Integrin molecular tension required for focal adhesion maturation and YAP nuclear translocation

Unraveling the Dual-Stretch-Mode Impact on Tension Gauge Tethers' Mechanical Stability

Tension gauge tethers (TGTs), short DNA segments serving as extracellular tension sensors, are instrumental in assessing the tension dynamics in mechanotransduction. These TGTs feature an initial shear-stretch region and an unzip-stretch region. Despite their utility, no theoretical model has been available to estimate their tension-dependent lifetimes [τ(f)], restricting insights from cellular mechanotransduction experiments. We have now formulated a concise expression for τ(f) of TGTs, accommodating contributions from both stretch regions. Our model uncovers a tension-dependent energy barrier shift occurring when tension surpasses a switching force of approximately 13 pN for the recently developed TGTs, greatly influencing τ(f) profiles. Experimental data from several TGTs validated our model. The calibrated expression can predict τ(f) of TGTs at 37 °C based on their sequences with minor fold changes, supporting future applications of TGTs.

Remodeling of the focal adhesion complex by hydrogen-peroxide-induced senescence

Cellular senescence is a phenotype characterized by cessation of cell division, which can be caused by exhaustive replication or environmental stress. It is involved in age-related pathophysiological conditions and affects both the cellular cytoskeleton and the prime cellular mechanosensors, focal adhesion complexes. While the size of focal adhesions increases during senescence, it is unknown if and how this is accompanied by a remodeling of the internal focal adhesion structure. Our study uses metal-induced energy transfer to study the axial dimension of focal adhesion proteins from oxidative-stress-induced senescent cells with nanometer precision, and compares these to unstressed cells. We influenced cytoskeletal tension and the functioning of mechanosensitive ion channels using drugs and studied the combined effect of senescence and drug intervention on the focal adhesion structure. We found that H2O2-induced restructuring of the focal adhesion complex indicates a loss of tension and altered talin complexation. Mass spectroscopy-based proteomics confirmed the differential regulation of several cytoskeletal proteins induced by H2O2 treatment.

Tension Gauge Tethers as Tension Threshold and Duration Sensors

Mechanotransduction, the process by which cells respond to tension transmitted through various supramolecular linkages, is important for understanding cellular behavior. Tension gauge tethers (TGTs), short fragments of double-stranded DNA that irreversibly break under shear-stretch conditions, have been used in live cell experiments to study mechanotransduction. However, our current understanding of TGTs' mechanical responses is limited, which limits the information that can be gleaned from experimental observations. In this study, we quantified the tension-dependent lifetime of TGTs to better understand their mechanical stability under various physiologically relevant stretching conditions. This work has broad applications for using TGTs as tension threshold and duration sensors and also suggests the need to revisit previous interpretations of experimental observations.