Left‐sided cryptorchidism in mice with Wilms' tumour 1 gene deletion in gubernaculum testis

Abstract

A significant number of patients with germline mutations in the Wilms tumour 1 (WT1) gene, a transcriptional factor essential for early renal and gonadal development, displays cryptorchidism or non-scrotal testis position. We show here that WT1 is expressed during development in the mouse gubernacular ligament connecting the testis to the abdominal wall. Conditional inactivation of Wt1 in the gubernaculum (GU-WT1KO animals) resulted in abnormal differentiation of the gubernacula during development and in about 40 % adult males, unilateral, always left-sided, cryptorchidism. At birth the right testis was positioned above the processus vaginalis and eventually moved into the developing scrotal pouch. In affected mutants the left testis was displaced from the normal position and the left processus vaginalis failed to form. The analysis of testicular descent at different stages of postnatal development suggests that the unilateral cryptorchidism might be caused by the asymmetry in the position of abdominal organs providing a higher degree of mobility for the left testis. Spermatogenesis in GU-WT1KO animals was blocked in cryptorchid testes located in a high pararenal position but was maintained in testes located in a low abdominal position. Conditional inactivation of both Wt1 and androgen receptor (Ar) genes in gubernaculum led to a bilateral asymmetrical cryptorchidism in all mutant males with the left testis again located higher than the right one. The malformations induced by WT1 and AR deficiency in gubernaculum and processus vaginalis, in combination with mechanical constraints on testis descent, determine the final position of the testes. In summary, our data indicate that WT1 is directly involved in gubernaculum differentiation. Taken together the results of the study underline the complex nature of testicular descent with an involvement in this process of several genetic factors and developmental events.

Genetic ablation of androgen receptor signaling in fetal Leydig cell lineage affects Leydig cell functions in adult testis

“…In contrast, abnormal differentiation of ALC, lipid droplet accumulation, or corresponding misexpression of FLC or ALC markers was not detected in other cryptorchid mice, such as with the ablation of INSL3/ RXFP2 (relaxin/insulin‐like family peptide receptor 2) signaling (Supplemental Fig. S5) or in males with a conditional deletion of Wilms tumor 1 gene using the same Rarb‐cre transgene (33–35).…”

Fetal Rat Gubernaculum Mesenchymal Cells Adopt Myogenic and Myofibroblast-Like Phenotypes

“…In animal models of UDT, including deleted Ar, Wt1, Insl3, Rxfp2, Ctnnb, and Notch1 transgenic mice, fetal cremaster muscle development is absent, impaired, or disorganized. 6,7,10,14 The cremaster is more prominent in rodents, but imaging studies show embedded cremaster muscle bundles within human fetal gubernaculum. 4 Hutson and colleagues have focused primarily on the properties of the GCC that promote its elongation once inversion is complete.…”

“…24 CellTracker™+ mesothelial cells and EdU+ non-muscle cells became incorporated into cremaster muscle of cultured GCCs. GCC mesothelial cells are prominent, 25 and express WT1 in the E13.5 mouse 10 and E17 rat (Barthold et al, unpublished). Notably, cell fate mapping of WT1-expressing or lipophilic dye-labeled mesothelial cells show similar internal migration 26 and contribute to vascular smooth muscle and mesenchyme, including myofibroblasts, within lung and abdominal organs.…”

“…9 Beta-catenin (CTNNB), Notch and Wilm’s tumor 1 (WT1) are also required for myogenic differentiation of the GCC. 6,10 Moreover, altered expression of muscle-specific genes and focally defective muscle development occur in the fetal GCC of the congenitally cryptorchid LE/orl rat. 11,12 …”

Testicular Cancer and Cryptorchidism

“…Little is known, however, about local cell signaling pathways activated by androgen signaling in the developing gubernaculum, scrotum, cranial ligament, and epididymis. The link between inguinoscrotal cryptorchidism detected in the transgenic mouse and in some cases human mutants for several transcriptional factors, such as homeobox genes HOXA10 or HOXA11; Wilms tumor 1 (WT1); ARID domain-containing protein 5B (ARID5B), and androgen signaling in gubernaculum development still need to be determined (Klonisch et al, 2004; Kaftanovskaya et al, 2013). …”