Protein Phosphatase 4 (PPP4) Prevents Female Reprogramming in the Mouse Testis After Sex Determination and Protects Male Fertility

Abstract

Background: Impairment of lineage specification and function of gonadal somatic cells can lead to disorders of sexual development (DSDs) and fertility defects in humans. However, little is known about the function of protein phosphatases in testis development. Results: We showed that protein phosphatase 4 (PPP4) could maintain SOX9 expression in Sertoli cells and play an essential role in Sertoli cell lineage maintenance and male fertility. Conditional deletion of Ppp4c, a PPP4 catalytic subunit gene, caused the reprogramming of Sertoli cells to granulosa-like cells postnatally by inducing ectopic expression of FOXL2, which in turn led to testicular BTB structure damage, germ cell loss and ultimate testis to ovary-like gland transformation. Conclusion: Reprogramming of Sertoli cells due to absence of PPP4 may help explain the etiology of disorders of sexual differentiation and male infertility.