Collective properties of plasma membrane components are hypothesized to play important roles in how cells sense and respond to tension. For example, caveolae protect against tension by flattening to release a reservoir of membrane. The lipids freed as a result are thought to modulate the biophysical properties of the membrane and to participate in signaling. Similarly, the properties of the curved membrane dome and footprint surrounding the mechanosensitive ion channel Piezo1 are thought to contribute to its gating. In this study, we use Exchange-PAINT microscopy to directly image the local membrane composition of these structures in chemically fixed cells. Exchange-PAINT achieves a resolution of <10 nm and enables us to directly compare the sorting of multiple membrane components within single cells. We found that a GPI-linked fluorescent protein is enriched in the center of caveolae, while an inner-leaflet probe was excluded. These results support the hypothesis that cav1 disks displace inner leaflet lipids, and that caveolae stabilize a distinct lipid environment in the outer leaflet. Using the same approach, we found that Piezo1 also displaces lipids but locally enriches markers of lipid disorder relative to an order-preferring probe. Ongoing work is aimed at further characterizing the lipid environment of caveolae and of Piezo1.
Rogers et al. (Sun,) studied this question.