RTK-integrin interactions universally modulate αVβ3 integrin-mediated cell adhesion.

Abstract

Cells sense and respond to physical forces from the local environment, and aberrations in this bi-directional exchange are implicated in disease. Integrins and receptor tyrosine kinases (RTKs) display robust synergy, with integrins establishing the physical link between the microenvironment and cytoskeleton and RTKs regulating growth, proliferation, and survival. Previously, we found ligand-activated EGFR can tune integrin mechanics, facilitating cell attachment and spreading by influencing focal adhesion (FA) growth and maturation in Cos-7 cells. However, the universality across different RTK family members and cell types and the underlying mechanism remain unknown. To investigate this, we employed tension gauge tether (TGT) probes displaying the integrin ligand cRGDfK and quantified mechanical outcomes due to RTK activation in three different cell lines belonging to the fibroblast, epithelial and endothelial lineages. Irrespective of the RTK (EGFR, FGFR, or VEGFR) involved, activation with the corresponding ligand increased integrin-based mechanical force generation and consequently enhanced cell spreading, adhesion formation and maturity. Different RTK family members display functional redundancy in terms of the regulated downstream mechanical outcomes and biased agonism to enhance associated changes in cell mechanics. Since multiple ligands can activate RTKs with distinct signaling outcomes, we investigated the influence of different ligands on cell mechanics. Ligand affinity inversely correlated with cell mechanical changes where low-affinity ligands increased integrin activation and spreading via sustained RTK signaling. Finally, the concentration of the available ligand directly impacts the observed changes in mechanical outcomes. Together, different ligand availability provides an additional layer of control to ‘fine-tune’ cell mechanical outcomes. Our results reveal RTKs as universal mechano-organizers which can synergistically function with integrins as joint-signaling rheostats to modulate adhesion and cell spreading.