
D020121:5' Untranslated Regions / Q000502:physiology; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D006224:Cricetinae; D004268:DNA-Binding Proteins; D005786:Gene Expression Regulation / Q000502:physiology; D017930:Genes, Reporter; D051273:Glucose Transporter Type 2; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D006801:Humans; D007515:Islets of Langerhans / Q000502:physiology; D009004:Monosaccharide Transport Proteins / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000502:physiology; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology
D020121:5' Untranslated Regions; D004268:DNA-Binding Proteins; D051273:Glucose Transporter Type 2; C496487:HNF1A protein, human; C496495:HNF1B protein, human; D051538:Hepatocyte Nuclear Factor 1-alpha; D009004:Monosaccharide Transport Proteins; D009687:Nuclear Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta