Mammalian Sox15 gene: promoter analysis and implications for placental evolution.
Sox15 belongs to the Sox (Sry-type HMG box) protein family, which is involved in placental development and muscle regeneration. Previously, we showed that the Sox15 gene is highly expressed in the trophoblast giant cells of the mouse placenta. To elucidate the molecular mechanisms of the tissue-dependent transcription of the gene, we isolated approximately 2.2 kb of the 5'-flanking sequence upstream of the transcription initiation site and used it to construct luciferase reporter plasmids. A variety of cell lines, including trophoblast stem (TS) cells, placenta-derived Rcho-1 cells, and myoblast C2C12 cells, required the same 5'-flanking sequence, from -109 to -8, for basal promoter activity. In contrast, the sequences from -297 to -149 and from -148 to -110 were required for cell-type-specific promoter activity in myoblast-derived C2C12 cells and placenta-derived Rcho-1 and TS cells, respectively. These results suggest that the region from -297 to -8 of the Sox15 gene contains three distinct cis-elements that respectively control placenta-specific, myoblast-specific, and common basal expression. We also searched for Sox15 ortholog(s) in the genome databases of various vertebrate species. The results indicated that the three regulatory promoter sequences of the Sox15 genes were conserved among eutherian mammals during vertebrate evolution. Interestingly, the marsupial opossum gene that is closest to Sox15 appeared to be a pseudogene. These findings indicate that Sox15 may have been involved in placental evolution.
Yamada
Kayo
K
Department of Biosciences, School of Science, Kitasato University, Kanagawa, Japan.
Kanda
Hiromi
H
Aihara
Takashi
T
Takamatsu
Nobuhiko
N
Shiba
Tadayoshi
T
Ito
Michihiko
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D002460:Cell Line; D017124:Conserved Sequence; D005260:Female; D005786:Gene Expression Regulation; D006609:High Mobility Group Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D010920:Placenta; D011401:Promoter Regions, Genetic / Q000235:genetics*; D055747:SOX Transcription Factors; D013234:Stem Cells; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D024363:Transcription Initiation Site; D014327:Trophoblasts / Q000166:cytology
D006609:High Mobility Group Proteins; D055747:SOX Transcription Factors; C080886:Sox15 protein, mouse; D014157:Transcription Factors