Self-Assembly and Growth of Intercellular Junctions in Response to Membrane Tension and Cytoskeletal Contraction

Mechanical forces are crucial to the regulation of different aspects of cellular phenotype. These forces are transmitted between cells primarily through the bonds of intercellular junctions. A striking feature of cell adhesion junctions is their ability to sense and respond to force. It is known that the size of the junctions correlates with the magnitude of transmitted traction. In this study, we present a physical model for the interaction between two flexible membranes conjugated by a number of mobile bonds. The membranes have finite bending rigidity and are subjected to membrane tension and intracellular contraction. Implementing the first and second laws of thermodynamics, we derived the fundamental equations that control the self-assembly or growth kinetics of the junction. We predict that the junction may grow or shrink in size depending on the magnitude of membrane tension. More importantly, an increase in intracellular contraction always leads to spontaneous growth of the junctions. The balance between the lateral osmotic pressure of aggregated bonds, inter-membrane repulsive pressure, and elastic energy density of deformed membranes controls the equilibrium size of the junction. These passive sensory functions are purely mechanistic, independent from any internal signaling within the cells.