Membrane curvature governs the distribution of Piezo1 in live cells.

Abstract

Piezo1 is an evolutionarily conserved mechanosensitive ion channel in eukaryotic cells. Since its discovery, vital biological roles of Piezo1 have been found in cell migration, cell-cell adhesion and cell differentiation, featuring Piezo1's force sensing capability. However, mechanosensitive Ca2+ signals in filopodia were reported to be independent of Piezo1. Moreover, inhomogeneous distributions of Piezo1 were observed in cell migration, cytokinesis, and on the surface of red blood cells. Understanding the subcellular distribution of Piezo1 can be critical for explaining many biological processes. Using live cell fluorescence microscopy, first, we show that Piezo1 is depleted from highly curved membrane protrusions, such as filopodia and manually pulled membrane tethers. Further experiments on nanopatterned substrates show an enrichment of Piezo1 to membrane invaginations. The correlation between Piezo1 density and membrane curvature fits well to a 2-parameter membrane bending model, revealing the nano-geometries of Piezo1-membrane complexes. Chemically activated Piezo1 has higher density on filopodia, with or without Ca2+. These observations are consistent with flattening of Piezo1 upon activation. Furthermore, Piezo1 expression mechanically suppresses filopodia formation, an effect that is weakened by chemical activation.