scholarly journals A Regulatory Role for Src Homology 2 Domain–Containing Inositol 5′-Phosphatase (Ship) in Phagocytosis Mediated by Fcγ Receptors and Complement Receptor 3 (αMβ2; Cd11b/Cd18)

2000 ◽  
Vol 193 (1) ◽  
pp. 61-72 ◽  
Author(s):  
Dianne Cox ◽  
Benjamin M. Dale ◽  
Masaki Kashiwada ◽  
Cheryl D. Helgason ◽  
Steven Greenberg
Keyword(s):  
Cell Model ◽  
Complement Receptor ◽  
Phosphatidylinositol 3 Kinase ◽  
Src Homology 2 ◽  
Catalytically Active ◽  
Src Homology ◽  
Complement Receptor 3 ◽  
Phagocytic Cups ◽  
Src Homology 2 Domain

The Src homology 2 domain–containing inositol 5′-phosphatase (SHIP) is recruited to immunoreceptor tyrosine-based inhibition motif (ITIM)–containing proteins, thereby suppressing phosphatidylinositol 3-kinase (PI 3-kinase)–dependent pathways. The role of SHIP in phagocytosis, a PI 3-kinase–dependent pathway, is unknown. Overexpression of SHIP in macrophages led to an inhibition of phagocytosis mediated by receptors for the Fc portion of IgG (FcγRs). In contrast, macrophages expressing catalytically inactive SHIP or lacking SHIP expression demonstrated enhanced phagocytosis. To determine whether SHIP regulates phagocytosis mediated by receptors that are not known to recruit ITIMs, we determined the effect of SHIP expression on complement receptor 3 (CR3; CD11b/CD18; αMβ2)–dependent phagocytosis. Macrophages overexpressing SHIP demonstrated impaired CR3-mediated phagocytosis, whereas macrophages expressing catalytically inactive SHIP demonstrated enhanced phagocytosis. CR3-mediated phagocytosis in macrophages derived from SHIP−/− mice was up to 2.5 times as efficient as that observed in macrophages derived from littermate controls. SHIP was localized to FcγR- and CR3-containing phagocytic cups and was recruited to the cytoskeleton upon clustering of CR3. In a transfected COS cell model of activation-independent CR3-mediated phagocytosis, catalytically active but not inactive SHIP also inhibited phagocytosis. We conclude that PI 3-kinase(s) and SHIP regulate multiple forms of phagocytosis and that endogenous SHIP plays a role in modulating β2 integrin outside-in signaling.

Anemia, thrombocytopenia, leukocytosis, extramedullary hematopoiesis, and impaired progenitor function in Pten+/-SHIP-/- mice: a novel model of myelodysplasia

Blood ◽  
2004 ◽  
Vol 103 (12) ◽  
pp. 4503-4510 ◽  
Author(s):  
Jennifer L. Moody ◽  
Lixin Xu ◽  
Cheryl D. Helgason ◽  
Frank R. Jirik
Keyword(s):  
Extramedullary Hematopoiesis ◽  
Pi3k Pathway ◽  
Phosphatidylinositol 3 Kinase ◽  
Short Term ◽  
Src Homology 2 ◽  
Donor Cells ◽  
Src Homology ◽  
Novel Model ◽  
Pheno Type

Abstract The myeloproliferative disorder of mice lacking the Src homology 2 (SH2)-containing 5′ phosphoinositol phosphatase, SHIP, underscores the need for closely regulating phosphatidylinositol 3-kinase (PI3K) pathway activity, and hence levels of phosphatidylinositol species during hematopoiesis. The role of the 3′ phosphoinositol phosphatase Pten in this process is less clear, as its absence leads to embryonic lethality. Despite Pten heterozygosity being associated with a lymphoproliferative disorder, we found no evidence of a hematopoietic defect in Pten+/- mice. Since SHIP shares the same substrate (PIP3) with Pten, we hypothesized that the former might compensate for Pten haploinsufficiency in the marrow. Thus, we examined the effect of Pten heterozygosity in SHIP-/- mice, predicting that further dysregulation of PIP3 metabolism would exacerbate the pheno-type of the latter. Indeed, compared with SHIP-/- mice, Pten+/-SHIP-/- animals developed a myelodysplastic phenotype characterized by increased hepatosplenomegaly, extramedullary hematopoiesis, anemia, and thrombocytopenia. Consistent with a marrow defect, clonogenic assays demonstrated reductions in committed myeloid and megakaryocytic progenitors in these animals. Providing further evidence of a Pten+/-SHIP-/- progenitor abnormality, reconstitution of irradiated mice with marrows from these mice led to a marked defect in short-term repopulation of peripheral blood by donor cells. These studies suggest that the regulation of the levels and/or ratios of PI3K-derived phosphoinositol species by these 2 phosphatases is critical to normal hematopoiesis. (Blood. 2004;103:4503-4510)

scholarly journals Disparate effects of Shb gene deficiency on disease characteristics in murine models of myeloid, B-cell, and T-cell leukemia

Tumor Biology ◽  
2018 ◽  
Vol 40 (4) ◽  
pp. 101042831877147 ◽  
Author(s):  
Maria Jamalpour ◽  
Xiujuan Li ◽  
Karin Gustafsson ◽  
Jeffrey W Tyner ◽  
Michael Welsh
Keyword(s):  
T Cell ◽  
B Cell ◽  
Cell Model ◽  
Cell Leukemia ◽  
Breakpoint Cluster Region ◽  
Cluster Region ◽  
Src Homology 2 ◽  
Disease Characteristics ◽  
Src Homology ◽  
Src Homology 2 Domain

The Src homology-2 domain protein B is an adaptor protein operating downstream of tyrosine kinases. The Shb gene knockout has been found to accelerate p210 Breakpoint cluster region-cAbl oncogene 1 tyrosine kinase-induced leukemia. In human myeloid leukemia were tumors with high Src homology-2 domain protein B mRNA content, tumors were, however, associated with decreased latency and myeloid leukemia exhibiting immune cell characteristics. Thus, the aim of this study was to investigate the effects of Shb knockout on the development of leukemia in three additional models, that is, colony stimulating factor 3 receptor-T618I–induced neutrophilic leukemia, p190 Breakpoint cluster region-cAbl oncogene 1 tyrosine kinase-induced B-cell leukemia, and G12D-Kras-induced T-cell leukemia/thymic lymphoma. Wild-type or Shb knockout bone marrow cells expressing the oncogenes were transplanted to bone marrow–deficient recipients. Organs from moribund mice were collected and further analyzed. Shb knockout increased the development of CSF3RT618I-induced leukemia and increased the white blood cell count at the time of death. In the p190 Breakpoint cluster region-cAbl oncogene 1 tyrosine kinase B-cell model, Shb knockout reduced white blood cell counts without affecting latency, whereas in the G12D-Kras T-cell model, thymus size was increased without major effects on latency, suggesting that Shb knockout accelerates the development thymic lymphoma. Cytokine secretion plays a role in the progression of leukemia, and consequently Shb knockout bone marrows exhibited lower expression of granulocyte colony stimulating factor and interleukin 6 in the neutrophilic model and interleukin 7 and chemokine C-X-C motif ligand 12 (C-X-C motif chemokine 12) in the B-cell model. It is concluded that in experimental mouse models, the absence of the Shb gene exacerbates the disease in myeloid leukemia, whereas it alters the disease characteristics without affecting latency in B- and T-cell leukemia. The results suggest a role of Shb in modulating the disease characteristics depending on the oncogenic insult operating on hematopoietic cells. These findings help explain the outcome of human disease in relation to Src homology-2 domain protein B mRNA content.

scholarly journals Multiple stimuli induce tyrosine phosphorylation of the Crk-binding sites of paxillin

2001 ◽  
Vol 360 (1) ◽  
pp. 57-66 ◽  
Author(s):  
Michael D. SCHALLER ◽  
Erik M. SCHAEFER
Keyword(s):  
Cell Adhesion ◽  
Tyrosine Phosphorylation ◽  
Binding Sites ◽  
Signalling Molecules ◽  
Src Homology 2 ◽  
Dependent Cell ◽  
Src Homology ◽  
Tyrosine Phosphorylated Protein ◽  
Src Homology 2 Domain

Paxillin is a focal-adhesion-associated, tyrosine-phosphorylated protein. In cells transformed by the src, crk or BCR-Abl oncogenes, the phosphotyrosine content of paxillin is elevated. In normal cells paxillin functions in signalling following integrin-dependent cell adhesion or exposure to a number of stimuli, including growth factors and neuropeptides. These stimuli induce tyrosine phosphorylation of paxillin, regulating the association of Src homology 2 domain-containing signalling molecules with paxillin. There are multiple sites of tyrosine phosphorylation on paxillin. To elucidate the role of paxillin in transducing signals in response to various stimuli, it is essential to identify all of the sites of phosphorylation on paxillin and to define which residues are phosphorylated in response to distinct stimuli. We describe two new sites of tyrosine phosphorylation on paxillin, residues at positions 40 and 88. Using paxillin variants with phenylalanine substitutions at phosphorylation sites and phospho-specific paxillin antibodies, tyrosine phosphorylation of paxillin in response to distinct stimuli was examined. The results demonstrate that Tyr31 and Tyr118, which are binding sites for Crk, are major sites of tyrosine phosphorylation following cell adhesion or stimulation with platelet-derived growth factor or angiotensin II. Thus multiple stimuli may elicit similar signalling events downstream of paxillin.

scholarly journals Cd47-Signal Regulatory Protein α (Sirpα) Regulates Fcγ and Complement Receptor–Mediated Phagocytosis

2001 ◽  
Vol 193 (7) ◽  
pp. 855-862 ◽  
Author(s):  
Per-Arne Oldenborg ◽  
Hattie D. Gresham ◽  
Frederik P. Lindberg
Keyword(s):  
Tyrosine Phosphatase ◽  
Regulatory Protein ◽  
Residual Activity ◽  
Receptor Activation ◽  
Complement Receptor ◽  
Src Homology 2 ◽  
Splenic Macrophages ◽  
Src Homology ◽  
Src Homology 2 Domain ◽  
Phagocytic Response

In autoimmune hemolytic anemia (AIHA), circulating red blood cells (RBCs) opsonized with autoantibody are recognized by macrophage Fcγ and complement receptors. This triggers phagocytosis and elimination of RBCs from the circulation by splenic macrophages. We recently found that CD47 on unopsonized RBCs binds macrophage signal regulatory protein α (SIRPα), generating a negative signal that prevents phagocytosis of the unopsonized RBCs. We show here that clearance and phagocytosis of opsonized RBCs is also regulated by CD47-SIRPα. The inhibition generated by CD47-SIRPα interaction is strongly attenuated but not absent in mice with only residual activity of the phosphatase Src homology 2 domain–containing protein tyrosine phosphatase (SHP)-1, suggesting that most SIRPα signaling in this system is mediated by SHP-1 phosphatase activity. The macrophage phagocytic response is controlled by an integration of the inhibitory SIRPα signal with prophagocytic signals such as from Fcγ and complement receptor activation. Thus, augmentation of inhibitory CD47-SIRPα signaling may prevent or attenuate RBC clearance in AIHA.

scholarly journals Role of SHPS-1 in the Regulation of Insulin-like Growth Factor I–stimulated Shc and Mitogen-activated Protein Kinase Activation in Vascular Smooth Muscle Cells

2005 ◽  
Vol 16 (7) ◽  
pp. 3353-3364 ◽  
Author(s):  
Yan Ling ◽  
Laura A. Maile ◽  
Jaroslava Lieskovska ◽  
Jane Badley-Clarke ◽  
David R. Clemmons
Keyword(s):  
Tyrosine Phosphatase ◽  
Mitogen Activated Protein Kinase ◽  
Mutant Form ◽  
Mapk Phosphorylation ◽  
Src Homology 2 ◽  
Igf I ◽  
Mitogen Activated Protein ◽  
Src Homology ◽  
Src Homology 2 Domain

Insulin-like growth factor I (IGF-I) stimulates smooth muscle cell (SMC) proliferation, and the mitogen-activated protein kinase (MAPK) pathway plays an important role in mediating IGF-I–induced mitogenic signaling. Our prior studies have shown that recruitment of Src homology 2 domain tyrosine phosphatase (SHP-2) to the membrane scaffolding protein Src homology 2 domain–containing protein tyrosine phosphatase substrate-1 (SHPS-1) is required for IGF-I–dependent MAPK activation. The current studies were undertaken to define the upstream signaling components that are required for IGF-I–stimulated MAPK activation and the role of SHPS-1 in regulating this process. The results show that IGF-I–induced Shc phosphorylation and its subsequent binding to Grb2 is required for sustained phosphorylation of MAPK and increased cell proliferation in SMCs. Furthermore, for Shc to be phosphorylated in response to IGF-I requires that Shc must associate with SHPS-1 and this association is mediated in part by SHP-2. Preincubation of cells with a peptide that contains a phospho-tyrosine binding motif sequence derived from SHPS-1 inhibited IGF-I–stimulated SHP-2 transfer to SHPS-1, the association of Shc with SHPS-1, and IGF-I–dependent Shc phosphorylation. Expression of an SHPS-1 mutant that did not bind to Shc or SHP-2 resulted in decreased Shc and MAPK phosphorylation in response to IGF-I. In addition, SMCs expressing a mutant form of the β3 subunit of the αVβ3, which results in impairment of SHP-2 transfer to SHPS-1, also showed attenuated IGF-I–dependent Shc and MAPK phosphorylation. Further analysis showed that Shc and SHP-2 can be coimmunoprecipitated after IGF-I stimulation. A cell-permeable peptide that contained a polyproline sequence from Shc selectively inhibited Shc/SHP-2 association and impaired Shc but not SHP-2 binding to SHPS-1. Exposure to this peptide also inhibited IGF-I–stimulated Shc and MAPK phosphorylation. Cells expressing a mutant form of Shc with the four prolines substituted with alanines showed no Shc/SHPS-1 association in response to IGF-I. We conclude that SHPS-1 functions as an anchor protein that recruits both Shc and SHP-2 and that their recruitment is necessary for IGF-I–dependent Shc phosphorylation, which is required for an optimal mitogenic response in SMCs.

Functional specificity of cytoplasmic and transmembrane tyrosine kinases: identification of 130- and 75-kilodalton substrates of c-fps/fes tyrosine kinase in macrophages

1994 ◽  
Vol 14 (7) ◽  
pp. 4606-4615
Author(s):  
L B Areces ◽  
P Dello Sbarba ◽  
M Jücker ◽  
E R Stanley ◽  
R A Feldman
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Protein Tyrosine Kinase ◽  
Phosphatidylinositol 3 Kinase ◽  
Macrophage Cell ◽  
Src Homology 2 ◽  
Src Homology ◽  
Src Homology 2 Domain ◽  
Stimulating Factor

c-fps/fes encodes a 92-kDa protein-tyrosine kinase (NCP92) that is expressed at the highest levels in macrophages. To determine if c-fps/fes can mediate the action of the colony-stimulating factor 1 (CSF-1) receptor (CSF-1R) and to identify potential targets of c-fps/fes in macrophages, we have overexpressed c-fps/fes in a CSF-1-dependent macrophage cell line. A 30- to 50-fold overexpression of c-fps/fes partially released these cells from their factor dependence by a nonautocrine mechanism, and this correlated with the tyrosine phosphorylation of two proteins of 130 and 75 kDa (P130 and P75). c-fps/fes did not cause tyrosine phosphorylation or activation of CSF-1 dependent targets, including CSF-1R, Shc, and phosphatidylinositol 3-kinase, and conversely, CSF-1 did not induce tyrosine phosphorylation of P130 and P75. P75 appears to be a novel phosphotyrosyl protein, whereas P130 cross-reacts with a known substrate of v-src. P130 and P75 may be direct substrates of c-fps/fes: P130 was tightly associated with NCP92, and the src homology 2 domain of NCP92 specifically bound phosphorylated P130 and P75 but not the CSF-1-induced phosphotyrosyl proteins, consistent with the possibility that P130 and P75 are physiological targets of c-fps/fes. We conclude that although c-fps/fes can functionally substitute for CSF-1R to a certain extent, these tyrosine kinases act largely independently of each other and that P130 and P75 are novel targets whose mechanisms of action may be unrelated to the signalling pathways utilized by receptor tyrosine kinases.

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