Role of Caveolae in Membrane Mechanics

Caveolae, the characteristic plasma membrane invaginations present in many cells, have been associated with numerous functions that still remain debated. Taking into account the particular abundance of caveolae in cellsexperiencing mechanical stress, it was proposed that caveolae constitute a membrane reservoir and buffer the membrane tension upon mechanical stress. The present work aimed to check this proposition experimentally. First, the influence of caveolae on the membrane tension was studied on mouse lung endothelial cells in resting conditions using tether extraction with optically trapped beads. Second, experiments on cells upon acute mechanical stress showed that caveolae serve as a membrane reservoir buffering surges in membrane tension in their immediate, ATP- and cytoskeleton-independent flattening and disassembly. Third, caveolae incorporated in membrane vesicles also showed the tension buffering. Finally, in a physiologically more relevant case, human muscle cells were studied, and it was shown that mutations with impaired caveolae (described in muscular dystrophies) render muscle cells less resistant to mechanical stress.