High-Affinity Bent β 2-Integrin Molecules in Arresting Neutrophils Face Each Other through Binding to ICAMs In cis

Cell Rep. 2019 Jan 2;26(1):119-130.e5. doi: 10.1016/j.celrep.2018.12.038.

Abstract

Leukocyte adhesion requires β2-integrin activation. Resting integrins exist in a bent-closed conformation-i.e., not extended (E-) and not high affinity (H-)-unable to bind ligand. Fully activated E+H+ integrin binds intercellular adhesion molecules (ICAMs) expressed on the opposing cell in trans. E-H- transitions to E+H+ through E+H- or through E-H+, which binds to ICAMs on the same cell in cis. Spatial patterning of activated integrins is thought to be required for effective arrest, but no high-resolution cell surface localization maps of activated integrins exist. Here, we developed Super-STORM by combining super-resolution microscopy with molecular modeling to precisely localize activated integrin molecules and identify the molecular patterns of activated integrins on primary human neutrophils. At the time of neutrophil arrest, E-H+ integrins face each other to form oriented (non-random) nanoclusters. To address the mechanism causing this pattern, we blocked integrin binding to ICAMs in cis, which significantly relieved the face-to-face orientation.

Keywords: STORM; TIRF; human; integrin; integrin activation; molecular modeling; neutrophil; superresolution.

Publication types

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

MeSH terms

  • CD18 Antigens / blood*
  • Cell Adhesion Molecules / blood*
  • Humans
  • Neutrophils / metabolism*
  • Protein Binding

Substances

  • CD18 Antigens
  • Cell Adhesion Molecules