Biology subjects

Blin, G.

Publications and source records attributed to Blin, G..

8 recordsLinked to original sources

bioRxiv2026

Notch signalling governs human enteric nervous system progenitor dynamics

The enteric nervous system (ENS) is the main branch of the peripheral nervous system that innervates the gastrointestinal tract controlling vital functions. It arises during embryogenesis via migration, proliferation and differentiation of neural crest-derived ENS progenitors. Perturbation of these processes, caused by mutations in key signalling pathway components and transcription factors, prevents progenitor colonisation of the distal gut causing aganglionic phenotypes and enteric neuropathies such as Hirschsprung (HSCR) disease. While animal models implicate Notch signalling in ENS specification, its role in human ENS progenitor cell fate decisions remains unclear. Here, we employ a human pluripotent stem cell-based model to show that Notch signalling is a key regulator of human ENS progenitor dynamics. Quantitative modelling of our in vitro data indicates that Notch inhibition accelerates progenitor differentiation without substantially altering neuronal versus glial lineage bias. Furthermore, we establish that Notch signalling controls human ENS progenitor migration by influencing migration velocity and directionality. Together, these findings provide mechanistic insights into how Notch signalling disruption may contribute to the pathogenesis of human intestinal aganglionosis.

developmental biology↗

bioRxiv2024

A toolkit for mapping cell identities in relation to neighbours reveals Notch-dependent heterogeneity within neuromesodermal progenitor populations

Patterning of cell fates is central to embryonic development, tissue homeostasis, and disease. Quantitative analysis of patterning reveals the logic by which cell-cell interactions orchestrate changes in cell fate. However, it is challenging to quantify patterning when graded changes in identity occur over complex 4D trajectories, or where different cell states are intermingled. Furthermore, comparing patterns across multiple individual embryos, tissues, or organoids is difficult because these often vary in shape and size. Here we present a toolkit of computational approaches to tackle these problems. These strategies are based on measuring properties of each cell in relation to the properties of its neighbours to quantify patterning, and on using embryonic landmarks in order to compare these patterns between embryos. We use this toolkit to characterise patterning of cell identities within the caudal lateral epiblast of E8.5 embryos, revealing local patterning in emergence of early mesoderm cells that is sensitive to inhibition of Notch activity.

developmental biology↗

bioRxiv2023

In vitro modelling of anterior primitive streak patterning with hESC reveals the dynamic of WNT and NODAL signalling required to specify notochord progenitors

Notochord progenitors (NotoPs) represent a scarce yet crucial embryonic cell population, playing important roles in embryo patterning and eventually giving rise to the cells that form and maintain intervertebral discs. The mechanisms regulating NotoPs emergence are unclear. This knowledge gap persists due to the inherent complexity of cell fate patterning during gastrulation, particularly within the anterior primitive streak (APS), where NotoPs first arise alongside other important progenitors including neuro-mesodermal and endodermal progenitors. To gain insights into this process, we use micropatterning together with FGF and the WNT pathway activator CHIR9901, to guide the development of human embryonic stem cells into reproducible patterns of APS cell fates. We show that small variations in CHIR9901 dosage dictate the downstream dynamics of endogenous TGFbeta signalling which in turn controls cell fate decisions. We show that sustained NODAL signalling induces endoderm while NODAL inhibition is needed for NMP specification. Furthermore, we unveil a crosstalk between TGFbeta and WNT signaling pathways, wherein TGFbeta inhibition enhances WNT activity. Finally, we demonstrate that the timely inhibition of TGFbeta signalling is imperative for the emergence of NotoPs. Our work elucidates the signalling regimes underpinning NotoPs emergence and provides novel insights into the regulatory mechanisms controlling the balance of APS cell fates during gastrulation.

developmental biology↗

bioRxiv2021

SyNPL: Synthetic Notch pluripotent cell lines to monitor and manipulate cell interactions in vitro and in vivo.

Cell-cell interactions govern differentiation and cell competition in pluripotent cells during early development, but the investigation of such processes is hindered by a lack of efficient analysis tools. Here we introduce SyNPL: clonal pluripotent stem cell lines which employ optimised Synthetic Notch (SynNotch) technology to report cell-cell interactions between engineered "sender" and "receiver" cells in cultured pluripotent cells and chimaeric mouse embryos. A modular design makes it straightforward to adapt the system for programming differentiation decisions non-cell-autonomously in receiver cells in response to direct contact with sender cells. We demonstrate the utility of this system by enforcing neuronal differentiation at the boundary between two cell populations. In summary, we provide a new tool which could be used to identify cell interactions and to profile changes in gene or protein expression that result from direct cell-cell contact with defined cell populations in culture and in early embryos, and which can be adapted to generate synthetic patterning of cell fate decisions. SUMMARY STATEMENTOptimised Synthetic Notch circuitry in mouse pluripotent stem cells provides a modular tool to monitor cell-cell interactions and program synthetic patterning of cell fates in culture and in embryos.

developmental biology↗

bioRxiv2019

Competence to epithelialise coincides with competence to differentiate in pluripotent cells

Pluripotent cells reorganise themselves into an epithelium before they initiate differentiation, but it is not clear how these two events are mechanistically linked. Here we use quantitative imaging approaches to measure cellular rearrangements that accompany exit from naive pluripotency. We show that competence to epithelialise, like competence to differentiate, is a regulated process. The pro-differentiation transcription factor Tcf15 prospectively identifies cells that are competent to epithelialise. We identify early upregulation of the laminin receptor integrin alpha3 prior to differentiation and show that Tcf15 helps to regulate this change. Finally, we show that Tcf15 identifies and is required for efficient differentiation of a primed subpopulation of pluripotent cells. We conclude that competence to epithelialise is actively regulated and linked to differentiation-competence through the transcription factor Tcf15.

developmental biology↗

bioRxiv2019

N-cadherin stabilises neural identity by dampening anti-neural signals

A switch from E-to N-cadherin regulates the transition from pluripotency to neural identity but the mechanism by which cadherins regulate differentiation was previously unknown. Here we show that the acquisition of N-cadherin stabilises neural identity by dampening anti-neural signals. We use quantitative image-analysis to identify an effect of N-cadherin to promote neural differentiation independently of effects on cell cohesiveness. We reveal that cadherin switching diminishes the level of nuclear {beta}-catenin, and that N-cadherin also dampens FGF activity and consequently stabilises neural fate. Finally, we compare the timing of cadherin switching and differentiation in vivo and in vitro, and find that this process becomes dysregulated during in vitro differentiation. We propose that N-cadherin helps to propagate a stable neural identity throughout the emerging neuroepithelium, and that dysregulation of this process contributes to asynchronous differentiation in culture.

developmental biology↗

bioRxiv2018

Nessys: a novel method for accurate nuclear segmentation in 3D

Methods for measuring the properties of individual cells within their native 3D environment will enable a deeper understanding of embryonic development, tissue regeneration, and tumorigenesis. However current methods for segmenting nuclei in 3D tissues are not designed for situations where nuclei are densely packed, non-spherical, heterogeneous in shape, size, or texture, all of which are true of many embryonic and adult tissue types as well as in many cases for cells differentiating in culture.\n\nHere we overcome this bottleneck by devising a novel method based on labelling the nuclear envelope (NE) and automatically distinguishing individual nuclei using a tree structured ridge tracing method followed by shape ranking according to a trained classifier. The method is fast and makes it possible to process images that are larger than the computers memory. We consistently obtain accurate segmentation rates of >90% even for challenging images such as mid-gestation embryos or 3D cultures. We provide a 3D editor and inspector for the manual curation of the segmentation results as well as a program to assess the accuracy of the segmentation.\n\nWe have also generated a live reporter of the NE that can be used to track live cells in three dimensions over time. We use this to monitor the history of cell interactions and occurrences of neighbour exchange within cultures of pluripotent cells during differentiation.\n\nWe provide these tools in an open-access user-friendly format.

developmental biology↗

bioRxiv2017

Geometrical confinement guides Brachyury self-patterning in embryonic stem cells.

During embryogenesis, signaling molecules initiate cell diversification, sometimes via stochastic processes, other times via the formation of long range gradients of activity which pattern entire fields of cells. Such mechanisms are not insensitive to noise (Lander, 2011), yet embryogenesis is a remarkably robust process suggesting that multiple layers of regulations secure patterning during development. In the present study, we present a proof of concept according to which an asymmetric pattern of gene expression obtained from a spatially disorganised population of cells can be guided by the geometry of the environment in a reproducible and robust manner. We used ESC as a model system whithin which multiple developmental cell states coexist (MacArthur and Lemischka, 2013; Smith, 2017; Torres-Padilla and Chambers, 2014). We first present evidence that a reciprocal regulation of genes involved in the establishment of antero-posterior polarity during peri-implantation stages of mouse development is spontaneously occuring within ESC. We then show that a population of cells with primitive streak characteristics localise in regions of high curvature and low cell density. Finally, we show that this patterning did not depend on self-organised gradients of morphogen activity but instead could be attributed to positional rearrangements. Our findings unveil a novel role for tissue geometry in guiding the self-patterning of primitive streak cells and provide a framework to further refine our understanding of symmetry breaking events occuring in ESC aggregates. Finally, this work demonstrates that the self-patterning of a specific population of ESC, Brachyury positive cells in this case, can be directed by providing engineered external geometrical cues.

developmental biology↗