Effect of Actomyosin Contractility on Lamellipodial Protrusion Dynamics on a Micropatterned Substrate

Abstract

Actin polymerization-driven protrusion of the lamellipodia is a requisite initial step during actin-based cell migration, and is closely associated with attachment to the substrate. Although tremendous progress has been made in recent years toward elucidating the molecular details of focal adhesions, our understanding of the basic coordination of protrusion and adhesion, and how the two fundamental processes relate to actomyosin contractility is still inadequate. Therefore, to highlight the effect of cell-substrate interactions on the protrusive dynamics of the lamellipodia and to correlate protrusion with actomyosin activities, this study investigated the migration of fish epidermal keratocytes on fibronectin micropatterns intercalated with adhesionsuppressed gaps of varying widths. We show that insufficient adhesion associated with the gaps could limit lamellipodial protrusion such that the percentage of migrating cells decreases with an increase in gap width, and protrusion across the gaps is accompanied by ruffling. Moreover, our results suggest that up-regulating actomyosin contractility enhances the mechanical integrity of the actin cytoskeleton, leading to an increase in the width of the lamellipodia, and consequently, an increase in the percentage of cells migrating across the gaps. Thus, we demonstrate that the protrusion dynamics at the leading edge of migrating cells are functionally involved in the global mechanical regulation of actin cytoskeletal components that enable cell migration.

Symmetry‐breaking in branching epithelia: cells on micro‐patterns under flow challenge the hypothesis of positive feedback by a secreted autocrine inhibitor of motility

“…Live imaging of the micro-patterned Lifeact-MDCK also enabled limited observation of actin-based dynamics on the apical surfaces of cells. This surface showed ruffles, which are folds in the surface of cells associated with compacted actin that move centripetally from the cell periphery and are associated with frustrated adhesion of motile cells (Borm et al 2005;Giannone et al 2007;Okeyo et al 2011). One representative ruffle is highlighted in Fig.…”