title: Identification of major binding proteins and substrates for the SH2-containing protein tyrosine phosphatase SHP-1 in macrophages.
abstract: The protein tyrosine phosphatase SHP-1 is a critical regulator of macrophage biology, but its detailed mechanism of action remains largely undefined. SHP-1 associates with a 130-kDa tyrosyl-phosphorylated species (P130) in macrophages, suggesting that P130 might be an SHP-1 regulator and/or substrate. Here we show that P130 consists of two transmembrane glycoproteins, which we identify as PIR-B/p91A and the signal-regulatory protein (SIRP) family member BIT. These proteins also form separate complexes with SHP-2. BIT, but not PIR-B, is in a complex with the colony-stimulating factor 1 receptor (CSF-1R), suggesting that BIT may direct SHP-1 to the CSF-1R. BIT and PIR-B bind preferentially to substrate-trapping mutants of SHP-1 and are hyperphosphorylated in macrophages from motheaten viable mice, which express catalytically impaired forms of SHP-1, indicating that these proteins are SHP-1 substrates. However, BIT and PIR-B are hypophosphorylated in motheaten macrophages, which completely lack SHP-1 expression. These data suggest a model in which SHP-1 dephosphorylates specific sites on BIT and PIR-B while protecting other sites from dephosphorylation via its SH2 domains. Finally, BIT and PIR-B associate with two tyrosyl phosphoproteins and a tyrosine kinase activity. Tyrosyl phosphorylation of these proteins and the level of the associated kinase activity are increased in the absence of SHP-1. Our data suggest that BIT and PIR-B recruit multiple signaling molecules to receptor complexes, where they are regulated by SHP-1 and/or SHP-2.
authors.affiliation: Cancer Biology Program, Division of Hematology-Oncology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA. jtimms@bidmc.harvard.edu
authors.forename: J F
authors.initials: JF
authors.lastname: Timms
authors.forename: K
authors.initials: K
authors.lastname: Carlberg
authors.forename: H
authors.initials: H
authors.lastname: Gu
authors.forename: H
authors.initials: H
authors.lastname: Chen
authors.forename: S
authors.initials: S
authors.lastname: Kamatkar
authors.forename: M J
authors.initials: MJ
authors.lastname: Nadler
authors.forename: L R
authors.initials: LR
authors.lastname: Rohrschneider
authors.forename: B G
authors.initials: BG
authors.lastname: Neel
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation; D006649:Histocompatibility Antigens / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D008264:Macrophages / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins; D039842:Neural Cell Adhesion Molecule L1; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000378:metabolism; D011971:Receptors, Immunologic; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D013379:Substrate Specificity; D018909:src Homology Domains
chemical_list: D000943:Antigens, Differentiation; D006649:Histocompatibility Antigens; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D039842:Neural Cell Adhesion Molecule L1; D019006:Neural Cell Adhesion Molecules; D011971:Receptors, Immunologic; D011993:Recombinant Fusion Proteins; C070850:transplantation antigen P91A, mouse; D019000:Phosphotyrosine; D016186:Receptor, Macrophage Colony-Stimulating Factor; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse; C509248:Ptpn6 protein, mouse; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases