Colloquium on December 14, 2009

Pierre Sens
Laboratoire de Physico-Chimie Théorique, CNRS-ESPCI, Paris

Membrane-cytoskeleton interactions and mechanical regulation at the cell interface

Biological cells are able to cope with mechanical perturbations from the outside world, such as osmotic shocks. Cells are also able to generate mechanical stress that allows for shape changes and motility. Many of the mechanisms allowing this versatile behaviour occur at the cell interface, and involve physical interactions between the cell membrane and the underlying cytoskeleton, the meshwork of biopolymer and molecular motors able to convert chemical energy into mechanical forces. In this talk, I will describe our theoretical and experimental efforts to understand membrane cytoskeleton interaction from the study of cellular blebs. Blebs are micron-size spherical membrane blisters transiently appearing at the plasma membrane following membrane detachment from the cytoskeleton, and retracting after cytoskeleton rejuvenation. We will see that blebbing can be induced by subjecting cells to important mechanical perturbations, and that the disappearance of blebs can be linked to membrane homeostasis by endo and exocytosis. Blebs are also actively generated by some cells and can be harnessed for motility. I will describe a combination of theoretical modeling and experimental observations that illustrate the dynamical nature of membrane-cytoskeleton interactions. We will see that subjecting the cell to a controlled mechanical perturbation can lead to a variety of responses, including remarkable spontaneous oscillations of mostly physical origin.