Membrane Homeostasis: The Role of Actin Cytoskeleton

Abstract

The plasma membrane of a cell undergoes continuous deformations and turning-over of its constituents required for a diverse set of functions. And yet, the membrane retains its steady-state surface tension—without which these functions are adversely affected. In this review, we discuss how the establishment and maintenance of the homeostatic state of the membrane has a major contribution from the actin cytoskeleton. The regulation of tension at the global (or cellular) scale is extensively studied for the past few decades, leading to our understanding of how actin polymerization forces, myosin-II based contractile forces, and ezrin-mediated attachment to the membrane—each have a separate and sometimes multiple possible effects on membrane tension. Drawing examples from cell motility and blebbing cells, we highlight how the dynamics of the cytoskeleton decides if the steady-state tension has a uniform profile, front-rear gradients, or temporally varying tension profiles in single cells. Non-invasive studies open up new avenues especially allowing the investigations focusing on local regulation of tension—at the plasma membrane and inside cells.