HNF-1 regulates the promoter activity of the HP-27 gene.
The hibernation-specific HP-27 gene is expressed specifically in the liver of the chipmunk, a hibernating species of the squirrel family, and exists as a pseudogene in the tree squirrel, a nonhibernating species. In the promoter region, the chipmunk gene has a potential HNF-1 binding site, and the tree squirrel gene has two base substitutions in the corresponding sequence. In this paper, we investigated the role of HNF-1 in the HP-27 gene promoter activity. Gel retardation assays with in vitro-translated HNF-1 and super-shift assays using HepG2 nuclear extracts and an anti-HNF-1 antibody revealed that HNF-1 bound to the chipmunk gene sequence. HNF-1 also bound to the tree squirrel sequence, but with much lower affinity. In HepG2 cells, HNF-1 activated transcription from the chipmunk HP-27 gene, but not from the tree squirrel gene. In addition, the tree squirrel-type base substitutions in the HNF-1 binding site greatly reduced the promoter activity of the chipmunk HP-27 gene. These results indicate that HNF-1 is required for the promoter activity of the chipmunk HP-27 gene, and that the base substitutions in the HNF-1 binding site are involved in the lack of HP-27 gene expression in the tree squirrel.
Ono
Motoharu
M
Department of Biosciences, School of Science, Kitasato University, 1-15-1 Kitasato, Sagamihara, Kanagawa 228-8555, Japan.
Kojima-Kawagoe
Miho
M
Ito
Michihiko
M
Kondo
Noriaki
N
Shiba
Tadayoshi
T
Takamatsu
Nobuhiko
N
D000818:Animals; D001345:Autoradiography; D001483:Base Sequence; D001665:Binding Sites; D001798:Blood Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D051537:Hepatocyte Nuclear Factor 1; D008099:Liver / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012589:Sciuridae / Q000235:genetics* / Q000378:metabolism*; D016415:Sequence Alignment; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection
D001798:Blood Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; C081700:HP-27 protein, Tamias asiaticus; D009687:Nuclear Proteins; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D008156:Luciferases