Takasaki N, et al 2000 reported that 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.
General function
Nucleic acid binding, DNA binding, Transcription factor
Comment
Cellular localization
Nuclear
Comment
Ovarian function
Germ cell development
Comment
Expression regulated by
Comment
Ovarian localization
Comment
Follicle stages
Comment
Phenotypes
Mutations
1 mutations
Species: mouse
Mutation name: None
type: null mutation fertility: fertile Comment:Nobuyoshi Takasaki, et al 2001 reported the
Normal Gonadal Development in Mice Lacking
GPBOX, a Homeobox Protein Expressed in Germ
Cells at the Onset of Sexual Dimorphism.
Gpbox is a paired-like homeobox gene that colocalizes with two other members of the family, PsxI and Pem, on the
proximal portion of the mouse X chromosome. Gpbox is expressed in the extraembryonic placenta and within the germ
cells of the embryonic gonad. Beginning with the onset of sexual dimorphism (embryonic day [E]11.5 to 12.5), GPBOX
transcripts accumulate faster in female than in male germ cells but disappear later in embryogenesis (E16) and have not
been reported in adult tissues. Both homozygous Gpbox null female and hemizygous Gpbox null
male mice were fertile and reproduced normally. Additionally, the development of male and female gonads in the null
background was indistinguishable from that observed in normal littermates. The lack of an obvious phenotype raises the
possibility that another member of this homeobox gene family provides the absent Gpbox function.