title: Expression and functional analysis of Dkk1 during early gonadal development.
abstract: WNT signalling plays a central role in mammalian sex determination by promoting ovarian development and repressing aspects of testis development in the early gonad. Dickkopf homolog 1 (DKK1) is a WNT signalling antagonist that plays critical roles in multiple developmental systems by modulating WNT activity. Here, we examined the role of DKK1 in mouse sex determination and early gonadal development. Dkk1 mRNA was upregulated sex-specifically during testis differentiation, suggesting that DKK1 could repress WNT signalling in the developing testis. However, we observed overtly normal testis development in Dkk1-null XY gonads, and found no significant upregulation of Axin2 or Sp5 that would indicate increased canonical WNT signalling. Nor did we find significant differences in expression of key markers of testis and ovarian development. We propose that DKK1 may play a protective role that is not unmasked by loss-of-function in the absence of other stressors.
authors.affiliation: Division of Molecular Genetics and Development, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Qld., Australia.
authors.forename: A N
authors.initials: AN
authors.lastname: Combes
authors.forename: J
authors.initials: J
authors.lastname: Bowles
authors.forename: C-W
authors.initials: CW
authors.lastname: Feng
authors.forename: H S
authors.initials: HS
authors.lastname: Chiu
authors.forename: P-L
authors.initials: PL
authors.lastname: Khoo
authors.forename: A
authors.initials: A
authors.lastname: Jackson
authors.forename: M H
authors.initials: MH
authors.lastname: Little
authors.forename: P P L
authors.initials: PP
authors.lastname: Tam
authors.forename: P
authors.initials: P
authors.lastname: Koopman
mesh_terms: D000818:Animals; D005260:Female; D006066:Gonads / Q000254:growth & development* / Q000378:metabolism*; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D010053:Ovary / Q000254:growth & development / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019849:Sex Determination Processes / Q000235:genetics / Q000502:physiology; D013737:Testis / Q000254:growth & development / Q000378:metabolism
chemical_list: C501127:Dkk1 protein, mouse; D036341:Intercellular Signaling Peptides and Proteins