Biology subjects

Boutillon, A.

Publications and source records attributed to Boutillon, A..

7 recordsLinked to original sources

bioRxiv2026

Non-muscle myosin II acts non-cell autonomously to guide collective migration of the zebrafish polster cells

Collective cell migration is crucial in embryonic development and tumour dissemination. How cell-cell interactions guide collective cell migration is partially understood with a growing body of evidence pointing to a role for mechanical signals and intercellular tension. During zebrafish gastrulation, the anterior axial mesendoderm, also called polster, migrates collectively towards the animal pole. We here investigate the role of non-muscle myosin II (NMII), a well-known generator of intracellular tension, in this migration and uncover an unexpected non-cell-autonomous function. Inhibiting NMII activity, via genetic or pharmacological approaches, impairs both the speed and orientation of polster cells. Transplant experiments show that while NMII is required within the polster for proper cell orientation, it is not required in a cell-autonomous manner. Instead, NMII activity in neighbouring cells is essential to orient a given cells protrusions. Mechanistically, NMII localizes to the rear of cells and the base of actin-rich protrusions, where it promotes F-actin retrograde flow and generates mechanical tension. Using a conformation-specific -catenin antibody, we show that NMII-dependent tension is required to open -catenin in adjacent cells, providing a direct mechanotransductive link between neighbouring cells. These findings suggest a model in which protrusions not only serve as locomotory structures, but also as physical conduits for directional cues via transmission of a mechanical signal. Actomyosin-based contractility in one cell influences polarity in its neighbour, thereby ensuring directional coherence of the migrating group.

Developmental Biology↗

bioRxiv2025

Tissue surface mechanics constrains proliferation-driven forces to guide mammalian body axis elongation

Mammalian embryos undergo complex morphogenetic changes after implantation in the uterus. The elongation of the body along a head-to-tail axis is a pivotal event, as it lays the foundation of the body plan. While genetic and biochemical aspects of mammalian body elongation have been uncovered, the physical mechanism of axial morphogenesis remains unknown, largely due to the inaccessibility of the implanted embryo to physical measurements and manipulations in utero. Gastruloids, a stem-cell-based embryo model of mammalian axial morphogenesis, lift such limitations. Combining live imaging, direct mechanical measurements, and chemical and mechanical perturbations, here we show that axis elongation in mouse and human gastruloids is guided by a posterior actin cap at the tissue surface that constrains the expansive forces of cell proliferation. Measurements of mechanical stresses using oil microdroplets, as well as inhibition of cell proliferation and myosin activity, show that the forces driving elongation arise from cell proliferation, and not from convergent extension movements. We find that isotropic tissue expansion is redirected into posterior elongation by the formation of a supracellular actin cap at the posterior tissue surface that restricts lateral tissue expansion. Finally, we show that posterior elongation in mouse embryos displays the key features of the physical elongation mechanism reported for mouse and human gastruloids. These findings reveal that mammalian body axis elongation, including human, occurs via a different physical mechanism from other vertebrate species.

biophysics↗

bioRxiv2024

Interplay of actin nematodynamics and anisotropic tension controls endothelial mechanics

Blood vessels expand and contract actively, while continuously experiencing dynamic external stresses from the blood flow. The mechanical response of the vessel wall is that of a composite material: its mechanical properties depend on a diverse set of cellular mechanical components, which change dynamically as cells respond to external stress. Mapping the relationship between these underlying cellular processes and emergent tissue mechanics is an on-going challenge, in particular in endothelial cells. Here we use a microstretcher mimicking the native environment of blood vessels to assess both the mechanics and cellular dynamics of an endothelial tube in response to a physiological increase in luminal pressure. The characterization of the instantaneous monolayer elasticity reveals a strain-stiffening, actin-dependent and substrate-responsive behavior. In response to a maintained pressure increase, the tissue displays a fluid-like expansion, accompanied by the reorientation of cell shape and of actin fibers. This actin-driven reorientation depends on focal adhesions and adherens junctions, two key mechanosensors. We introduce a mechanical model coupling actin fiber nematodynamics with active and elastic tension generation by actin fibers in the endothelium, which recapitulates the response to pressure of endothelial tubes.

biophysics↗

bioRxiv2023

Inactivating Negative Regulators of Cortical Branched Actin Enhances Persistence of Single Cell Migration

The Rac1-WAVE-Arp2/3 pathway pushes the plasma membrane by polymerizing branched actin at the cell cortex and thereby powering membrane protrusions that mediate cell migration. Here, using knock-down (KD) or knock-out (KO), we combine the inactivation of the Arp2/3 inhibitory protein Arpin, the Arp2/3 subunit ARPC1A and the WAVE complex subunit, CYFIP2, that all enhance the polymerization of cortical branched actin (CBA). Inactivation of the 3 CBA negative regulators increases migration persistence of human breast MCF10A cells, and of endodermal cells in the zebrafish embryo, significantly more than any single or double inactivation. In the triple KO, but not triple KD cells, the "super-migrator" phenotype was associated with a heterogenous down-regulation of vimentin expression and a lack of coordination in collective behaviors, such as wound healing and acinus morphogenesis. Re-expression of vimentin in triple KO cells restored the normal persistence of single cell migration to a large extent, suggesting that vimentin down-regulation is one of the adjustments in gene expression through which the super-migrator phenotype is stably maintained in triple KO cells. Constant excessive production of branched actin at the cell cortex thus commits cells into a motile state through changes in gene expression.

cell biology↗

bioRxiv2023

Collective cell migration due to guidance-by-followers is robust to multiple stimuli

Collective cell migration is an important process during biological development and tissue repair, but may turn malignant during tumor invasion. Mathematical and computational models are essential to unravel the mechanisms of self-organization that underlie the emergence of collective migration from the interactions among individual cells. Recently, guidance-by-followers was identified as one such underlying mechanism of collective cell migration in the zebrafish embryo. This poses the question how guidance stimuli are integrated when multiple cells interact simultaneously. Here, we extend a recent individual-based model by an integration step of the vectorial guidance stimuli and compare model predictions obtained for various variants of the mechanism (arithmetic mean of stimuli, dominance of stimulus with largest transmission interface, dominance of most head-on stimulus). Simulations are carried out and quantified within the modeling and simulation framework Morpheus. Collective cell migration is sfound to be robust and qualitatively identical for all considered variants of stimulus integration. Moreover, this study highlights the role of individual-based modeling approaches for understanding collective phenomena at the population scale that emerge from cell-cell interactions.

developmental biology↗

bioRxiv2021

Guidance by followers ensures long-range coordination of cell migration through α-Catenin mechanoperception

Morphogenesis, wound healing and some cancer metastases depend upon migration of cell collectives that need to be guided to their destination as well as coordinated with other cell movements. During zebrafish gastrulation, extension of the embryonic axis is led by the mesendodermal polster that migrates towards the animal pole, followed by axial mesoderm that undergoes convergence and extension. We here investigate how polster cells are guided towards the animal pole. Using a combination of precise laser ablations, advanced transplants and functional as well as in silico approaches, we establish that each polster cell is oriented by its immediate follower cells. Each cell perceives the migration of followers, through E-Cadherin/-Catenin mechanotransduction, and aligns with them. Directional information therefore propagates from cell to cell over the whole tissue. Such guidance of migrating cells by followers ensures long-range coordination of movements and developmental robustness.

developmental biology↗

bioRxiv2020

CYFIP2 containing WAVE complexes inhibit cell migration

Branched actin networks polymerized by the Arp2/3 complex are critical for cell migration. The WAVE complex is the machinery that activates Arp2/3 in a RAC1-dependent manner at the leading edge of migrating cells. Multiple WAVE complexes are assembled in a cell through various combinations of paralogous subunits. Here we report the surprising phenotype associated with loss-of-function of CYFIP2, a subunit of the WAVE complex. In three different human mammary cell lines and in prechordal plate cells of gastrulating zebrafish embryos, CYFIP2 depletion promoted, rather than impaired, membrane protrusions and migration persistence. CYFIP2, however, assembled WAVE complexes that polymerize branched actin at the cell cortex and rescued membrane protrusions of CYFIP1/2 double knock-out cells, although less efficiently than CYFIP1. Point mutations of CYFIP2 associated with intellectual disability in children were gain-of-function, as they made CYFIP2 as active as CYFIP1 in this rescue experiment. Biochemical reconstitutions of CYFIP2-containing WAVE complexes showed that they bound equally well to active RAC1 as CYFIP1-containing WAVE complexes, yet they were poorly activated in response to RAC1 binding. Together these results suggest that CYFIP2-containing WAVE complexes titrate active RAC1 and thereby prevent efficient CYFIP1-containing complexes from being activated. In this context, where cell migration is governed by the balance of CYFIP1/2 expression, releasing the restrained activity of CYFIP2-containing WAVE complexes leads to pathology.

cell biology↗