Biology subjects

Poulat, F.

Publications and source records attributed to Poulat, F..

5 recordsLinked to original sources

bioRxiv2026

PKA disrupts adult ovarian identity circuits through direct inhibition of TRIM28-chromatin binding

Functional ovarian plasticity depends on the granulosa cell (GC) fate determination, differentiation, oocyte support and steroid production. After birth, GC identity must be maintained in differentiating follicles, while from puberty, ovarian plasticity is cyclically challenged by gonadotropic hormones. TRIM28-FOXL2 interactions form a key chromatin component maintaining ovarian identity programs and repressing testis-specific genes. This TRIM28 role depends on its E3-SUMO-ligase activity, suggesting SUMOylation in GC can be regulated by transient hormonal cues, although hormonal involvement in modulating GC identity remains to be established. Here, we demonstrated the in vivo interplay between gonadotropic-PKA-signaling and hypo-SUMOylation waves underlying ovarian GC plasticity. In vitro TRIM28 mutagenesis and phospho-proteomics demonstrated direct PKA inhibitory control on TRIM28. This prompted us to highlight SUMOylation alterations in Carney Complex ovarian lesions resulting from chronic PKA activity from rare genetic mutations. Using mutant models, transcriptomics and TRIM28/FOXL2-ChIP-Seq analyses, we specified the in vivo PKA inhibitory mechanisms on TRIM28/FOXL2 chromatin binding and its consequences on adult ovarian somatic cell identity. Together, our data support an integrative model where gonadotrophin pulses create transient windows of PKA-mediated TRIM28 phosphorylation, hypo-SUMOylation, and FOXL2-TRIM28 destabilization. This positions SUMOylation dynamics as central integrator of hormonal signaling and epigenetic identity maintenance in the ovary.

physiology↗

bioRxiv2026

TRIM28 preserves ovarian identity by stabilising lineage-specific transcription factor hubs

Maintenance of ovarian cell identity is required throughout life to prevent the activation of the testicular program, but the epigenetic mechanisms underlying this process remain poorly understood. Although TRIM28 is required to prevent granulosa-to-Sertoli transdifferentiation, it can act both as a regulator of H3K9me3-dependent heterochromatin and as a transcriptional activator through its E3 SUMOligase activity. Here, we combined CUT&RUN, ATAC-seq and RNA-seq to define the respective contributions of these activities to maintain ovarian cell identity. Strikingly, only a small fraction of TRIM28-bound regions was associated with H3K9me3. Although Trim28 deletion induced focal H3K9me3 loss, it had limited transcriptional consequences and primarily affected repetitive elements rather than regions controlling testis-determining genes. In contrast, Trim28 loss led to reductions in chromatin accessibility and H3K27ac at regions enriched for ovarian transcription factor (TF) motifs FOXL2, NR5A2, ESR2 and RUNX1. Moreover, TRIM28 was frequently co-localized with these TFs on chromatin, and the accessibility and the SUMOylation at these co-bound regions were reduced by Trim28 deletion. Together, our findings identify TRIM28 as a central organizer of ovarian TF hubs whose predominant function is to preserve granulosa cell identity through stabilization of lineage-specific TFs rather than H3K9me3-dependent heterochromatin. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=75 SRC="FIGDIR/small/739817v2_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@b39856org.highwire.dtl.DTLVardef@d65435org.highwire.dtl.DTLVardef@132974borg.highwire.dtl.DTLVardef@6ad72f_HPS_FORMAT_FIGEXP M_FIG C_FIG

genomics↗

bioRxiv2023

Transposable elements acquire time- and sex-specific transcriptional and epigenetic signatures along mouse fetal gonad development

Gonadal sex determination in mice is a complex and dynamic process, crucial for the development of functional reproductive organs. The expression of genes involved in this process is regulated by a variety of genetic and epigenetic mechanisms. Recently, there has been increasing evidence that transposable elements (TEs), which are a class of mobile genetic elements, play a significant role in regulating gene expression during embryogenesis and organ development. In this study, we aimed to investigate the involvement of TEs in the regulation of gene expression during mouse embryonic gonadal development. Through bioinformatic analysis, we aimed to identify and characterize specific TEs acting as regulatory elements for sex-specific genes, as well as their potential mechanisms of regulation. We identified TE loci expressed in a time- and sex-specific manner along fetal gonad development that correlate positively and negatively with nearby gene expression, suggesting that their expression is integrated to the gonadal regulatory network. Moreover, chromatin accessibility and histone post-transcriptional modification analyses in the differentiating supporting cells revealed that TEs are acquiring sex-specific signature for promoter-, enhancer-, and silencer-like elements with some of them being proximal to critical sex determining genes. Altogether, our study introduces TEs as new potential players of the gene regulatory network controlling gonadal development in mammals.

developmental biology↗

bioRxiv2023

DMRT1 is a Testis Determining Gene in Rabbits and is Also Essential for Female Fertility

DMRT1 is the testis-determining factor in several species of vertebrates, but its involvement in mammalian testes differentiation, where SRY is the testis-determining gene, remains ambiguous. So far, DMRT1 loss of function has been described in two mammalian species and induces different phenotypes: disorders of sex development (46, XY DSD) in men and male infertility in mice. We thus abolished DMRT1 expression by CRISPR/Cas9 in a third species of mammal, the rabbit. First, we observed that gonads from XY DMRT1-/- rabbit fetuses differentiated like ovaries, highlighting that DMRT1 is involved in testis determination. In addition to SRY, DMRT1 is required in the supporting cells to increase the expression of the SOX9 gene, which heads the testicular genetic cascade. Second, we highlighted another function of DMRT1 in the germline since XX and XY DMRT1-/- ovaries did not undergo meiosis and folliculogenesis. XX DMRT1-/- adult females were sterile, showing that DMRT1 is also crucial for female fertility. To conclude, these phenotypes indicate an evolutionary continuum between non-mammalian vertebrates such as birds and non-rodent mammals. Furthermore, our data support the potential involvement of DMRT1 mutations in different human pathologies, such as 46, XY DSD as well as male and female infertility.

developmental biology↗

bioRxiv2021

TRIM28-dependent SUMOylation protects the adult ovary from the male pathway

Gonadal sexual fate in mammals is determined during embryonic development and must be actively maintained in adulthood. In the mouse ovary, oestrogen receptors and FOXL2 protect ovarian granulosa cells from transdifferentiation into Sertoli cells, their testicular counterpart. However, the mechanism underlying their protective effect is unknown. Here, we show that TRIM28 is required to prevent female-to-male sex reversal of the mouse ovary after birth. We found that upon loss of Trim28, ovarian granulosa cells transdifferentiate to Sertoli cells through an intermediate cell type, different from gonadal embryonic progenitors. TRIM28 is recruited on chromatin in the proximity of FOXL2 to maintain the ovarian pathway and to repress testicular-specific genes. The role of TRIM28 in ovarian maintenance depends on its E3-SUMO ligase activity that regulates the sex-specific SUMOylation profile of ovarian-specific genes. Our study identifies TRIM28 as a key factor in protecting the adult ovary from the testicular pathway.

developmental biology↗