High-Affinity Bent β2-Integrin Molecules in Arresting Neutrophils Face Each Other through Binding to ICAMs In cis.

Zhichao Fan, William Bill Kiosses, Hao Sun, Marco Orecchioni, Yanal Ghosheh, Dirk M Zajonc, M Amin Arnaout, Edgar Gutierrez, Alex Groisman, Mark H Ginsberg, Klaus Ley

Cell reports 2019 Jan 02

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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. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Citation

Zhichao Fan, William Bill Kiosses, Hao Sun, Marco Orecchioni, Yanal Ghosheh, Dirk M Zajonc, M Amin Arnaout, Edgar Gutierrez, Alex Groisman, Mark H Ginsberg, Klaus Ley. High-Affinity Bent β2-Integrin Molecules in Arresting Neutrophils Face Each Other through Binding to ICAMs In cis. Cell reports. 2019 Jan 02;26(1):119-130.e5