Biology subjects

Coirault, C.

Publications and source records attributed to Coirault, C..

4 recordsLinked to original sources

bioRxiv2024

A Variational Autoencoder Model for Clustering of Cell Nuclei on Microgroove Substrates: Potential for Disease Diagnosis

Various diseases including laminopathies and certain types of cancer are associated with abnormal nuclear mechanical properties that influence cellular and nuclear deformations in complex environments. Recently, microgroove substrates designed to mimic the anisotropic topography of the basement membrane have been shown to induce significant 3D nuclear deformations in various adherent cell types. Importantly, these deformations are different in myoblast cells derived from laminopathy patients from those in cells derived from normal individuals. Here we assess the ability of a variational autoencoder (VAE) and a Gaussian Mixture Model (GMM) to cluster patches of nuclei of both wildtype myoblast cells and myoblast cells with laminopathy-associated mutations cultured on microgroove substrates, and we explore the impact of image processing parameters on clustering performance. We show that a standard VAE with GMM is able to cluster nuclei based on their morphologies and degrees of deformations and that these clusters correspond to either wildtype myoblasts or myoblasts with LMNA mutations. The current results suggest that combining deep learning techniques with microgroove substrates enables automatic classification of nuclear deformations and thus provides a promising approach for easy and rapid diagnosis of pathologies that involve abnormalities in nuclear deformation.

cell biology↗

bioRxiv2024

Microgroove substrates unveil topography-driven, dynamic 3D nuclear deformations

Navigating complex extracellular environments requires extensive deformation of cells and their nuclei. Nuclear deformations are intricately linked to nuclear structure and mechanical properties, and abnormalities in nuclear mechanics contribute to various diseases including laminopathies and cancer. Most in vitro systems used to study nuclear deformations are typically designed to generate strong whole-cell confinement relevant for specific cell types such as immune or cancer cells. Here, we use microgroove substrates as a model of anisotropic basement membrane topography and we report that adherent cells including endothelial cells and myoblasts exhibit significant 3D (in-plane and out-of-plane) nuclear deformations, with partial to complete penetration into the microgrooves. These deformations are dynamic with nuclei cyclically entering and exiting the microgrooves. AFM measurements show that these deformation cycles are accompanied by transient changes in nuclear mechanical properties. We also show that nuclear penetration into the grooves is principally driven by cell-substrate adhesion, without the need for cytoskeleton-associated forces. Finally, we demonstrate that myoblasts from patients with LMNA mutations exhibit abnormal nuclear deformations which can be rapidly identified and quantified using automated image analysis. We therefore propose the use of microgrooves as a novel simple, tunable, and high throughput system to study nuclear deformations in adherent cells, with the potential to serve as a functional diagnostic platform for pathological alterations in nuclear mechanics.

cell biology↗

bioRxiv2020

Lamin-related congenital muscular dystrophy alters mechanical signaling and skeletal muscle growth

BackgroundLaminopathies are a clinically heterogeneous group of disorders caused by mutations in the LMNA gene, which encodes the nuclear envelope proteins lamins A and C. The most frequent diseases associated with LMNA mutations are characterized by skeletal and cardiac involvement, and include autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD), limb-girdle muscular dystrophy type 1B, and LMNA-related congenital muscular dystrophy (LMNA-CMD). Although the exact pathophysiological mechanisms responsible for LMNA-CMD are not yet understood, severe contracture and muscle atrophy suggest that impair skeletal muscle growth may contribute to the disease severity. MethodsWe used human muscle stem cells (MuSCs) carrying 4 different LMNA mutations and two mouse models of muscle laminopathies, representing a spectrum of disease severity, to investigate the ability of skeletal muscle to differentiate and to hypertrophy in response to mechanical challenges. We extended these finding to individuals with LMNA-related muscular dystrophy using muscle biopsies. ResultsIn vitro, we observe impaired myogenic differentiation with disorganized cadherin/{beta} catenin adhesion complexes in MuSCs carrying LMNA-CMD. We show that skeletal muscle from Lmna-CMD mice is unable to hypertrophy in response to functional overload, due to defective accretion of activated MuSCs, defective protein synthesis and defective remodeling of the neuro-muscular junction. Moreover, stretched myotubes and overloaded muscle fibers with LMNA-CMD mutations display aberrant mechanical regulation of the Yes-Associated Protein (YAP), a key sensor and mediator of mechanical cues. We also observe defects in MuSC activation and YAP signaling in muscle biopsies from LMNA-CMD patients. These phenotypes are not recapitulated in closely-related EDMD models. ConclusionsCombining studies in vitro, in vivo and patient samples, we find that LMNA-CMD mutations interfere with mechano-signaling pathways in skeletal muscle, implicating defective skeletal muscle growth as a pathogenic contributor for the severity of LMNA-related muscular dystrophy.

physiology↗

bioRxiv2018

Clathrin plaques form mechanotransducing platforms

Large flat clathrin plaques are stable features of the plasma membrane associated with sites of strong adhesion suggesting that they could also play a role in force transduction. Here, we analyzed how clathrin plaques interact with the cytoskeleton and how they respond to mechanical cues in skeletal muscle myotubes. We show that branched actin networks surrounding clathrin plaques are directly regulated by dynamin 2, anchor intermediate filaments and sequester YAP at the plasma membrane. Dynamin 2, clathrin and desmin intermediate filaments are all required for basal YAP nucleocytoplasmic distribution and efficient nuclear translocation in response to mechanical stimuli. Dynamin 2 mutations that are responsible for centronuclear myopathy in humans disorganize the desmin network and deregulate YAP signaling both in vitro and in vivo. Thus, clathrin plaques and associated dynamin 2 are defined here as a new sensor conveying mechanical cues and integrate cell signaling with cytoskeletal regulation.

cell biology↗