Wnt signaling in ovarian development inhibits Sf1 activation of Sox9 via the Tesco enhancer

Bernard, Pascal, Ryan, Janelle, Sim, Helena, Czech, Daniel P., Sinclair, Andrew H., Koopman, Peter and Harley, Vincent R. (2012) Wnt signaling in ovarian development inhibits Sf1 activation of Sox9 via the Tesco enhancer. Endocrinology, 153 2: 901-912. doi:10.1210/en.2011-1347


Author Bernard, Pascal
Ryan, Janelle
Sim, Helena
Czech, Daniel P.
Sinclair, Andrew H.
Koopman, Peter
Harley, Vincent R.
Title Wnt signaling in ovarian development inhibits Sf1 activation of Sox9 via the Tesco enhancer
Formatted title
Wnt signaling in ovarian development inhibits Sf1 activation of Sox9 via the Tesco enhancer
Journal name Endocrinology   Check publisher's open access policy
ISSN 0013-7227
1945-7170
Publication date 2012-02-01
Year available 2011
Sub-type Article (original research)
DOI 10.1210/en.2011-1347
Open Access Status DOI
Volume 153
Issue 2
Start page 901
End page 912
Total pages 12
Place of publication Chevy Chase, MD, U.S.A.
Publisher The Endocrine Society
Language eng
Abstract During mouse sex determination, transient expression of the Y-linked gene Sry up-regulates its direct target gene Sox9, via a 3.2 kb testis specific enhancer of Sox9 (TES), which includes a core 1.4 kb element, TESCO. SOX9 activity leads to differentiation of Sertoli cells, rather than granulosa cells from the bipotential supporting cell precursor lineage. Here, we present functional analysis of TES/TESCO, using CRISPR/Cas9 genome editing in mice. Deletion of TESCO or TES reduced Sox9 expression levels in XY fetal gonads to 60 or 45% respectively relative to wild type gonads, and reduced expression of the SOX9 target Amh. Although human patients heterozygous for null mutations in SOX9, which are assumed to have 50% of normal expression, often show XY female sex reversal, mice deleted for one copy of Sox9 do not. Consistent with this, we did not observe sex reversal in either TESCO-/- or TES-/- XY embryos or adult mice. However, embryos carrying both a conditional Sox9 null allele and the TES deletion developed ovotestes. Quantitative analysis of these revealed levels of 23% expression of Sox9 compared to wild type, and a significant increase in the expression of the granulosa cell marker Foxl2. This indicates that the threshold in mice where sex reversal begins to be seen is about half that of the ~50% levels predicted in humans. Our results demonstrate that TES/TESCO is a crucial enhancer regulating Sox9 expression in the gonad, but point to the existence of additional enhancers that act redundantly.
Formatted abstract
Genome analysis of patients with disorders of sex development, and gain- and loss-of-function studies in mice indicate that gonadal development is regulated by opposing signals. In females, the Wnt/β-catenin canonical pathway blocks testicular differentiation by repressing the expression of the Sertoli cell-specific gene Sox9 by an unknown mechanism. Using cell and embryonic gonad culture models, we show that activation of the Wnt/β-catenin pathway inhibits the expression of Sox9 and Amh, whereas mRNA and protein levels of Sry and steroidogenic factor 1 (Sf1), two key transcriptional regulators of Sox9, are not altered. Ectopic activation of Wnt/β-catenin signaling in male gonads led to a loss of Sf1 binding to the Tesco enhancer and absent Sox9 expression that we also observed in wild-type ovaries. Moreover, ectopic Wnt/β-catenin signaling induced the expression of the female somatic cell markers, Bmp2 and Rspo1, as a likely consequence of Sox9 loss. Wnt/β-catenin signaling in XY gonads did not, however, affect gene expression of the steroidogenic Leydig cell Sf1 target gene, Cyp11a1, or Sf1 binding to the Cyp11a1 promoter. Our data support a model in ovary development whereby activation of β-catenin prevents Sf1 binding to the Sox9 enhancer, thereby inhibiting Sox9 expression and Sertoli cell differentiation.
Keyword Endocrinology & Metabolism
Endocrinology & Metabolism
ENDOCRINOLOGY & METABOLISM
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID 13-1270
MC_U117562207
Institutional Status UQ
Additional Notes Published online before print November 29, 2011

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
Institute for Molecular Bioscience - Publications
 
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Created: Wed, 18 Jan 2012, 20:08:38 EST by Susan Allen on behalf of Institute for Molecular Bioscience