Foxn1 and Prkdc genes are important for testis function: evidence from nude and scid adult mice

Mutations in Foxn1 and Prkdc genes lead to nude and severe combined immunodeficiency (scid) phenotypes, respectively. Besides being immunodeficient, previous reports have shown that nude mice have lower gonadotropins and testosterone levels, while scid mice present increased pachytene spermatocyte (PS) apoptosis. Therefore, these specific features make them important experimental models for understanding Foxn1 and Prkdc roles in reproduction. Hence, we conducted an investigation of the testicular function in nude and scid BALB/c adult male mice and significant differences were observed, especially in Leydig cell (LC) parameters. Although the differences were more pronounced in nude mice, both immunodeficient strains presented a larger number of LC, whereas its cellular volume was smaller in comparison to the wild type. Besides these alterations in LC, we also observed differences in androgen receptor and steroidogenic enzyme expression in nude and scid mice, suggesting the importance of Foxn1 and Prkdc genes in androgen synthesis. Specifically in scid mice, we found a smaller meiotic index, which represents the number of round spermatids per PS, indicating a greater cell loss during meiosis, as previously described in the literature. In addition and for the first time, Foxn1 was identified in the testis, being expressed in LC, whereas DNA-PKc (the protein produced by Prkdc) was observed in LC and Sertoli cells. Taken together, our results show that the changes in LC composition added to the higher expression of steroidogenesis-related genes in nude mice and imply that Foxn1 transcription factor may be associated to androgen production regulation, while Prkdc expression is also important for the meiotic process.