DNA mechanotechnology reveals that integrin receptors apply pN forces in podosomes on fluid substrates

Abstract

Podosomes are ubiquitous cellular structures important to diverse processes including cell invasion, migration, bone resorption, and immune surveillance. Structurally, podosomes consist of a protrusive actin core surrounded by adhesion proteins. Although podosome protrusion forces have been quantified, the magnitude, spatial distribution, and orientation of the opposing tensile forces remain poorly characterized. Here we use DNA nanotechnology to create probes that measure and manipulate podosome tensile forces with molecular piconewton (pN) resolution. Specifically, Molecular Tension-Fluorescence Lifetime Imaging Microscopy (MT-FLIM) produces maps of the cellular adhesive landscape, revealing ring-like tensile forces surrounding podosome cores. Photocleavable adhesion ligands, breakable DNA force probes, and pharmacological inhibition demonstrate local mechanical coupling between integrin tension and actin protrusion. Thus, podosomes use pN integrin forces to sense and respond to substrate mechanics. This work deepens our understanding of podosome mechanotransduction and contributes tools that are widely applicable for studying receptor mechanics at dynamic interfaces.

Crosstalk between Cell Adhesion Complexes in Regulation of Mechanotransduction

“…[52] Recent work by Glazier et al showed that integrins residing in the podosomal ring surrounding its actin core apply tensile forces on RGD ligands needed for podosome stability and maturation. [53] However, these tensile forces are controlled by the polymerization of the actin core but not by actomyosin contractions in the podosomal ring [53] and seem to be the result of local forces needed to stabilize actin protrusion into the ECM. Indeed, the integrity of the podosomal ring is needed to support actin polymerization and protrusion at the core, as depletion of talin and vinculin decreases protrusion force.…”

Mechanical Characterization for Cellular Mechanobiology: Current Trends and Future Prospects

“…Cellsubstrate interactions are also highly relevant to assess mechanotransduction and techniques such as traction force microscopy and magnetic tweezers can be applied to survey such interactions. Forces in the order of pico-Newtons, applied by integrins on ligands, have also been assessed by DNA mechanotechnology (Brockman et al, 2018;Glazier et al, 2019;. However, significant challenges regarding the integrity of the DNA probes in cell culture conditions and the type of receptor-ligand interactions that can be probed remain (Ma and Salaita, 2019;Yasunaga et al, 2019).…”

Meeting Report – Workshop ‘Actin-based mechanosensation and force generation in health and disease’

“…The second demonstration of mechanical proofreading highlighted the role of forces in podosome formation. In this context, actin-pushing forces generated in podosomes depend on specific picoNewton-scale pulling forces that are applied by integrin receptors in the ring complex (Glazier et al, 2019).…”