PIEZO1 Mediated Currents are Modulated by Substrate Mechanics.

PIEZO1 is a bona fide mammalian mechanically activated channel that has recently been shown to provide instructive cues during neuronal specification, texture sensing and cell migration where mechanical inputs arise at the interface between the cells and their substrate. Here, we have investigated whether the mechanical properties of the substrate alone can modulate PIEZO1 activity, in response to exogenously applied stimuli, using elastomeric pillar arrays as force transducers. This methodology enables application of mechanical stimuli at cell-substrate contact points by deflecting individual pili. We found that PIEZO1 is more sensitive to substrate deflections with increased spacing between pili (reducing surface roughness), but not on more stiff substrates. Cellular contractility was required for the sensitization of PIEZO1 but was not essential for PIEZO1 activation. Computational modelling suggested that the membrane tension changes generated by pillar deflections were below the membrane tension changes that arise from cellular indentation or high-speed pressure clamp assays. We conclude that the mechanics of the microenvironment can modulate PIEZO1 signaling, highlighting the importance of studying channel activation directly at the cell-substrate interface. We propose that forces arising from actin-mediated contractility and within the lipid bilayer act synergistically to regulate PIEZO1 activation by stimuli applied at contacts between cells and their surroundings.