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Direction of actin flow dictates integrin LFA-1 orientation during leukocyte migration.

Pontus NordenfeltTravis I MooreShalin B MehtaJoseph Mathew KalappurakkalVinay SwaminathanNobuyasu KogaTalley J LambertDavid BakerJennifer C WatersRudolf OldenbourgTomomi TaniSatyajit MayorClare M WatermanTimothy A Springer
Published in: Nature communications (2017)
Integrin αβ heterodimer cell surface receptors mediate adhesive interactions that provide traction for cell migration. Here, we test whether the integrin, when engaged to an extracellular ligand and the cytoskeleton, adopts a specific orientation dictated by the direction of actin flow on the surface of migrating cells. We insert GFP into the rigid, ligand-binding head of the integrin, model with Rosetta the orientation of GFP and its transition dipole relative to the integrin head, and measure orientation with fluorescence polarization microscopy. Cytoskeleton and ligand-bound integrins orient in the same direction as retrograde actin flow with their cytoskeleton-binding β-subunits tilted by applied force. The measurements demonstrate that intracellular forces can orient cell surface integrins and support a molecular model of integrin activation by cytoskeletal force. Our results place atomic, Å-scale structures of cell surface receptors in the context of functional and cellular, μm-scale measurements.
Keyphrases
  • cell migration
  • cell surface
  • single molecule
  • cell adhesion
  • high resolution
  • mass spectrometry
  • reactive oxygen species
  • peripheral blood
  • high speed
  • signaling pathway
  • quantum dots
  • cell proliferation
  • label free