Loss of NR5A1 in mouse Sertoli cells after sex determination changes cellular identity and induces cell-death by anoikis.

To investigate the role of the nuclear receptor NR5A1 in testis after sex determination, we have analyzed mice lacking NR5A1 in Sertoli cells (SC) from embryonic day (E) 13.5 onwards. Ablation of Nr5a1 impairs the expression of genes characteristic of the SC identity (e.g., Sox9, Amh), causes SC death from E14.5 through a Trp53-independent mechanism related to anoikis, and induces disorganization of the testis cords. Together, these effects cause germ cells to enter meiosis and die. Single-cell RNA-sequencing experiments revealed that NR5A1-deficient SC change their molecular identity: some acquire a "pre-granulosa-like" identity, while other revert to a "supporting progenitor-like" cell identity, most of them being "intersex" because they express both testicular and ovarian genes. Fetal Leydig cells (LC) do not display significant changes, indicating that SC are not required beyond E14.5 for their emergence or maintenance. In contrast, adult LC were absent from the postnatal testes. In addition, adult mutant males display persistence of Müllerian duct derivatives, decreased anogenital distance and reduced penis length, which can be explained by the loss of AMH and testosterone synthesis due to SC failure.