Cell-extracellular matrix sensing plays a crucial role in cellular behavior and leads to the formation of a macromolecular protein complex called the focal adhesion. Despite their importance in cellular decision making, relatively little is known about cell-matrix interactions and the intracellular transduction of an initial ligand-receptor binding event on the single-molecule level. Here, we combine cRGD-ligand-decorated DNA tension sensors with DNA-PAINT super-resolution microscopy to study the mechanical engagement of single integrin receptors and the downstream influence on actin bundling.
Fig: Single-receptor tension sensor: Biotinylated DNA-based hairpin sensors are immobilized on a streptavidin-coated glass surface. The location of the sensor is super-resolved via DNA-PAINT microscopy by sequence-specific targeting of the blue-colored DNA sequence. Upon cell attachment and integrin-binding of the cRGD motif on the sensor, the hairpin is opened, and the extended sensor conformation can be detected by DNA-PAINT through targeting of a previously sequestered orange-colored sequence. Subsequent binding of focal adhesion proteins such as talin to the beta-integrin tail eventually leads to a full force transduction path and coupling to intracellular actin filaments.
We uncover that integrin receptor clustering is governed by a non-random organization with complexes spaced at 20–30 nm distances. The DNA-based tension sensor and analysis framework provide powerful tools to study a multitude of receptor-ligand interactions where forces are involved in ligand-receptor binding.
Schlichthaerle, T., Lindner, C. & Jungmann, R. Super-resolved visualization of single DNA-based tension sensors in cell adhesion.Nat Commun 12, 2510 (2021). https://doi.org/10.1038/s41467-021-22606-1