Submitted July 8, 2003
Returned for revision July 25, 2003
Accepted November 7, 2003
Testis
A Novel PEPP Homeobox Gene, TOX, Is Highly
Glutamic Acid Rich and Specifically Expressed in Murine
Testis and Ovary
Yuan-Lin Kang ,
Hung Li ,
Wei-Hwa Chen ,
Yi-Shiuan Tzeng ,
Yi-Lun Lai ,
and
Hsiu Mei Hsieh-Li *
* To whom correspondence should be addressed. E-mail: hmhsieh{at}cc.ntnu.edu.tw.
Abstract
The homeobox gene superfamily has been highly conserved
throughout evolution. These genes act as transcription
factors during several important developmental processes.
To explore the functional roles of homeobox genes in
spermatogenesis, we performed a degenerate oligonucleotide
polymerase chain reaction (PCR) screening of a testis cDNA
library and isolated a novel mouse homeobox gene. This
gene, which we named Tox, encodes a homeodomain
protein distantly related to members of the Paired/Pax
(Prd/Pax) family. A phylogenetic analysis revealed
Tox to be a member of the recently defined
PEPP subfamily of paired-like homeobox
genes. Tox was mapped to chromosome X, with its
homeodomain organized into three exons. A special feature
of Tox is that the encoded protein sequence
contains two poly-glutamic acid (poly E) stretches, which
make Tox highly acidic. Tox transcripts were
detected predominately in the testis and ovary of mice.
Tox expression in testes was initiated soon after
birth, mainly in Sertoli cells and spermatogonia; however,
in adult mice, Tox expression shifts to the
spermatids and spermatozoa. Tox expression in
ovaries was detected in somatic cells of follicles, early
on in theca cells and in both granulosa and theca cells at
the later stages of follicular development. Based on these
results, Tox may play an important role during
gametogenesis.
Key words:
Ovary •
Testis
