| 1. |
- Murata, Takaaki, et al.
(författare)
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CD47 promotes neuronal development through Src- and FRG/Vav2-mediated activation of Rac and Cdc42.
- 2006
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Ingår i: Journal of Neuroscience. - 1529-2401. ; 26:48, s. 12397-407
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Tidskriftsartikel (refereegranskat)abstract
- The development of axons and dendrites is controlled by small GTP-binding proteins of the Rho family, but the upstream signaling mechanisms responsible for such regulation remain unclear. We have now investigated the role of the transmembrane protein cluster of differentiation 47 (CD47) in this process with hippocampal neurons. CD47-deficient neurons manifested markedly impaired development of dendrites and axons, whereas overexpression of CD47 promoted such development. Interaction of SH2 domain-containing protein tyrosine phosphatase substrate-1 (SHPS-1) with CD47 also induced the formation of dendritic filopodia and spines. These effects of CD47 were prevented by inhibition of either cell division cycle 42 (Cdc42) or Rac. In CD47-deficient neurons, autophosphorylation of Src was markedly reduced. In addition, overexpression of CD47 promoted the autophosphorylation of Src. Inhibition of Src family kinases indeed prevented CD47-promoted dendritic development. Inhibition of either FGD1-related Cdc42-guanine nucleotide exchange factor (GEF) (FRG) or Vav2, which is a GEF for Cdc42 and Rac and is activated by Src, also prevented the effects of CD47 on dendritic development. These results indicate that CD47 promotes development of dendrites and axons in hippocampal neurons in a manner dependent, at least in part, on activation of Cdc42 and Rac mediated by Src as well as by FRG and Vav2.
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| 2. |
- Ohnishi, Hiroshi, et al.
(författare)
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Stress-evoked tyrosine phosphorylation of signal regulatory protein α regulates behavioral immobility in the forced swim test
- 2010
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Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 30:31, s. 10472-10483
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Tidskriftsartikel (refereegranskat)abstract
- Severe stress induces changes in neuronal function that are implicated in stress-related disorders such as depression. The molecular mechanisms underlying the response of the brain to stress remain primarily unknown, however. Signal regulatory protein alpha (SIRPalpha) is an Ig-superfamily protein that undergoes tyrosine phosphorylation and binds the protein tyrosine phosphatase Shp2. Here we show that mice expressing a form of SIRPalpha that lacks most of the cytoplasmic region manifest prolonged immobility (depression-like behavior) in the forced swim (FS) test. FS stress induced marked tyrosine phosphorylation of SIRPalpha in the brain of wild-type mice through activation of Src family kinases. The SIRPalpha ligand CD47 was important for such SIRPalpha phosphorylation, and CD47-deficient mice also manifested prolonged immobility in the FS test. Moreover, FS stress-induced tyrosine phosphorylation of both the NR2B subunit of the NMDA subtype of glutamate receptor and the K+-channel subunit Kvbeta2 was regulated by SIRPalpha. Thus, tyrosine phosphorylation of SIRPalpha is important for regulation of depression-like behavior in the response of the brain to stress.
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| 3. |
- Ikeda, Hiroshi, et al.
(författare)
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Mutational analysis of the mechanism of negative regulation by SRC homology 2 domain-containing protein tyrosine phosphatase substrate-1 of phagocytosis in macrophages.
- 2006
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Ingår i: Journal of Immunology. - 0022-1767. ; 177:5, s. 3123-32
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Tidskriftsartikel (refereegranskat)abstract
- Src homology 2 domain-containing protein tyrosine phosphatase substrate-1 (SHPS-1) is a transmembrane protein predominantly expressed in macrophages. The binding of CD47 on RBCs to SHPS-1 on macrophages is implicated in inhibition of phagocytosis of the former cells by the latter. We have now shown that forced expression in mouse RAW264.7 macrophages of a mutant version (SHPS-1-4F) of mouse SHPS-1, in which four tyrosine phosphorylation sites are replaced by phenylalanine, markedly promoted Fc gammaR-mediated phagocytosis of mouse RBCs or SRBCs. Forced expression of another mutant form (SHPS-1-deltaCyto) of mouse SHPS-1, which lacks most of the cytoplasmic region, did not promote such phagocytosis. Similarly, forced expression of a rat version of SHPS-1-4F, but not that of rat wild-type SHPS-1 or SHPS-1-deltaCyto, in RAW264.7 cells enhanced Fc gammaR-mediated phagocytosis of RBCs. Tyrosine phosphorylation of endogenous SHPS-1 as well as its association with Src homology 2 domain-containing protein tyrosine phosphatase-1 were not markedly inhibited by expression of SHPS-1-4F. Furthermore, the attachment of IgG-opsonized RBCs to RAW264.7 cells was markedly increased by expression of SHPS-1-4F, and this effect did not appear to be mediated by the interaction between CD47 and SHPS-1. These data suggest that inhibition by SHPS-1 of phagocytosis in macrophages is mediated, at least in part, in a manner independent of the transinteraction between CD47 and SHPS-1. In addition, the cytoplasmic region as well as tyrosine phosphorylation sites in this region of SHPS-1 appear indispensable for this inhibitory action of SHPS-1. Moreover, SHPS-1 may regulate the attachment of RBCs to macrophages by an as yet unidentified mechanism.
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| 4. |
- Ishikawa-Sekigami, Tomomi, et al.
(författare)
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Enhanced phagocytosis of CD47-deficient red blood cells by splenic macrophages requires SHPS-1.
- 2006
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 343:4, s. 1197-200
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Tidskriftsartikel (refereegranskat)abstract
- The interaction of CD47 on red blood cells (RBCs) with SHPS-1 on macrophages is implicated to prevent the phagocytosis of the former cells by the latter cells. Indeed, the rate of clearance of transfused CD47-deficient (CD47(-/-)) RBCs from the bloodstream of wild-type mice was markedly increased compared with wild-type RBCs. Conversely, the rate of clearance of transfused wild-type RBCs was markedly increased in mice that expressed a mutant form of SHPS-1 lacking most of the cytoplasmic region of the protein. However, we here found that the clearance of CD47(-/-) RBCs in SHPS-1 mutant mice was minimal. In addition, the phagocytosis of CD47(-/-) RBCs by splenic macrophages from SHPS-1 mutant mice was markedly reduced compared with wild-type macrophages. These results thus suggest an additional role for CD47 on RBCs in the negative regulation of phagocytosis by macrophages and in determination of the life span of circulating RBCs.
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| 5. |
- Maruyama, Toshi, et al.
(författare)
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Hypothermia-induced tyrosine phosphorylation of SIRPα in the brain
- 2012
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Ingår i: Journal of Neurochemistry. - : John Wiley & Sons. - 0022-3042 .- 1471-4159. ; 121:6, s. 891-902
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Tidskriftsartikel (refereegranskat)abstract
- Signal regulatory protein α (SIRPα) is a neuronal membrane protein that undergoes tyrosine phosphorylation in the brain of mice in response to forced swim (FS) stress in cold water, and this response is implicated in regulation of depression-like behavior in the FS test. We now show that subjection of mice to the FS in warm (37°C) water does not induce the tyrosine phosphorylation of SIRPα in the brain. The rectal temperature (T(rec) ) of mice was reduced to 27° to 30°C by performance of the FS for 10 min in cold water, whereas it was not affected by the same treatment in warm water. The level of tyrosine phosphorylation of SIRPα in the brain was increased by administration of ethanol or picrotoxin, starvation, or cooling after anesthesia, all of which also induced hypothermia. Furthermore, the tyrosine phosphorylation of SIRPα in cultured hippocampal neurons was induced by lowering the temperature of the culture medium. CD47, a ligand of SIRPα, as well as Src family kinases or SH2 domain-containing protein phosphatase 2 (Shp2), might be important for the basal and the hypothermia-induced tyrosine phosphorylation of SIRPα. Hypothermia is therefore likely an important determinant of both the behavioral immobility and tyrosine phosphorylation of SIRPα observed in the FS test.
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| 6. |
- Motegi, Sei-Ichiro, et al.
(författare)
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Essential roles of SHPS-1 in induction of contact hypersensitivity of skin.
- 2008
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Ingår i: Immunology Letters. - : Elsevier BV. - 0165-2478 .- 1879-0542. ; 121:1, s. 52-60
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Tidskriftsartikel (refereegranskat)abstract
- SHPS-1 is a transmembrane protein that binds the protein tyrosine phosphatases SHP-1 and SHP-2 and is abundant on the surface of CD11c(+) dendritic cells (DCs). We recently showed that SHPS-1 is essential for priming by DCs of CD4(+) T cells and for development of Th17 cell-mediated experimental autoimmunity. We have now further evaluated the importance of SHPS-1 and that of its ligand CD47 in contact hypersensitivity (CHS) to 2,4-dinitro-1-fluorobenzene (DNFB). Whereas the DNFB-induced CHS response was impaired in mice that express a mutant form of SHPS-1 lacking most of the cytoplasmic region, it was unaffected in CD47-deficient mice. Moreover, treatment of wild-type mice with mAbs to SHPS-1 that either block or do not block the binding of SHPS-1 to CD47 inhibited the CHS response. A mAb to CD47 had no such effect. The 2,4-dinitro-benzenesulfonic acid-induced proliferation of, and production of IFN-gamma or IL-17 by, T cells from DNFB-sensitized wild-type mice were inhibited by either mAb to SHPS-1 but not by that to CD47. In contrast, the blocking mAbs to SHPS-1, but not that to CD47, inhibited an allogeneic mixed leukocyte reaction. Both mAbs to SHPS-1, but not that to CD47, also inhibited the lipopolysaccharide- or polyinosinic-polycytidylic acid-induced production of TNF-alpha by DCs. These results suggest that SHPS-1 is essential for development of CHS, likely as a result of its positive regulation of the priming by DCs of CD4(+) T cells. However, such regulation by SHPS-1 does not appear to require its interaction with CD47.
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| 7. |
- Murata, Yoji, et al.
(författare)
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Anti-human SIRP antibody is a new tool for cancer immunotherapy
- 2018
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Ingår i: Cancer Science. - : WILEY. - 1347-9032 .- 1349-7006. ; 109:5, s. 1300-1308
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Tidskriftsartikel (refereegranskat)abstract
- Interaction of signal regulatory protein (SIRP) expressed on the surface of macrophages with its ligand CD47 expressed on target cells negatively regulates phagocytosis of the latter cells by the former. We recently showed that blocking Abs to mouse SIRP enhanced both the Ab-dependent cellular phagocytosis (ADCP) activity of mouse macrophages for Burkitt's lymphoma Raji cells opsonized with an Ab to CD20 (rituximab) invitro as well as the inhibitory effect of rituximab on the growth of tumors formed by Raji cells in nonobese diabetic (NOD)/SCID mice. However, the effects of blocking Abs to human SIRP in preclinical cancer models have remained unclear given that such Abs have failed to interact with endogenous SIRP expressed on macrophages of immunodeficient mice. With the use of Rag2(c)(-/-)(-/-) mice harboring a transgene for human SIRP under the control of human regulatory elements (hSIRP-DKO mice), we here show that a blocking Ab to human SIRP significantly enhanced the ADCP activity of macrophages derived from these mice for human cancer cells. The anti-human SIRP Ab also markedly enhanced the inhibitory effect of rituximab on the growth of tumors formed by Raji cells in hSIRP-DKO mice. Our results thus suggest that the combination of Abs to human SIRP with therapeutic Abs specific for tumor antigens warrants further investigation for potential application to cancer immunotherapy. In addition, humanized mice, such as hSIRP-DKO mice, should prove useful for validation of the antitumor effects of checkpoint inhibitors before testing in clinical trials.
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| 8. |
- Saito, Yasuyuki, et al.
(författare)
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Regulation by SIRPα of dendritic cell homeostasis in lymphoid tissues
- 2010
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 116:18, s. 3517-3525
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Tidskriftsartikel (refereegranskat)abstract
- The molecular basis for regulation of dendritic cell (DC) development and homeostasis remains unclear. Signal regulatory protein α (SIRPα), an immunoglobulin superfamily protein that is predominantly expressed in DCs, mediates cell-cell signaling by interacting with CD47, another immunoglobulin superfamily protein. We now show that the number of CD11c(high) DCs (conventional DCs, or cDCs), in particular, that of CD8-CD4+ (CD4+) cDCs, is selectively reduced in secondary lymphoid tissues of mice expressing a mutant form of SIRPα that lacks the cytoplasmic region. We also found that SIRPα is required intrinsically within cDCs or DC precursors for the homeostasis of splenic CD4+ cDCs. Differentiation of bone marrow cells from SIRPα mutant mice into DCs induced by either macrophage-granulocyte colony-stimulating factor or Flt3 ligand in vitro was not impaired. Although the accumulation of the immediate precursors of cDCs in the spleen was also not impaired, the half-life of newly generated splenic CD4+ cDCs was markedly reduced in SIRPα mutant mice. Both hematopoietic and nonhematopoietic CD47 was found to be required for the homeostasis of CD4+ cDCs and CD8-CD4- (double negative) cDCs in the spleen. SIRPα as well as its ligand, CD47, are thus important for the homeostasis of CD4+ cDCs or double negative cDCs in lymphoid tissues.
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| 9. |
- Sato-Hashimoto, Miho, et al.
(författare)
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Microglial SIRP alpha regulates the emergence of CD11c(+) microglia and demyelination damage in white matter
- 2019
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Ingår i: eLIFE. - : eLIFE Sciences Publications. - 2050-084X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- A characteristic subset of microglia expressing CD11c appears in response to brain damage. However, the functional role of CD11c(+) microglia, as well as the mechanism of its induction, are poorly understood. Here we report that the genetic ablation of signal regulatory protein alpha (SIRP alpha), a membrane protein, induced the emergence of CD11c(+) microglia in the brain white matter. Mice lacking CD47, a physiological ligand of SIRP alpha, and microglia-specific SIRP alpha-knockout mice exhibited the same phenotype, suggesting that an interaction between microglial SIRP alpha and CD47 on neighbouring cells suppressed the emergence of CD11c(+) microglia. A lack of SIRP alpha did not cause detectable damage to the white matter, but resulted in the increased expression of genes whose expression is characteristic of the repair phase after demyelination. In addition, cuprizone-induced demyelination was alleviated by the microglia-specific ablation of SIRP alpha. Thus, microglial SIRP alpha suppresses the induction of CD11c(+) microglia that have the potential to accelerate the repair of damaged white matter.
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| 10. |
- Sato-Hashimoto, Miho, et al.
(författare)
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Signal regulatory protein α regulates the homeostasis of T lymphocytes in the spleen.
- 2011
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Ingår i: Journal of Immunology. - : American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 187:1, s. 291-297
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Tidskriftsartikel (refereegranskat)abstract
- The molecular basis for formation of lymphoid follicle and its homeostasis in the secondary lymphoid organs remains unclear. Signal regulatory protein α (SIRPα), an Ig superfamily protein that is predominantly expressed in dendritic cells or macrophages, mediates cell-cell signaling by interacting with CD47, another Ig superfamily protein. In this study, we show that the size of the T cell zone as well as the number of CD4(+) T cells were markedly reduced in the spleen of mice bearing a mutant (MT) SIRPα that lacks the cytoplasmic region compared with those of wild-type mice. In addition, the expression of CCL19 and CCL21, as well as of IL-7, which are thought to be important for development or homeostasis of the T cell zone, was markedly decreased in the spleen of SIRPα MT mice. By the use of bone marrow chimera, we found that hematopoietic SIRPα is important for development of the T cell zone as well as the expression of CCL19 and CCL21 in the spleen. The expression of lymphotoxin and its receptor, lymphotoxin β receptor, as well as the in vivo response to lymphotoxin β receptor stimulation were also decreased in the spleen of SIRPα MT mice. CD47-deficient mice also manifested phenotypes similar to SIRPα MT mice. These data suggest that SIRPα as well as its ligand CD47 are thus essential for steady-state homeostasis of T cells in the spleen.
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