Nesprins are mechanotransducers that discriminate epithelial-mesenchymal transition programs

© 2020 Déjardin et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms/). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 International license, as described at https://creativecommons.org/licenses/by-nc-sa/4.0/).LINC complexes are transmembrane protein assemblies that physically connect the nucleoskeleton and cytoskeleton through the nuclear envelope. Dysfunctions of LINC complexes are associated with pathologies such as cancer and muscular disorders. The mechanical roles of LINC complexes are poorly understood. To address this, we used genetically encoded FRET biosensors of molecular tension in a nesprin protein of the LINC complex of fibroblastic and epithelial cells in culture. We exposed cells to mechanical, genetic, and pharmacological perturbations, mimicking a range of physiological and pathological situations. We show that nesprin experiences tension generated by the cytoskeleton and acts as a mechanical sensor of cell packing. Moreover, nesprin discriminates between inductions of partial and complete epithelial-mesenchymal transitions. We identify the implicated mechanisms, which involve α-catenin capture at the nuclear envelope by nesprin upon its relaxation, thereby regulating β-catenin transcription. Our data thus implicate LINC complex proteins as mechanotransducers that fine-tune β-catenin signaling in a manner dependent on the epithelial-mesenchymal transition program.This material is based on work supported by the Centre national de la recherche scientifique (CNRS), Agence nationale de la recherche (ANR; grants ANR-13-JSV5-0007 and ANR-14-CE09-0006), France BioImaging (ANR-10-INBS-04), la Ligue contre le Cancer (REMX17751 to P.M. Davidson), and the Fondation ARC pour la Recherche sur le Cancer (PDF20161205227 to P.M. Davidson). P.S. Carollo has received funding from the European Union’s Horizon 2020 Framework Programme for Research and Innovation (Marie Skłodowska-Curie grant agreement 665850-INSPIRE) and acknowledges the Ecole Doctorale Frontières de l'Innovation en Recherche et Éducation (FIRE) Programme Bettencourt. E.R. Gomes was supported by a European Research Council consolidator grant (617676).info:eu-repo/semantics/publishedVersio

Src- and confinement-dependent FAK activation causes E-cadherin relaxation and β-catenin activity

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Nesprin‐2 accumulates at the front of the nucleus during confined cell migration

International audienceThe mechanisms by which cells exert forces on their nuclei to migrate through openings smaller than the nuclear diameter remain unclear. We use CRISPR/Cas9 to fluorescently label nesprin-2 giant, which links the cytoskeleton to the nuclear interior. We demonstrate that nesprin-2 accumulates at the front of the nucleus during nuclear deformation through narrow constrictions, independently of the nuclear lamina. We find that nesprins are mobile at time scales similar to the accumulation. Using artificial constructs, we show that the actin-binding domain of nesprin-2 is necessary and sufficient for this accumulation. Actin filaments are organized in a barrel structure around the nucleus in the direction of movement. Using two-photon ablation and cytoskeleton-inhibiting drugs, we demonstrate an actomyosin-dependent pulling force on the nucleus from the front of the cell. The elastic recoil upon ablation is dampened when nesprins are reduced at the nuclear envelope. We thus show that actin redistributes nesprin-2 giant toward the front of the nucleus and contributes to pulling the nucleus through narrow constrictions, in concert with myosin