Abstract
Focal adhesions are force-sensitive, multiprotein complexes that anchor cells to the extracellular substrate. Previous studies have revealed the composition, ultrastructure, and dynamics of focal adhesions, and how they change upon intracellular and/or extracellular forces. However, little is known regarding how focal adhesions sense the geometry of the extracellular substrate. Here we develop a novel traction microscopy that allows for simultaneous evaluation of the cellular forces and the effect of local substrate curvature, i.e. how the substrate is curved out of the plane to have a 2.5D surface. While it is well known that force-induced elongation of focal adhesions occurs on a flat surface, here we interestingly found that the dynamics of individual focal adhesions is abrogated by a certain level of local substrate curvature, or 2.5D substrates. Thus, further development of focal adhesions is allowed only when they retain a straight shape on a planar surface.
