Mutation analysis of HNF-4 binding sites in the human glucose-6-phosphatase promoter.
Int J Mol Med
; 15(3): 487-90, 2005 Mar.
Article
em En
| MEDLINE
| ID: mdl-15702243
ABSTRACT
HNF-4, a member of the nuclear receptor superfamily, binds to HNF-4 response elements (HRE), consisting of a direct repeat of the hexameric half-sites spaced by 1 nt (direct repeat 1) and activates a number of genes, which play central roles in fatty acids and glucose metabolism. Glucose-6-phosphatase (G6Pase) catalyzes the terminal step in the gluconeogenic and glycogenolytic pathways. A previous study has shown that HNF-4 binds to two DR1s in the regions A (located between -266 and -234) and B (located between -306 and -274) on the human G6Pase promoter. We found that the region B contains the one more DR1 element, composed of the two half-sites, designated half-sites a and b, the latter of which overlaps with the previously identified DR1 consisting of two half-sites, designated half-sites b and c. In this study, electrophoretic mobility shift assay (EMSA) using point mutations in each half-site a, b, or c indicated that HNF-4 binds to the combination of half-sites a and b, but not to half-sites b and c. Furthermore, mutational analysis demonstrated that, in the context of the human G6Pase promoter, the half-sites a and b, but not the half-sites b and c, are required for the stimulatory effect of HNF-4. These results suggested that the DR1 element containing the half-sites a and b is a functional HRE that mediates the induction of hG6Pase promoter activity by HNF-4.
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Base de dados:
MEDLINE
Assunto principal:
Fosfoproteínas
/
Fatores de Transcrição
/
Regiões Promotoras Genéticas
/
Glucose-6-Fosfatase
/
Proteínas de Ligação a DNA
/
Mutação
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Ano de publicação:
2005
Tipo de documento:
Article