title: Membrane nanoclusters of FcγRI segregate from inhibitory SIRPα upon activation of human macrophages.
abstract: 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.
authors.affiliation: Manchester Collaborative Centre for Inflammation Research, University of Manchester, Manchester M13 9NT, England, UK.
authors.forename: Filipa B
authors.identifier: 0000-0002-9338-4060
authors.initials: FB
authors.lastname: Lopes
authors.affiliation: Manchester Collaborative Centre for Inflammation Research, University of Manchester, Manchester M13 9NT, England, UK.
authors.forename: Štefan
authors.identifier: 0000-0003-4470-5881
authors.initials: Š
authors.lastname: Bálint
authors.affiliation: Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, England, UK.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Valvo
authors.affiliation: Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, England, UK.
authors.forename: James H
authors.initials: JH
authors.lastname: Felce
authors.affiliation: Refractory Respiratory Inflammation Discovery Performance Unit, GlaxoSmithKline, Hertfordshire SG1 2NY, England, UK.
authors.forename: Edith M
authors.identifier: 0000-0002-2339-4482
authors.initials: EM
authors.lastname: Hessel
authors.affiliation: Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, England, UK.
authors.forename: Michael L
authors.identifier: 0000-0003-4983-6389
authors.initials: ML
authors.lastname: Dustin
authors.affiliation: Manchester Collaborative Centre for Inflammation Research, University of Manchester, Manchester M13 9NT, England, UK daniel.davis@manchester.ac.uk.
authors.forename: Daniel M
authors.identifier: 0000-0002-9182-291X
authors.initials: DM
authors.lastname: Davis
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D051928:CD47 Antigen / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D008566:Membranes / Q000378:metabolism*; D010587:Phagocytosis / Q000502:physiology; D011485:Protein Binding / Q000502:physiology; D017452:Receptors, IgG / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D051928:CD47 Antigen; C497894:CD47 protein, human; D002352:Carrier Proteins; D017452:Receptors, IgG; D011971:Receptors, Immunologic; D019061:src-Family Kinases