Biology subjects

Allegre, N.

Publications and source records attributed to Allegre, N..

4 recordsLinked to original sources

bioRxiv2025

A ligand/receptor trafficking clock governs self-renewal and abscission dynamics in pluripotent stem cells

Summary/AbstractHow extracellular cues are temporally integrated to regulate self-renewal and differentiation propensities across the cell cycle remains largely unresolved. We identify a ligand/receptor trafficking clock in rodent and human pluripotent stem cells (PSCs) in which the cyclic turnover of Netrin-1 and its receptors Neo1 and Unc5b (NNU) governs self-renewal capacity and abscission dynamics. In G1, NNU complexes undergo Clathrin-mediated internalization and lysosomal degradation, a process required for timely post-mitotic bridge abscission. At later stages of the cycle, NNU activate Src within early endosomes, inducing a genome-wide redistribution of the transcriptional co-activator Yap1. This reshapes gene regulatory networks by activating stemness- and ectoderm-associated transcriptional programs enriched for Sox2/Nanog binding and by repressing mesodermal- and cell cycle-related targets enriched for Sox2 and Tcf3. Functionally, recombinant Netrin-1 reduces functional heterogeneity and enhances clonogenicity in G1, uncovering a tractable strategy to canalize stem cell behavior. Collectively, our results reveal cell cycle-dependent ligand/receptor trafficking as a temporal clock that directly links membrane dynamics to epigenetic regulation and stem cell fate, opening new avenues for regenerative medicine.

cell biology↗

bioRxiv2025

Enhanced Multiplexed Single-Cell RNA-Sequencing for Accurate Detection of Treatment Effects Without Batch Correction in the Avian Embryonic Model

Single-cell RNA sequencing has revolutionized our ability to explore cellular heterogeneity and is a powerful tool to study the impact of environmental perturbations on multiple cell states. However, environmental perturbations can be subtle, and the associated biological effects could be masked by experimental noise and bioinformatic processing, especially when the samples are generated separately. Multiplexing strategies have been developed to label each sample and process them together to reduce experimental noise, but existing multiplexing methods often fall short for non-human and non-mouse models in established single-cell RNA sequencing protocols like the BD Rhapsody technology. To address this gap, we combined Lipid Modified Oligonucleotide (LMO) cell tagging with the BD Rhapsody platform to achieve efficient and scalable multiplexing of early embryonic chick cells under different environmental conditions. This species-agnostic LMO approach overcomes limitations of antibody-based multiplexing methods that are often restricted to human and mouse systems, and the only multiplexing option available with the BD Rhapsody system. In our study, we successfully compartmentalized and multiplexed chick embryonic cells under different treatment conditions, analyzing up to 40,000 viable cells per experiment. This strategy minimized experimental noise, eliminating the need for bioinformatics-based batch correction. As a result, we were able to achieve high-quality transcriptomic profiling with minimal loss of critical biological information and identified subtle biological differences that were masked when using data integration pipelines. Our workflow provides an adaptable, robust solution for LMO-tagged single-cell analyses of complex non-human models with the BD Rhapsody technology and opens new avenues for developmental biology research by accurately capturing treatment-induced effects in embryonic tissues.

developmental biology↗

bioRxiv2025

A STAT3-regulated lncRNA integrates microRNA biogenesis and sequestration to safeguard naive pluripotency

Leukemia inhibitory factor (LIF)/STAT3 signaling is central to maintaining naive pluripotency in mouse embryonic stem cells (mESCs). We identify Asgard, a previously uncharacterized long non-coding RNA, as a direct STAT3 target required for efficient self-renewal. Asgard is rapidly induced by LIF, enriched in the epiblast, and its depletion reduces alkaline phosphatase-positive colony formation while enhancing differentiation. Mechanistically, Asgard fulfils a dual role: it acts as the primary transcript for the differentiation-promoting microRNA Odin, while also functioning as a sponge to sequester Odin and related miRNAs. This dual mechanism enables Asgard to both generate and buffer pro-differentiation signals, thereby stabilizing the pluripotent state while preserving responsiveness to lineage cues. Our work reveals a new paradigm in RNA-mediated control of stem cell identity, where a single STAT3-regulated lncRNA couples microRNA production with competitive inhibition to safeguard naive pluripotency.

developmental biology↗

bioRxiv2019

A Nanog-dependent gene cluster initiates the specification of the pluripotent epiblast

The epiblast (Epi) is the source of embryonic stem (ES) cells and all embryonic tissues. It differentiates alongside the primitive endoderm (PrE) in a randomly distributed \"salt and pepper\" pattern from the inner cell mass (ICM) during preimplantation of the mammalian embryo. NANOG and GATA6 are key regulators of this binary differentiation event, which is further modulated by heterogeneous FGF signalling. When and how Epi and PrE lineage specification is initiated within the developing embryo is still unclear. Here we generated NANOG and GATA6 double KO (DKO) mouse embryos and performed single-cell expression analyses. We found that the ICM was unable to differentiate in the DKO mice, allowing us to characterize the ICM precursor state. The normally heterogeneous expression of Fgf4 between cells was significantly reduced in DKO ICMs, impairing FGF signalling. In contrast, several pluripotency markers did still display cell-to-cell expression variability in DKO ICMs. This revealed a primary heterogeneity independent of NANOG, GATA6 and FGF signalling that may also be conserved in humans. We found that NANOG is key in the initiation of epiblast specification already between the 16- and 32-cell stages, enabling the cell-clustered expression of many pluripotency genes. Our data uncover previously unknown biology in the early mouse embryo with potential implications for the field of pluripotent stem cells in human and other mammals.

developmental biology↗