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Signal integration between activating Fc receptors and inhibitory signal regulatory protein α (SIRPα) controls macrophage phagocytosis. Here, using dual-color direct stochastic optical reconstruction microscopy, we report that Fcγ receptor I (FcγRI), FcγRII, and SIRPα are not homogeneously distributed at macrophage surfaces but are organized in discrete nanoclusters, with a mean radius of 71 ± 11 nm, 60 ± 6 nm, and 48 ± 3 nm, respectively. Nanoclusters of FcγRI, but not FcγRII, are constitutively associated with nanoclusters of SIRPα, within 62 ± 5 nm, mediated by the actin cytoskeleton. Upon Fc receptor activation, Src-family kinase signaling leads to segregation of FcγRI and SIRPα nanoclusters to be 197 ± 3 nm apart. Co-ligation of SIRPα with CD47 abrogates nanocluster segregation. If the balance of signals favors activation, FcγRI nanoclusters reorganize into periodically spaced concentric rings. Thus, a nanometer- and micron-scale reorganization of activating and inhibitory receptors occurs at the surface of human macrophages concurrent with signal integration.

Original publication

DOI

10.1083/jcb.201608094

Type

Journal article

Journal

J Cell Biol

Publication Date

03/04/2017

Volume

216

Pages

1123 - 1141

Keywords

Actin Cytoskeleton, Antigens, CD47, Carrier Proteins, Humans, Leukocytes, Mononuclear, Macrophages, Membranes, Phagocytosis, Protein Binding, Receptors, IgG, Receptors, Immunologic, Signal Transduction, src-Family Kinases