Transduction of Substrate Mechanical Cues via Piezo1 Ion Channels

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This award will advance our fundamental understanding of how cells sense and react to diverse mechanical inputs from their environments. Cells utilize local environmental cues from the extracellular matrix (ECM), adhesive molecules, and local stiffness to make decisions about growth and movement. The process of converting mechanical stimulus to electrical energy at the ECM is commonly thought to act via adhesion proteins such as integrins. Emerging research on Piezo ion channels reveals that these channels can also respond to changes in the substrate mechanical properties. Therefore, these channels may serve as additional force sensors. This work will explore the role of a novel cell sensor, called Piezo1, in detecting ECM forces. The results may ultimately impact on human health. For example, the body’s mishandling of these mechanical signals results in a variety of diseases, including chronic kidney disease and cancer. The results of this work may lead to new types of treatment for these conditions. The outcome has the potential to be broadly applicable, since Piezo1 is found in many cell types and organs where the mechanical environment plays a major role in proper function. The research findings will be integrated into outreach activities through an Education through Experimentation (E2E) platform that involves graduate, undergraduate, and local high school students in this project.The project is based on the hypothesis that Piezo1 is the primary force sensor in epithelial cells, and that it detects the substrate mechanical cues translated into membrane tension. This occurs through a feedforward mechanism: local tension activates Piezo1 channels and calcium influx, which stimulates calcium-dependent contractility and cell spreading; the changes in cell geometry in turn, promote more Piezo1 activity and the migration of Piezo1 to regions under stress, causing further growth in the same direction. This hypothesis will be tested with substrate modulation as mechanical stimulus, a FRET-based fluorescent probe to report opening transitions in Piezo1, and a wound healing assay to screen cell mobility. There are three primary objectives. First, to identify ECM force sensors in cells by inhibiting Piezo1 activity and by knockdown of Piezo1. Second, to investigate how substrates alter Piezo1 responsiveness by visualizing the location and opening of channels during cell reshaping. Third, to test the hypothesis that functional Piezo1 expression level determines the identity of leader cells guiding collective cell migration. Taken together, the results of this work have the potential to transform our understanding of the mechanisms of various disease states that affect epithelial cells.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.