Biology subjects

Bagheri-Fam, S.

Publications and source records attributed to Bagheri-Fam, S..

3 recordsLinked to original sources

bioRxiv2024

Roles of TYRO3 Family Receptors in Germ Cell Development During Mouse Testis Formation

Structured AbstractO_ST_ABSObjectiveC_ST_ABSTo investigate the role of a potential SOX9 target gene, Tyro3, along with its family members, Axl and Mertk (TAM family) in mouse testis development. DesignExperimental laboratory study. SettingResearch institute units. Subject(s)Embryonic day (E)11.5 Swiss mouse gonads for ex vivo gonad culture; Tyro3 knockout mouse embryos. Intervention(s)E11.5 Swiss mouse gonads were cultured in hanging droplets of 30 {micro}L DMEM medium supplemented with 10% FBS and 1% antibiotic-antimycotic. A pair of gonads were treated with 20 M of BMS-777607 or 30 M of LDC1267 and an equivalent volume of the vehicle control DMSO. Main Outcome Measure(s)Immunofluorescence to measure morphological changes of ex vivo cultured gonads and in vivo Tyro3 mouse testes; qRT-PCR to measure gene expressions. Result(s)Inhibition of the TAM family in E11.5 ex vivo cultured male mouse gonads led to reduced germ cell numbers caused by reduced proliferation and increased apoptosis of the germ cells. Tyro3 knockout mice exhibited reduced expression levels of the germ cell genes Ddx4, Dazl and Pou5f1 and increased expression levels of the Sertoli cell genes Sox9 and Amh at E12.5. However, by E14.5, the expression of Ddx4, Dazl, Sox9 and Amh had returned to normal levels in Tyro3 knockout testes. Tyro3 knockout testes displayed normal morphology and structures during fetal testis development. Conclusion(s)TAM family members have redundant roles in regulating germ cell development during early testis development. Attestation StatementO_LIData regarding any of the subjects in the study has not been previously published unless specified. C_LIO_LIData will be made available to the editors of the journal for review or query upon request. C_LI Data Sharing StatementN/A CapsuleInhibition of the TAM family led to loss of germ cells in fetal gonads and deletion of Tyro3 alone disturbed gene expressions of germ cells and Sertoli cells.

developmental biology↗

bioRxiv2023

Y chromosome damage underlies testicular abnormalities in ATR-X syndrome

ATR-X (alpha thalassemia, mental retardation, X-linked) syndrome is a severe developmental disorder affecting males caused by mutations in the chromatin remodelling gene ATRX. Genital abnormalities in affected boys include hypospadias and ambiguous genitalia, and patients show small poorly formed testes with only a few seminiferous tubules. Our mouse model recapitulated these testicular defects when Atrx was specifically deleted in Sertoli cells (ScAtrxKO). ScAtrxKO mice develop small testes with fewer and discontinuous tubules due to G2/M arrest and apoptosis of Sertoli cells. Here, we investigated the mechanism underlying the Sertoli cell defects in ATR-X syndrome. In healthy male control mice, Sertoli cell nuclei contain a single novel "GATA4 PML nuclear body (NB)" that strongly expresses the transcription factor GATA4, as well as ATRX and its binding partner DAXX. The GATA4 PML NB co-localizes with heterochromatin protein HP1 and PH3 (a marker of chromosome condensation), and with the short arm of the Y chromosome (Yp). In contrast, ScAtrxKO Sertoli cells contain a single giant GATA4 PML NB, frequently associated with DNA double-strand breaks in G2/M-arrested Sertoli cells that underwent apoptosis. HP1 and PH3 were absent from the giant GATA4 foci suggesting a local failure in heterochromatin formation and chromosome condensation. Our data indicate that in Sertoli cells, ATRX protects a chromosomal region of Yp from DNA damage, probably during replication stress, and thus protects Sertoli cells from cell death. We discuss Y chromosome damage as a novel mechanism for testicular failure and the potential role of GATA4 during this process. Disclosure SummaryThe authors have nothing to disclose.

developmental biology↗

bioRxiv2021

Functional analysis of Mmd2 and related PAQR genes during sex determination in mice

Sex determination in eutherian mammals is controlled by the Y-linked gene Sry, which drives the formation of testes in male embryos. Despite extensive study, the genetic steps linking Sry action and male sex determination remain largely unknown. Here, we focused on Mmd2, a gene that encodes a member of the progestin and adipoQ receptor (PAQR) family. We show that Mmd2 is expressed during the sex-determining period in XY but not XX gonads, specifically in the Sertoli cell lineage which orchestrates early testis development. Analysis of knockout mice deficient in Sox9 and Sf1 revealed that Mmd2 operates downstream of these known sex-determining genes. However, when we used CRISPR to ablate Mmd2 in the mouse, fetal testis development appeared to progress normally. To determine if other genes might have compensated for the loss of Mmd2, we identified the closely related PAQR family members Paqr8 and Mmd as also being expressed during testis development. We used CRISPR to generate mouse strains deficient in Paqr8 and Mmd, but both knockout lines appeared phenotypically normal and fertile. Finally, we generated Mmd2;Mmd and Mmd2;Paqr8 double-null embryos and again observed normal testis development. These results may reflect functional redundancy among these factors. Our findings highlight the difficulties involved in identifying genes with a functional role in sex determination and gonadal development through expression screening and loss-of-function analyses of individual candidate genes, and may help to explain the paucity of genes in which variations have been found to cause human disorders/differences of sex development.

developmental biology↗