DNA-based molecular force sensors in reconstituted actin networks*

Actin, a major cytoskeletal biopolymer of eukaryotic cells self-assembles into networks of crosslinked filaments and bundles and is largely responsible for cellular shape and mechanical stability. Actin assemblies are also responsible for active cellular processes ranging from migration, division and intracellular transport to morphogenesis. Crucial for such processes is the spatial and temporal regulation of the structure and dynamics of the networks and the generation of force, mostly by myosin motors. To measure forces in cytoskeletal networks, we have developed a FRET based molecular force sensor consisting of a DNA hairpin loop, which can be cross-linked into actin networks. We characterized the force sensor via fluorescence lifetime imaging.