Keiko HIROTA    Department   School of Medicine, School of Medicine    Position   Assistant Professor
Article types	Original article
Language	English
Peer review	Peer reviewed
Title	Mutation analysis of HNF-4 binding sites in the human glucose-6-phosphatase promoter.
Journal	Formal name：International journal of molecular medicine Abbreviation：Int J Mol Med ISSN code：11073756
Domestic / Foregin	Foregin
Volume, Issue, Page	15,pp.487-490
Author and coauthor	HIROTA Keiko†, AOYAMA Hisanori, FUKAMIZU Akiyoshi*
Authorship	Lead author
Publication date	2005/03
Summary	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.