Biology subjects

Joumier, L.

Publications and source records attributed to Joumier, L..

4 recordsLinked to original sources

bioRxiv2025

BMP and NODAL Paracrine Signalling Regulate the Totipotent-like Cell State in Embryonic Stem Cells.

1)Cell-cell communication coordinates signalling between cells to guide context-dependent cell fate decisions such as proliferation, differentiation, and lineage specification. Such communication mechanisms are poorly understood in regulating the stem cell states. In this study, we investigate how cell-cell communication regulates cell fate transitions in heterogeneous embryonic stem cell populations, with a particular focus on totipotent-like cells that resemble the two-cell stage embryo. Using single-cell RNA sequencing in combination with computational frameworks, we map ligand- receptor interactions and model downstream regulatory effects across various stem cell states. We functionally validate the predictions by selectively perturbing signalling pathways under specific culture conditions. Our data reveal the key roles of BMP and NODAL (TGF-{beta}) signalling in mediating intercellular communication to shape stem cell identity and heterogeneity. These findings enhance our understanding of the signalling logic that governs early developmental cell fate decisions, providing new insights into stem cell biology with broad implications for regenerative medicine and developmental modelling.

cell biology↗

bioRxiv2025

Induction of cellular totipotency by NACC1-driven feed-forward regulation.

Mammalian embryo development begins with totipotent cells. Despite its significance, gene regulatory mechanisms controlling the totipotent cell stage are poorly understood. Based on single-cell proteomics and transcriptomics, we identified nucleus accumbens-associated 1 (NACC1) as a critical regulator of totipotent-like cell state in mouse embryonic stem cells. Using a combination of genomics approaches, we found that NACC1 directly binds to gene-regulatory regions and favours chromatin accessibility to induce the expression of totipotency and zygotic genome activation genes, as well as retrotransposons associated with totipotency. In parallel, NACC1-regulated retrotransposons further modulate the expression of proximal totipotency genes, forming a coherent feed-forward mechanism that regulates totipotent-like cells. Furthermore, NACC1 is crucial for the progression of embryogenesis beyond the totipotency stage. Thus, we uncover a genome-level NACC1-driven feed-forward gene regulatory mechanism that governs totipotent-like cells and has a crucial role during embryonic development.

developmental biology↗

bioRxiv2022

Cross-activation of the FGF, TGF-β and WNT pathways constrains BMP4-mediated induction of the Totipotent state in mouse embryonic stem cells.

Cell signaling induced cell fate determination is central to stem cell and developmental biology. Embryonic stem cells (ESC) are an attractive model for understanding the relationship between cell signaling and cell fates. Cultured mouse ESCs can exist in multiple cell states resembling distinct stages of early embryogenesis, such as Totipotent, Pluripotent, Primed and Primitive Endoderm. The signaling mechanisms regulating the Totipotent state acquisition and coexistence of these states are poorly understood. Here we identify BMP4 as an inducer of the Totipotent state. However, we discovered that BMP4-mediated induction of the Totipotent state is constrained by the cross-activation of FGF, TGF-{beta} and WNT pathways. We exploited this finding to enhance the proportion of Totipotent cells in ESCs by rationally inhibiting these cross-activated pathways using small molecules. Single-cell mRNA-sequencing further revealed that induction of the Totipotent state is accompanied by the suppression of both the Primed and Primitive Endoderm states. Furthermore, the reprogrammed Totipotent cells generated in culture have a molecular and functional resemblance to Totipotent cell stages of preimplantation embryos. Our findings reveal a novel BMP4 signaling mechanism in ESCs to regulate multiple cell states, potentially significant for managing stem cell heterogeneity in differentiation and reprogramming.

developmental biology↗

bioRxiv2021

Direct reprogramming of the intestinal epithelium by parasitic helminths subverts type 2 immunity

Enteric helminths form intimate physical connections with the intestinal epithelium, yet their ability to directly alter epithelial stem cell fate has not been resolved. Here we demonstrate that infection of mice with the symbiotic parasite Heligmosomoides polygyrus bakeri (Hbp), reprograms the intestinal epithelium into a fetal-like state marked by the emergence of Clusterin-expressing revival stem cells (revSCs). Organoid-based studies using parasite-derived excretory/secretory products reveal that Hpb-mediated revSC generation occurs independent of host-derived immune signals and inhibits type 2 cytokine-driven differentiation of secretory epithelial lineages that promote their expulsion. Reciprocally, type 2 cytokine signals limit revSC differentiation and, consequently, Hpb fitness indicating that helminths compete with their host for control of the intestinal stem cell niche to promote continuation of their life cycle.

immunology↗