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

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 testisdetermining 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.Sertoli cell ͉ testicular cord ͉ Mü llerian duct ͉ Amh ͉ Sox8

Correct dosage of Fog2 and Gata4 transcription factors is critical for fetal testis development in mice

“…The following antibodies were used: CD31 (1:250, clone MEC13.3; BD PharMingen, San Diego, CA), FOXL2 (1:500; gift from Marc Fellous, Cochin Institute, Paris, France), FGFR2 (1:500, C17, sc-122; Santa Cruz Biotechnology, Santa Cruz, CA), and AMH (1:200, C20, sc-6886; Santa Cruz Biotechnology). All antibodies used in this work have been validated and used in previous published reports (15,(46)(47)(48)(49). Images were obtained by using a Zeiss (Thornwood, NY) LSM 510 confocal microscope.…”

Identification of Novel Wilms' Tumor Suppressor Gene Target Genes Implicated in Kidney Development

“…Another interesting WT1(ϪKTS) target gene is SOX9, although this gene was not characterized beyond qRT-PCR analysis due to its low level of induction. Recently, using a conditional WT1 knock-out approach, Gao et al (66) demonstrated that ablation of Wt1 expression in Sertoli cells led to a concomitant loss of Sox9 expression, suggesting that WT1 either directly or indirectly regulates Sox9 expression. Our study supports this in vivo observation and further suggests that WT1 may play a direct role in regulating SOX9 expression.…”

Transcription and post-transcriptional regulation of spermatogenesis

“…WT1 expression persists in Sertoli cells after gonad formation, but until recently, its functional role in this context was not known, as Wt1-mutant mice die early during embryogenesis. The role of WT1 in Sertoli cells after the bipotential gonad stage was recently addressed by two studies (Gao et al 2006;Rao et al 2006). Gao et al (2006) used a conditional knockout approach to disrupt the Wt1 gene in foetal Sertoli cells at approximately e14.5 and found that this severely disrupted testis cord formation in male embryos and subsequently led to the formation of abnormal tubular architecture and reduced testes size in adult males.…”