Contractile myosin rings and cofilin-mediated actin disassembly orchestrate ECM nanotopography sensing

Thomas Iskratsch,Stefania Di Cio,Julien E Gautrot,John T Connelly

doi:10.1016/j.biomaterials.2019.119683

Thomas Iskratsch, Stefania Di Cio + Show 2 more

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https://doi.org/10.1016/j.biomaterials.2019.119683

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Journal: Biomaterials	Publication Date: Dec 16, 2019
Citations: 16	License type: cc-by

Affiliation: Queen Mary University of London

Abstract

The nanotopography and nanoscale geometry of the extra-cellular matrix (ECM) are important regulators of cell adhesion, motility and fate decision. However, unlike the sensing of matrix mechanics and ECM density, the molecular processes regulating the direct sensing of the ECM nanotopography and nanoscale geometry are not well understood. Here, we use nanotopographical patterns generated via electrospun nanofibre lithography (ENL) to investigate the mechanisms of nanotopography sensing by cells. We observe the dysregulation of actin dynamics, resulting in the surprising formation of actin foci. This alteration of actin organisation is regulated by myosin contractility but independent of adapter proteins such as vinculin. This process is highly dependent on differential integrin expression as β3 integrin expressing cells, more sensitive to nanopattern dimensions than β1 integrin expressing cells, also display increased perturbation of actin assembly and actin foci formation. We propose that, in β3 integrin expressing cells, contractility results in the destabilisation of nanopatterned actin networks, collapsing into foci and sequestering regulators of actin dynamics such as cofilin that orchestrate disassembly. Therefore, in contrast to the sensing of substrate mechanics and ECM ligand density, which are directly orchestrated by focal adhesion assembly, we propose that nanotopography sensing is regulated by a long-range sensing mechanism, remote from focal adhesions and mediated by the actin architecture.

Highlights

Cell adhesion to the extra-cellular matrix (ECM) constitutes an important determinant of cell phenotype and plays an essential role in the maintenance of stem cell niches and tissue homeostasis [1,2,3,4]
Our results demonstrate that nanotopography sensing is regulated by different molecular mechanisms than the sensing of substrate mechanics and that of ligand molecular distribution (Fig. 8), yet is sensitive to the type of integrin heterodimers expressed
Β1 expressing cells are relatively insensitive to nanopattern dimensions, at least in the range tested, β3 expressing cells are found to be sensitive to nanofibre width

Summary

Introduction

Cell adhesion to the extra-cellular matrix (ECM) constitutes an important determinant of cell phenotype and plays an essential role in the maintenance of stem cell niches and tissue homeostasis [1,2,3,4]. Cell adhesions are modulated by nanoscale physical properties of the ECM, such as the mechanical properties of the matrix [11,12], the topography [13,14] and the geometry with which adhesive ligands are presented [15,16,17,18] In these interactions, two important principles mediate the sensing of the physical properties of the ECM by cell adhesions: the molecular clutch that regulates mechanosensing [19] and ligand clustering that is controlled by the geometry and distribution of the adhesive landscape [20,21]. The mechanism controlling cell sensing of the nanotopography and nano- to micro-scale geometry of adhesive ligands (regulating the size and shape of adhesions rather than early recruitment and clustering of membrane receptors) remains poorly understood.

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