Single molecule Grb2 dynamics reveal spatiomechanical modulation of RTK signaling across length scales
Extracellular matrix (ECM)-mediated cell adhesion and tension regulate development and disease through crosstalk with Receptor Tyrosine Kinases (RTKs). RTKs stimulate proliferation, survival, and metabolic reprogramming via Ras/ERK and PI3K/Akt signaling. Emerging evidence identify the biophysical and biochemical integration of integrin-mediated adhesions with RTK signaling, however, the molecular mechanisms regulating this phenotype remain poorly understood. Here, we demonstrate that ECM stiffness potentiates ligand-mediated epidermal growth factor receptor (EGFR) signaling at scales ranging from the single adaptor protein, Grb2 upward to multicellular spheroids and tissues. We show that ECM stiffness-driven RTK signaling is mediated by integrin adhesions that reshape the membrane to induce the formation of RTK signaling hotspots distributed globally across the cell membrane. A parsimonious computational model and biochemical membrane perturbations causally implicate membrane curvature and topography in tension-dependent integrin-EGFR crosstalk. The results demonstrate how the mechanical properties of the ECM direct molecular recruitment and confinement of signaling molecules to regulate growth factor-dependent RTK signaling. Given that many RTK-driven solid tumors develop a stiff stroma, the findings could explain why many therapeutic tyrosine kinase inhibitors develop clinical resistance. The findings suggest clarifying how tension regulates transmembrane receptor signaling could identify unique force-dependent molecular regulators towards which new antitumor therapies could be applied.