Biology subjects

Labouesse, C.

Publications and source records attributed to Labouesse, C..

6 recordsLinked to original sources

bioRxiv2025

Intrinsic mechanotransduction during apical constriction licenses lineage competence in pluripotent stem cells

To acquire the capacity for multi-lineage differentiation, pluripotent stem cells must undergo a transition from naive pluripotency to lineage competency. This transition requires epithelialization and changes in nuclear architecture. We sought to determine whether the cell and tissue mechanics intrinsic to epithelialization drive pluripotency progression and subsequent lineage commitment to neuroectodermal fate. We demonstrate that naive mouse embryonic stem cells (mESCs) undergoing early differentiation in vitro recapitulate features of epithelialization in the peri-implantation epiblast, specifically apical constriction. We further demonstrate that cell contractility during apical constriction induces a distinct nuclear mechanoresponse, notably enrichment of emerin at the outer nuclear membrane, nuclear envelope localization of SUN2, and the global loss of H3K9me3 heterochromatin which is compensated by H3K27me3. Importantly, these nuclear phenotypes and subsequent neuroectodermal lineage priming require myosin II-mediated contractility, an intact LINC complex, and emerin. We demonstrate that LINC-dependent mechanotransduction through emerin regulates H3K27me3 occupancy on the key early neuroectodermal transcription factor gene, Sox1, implicating a mechanical switch in chromatin mediation of neuroectodermal lineage competence. These results indicate that epithelialization-induced nuclear mechanotransduction poises a critical lineage gene for subsequent expression. HighlightsO_LIAdherent naive mESCs in vitro recapitulate in utero apical constriction morphogenesis. C_LIO_LIContractility, the LINC complex and emerin are required for neuroectodermal lineage competence. C_LIO_LIContractility and the LINC complex are required for widespread loss of H3K9me3 and gain of H3K27me3 on Sox1 promoter. C_LI

cell biology↗

bioRxiv2025

HydroMEA: A 3D Hydrogel Based Microfluidic Device to Study Electrophysiology for Myelinated Nerve-on-Chip

Engineered in vitro platforms are powerful systems to study information flow in the nervous system. While existing polydimethylsiloxane (PDMS)-based microfluidic platforms offer precise architectures, the cultured neurons grow on two-dimensional (2D) planar multielectrode arrays (MEA). To mimic the native microenvironment, where neurons grow in three-dimensional (3D) extracellular matrices (ECM), 3D hydrogels can be designed to encapsulate cells and enable physiologically-mimicked behaviors. Here, we describe hydroMEA, a 3D platform fabricated by placing PDMS microstructures on a high-density MEA and filled with a desired hydrogel, to offer controlled topologies, physiologically-relevant microenvironments, and real-time electrophysiological measurements. First, we developed a gelatin methacryloyl (GelMA) hydrogel with incorporated ECM components and tuned the mechanical properties to match those of nerve tissue. The hydrogel was able to support: 1) the growth of iPSC-derived sensory neurons (hSNs) for >100 days; 2) co-cultures of hSN with human embryonic stem cell-derived Schwann cells (hSCs), to enable reliable 3D myelination. Next, hydroMEA were prepared for topologically- defined 3D growth and myelination in designated compartments. Finally, electrophysiological evaluation of hSN-hSCs co-cultures revealed increased conduction speeds indicating functional myelin. This platform is a promising tool to study cell-cell interactions and to functionally evaluate the effect of pharmacological compounds in a more translational manner.

bioengineering↗

bioRxiv2024

Tunable bicontinuous macroporous cell culture scaffolds via kinetically controlled phase separation

Three-dimensional (3D) scaffolds enable biological investigations with a more natural cell conformation. However, the porosity of synthetic hydrogels is often limited to the nanometer scale, which confines the movement of 3D encapsulated cells and restricts dynamic cell processes. Precise control of hydrogel porosity across length scales remains a challenge and the development of porous materials that allow cell infiltration, spreading, and migration in a manner more similar to natural ECM environments is desirable. Here, we present a straightforward and reliable method for generating kinetically-controlled macroporous systems using liquid-liquid phase separation between poly(ethylene glycol) (PEG) and dextran. Photopolymerization-induced phase separation resulted in macroporous hydrogels with tunable pore size. Varying light intensity and hydrogel composition controlled polymerization kinetics, time to percolation, and complete gelation, which defined the average pore diameter (O = 1- 300 m) and final gel stiffness of the formed hydrogels. Critically, for biological applications, macroporous hydrogels were prepared from aqueous polymer solutions at physiological pH and temperature using visible light, allowing for direct cell encapsulation. We encapsulated human dermal fibroblasts in a range of macroporous gels with different pore sizes. Porosity improved cell spreading with respect to bulk gels and allowed migration in the porous systems.

bioengineering↗

bioRxiv2024

Cell-matrix force transmission regulates the loss of naïve pluripotency in mouse embryonic stem cells.

The first step in the differentiation of mouse embryonic stem cells (mESCs) is the loss of naive pluripotency. This step involves a major reshaping of cells from a rounded to a spread, adhesive phenotype. Whereas such reshaping is typically associated with increased force transmission to the extracellular matrix (ECM), the magnitude and role of cell-matrix forces in the loss of naive pluripotency is unknown. Here, we show that cell-matrix forces increase during, and are required for, the loss of naive pluripotency in mESCs. Using traction force microscopy, we show that mESCs progressively increase cell-traction forces and mechanotransduction markers as naive pluripotency dissolves. Modulation of force transmission through myosin inhibition, substrate stiffness, or spatial differences within mESC colonies regulates the process. Increased force is triggered by GSK3-mediated signalling, and the effect of force is regulated in part by its transmission to the cell nucleus. Our work unveils a major role of cell-ECM forces in pluripotency dissolution, adding an important aspect to the interplay between biochemical and biophysical cues that drive this process.

developmental biology↗

bioRxiv2019

Abscission couples cell division to embryonic stem cell fate

Cell fate transitions are key to development and homeostasis. It is thus essential to understand the cellular mechanisms controlling fate transitions. Cell division has been implicated in fate decisions in many stem cells, including neuronal and epithelial progenitors. In other stem cells, such as embryonic stem (ES) cells, the role of division remains unclear. Here we show that exit from naive pluripotency in mouse ES cells generally occurs after a division. We further show that exit timing is strongly correlated between sister cells, which remain connected by cytoplasmic bridges long after division, and that bridge abscission progressively accelerates as cells exit naive pluripotency. Finally, interfering with abscission impairs exit from naive pluripotency. Altogether, our data indicate that a switch in the division machinery leading to faster abscission is crucial for pluripotency exit. Our study identifies abscission as a key step coupling cell division to fate transitions.

cell biology↗

bioRxiv2019

StemBond hydrogels optimise the mechanical microenvironment for embryonic stem cells

Studies of mechanical signalling are typically performed by comparing cells cultured on soft and stiff hydrogel-based substrates. However, it is challenging to independently and robustly control both substrate stiffness and tethering of extracellular matrix (ECM) to substrates, making ECM tethering a potentially confounding variable in mechanical signalling investigations. Moreover, poor ECM tethering can lead to weak cell attachment. To address this, we developed StemBond hydrogels, a hydrogel formulation in which ECM tethering is stable and can be varied independently of stiffness. We show that soft StemBond hydrogels provide an optimal format for culturing embryonic stem (ES) cells. We find that soft StemBond substrates improve the homogeneity of ES cell populations, boost their self-renewal, and increase the efficiency of cellular reprogramming. Our findings underline how soft microenvironments impact mechanosensitive signalling pathways regulating self-renewal and differentiation, indicating that optimising the complete mechanical microenvironment will offer greater control over stem cell fate specification.

cell biology↗