Comparative study of HP-27 gene promoter activities between the chipmunk and tree squirrel.
The chipmunk hibernation-specific protein HP-27 is a component of the 140-kDa complex that decreases in the blood during hibernation. Although the HP-27 gene is detected in both the chipmunk, a hibernating species of the squirrel family, and the tree squirrel, a nonhibernating species, it is expressed only in the chipmunk, in a liver-specific manner. To understand the difference in HP-27 gene expression between the chipmunk and tree squirrel, we isolated chipmunk and tree squirrel HP-27 genomic clones, and compared their promoter activities. Transient transfection studies in HepG2 cells revealed that the 170 bp 5'-flanking sequence of the chipmunk HP-27 gene was sufficient for liver-specific promoter activity and that deletion of the sequence from -170 to -140 reduced the promoter activity by 90%. Although the corresponding 170 bp 5'-flanking sequence of the tree squirrel HP-27 gene had 89% nucleotide sequence homology to that of the chipmunk, it showed almost no promoter activity in HepG2 cells. In a gel retardation assay using HepG2 or chipmunk liver nuclear extracts, the 5'-flanking sequence of the chipmunk HP-27 gene from -170 to -140 showed a shifted band, but the corresponding tree squirrel sequence did not. Taken together, these data indicate that a transcription factor that binds to this 5'-flanking sequence of the chipmunk HP-27 gene plays an important role in HP-27 gene expression, and the failure of this factor to bind in the case of the tree squirrel HP-27 gene could be responsible for this animal's lack of HP-27 gene expression.
Ono
Motoharu
M
Department of Biosciences, School of Science, Kitasato University, 1-15-1 Kitasato, Sagamihara, 228-8555, Kanagawa, Japan.
Kojima-Kawagoe
Miho
M
Kondo
Noriaki
N
Shiba
Tadayoshi
T
Takamatsu
Nobuhiko
N
D024506:5' Flanking Region / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001798:Blood Proteins / Q000235:genetics*; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D005091:Exons; D005796:Genes / Q000235:genetics; D006801:Humans; D007438:Introns; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012589:Sciuridae / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014407:Tumor Cells, Cultured
D001798:Blood Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C081700:HP-27 protein, Tamias asiaticus; D011993:Recombinant Fusion Proteins; D004247:DNA; D008156:Luciferases