Biology subjects

Mordier, J.

Publications and source records attributed to Mordier, J..

4 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

Transposable Element insertions Repurpose Immune Endonucleases as Drivers of Reproductive Isolation in Mice

The emergence of reproductive barriers between closely related populations is a fundamental step in speciation, yet the underlying genetic mechanisms remain poorly understood in mammals. Here we resolve the DDK syndrome, a long-standing model of hybrid incompatibility in mice, by showing that two independent retrotransposon insertions rewire immune Schlafen endoribonuclease genes expression, causing hybrid embryo death. A DDK-private MERVL element drives ectopic oocyte expression of Slfn1, while an intragenic ETn/MusD insertion in incompatible strains is associated with zygotic Slfn15 expression. SLFN1-SLFN15 heterodimerization constitutively activates tRNA ribonuclease activity, leading to global translation inhibition, and integrated stress response activation. Abolishing SLFN1 catalytic activity or SLFN15 expression rescues syndromic embryo development. Our findings uncover a previously unrecognized speciation mechanism in which transposable elements repurpose immune effectors as drivers of postzygotic reproductive isolation.

developmental biology↗

bioRxiv2024

Recurrent Evolutionary Innovations in Rodent and Primate Schlafen Genes

SCHLAFEN proteins are a large family of RNase-related enzymes carrying essential immune and developmental functions. Despite these important roles, Schlafen genes display varying degrees of evolutionary conservation in mammals. While this appears to influence their molecular activities, a detailed understanding of these evolutionary innovations is still lacking. Here, we used in depth phylogenomic approaches to characterize the evolutionary trajectories and selective forces shaping mammalian Schlafen genes. We traced lineage-specific Schlafen amplifications and found that recent duplicates evolved under distinct selective forces, supporting repeated sub-functionalization cycles. Codon-level natural selection analyses in primates and rodents, identified recurrent positive selection over Schlafen protein domains engaged in viral interactions. Combining crystal structures with machine learning predictions, we discovered a novel class of rapidly evolving residues enriched at the contact interface of SCHLAFEN protein dimers. Our results suggest that inter Schlafen compatibilities are under strong selective pressures and are likely to impact their molecular functions. We posit that cycles of genetic conflicts with pathogens and between paralogs drove Schlafens recurrent evolutionary innovations in mammals.

evolutionary biology↗

bioRxiv2021

Evolutionary conserved protein motifs drive attachment of the plant nucleoskeleton at nuclear pores

The nucleoskeleton forms a filamentous meshwork under the nuclear envelope and contributes to the regulation of nuclear morphology and gene expression. To understand how the Arabidopsis nucleoskeleton physically connects to the nuclear periphery, we investigated the nucleoskeleton protein KAKU4 and sought for functional regions responsible for its localization at the nuclear periphery. Computational predictions identified three evolutionary conserved peptide motifs within the N-terminal region of KAKU4. Functional analysis revealed that these motifs are required for homomerization of KAKU4, interaction with the nucleoskeleton proteins CROWDED NUCLEI (CRWN) and localization at the nuclear periphery. We find that similar protein motifs are present in NUP82 and NUP136, two plant specific nucleoporins from the Nuclear Pore Complex (NPC) basket. These conserved motifs allow the two nucleoporins to bind CRWN proteins, thus revealing a physical link between the nucleoskeleton and nuclear pores in plants. Finally, whilst NUP82, NUP136 and KAKU4 have a common evolutionary history predating non-vascular land plants, KAKU4 mainly localizes outside the NPC suggesting neofunctionalization of an ancient nucleoporin into a new nucleoskeleton component.

genetics↗