Single-Molecule Tracking and Super-Resolution Microscopy Unveil Actin-Driven Membrane Nanotopography Shaping Stable Integrin Adhesions in Developing Tissue.

Single molecule tracking and super-resolution microscopy of integrin adhesion proteins and actin in developing Drosophila muscle attachment sites reveals that nanotopography triggered by Arp2/3-dependent actin protrusions promotes stable adhesion formation. The nanodomains formed during this process confine the diffusion of integrins and promote their immobilization. Spatial confinement is also applied to the motion of actin filaments, resulting in enhanced mechanical connection with the integrin adhesion complex. Fabricated nano-structured surfaces mimicking the nanotopography observed in living tissue are able to recapitulate the formation of these adhesions in isolated muscle cells and the confinement of integrin diffusion. These results emphasize the importance of geometrical regulation of tissue morphogenesis at a single molecule level.