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

Nat Commun. 2017 Dec 11;8(1):2047. doi: 10.1038/s41467-017-01848-y.

Abstract

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism*
  • Actins / metabolism*
  • Amino Acid Sequence
  • Cell Membrane / metabolism*
  • Cell Movement*
  • Fluorescence Polarization / methods
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • HEK293 Cells
  • Humans
  • Jurkat Cells
  • Leukocytes / cytology
  • Leukocytes / metabolism*
  • Lymphocyte Function-Associated Antigen-1 / genetics
  • Lymphocyte Function-Associated Antigen-1 / metabolism*
  • Microscopy, Fluorescence / methods
  • Protein Binding
  • Sequence Homology, Amino Acid

Substances

  • Actins
  • Lymphocyte Function-Associated Antigen-1
  • Green Fluorescent Proteins