The dynamic mechanical adaptation of keratocytes squeezed on 2D micropatterns

Danahe Mohammed^a, Sylvain Gabriele^a, Guillaume Charras^b

^a1Mechanobiology & Soft Matter group, Research Institute for Biosciences, University of Mons, B-7000, Mons

^bLondon Centre for Nanotechnology, University College of London, 17–19 Gordon Street, London WC1H 0AH

Proceedings of New Advances in Probing Cell-ECM Interactions (CellMatrix)

Berlin, Germany, 2016 October 20th - 21st

Organizers: Ovijit Chaudhuri, Allen Liu and Sapun Parekh

Poster, Danahe Mohammed, 062
Publication date: 25th July 2016

Epithelial cell migration plays a central role in development and wound repair but it can also lead to the organism death by allowing metastatic cells to invade new organs. To migrate in confined environments imposed in vivo by neighbors and the extracellular matrix [1], epithelial cells need to change their shape and squeeze through narrow gaps [2]. Despite rapid advances in this field, many challenges remain to understand the mechanisms of epithelial migration in confined environments.To address this issue, we have studied the migration of fishepithelialkeratocytes squeezed on adhesive micropatternsof various widths and geometries that produce in vitroa well-defined 2D confinement by imposing specific boundary conditions. By tracking the migration of single keratocytes with time-lapse microscopy, we show that cell confinement modulates the fraction of polarized cells andtheir migrating speed. We developed a mechanical force assays based on an AFM cantilever to demonstrate that the lamellipodialprotusive force decreases with confinement and is linearly proportional to the cell velocity. We show that the density of vinculin-containing adhesionsdecreases on narrow tracks, suggesting that confined cells exert lower contractile forces.Interestingly, we used AFM imaging to show that modifications of the migrating parameters are also associated with large modifications of the 3D cell morphology. Indeed, the height of the cell body decreases from ~3.5 µm to ~1.5 µm in confined cells, whereas the lamellipodial thickness increases up to 700 nm. By combining confocal imaging and time-lapse assays on funnel-like micropatterns, we show that the dynamic mechanical adaptation of moving epithelial cells to confined environments is composed of three distinct stages that depend on drastic changes of the spatial organization of actin and microtubule networks. On the basis of these findings, we propose a simple mechanical model that quantitatively accounts for our experimental data and provides a conceptual framework for the mechanical adaptation of keratocytes that migrate in confined 2D epithelial tissues.

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