Supplementary Material for: Expression and Functional Analysis of Dkk1 during Early Gonadal Development Combes A.N. Bowles J. Feng C.-W. Chiu H.S. Khoo P.-L. Jackson A. Little M.H. Tam P.P.L. Koopman P. 10.6084/m9.figshare.5122426.v1 https://karger.figshare.com/articles/dataset/Supplementary_Material_for_Expression_and_Functional_Analysis_of_Dkk1_during_Early_Gonadal_Development/5122426 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. <i>Dkk1</i> 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 <i>Dkk1</i>-null XY gonads, and found no significant upregulation of <i>Axin2</i> or <i>Sp5</i> 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. 2011-05-24 00:00:00 Dkk1 Rspo1 Testis development Wnt4