Title : Force interacts with macromolecular structure in activation of TGF-β
Abstract :
- Integrins are adhesion receptors that transmit force across the plasma membrane between extracellular ligands and the actin cytoskeleton
- In activation of the transforming growth factor-β1 precursor (pro-TGF-β1), integrins bind to the prodomain, apply force, and release the TGF-β growth factor
- However, we know little about how integrins bind macromolecular ligands in the extracellular matrix or transmit force to them
- Here we show how integrin αVβ6 binds pro-TGF-β1 in an orientation biologically relevant for force-dependent release of TGF-β from latency
- The conformation of the prodomain integrin-binding motif differs in the presence and absence of integrin binding; differences extend well outside the interface and illustrate how integrins can remodel extracellular matrix
- Remodelled residues outside the interface stabilize the integrin-bound conformation, adopt a conformation similar to earlier-evolving family members, and show how macromolecular components outside the binding motif contribute to integrin recognition
- Regions in and outside the highly interdigitated interface stabilize a specific integrin/pro-TGF-β orientation that defines the pathway through these macromolecules which actin-cytoskeleton-generated tensile force takes when applied through the integrin β-subunit
- Simulations of force-dependent activation of TGF-β demonstrate evolutionary specializations for force application through the TGF-β prodomain and through the β- and not α-subunit of the integrin
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