Loss of Raptor induces Sertoli cells into an undifferentiated state in mice

Abstract

In mammals, testis development is triggered by expression of the sex-determining Y-chromosome gene SRY to commit Sertoli cell (SC) fate at gonadal sex determination in the fetus. Several genes have been identified to be required to promote the testis pathway following SRY activation (i.e. SOX9) in embryo; however, largely remains unknown about the genes and mechanisms involved in stabilizing the testis pathway after birth and throughout adulthood. Herein, we report that postnatal males with SC-specific deletion of Raptor demonstrated absence of SC unique identity and adversely acquired granulosa cell-like characteristics, along with loss of tubular architecture and scattered distribution of SCs and germ cells. Subsequent genome-wide analysis by RNA sequencing revealed a profound decrease in the transcripts of testis genes (i.e. Sox9, Sox8, and Amh) and conversely an increase in ovary genes (i.e. Lhx9, Foxl2, and Fst); these changes were further confirmed by immunofluorescence and quantitative reverse-transcription PCR. Importantly, co-immunofluorescence demonstrated that Raptor deficiency induced SCs dedifferentiation into a progenitor state; the Raptor-mutant gonads showed some ovarian somatic cell features, accompanied by enhanced female steroidogenesis and elevated estrogen levels, yet the ZP3-positive terminally feminized oocytes were not observed. In vitro experiments with primary SCs suggested that Raptor is likely involved in FGF9-induced formation of cell junctions among SCs. Taken together, our results established that Raptor is required to maintain SC identity, stabilize the male pathway, and promote testis development.

Unveiling the roles of Sertoli cells lineage differentiation in reproductive development and disorders: a review

“…Once a certain threshold is reached, SOX9 inhibits SRY expression and promotes its expression by interacting with SF1 ( 56 ). If either SRY or SOX9 activation fails to occur, the development of granulosa cells and ovarian pathways is initiated instead ( 57 , 58 ). The expression of SOX9 also enhances the expression of testicular development-related factors, such as prostaglandin D2 synthase ( PTGDS ), anti-Müllerian hormone ( AMH ), WT1 , GATA4 , and ex-determining region Y-box 8 ( SOX8 ), while concurrently inhibiting the expression of ovarian determinants, including WNT4 , R-spondin 1 ( RSPO1 ), and β-catenin ( 51 , 54 , 59 ).…”

“…During embryonic testis development, SF1 activates the promoter of anti-Müllerian hormone (AMH) in Sertoli cells and is directly involved in sex determination in mammals ( 106 ). Deleting SF1 in Sertoli cells results in fewer androgen receptors ( 58 , 105 ). Persistent Müllerian duct syndrome (PMDS) is a 46,XY DSD usually caused by mutations in AMH or a single-base deletion in the SF1 response element.…”

Role of Macroautophagy in Mammalian Male Reproductive Physiology

“…It was observed that the deficiency of Raptor in Sertoli cells displays severe tubular degeneration in the neonatal mouse testis as well as azoospermia in adult mice [181]. More recently, [182] proved that Raptor is required to maintain Sertoli cell identity, stabilize the male pathway, and promote testes development in mice.…”