The Wilms tumor gene, Wt1, is required for Sox9 expression and maintenance of tubular architecture in the developing testis

doi:10.1073/pnas.0600994103

The Wilms tumor gene, Wt1, is required for Sox9 expression and maintenance of tubular architecture in the developing testis

Departments of *Molecular Genetics/Cancer Genetics,
^†Experimental Radiation Oncology, and
^‡Molecular Genetics, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030; and
^§Unité Mixte de Recherche 6175, Physiologie de la Reproduction, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Université de Tours, Haras Nationaux, 37380 Nouzilly, France

Edited by Jordan Kreidberg, Children's Hospital, Boston, MA, and accepted by the Editorial Board June 16, 2006 (received for review February 9, 2006)

Abstract

Mutation of the transcription factor and tumor suppressor gene WT1 results in a range of genitourinary anomalies in humans, including 46,XY gonadal dysgenesis, indicating that WT1 plays a critical role in sex determination. However, because knockout of Wt1 in mice results in apoptosis of the genital ridge, it is unknown whether WT1 is required for testis development after the initial steps of sex determination. To address this question, we generated a mouse strain carrying a Wt1 conditional knockout allele and ablated Wt1 function specifically in Sertoli cells by embryonic day 14.5, several days after testis determination. Wt1 knockout resulted in disruption of developing seminiferous tubules and subsequent progressive loss of Sertoli cells and germ cells such that postnatal mutant testes were almost completely devoid of these cell types and were severely hypoplastic. Thus, Wt1 is essential for the maintenance of Sertoli cells and seminiferous tubules in the developing testes. Of particular note, expression of the testis-determining gene Sox9 in mutant Sertoli cells was turned off at embryonic day 14.5 after Wt1 ablation, suggesting that WT1 regulates Sox9, either directly or indirectly, after Sry expression ceases. Our data, along with previous work demonstrating the role of Wt1 at early stages of gonadal development, thus indicate that Wt1 is essential at multiple steps in testicular development.

Footnotes

^¶To whom correspondence should be addressed. E-mail: vhuff{at}mdacc.tmc.edu
Author contributions: F. Gao, S.M., and V.H. designed research; F. Gao, S.M., N.A., Z.Z., and J.M.D. performed research; C.L. and F. Guillou contributed new reagents/analytic tools; F. Gao, R.R.B., and V.H. analyzed data; and F. Gao and V.H. wrote the paper.
Conflict of interest statement: No conflicts declared.
This paper was submitted directly (Track II) to the PNAS office. J.K. is a guest editor invited by the Editorial Board.
↵ ‖ Huff, V., Villalba, F., Strong, L. C. & Saunder, G. F. (1991) Am. J. Hum. Genet. 49, 44 (Abstr.).
Abbreviations:

IHC,

immunohistochemistry;

En,

embryonic day n;

Amh,

anti-Müllerian hormone;

Pn,

postnatal day n;

GCNA-1,

germ cell nuclear antigen 1.