title: Negative regulation of phagocytosis in macrophages by the CD47-SHPS-1 system.
abstract: Src homology 2 domain-containing protein tyrosine phosphatase (SHP) substrate-1 (SHPS-1) is a transmembrane protein that is expressed predominantly in macrophages. Its extracellular region interacts with the transmembrane ligand CD47 expressed on the surface of adjacent cells, and its cytoplasmic region binds the protein tyrosine phosphatases SHP-1 and SHP-2. Phagocytosis of IgG- or complement-opsonized RBCs by peritoneal macrophages derived from mice that express a mutant SHPS-1 protein that lacks most of the cytoplasmic region was markedly enhanced compared with that apparent with wild-type macrophages. This effect was not observed either with CD47-deficient RBCs as the phagocytic target or in the presence of blocking Abs to SHPS-1. Depletion of SHPS-1 from wild-type macrophages by RNA interference also promoted FcgammaR-mediated phagocytosis of wild-type RBCs. Ligation of SHPS-1 on macrophages by CD47 on RBCs promoted tyrosine phosphorylation of SHPS-1 and its association with SHP-1, whereas tyrosine phosphorylation of SHPS-1 was markedly reduced in response to cross-linking of FcgammaRs. Treatment with inhibitors of PI3K or of Syk, but not with those of MEK or Src family kinases, abolished the enhancement of FcgammaR-mediated phagocytosis apparent in macrophages from SHPS-1 mutant mice. In contrast, FcgammaR-mediated tyrosine phosphorylation of Syk, Cbl, or the gamma subunit of FcR was similar in macrophages from wild-type and SHPS-1 mutant mice. These results suggest that ligation of SHPS-1 on macrophages by CD47 promotes the tyrosine phosphorylation of SHPS-1 and thereby prevents the FcgammaR-mediated disruption of the SHPS-1-SHP-1 complex, resulting in inhibition of phagocytosis. The inhibition of phagocytosis by the SHPS-1-SHP-1 complex may be mediated at the level of Syk or PI3K signaling.
authors.affiliation: Biosignal Research Center, Institute for Molecular and Cellular Regulation, and Department of Dermatology, Graduate School of Medicine, Gunma University, Showa-Machi, Maebashi, Gunma, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Okazawa
authors.forename: Sei-ichiro
authors.initials: S
authors.lastname: Motegi
authors.forename: Naoko
authors.initials: N
authors.lastname: Ohyama
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohnishi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tomizawa
authors.forename: Yoriaki
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Per-Arne
authors.initials: PA
authors.lastname: Oldenborg
authors.forename: Osamu
authors.initials: O
authors.lastname: Ishikawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Matozaki
mesh_terms: D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000235:genetics* / Q000276:immunology / Q000378:metabolism / Q000502:physiology; D000943:Antigens, Differentiation / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D051928:CD47 Antigen; D003179:Complement C3b / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology*; D004792:Enzyme Precursors / Q000037:antagonists & inhibitors; D004912:Erythrocytes / Q000276:immunology / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D017737:Macrophages, Peritoneal / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D039842:Neural Cell Adhesion Molecule L1 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D009895:Opsonin Proteins / Q000378:metabolism; D010587:Phagocytosis / Q000235:genetics / Q000276:immunology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D034741:RNA, Small Interfering / Q000494:pharmacology; D017452:Receptors, IgG / Q000378:metabolism / Q000502:physiology; D011971:Receptors, Immunologic / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D000072377:Syk Kinase; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000037:antagonists & inhibitors
chemical_list: D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D051928:CD47 Antigen; C497895:Cd47 protein, mouse; D003432:Cross-Linking Reagents; D004792:Enzyme Precursors; D007074:Immunoglobulin G; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D039842:Neural Cell Adhesion Molecule L1; D009895:Opsonin Proteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; C501922:Sirpa protein, mouse; D034741:RNA, Small Interfering; D017452:Receptors, IgG; D011971:Receptors, Immunologic; C501920:SIRPA protein, human; D014443:Tyrosine; D003179:Complement C3b; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; C000606897:Syk protein, mouse; D019061:src-Family Kinases