Mechanical signal transduction is fundamental to numerous cellular processes, particularly on membrane-anchored receptors such as integrins, acting as mechanosensors. Integrins exhibit force-dependent conformational transitions in response to mechanical loads in the piconewton range, a force scale equivalent to molecular interactions within the cell. In physiological frameworks, integrins are subjected to unidirectional forces and complex multi-axial mechanical stresses. These include hemodynamic shear, substrate-induced deformations, and cytoskeletal tractions, which influence integrin conformations, and downstream signaling. Understanding how integrins integrate and respond to these vectoral force components is essential for elucidating their role in mechanotransduction pathways relevant to cardiovascular function, and cancer metastasis. Despite the known sensitivity of integrins to mechanical inputs, existing biophysical tools primarily apply forces in a single axis, limiting our understanding of how integrins respond to the more complex mechanical environments found in vivo. To address this, a circular DNA origami imposes multi-directional forces on single integrin molecules. This platform uses programmable DNA springs to exert tension along orthogonal axes, enabling precise modulation of mechanical load on integrins. We aim to study integrin conformational states under varying tension with single-molecule FRET to monitor real-time structural dynamics. By incrementally adjusting the force along each axis, we expect to resolve transitions between the bent, extended-closed, and extended-open conformations of integrins. Moreover, coupling this force application with cryo-EM imaging will allow structural visualization of these tension-induced states at high resolution. This approach has the potential to reveal intermediate and transient conformations of integrins that are otherwise difficult to capture under conventional force assays. The insights gained could elucidate the biophysical principles of integrin activation and mechanotransduction. Our method represents a valuable advance for studying the mechanical basis of integrin function and could inform tuned therapeutic strategies targeting integrins in diseases.
Karna et al. (Sun,) studied this question.