Gpbox (Psx2), a homeobox gene preferentially expressed in female germ cells at the onset of sexual dimorphism in mice.
XX gonads differentiate into ovaries, a morphologic event evident by embryonic day 13.5 (E13.5) in mice. To identify early markers of oogenesis, sex-specific urogenital ridge cDNA libraries were constructed from E12-13 embryos. After mass excision and isolation of plasmid DNA, approximately 4800 expressed sequence tags were determined and compared to existing databases. Few cDNAs were specifically expressed in the urogenital ridge, but one, designated GPBOX, encodes a 227-amino-acid homeobox protein that is first expressed at E10.5 in the embryo as well as in the extraembryonic tissues. The Gpbox gene is single copy in the mouse genome and is located on the X chromosome in close proximity to two other homeobox genes, Pem and Psx1. Within the embryo, its expression is limited to the gonad, and transcripts are not detected in adult tissues. Although comparable levels are initially present in both sexes, GPBOX transcripts accumulate faster in female germ cells and peak at E12.5 when they are present in fivefold greater abundance than in males. The persistence of GPBOX transcripts in female germ cells until E15.5 and their virtual disappearance in males by E13.5 suggest that Gpbox may play a role in mammalian oogenesis.
Takasaki
N
N
Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
McIsaac
R
R
Dean
J
J
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D018076:DNA, Complementary / Q000378:metabolism; D005091:Exons; D020224:Expressed Sequence Tags; D005260:Female; D015723:Gene Library; D005854:Germ Cells / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D017403:In Situ Hybridization; D007438:Introns; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D011257:Pregnancy Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012260:Ribonucleases / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012727:Sex Characteristics; D019849:Sex Determination Processes; D012737:Sex Factors; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics; D014566:Urogenital System / Q000378:metabolism; D014960:X Chromosome
D018076:DNA, Complementary; D018398:Homeodomain Proteins; D011257:Pregnancy Proteins; D012260:Ribonucleases; D014157:Transcription Factors; C411783:Psx1 protein, mouse; C411782:Psx2 protein, mouse; C498048:Rhox5 protein, mouse