Project description:The main goal of our study is to identify the molecular events that determine the gonadal identity in mammals. Although testis and ovary arise from a common embryonic primordium, they represent outcomes of opposing fate determination. This decision to differentiate into a testis or an ovary hinges upon the balance between two antagonizing factors, pro-testis SOX9 and pro-ovary β-catenin. This microarray analysis led to the identification of the genes involved in the fate of XX and XY gonads in absence of SOX9 and beta-catenin We developed mouse genetic models that lack either Sox9, β-catenin, or both specifically in the somatic cells. All embryos used in this study resulted from the crossing between Ctnnb1f/f; Sox9f/f females with Sf1-cre+/Tg ; Ctnnb1+/f; Sox9+/f males. XX and XY fetal gonads were collected at embryonic day E14.5
Project description:The main goal of our study is to identify the molecular events that determine the gonadal identity in mammals. Although testis and ovary arise from a common embryonic primordium, they represent outcomes of opposing fate determination. This decision to differentiate into a testis or an ovary hinges upon the balance between two antagonizing factors, pro-testis SOX9 and pro-ovary β-catenin. This microarray analysis led to the identification of the genes involved in the fate of XX and XY gonads in absence of SOX9 and beta-catenin
Project description:: Sex determination triggers the differentiation of the bi-potential gonad into either an ovary or testis. In non-mammalian vertebrates, the presence or absence of oestrogen dictates gonad differ-entiation, while in mammals, this mechanism has been supplanted by the testis determining SRY gene. Exogenous oestrogen can override this genetic trigger to shift somatic cell fate in the gonad towards ovarian developmental pathways by limiting the bioavailability of the key testis factor SOX9 within somatic cells. Our previous work has implicated the MAPK pathway in mediating the rapid cellular response to oestrogen. We performed proteomic and phosphoproteomic anal-yses to investigate the precise mechanism through which oestrogen impacts these pathways to ac-tivate -catenin—a factor essential for ovarian development. We show that oestrogen can activate -catenin within 30 minutes, concomitant with the cytoplasmic retention of SOX9. This occurs through changes to the MAP3K1 cascade, suggesting this pathway is a mechanism through which oestrogen influences gonad somatic cell fate. We demonstrate that oestrogen can promote the shift from SOX9 pro-testis activity to -catenin pro-ovary activity through activation of MAP3K1. Our findings define a previously unknown mechanism through which oestrogen can promote a switch in gonad somatic cell fate and provided novel insights into the impacts of exogenous oestrogen exposure on the testis.
Project description:The identity of the gonads is determined by which fate, ovarian granulosa cell or testicular Sertoli cell, the bipotential somatic cell precursors choose to follow. In most vertebrates, the fate of granulosa cells is controlled by a conserved regulator FOXL2. To understand how FOXL2 elicits its fate-determining action, we performed genome-wide analysis of FOXL2 chromatin occupancy in fetal ovaries. Combining genome-wide analysis of FOXL2 binding in the fetal ovary with transcriptomic analyses of Foxl2 gain-of-function and Foxl2 loss-of-function models, we identified potential pathways responsible for the feminizing action of FOXL2. Finally, comparison of FOXL2 genome-wide occupancy in the fetal ovary with testis-determining factor SOX9 genome-wide occupancy in the fetal testis revealed extensive overlaps, implying that antagonistic signals between FOXL2 and SOX9 occur at the chromatin level.
Project description:We used two Sertoli-cell-specific Cre lines: Wt1-CreERT2 and Sox9-CreERT2, to induce Sox9 ablation on a Sox8 -/- background in the adult testis. Sox9/8 double KO testes undergo testis-to-ovary genetic reprogramming and Sertoli-to-granulosa cell transdifferentiation.
Project description:Transcription factors related to the insect sex determination gene Doublesex (DMRT proteins) control sex determination and/or sexual differentiation in diverse metazoans. They also are implicated in transitions between sex-determining mechanisms during vertebrate evolution. In mice Dmrt1 is required for male gonadal differentiation in somatic cells and germ cells. DMRT1 also maintains male gonadal sex: its loss, even in adults, can trigger sexual fate reprogramming in which male Sertoli cells transdifferentiate into their female equivalents - granulosa cells - and testicular tissue reorganizes to a more ovarian morphology. Here we use a conditional Dmrt1 transgene to show that Dmrt1 is not only necessary but also sufficient to specify male cell identity in the mouse gonad. DMRT1 expression in the ovary silenced the female sex-maintenance gene Foxl2 and reprogrammed juvenile and adult granulosa cells into Sertoli-like cells, triggering formation of structures resembling male seminiferous tubules. DMRT1 can silence Foxl2 even in the absence of the testis-determining genes Sox8 and Sox9. mRNA profiling found that DMRT1 activates many testicular genes and downregulates ovarian genes and single cell RNA-seq in transdifferentiating cells identified dynamically expressed candidate mediators of this process. Strongly upregulated genes were highly enriched on chromosome X, consistent with sexually antagonistic functions. This study provides an in vivo example of single gene reprogramming of cell sexual identity. Our findings suggest a reconsideration of mechanisms involved in human disorders of sexual development (DSD) and empirically support evolutionary models where loss or gain of Dmrt1 function promotes establishment of new vertebrate sex determination systems. RNA-Seq (3 conditions, 2 replicates per condition) and Single Cell RNA-Seq (68 individual cells and 1 bulk cell sample)
Project description:Gonadal trans-differentiation from ovary to testis occurs in a same individual, suggesting a role of epigenetic regulation. However, histone modifications concerning the sex reversal process remain elusive. Here, we report a developmental atlas of histone modifications in the gonadal differentiation, including acetylation, methylation, and ubiquitination, using liquid chromatography-tandem mass spectrometry (LC-MS/MS). We provided a detail distribution map of these modification sites including novel histone modifications along histones H2a, H2b, H3, and H4, and revealed their relationship with types of gonadal differentiation. We then determined a testis-enriched histone modification site, H2b monoubiquitination at K120, and its association with spermatogenesis. ChIP-seq demonstrated that the modification was highly enriched in the male sex-determining gene dmrt1, in particular association with its exon regions, suggesting its role in transcriptional elongation of dmrt1 in testis. Together, these data not only provide a new resource for epigenetic study in gonadal development, but also define an association of histone modifications in gonadal differentiation from ovary to testis.
Project description:In mammals, gonadal differentiation is the first step of sex determination, and the transcription factor Sox9 promotes testis differentiation. Here we used the XY Sox9flox/flox; Sf1:creTr/+ mouse model and show that the lack of Sox9 expression induces a full sex reversal of E13.5 XY Sox9flox/flox; Sf1:creTr/+ gonads compared to XY Sox9flox/flox. Keywords: gonads gene expression profiling in WT and Sox9flox/flox; Sf1:creTr/+ mice 3 WT versus 3 Sox9flox/flox; Sf1:creTr/+ mice.
Project description:In mammals, male fate is under the control of the master transcriptional regulator, SOX9: in its presence, somatic precursor cells of the embryonic gonads differentiate into Sertoli cells, the main organizers of testicular differentiation. Therefore, analyzing target genes of this transcription factor allows understanding mechanisms of cellular commitment at the genomic level. With the use of ChIP-seq in murine and bovine wild-type testes combined with RNAseq from mouse testes lacking SOX9, we identified SOX9 target genes in the mammalian fetal gonad. SOX9 in murine and bovine fetal testes binds to a large set of genes conserved among mammals, including those with well-established roles in testis and ovary development. RNAseq analysis shows that testis and ovary display sex specific RNA splicing and that SOX9 mediates both target gene transcription and differential splicing. Regions bound by SOX9 are predominantly 5’ proximal or intra-genic, and display a specific genomic features that we call "Sertoli cell signatures" or SCS. The SCS is conserved among mammals and comprises multiple binding motifs for the Sertoli reprogramming factors SOX9, GATA4 and DMRT1; indeed, independent DMRT1 ChIP-seq confirms the enrichment of the SCS. Bioinformatic analysis of SCSs regions predicts novel regulatory mechanisms prompting functional validation. For example, we detected SCS in target genes of the nuclear factor TRIM28 and we show experimentally that SOX9 and TRIM28 proteins interact in fetal testis.
Project description:In mammals, male fate is under the control of the master transcriptional regulator, SOX9: in its presence, somatic precursor cells of the embryonic gonads differentiate into Sertoli cells, the main organizers of testicular differentiation. Therefore, analyzing target genes of this transcription factor allows understanding mechanisms of cellular commitment at the genomic level. With the use of ChIP-seq in murine and bovine wild-type testes combined with RNAseq from mouse testes lacking SOX9, we identified SOX9 target genes in the mammalian fetal gonad. SOX9 in murine and bovine fetal testes binds to a large set of genes conserved among mammals, including those with well-established roles in testis and ovary development. RNAseq analysis shows that testis and ovary display sex specific RNA splicing and that SOX9 mediates both target gene transcription and differential splicing. Regions bound by SOX9 are predominantly 5’ proximal or intra-genic, and display a specific genomic features that we call "Sertoli cell signatures" or SCS. The SCS is conserved among mammals and comprises multiple binding motifs for the Sertoli reprogramming factors SOX9, GATA4 and DMRT1; indeed, independent DMRT1 ChIP-seq confirms the enrichment of the SCS. Bioinformatic analysis of SCSs regions predicts novel regulatory mechanisms prompting functional validation. For example, we detected SCS in target genes of the nuclear factor TRIM28 and we show experimentally that SOX9 and TRIM28 proteins interact in fetal testis.