Ligand binding promiscuity of αVβ3 integrin is enlarged in response to mechanical force

Abstract

AbstractαVβ3 integrin recognizes multiple extracellular matrix proteins, including vitronectin (Vn) and fibronectin (Fn). However, cell experiments are frequently performed on homogenously coated substrates with only one integrin ligand present. Here, we employed binary-choice substrates of Fn and Vn to dissect αVβ3 integrin-mediated binding to both ligands on the subcellular scale. Superresolution imaging revealed that αVβ3 integrin preferred binding to Vn under various conditions. In contrast, binding to Fn required mechanical load on αVβ3 integrin. Integrin mutations, structural analysis, and molecular dynamics simulations established a model where the extended-closed conformation of αVβ3 integrin binds Vn but not Fn. Force-mediated hybrid domain swing-out characterizes the extended-open conformation needed for efficient Fn binding. Thus, force-dependent conformational changes in αVβ3 integrin increase the number of available ligands and therefore the ligand promiscuity of this integrin. These findings for αVβ3 integrin were shown to regulate cell migration and mechanotransduction differentially on Fn compared to Vn and therefore to regulate cell behavior.