Positioning the nucleus for cell migration and muscle fiber function

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Publications

Ctdnep1 and Eps8L2 regulate dorsal actin cables for nuclear positioning during cell migration

Publication . Calero-Cuenca, Francisco J.; Osorio, Daniel S.; Carvalho-Marques, Sofia; Sridhara, Sree Rama Chaitanya; Oliveira, Luis M.; Jiao, Yue; Diaz, Jheimmy; Janota, Cátia; Cadot, Bruno; Gomes, Edgar

Cells actively position their nuclei within the cytoplasm for multiple cellular and physiological functions.1-3 Consequently, nuclear mispositioning is usually associated with cell dysfunction and disease, from muscular disorders to cancer metastasis.4-7 Different cell types position their nuclei away from the leading edge during cell migration.8-11 In migrating fibroblasts, nuclear positioning is driven by an actin retrograde flow originated at the leading edge that drives dorsal actin cables away from the leading edge. The dorsal actin cables connect to the nuclear envelope by the linker of nucleoskeleton and cytoskeleton (LINC) complex on transmembrane actin-associated nuclear (TAN) lines.12-14 Dorsal actin cables are required for the formation of TAN lines. How dorsal actin cables are organized to promote TAN lines formation is unknown. Here, we report a role for Ctdnep1/Dullard, a nuclear envelope phosphatase,15-22 and the actin regulator Eps8L223-25 on nuclear positioning and cell migration. We demonstrate that Ctdnep1 and Eps8L2 directly interact, and this interaction is important for nuclear positioning and cell migration. We also show that Ctdnep1 and Eps8L2 are involved in the formation and thickness of dorsal actin cables required for TAN lines engagement during nuclear movement. We propose that Ctdnep1-Eps8L2 interaction regulates dorsal actin cables for nuclear movement during cell migration.

2021Journal article

Open access

Shielding of actin by the endoplasmic reticulum impacts nuclear positioning

Publication . Janota, Cátia; Pinto, Andreia; Pezzarossa, Anna; Machado, Pedro; Costa, Judite; Campinho, Pedro; Franco, Claudio; Gomes, Edgar

Nuclear position is central to cell polarization, and its disruption is associated with various pathologies. The nucleus is moved away from the leading edge of migrating cells through its connection to moving dorsal actin cables, and the absence of connections to immobile ventral stress fibers. It is unclear how these asymmetric nucleo-cytoskeleton connections are established. Here, using an in vitro wound assay, we find that remodeling of endoplasmic reticulum (ER) impacts nuclear positioning through the formation of a barrier that shields immobile ventral stress fibers. The remodeling of ER and perinuclear ER accumulation is mediated by the ER shaping protein Climp-63. Furthermore, ectopic recruitment of the ER to stress fibers restores nuclear positioning in the absence of Climp-63. Our findings suggest that the ER mediates asymmetric nucleo-cytoskeleton connections to position the nucleus.

2022Journal article

Open access

Nesprins are mechanotransducers that discriminate epithelial-mesenchymal transition programs

Publication . Déjardin, Théophile; Carollo, Pietro Salvatore; Sipieter, François; Davidson, Patricia M; Seiler, Cynthia; Cuvelier, Damien; Cadot, Bruno; Sykes, Cecile; Gomes, Edgar; Borghi, Nicolas

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.

2020Journal article

Open access