Local shear signals propagate to suppress local cellular motion in stiff epithelia

TL;DR

This study investigates how localized shear forces propagate through epithelial layers, revealing that in stiffer tissues, shear suppresses cell movement and influences tissue mechanics, with implications for understanding tissue responses to mechanical stimuli.

Contribution

Developed a mesoscopic probe to apply and study local shear effects on epithelial monolayers, revealing propagation and suppression of cellular dynamics in stiff tissues.

Findings

Localized shear propagates beyond immediate neighbors.

Shear suppresses cell migration in stiffer layers.

Stiffening soft layers enhances shear responsiveness.

Abstract

As small particles skim our airways during breathing, or our intestines during digestion, the surface epithelium is subjected to local exogenous shear that deforms hundreds to thousands of tightly interacting cells. Unlike shear deformations applied at the macro-tissue scale or the micro-cell scale, the effects of such perturbations at the meso-scale remain largely unexplored. To address this, we developed a mesoscopic probe that adheres to the apical surface of an epithelial monolayer and applies magnetically derived local shear. We find that localized shear propagated way beyond immediate neighbors and suppressed cellular migratory dynamics in stiffer layers, yet dissipated locally and left dynamics unchanged in softer layers. This mechano-transductive view is reinforced by the observation that stiffening of a soft layer promotes responsiveness to shear. Interpreted within the epithelial jamming framework, shear-induced migratory suppression in stiff layers was accompanied by reduced MSD scaling exponents and changes in cell shape. These changes suggested a localized shift of the tissue toward a lower-energetic state. Together, these observations provide a new perspective on how a local mechanical perturbation traverses the epithelial monolayer to influence both nearby and distant cellular environments.