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van der Poel CE, Spaapen RM, van de Winkel JGJ, Leusen JHW. Functional Characteristics of the High Affinity IgG Receptor, FcγRI. THE JOURNAL OF IMMUNOLOGY 2011; 186:2699-704. [DOI: 10.4049/jimmunol.1003526] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Abstract
MicroRNAs are small noncoding RNAs that regulate cellular development by interfering with mRNA stability and translation. We examined global microRNA expression during the differentiation of murine hematopoietic progenitors into megakaryocytes. Of 435 miRNAs analyzed, 13 were up-regulated and 81 were down-regulated. Many of these changes are consistent with miRNA profiling studies of human megakaryocytes and platelets, although new patterns also emerged. Among 7 conserved miRNAs that were up-regulated most strongly in murine megakaryocytes, 6 were also induced in the related erythroid lineage. MiR-146a was strongly up-regulated during mouse and human megakaryopoiesis but not erythropoiesis. However, overexpression of miR-146a in mouse bone marrow hematopoietic progenitor populations produced no detectable alterations in megakaryocyte development or platelet production in vivo or in colony assays. Our findings extend the repertoire of differentially regulated miRNAs during murine megakaryopoiesis and provide a useful new dataset for hematopoiesis research. In addition, we show that enforced hematopoietic expression of miR-146a has minimal effects on megakaryopoiesis. These results are compatible with prior studies indicating that miR-146a inhibits megakaryocyte production indirectly by suppressing inflammatory cytokine production from innate immune cells, but cast doubt on a different study, which suggests that this miRNA inhibits megakaryopoiesis cell-autonomously.
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Reeve JL, Zou W, Liu Y, Maltzman JS, Ross FP, Teitelbaum SL. SLP-76 couples Syk to the osteoclast cytoskeleton. THE JOURNAL OF IMMUNOLOGY 2009; 183:1804-12. [PMID: 19592646 DOI: 10.4049/jimmunol.0804206] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The capacity of the osteoclast (OC) to resorb bone is dictated by cytoskeletal organization, which in turn emanates from signals derived from the alpha(v)beta(3) integrin and c-Fms. Syk is key to these signals and, in other cells, this tyrosine kinase exerts its effects via intermediaries including the SLP adaptors, SLP-76 and BLNK (B cell linker). Thus, we asked whether these two SLP proteins regulate OC function. We find BLNK-deficient OCs are normal, whereas cytoskeletal organization of those lacking SLP-76 is delayed, thus modestly reducing bone resorption in vitro. Cytoskeletal organization and bone resorption are more profoundly arrested in cultured OCs deficient in BLNK and SLP-76 double knockout (DKO) phenotypes. In contrast, stimulated bone resorption in vivo is inhibited approximately 40% in either SLP-76(-/-) or DKO mice. This observation, taken with the fact that DKO OCs are rescued by retroviral transduction of only SLP-76, indicates that SLP-76 is the dominant SLP family member in the resorptive process. We also find SLP-76 is phosphorylated in a Syk-dependent manner. Furthermore, in the absence of the adaptor protein, integrin-mediated phosphorylation of Vav3, the OC cytoskeleton-organizing guanine nucleotide exchange factor, is abrogated. In keeping with a central role of SLP-76/Vav3 association in osteoclastic resorption, retroviral transduction of SLP-76, in which the Vav binding site is disrupted (3YF), fails to normalize the cytoskeleton of DKO OCs and the resorptive capacity of the cells. Finally, c-Fms-activated Syk also exerts its OC cytoskeleton-organizing effect in a SLP-76/Vav3-dependent manner.
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Affiliation(s)
- Jennifer L Reeve
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110, USA
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Yamasaki S, Takase-Utsugi M, Ishikawa E, Sakuma M, Nishida K, Saito T, Kanagawa O. Selective impairment of FcepsilonRI-mediated allergic reaction in Gads-deficient mice. Int Immunol 2008; 20:1289-97. [PMID: 18664516 DOI: 10.1093/intimm/dxn085] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Gads is a Grb2-like adaptor protein expressed in hematopoietic cells. We demonstrated that mast cells from Gads(-/-) mice have selective functional defects. Bone marrow-derived mast cells from Gads(-/-) mice failed to induce Ca(2+) mobilization, degranulation and cytokine production upon cross-linking of FcepsilonRI. In vivo passive cutaneous anaphylaxis was also greatly impaired in Gads(-/-) mice. In contrast, Gads was dispensable for Toll-like receptor-mediated cytokine production in mast cells. Accordingly, mast cell-dependent resistance to acute peritoneal bacterial infection is not reduced in Gads(-/-) mice in vivo. Moreover, mature T and B cell responses and antibody production upon immunization were apparently normal in Gads(-/-) mice. Thus, inhibition of Gads in vivo would suppress the IgE-mediated allergic reaction with minimum adverse effects on both innate and acquired immune responses, and Gads could be an ideal target for the control of allergic responses.
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Affiliation(s)
- Sho Yamasaki
- Laboratory for Cell Signaling, RIKEN Research Center for Allergy and Immunology, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
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Abstract
Adapters are multidomain molecules that recruit effector proteins during signal transduction by immunoreceptors and integrins. The absence of these scaffolding molecules profoundly affects development and function of various hematopoietic lineages, underscoring their importance as regulators of signaling cascades. An emerging aspect of the mechanism by which engaged immunoreceptors and integrins transmit signals within the cell is by differential usage of various adapters that function to nucleate formation of distinct signaling complexes in a specific location within the cell. In this review, we discuss the mechanisms by which adapter proteins coordinate signal transduction with an emphasis on the role of subcellular compartmentalization in adapter function.
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Affiliation(s)
- Natalie Bezman
- Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
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Clemens RA, Lenox LE, Kambayashi T, Bezman N, Maltzman JS, Nichols KE, Koretzky GA. Loss of SLP-76 expression within myeloid cells confers resistance to neutrophil-mediated tissue damage while maintaining effective bacterial killing. THE JOURNAL OF IMMUNOLOGY 2007; 178:4606-14. [PMID: 17372019 DOI: 10.4049/jimmunol.178.7.4606] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The Src homology 2 domain-containing leukocyte phosphoprotein of 76 kDa (SLP-76) is an adaptor molecule critical for immunoreceptor and integrin signaling in multiple hemopoietic lineages. We showed previously that SLP-76 is required for neutrophil function in vitro, including integrin-induced adhesion and production of reactive oxygen intermediates, and to a lesser extent, FcgammaR-induced calcium flux and reactive oxygen intermediate production. It has been difficult to determine whether SLP-76 regulates neutrophil responses in vivo, because Slp-76(-/-) mice exhibit marked defects in thymocyte and vascular development, as well as platelet and mast cell function. To circumvent these issues, we generated mice with targeted loss of SLP-76 expression within myeloid cells. Neutrophils obtained from these animals failed to respond to integrin activation in vitro, similar to Slp-76(-/-) cells. Despite these abnormalities, SLP-76-deficient neutrophils migrated normally in vivo in response to Staphylococcus aureus infection and efficiently cleared micro-organisms. Interestingly, SLP-76-deficient neutrophils did not induce a robust inflammatory response in the localized Shwartzman reaction. Collectively, these data suggest that disruption of integrin signaling via loss of SLP-76 expression differentially impairs neutrophil functions in vivo, with preservation of migration and killing of S. aureus but reduction in LPS-induced tissue damage and vascular injury.
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Affiliation(s)
- Regina A Clemens
- Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, 421 Curie Boulevard, Philadelphia, PA 19104, USA
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Koretzky GA, Abtahian F, Silverman MA. SLP76 and SLP65: complex regulation of signalling in lymphocytes and beyond. Nat Rev Immunol 2006; 6:67-78. [PMID: 16493428 DOI: 10.1038/nri1750] [Citation(s) in RCA: 205] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
SLP76 and SLP65 are adaptor proteins that lack intrinsic enzymatic activity but contain multiple protein-binding domains. These proteins are essential for signalling downstream of integrins and receptors that contain immunoreceptor tyrosine-based activation motifs. The absence of these adaptor proteins profoundly affects various lineages in the haematopoietic compartment and severely compromises vascular development, highlighting their importance as regulators of signalling cascades. In this Review, we discuss the role of SLP76 and SLP65 in several signalling pathways in haematopoietic cells, with an emphasis on recent studies that provide insight into their mechanisms of action.
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Affiliation(s)
- Gary A Koretzky
- Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, University of Pennsylvania, 415 BRBII/III, 421 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA.
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Yen A, Varvayanis S, Smith JL, Lamkin TJ. Retinoic acid induces expression of SLP-76: expression with c-FMS enhances ERK activation and retinoic acid-induced differentiation/G0 arrest of HL-60 cells. Eur J Cell Biol 2005; 85:117-32. [PMID: 16439309 DOI: 10.1016/j.ejcb.2005.09.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Revised: 09/21/2005] [Accepted: 09/28/2005] [Indexed: 11/23/2022] Open
Abstract
Retinoic acid (RA) is known to cause MAPK signaling which propels G0 arrest and myeloid differentiation of HL-60 human myeloblastic leukemia cells. The present studies show that RA up-regulated expression of SLP-76 (Src-homology 2 domain-containing leukocyte-specific phospho-protein of 76 kDa), which became a prominent tyrosine-phosphorylated protein in RA-treated cells. SLP-76 is a known adaptor molecule associated with T-cell receptor and MAPK signaling. To characterize functional effects of SLP-76 expression in RA-induced differentiation and G0 arrest, HL-60 cells were stably transfected with SLP-76. Expression of SLP-76 had no discernable effect on RA-induced ERK activation, subsequent functional differentiation, or the rate of RA-induced G0 arrest. To determine the effects of SLP-76 in the presence of a RA-regulated receptor, SLP-76 was stably transfected into HL-60 cells already overexpressing the colony stimulating factor-1 (CSF-1) receptor, c-FMS, from a previous stable transfection. SLP-76 now enhanced RA-induced ERK activation, compared to parental c-FMS transfectants. It also enhanced RA-induced differentiation, evidenced by enhanced paxillin expression, inducible oxidative metabolism and superoxide production. RA-induced RB tumor suppressor protein hypophosphorylation was also enhanced, as was RA-induced G0 cell cycle arrest. A triple Y to F mutant SLP-76 known to be a dominant negative in T-cell receptor signaling failed to enhance RA-induced paxillin expression, but enhanced RA-induced ERK activation, differentiation and G0 arrest essentially as well as wild-type SLP-76. Thus, SLP-76 overexpression in the presence of c-FMS, a RA-induced receptor, had the effect of enhancing RA-induced cell differentiation. This is the first indication to our knowledge that RA induces the expression of an adapter molecule to facilitate induced differentiation via co-operation between c-FMS and SLP-76.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Blotting, Western
- Cell Differentiation/drug effects
- Enzyme Activation
- Extracellular Signal-Regulated MAP Kinases/genetics
- Extracellular Signal-Regulated MAP Kinases/physiology
- Gene Expression Regulation, Leukemic
- HL-60 Cells
- Humans
- Immunoprecipitation
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/pathology
- Leukemia, Myeloid, Acute/physiopathology
- Mutation
- Paxillin/genetics
- Paxillin/physiology
- Phosphoproteins/genetics
- Phosphoproteins/physiology
- Phosphorylation
- Receptor, Macrophage Colony-Stimulating Factor/genetics
- Receptor, Macrophage Colony-Stimulating Factor/physiology
- Receptors, Antigen, T-Cell/physiology
- Resting Phase, Cell Cycle/drug effects
- Signal Transduction
- Superoxides/metabolism
- Transfection
- Tretinoin/pharmacology
- Up-Regulation/drug effects
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Affiliation(s)
- Andrew Yen
- Department of Biomedical Sciences, T4-008 VRT, Cornell University, Ithaca, NY 14853, USA.
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Abstract
Adapter molecules are multidomain proteins lacking intrinsic catalytic activity, functioning instead by nucleating molecular complexes during signal transduction. The SLP-76 family of adapters includes SH2 domain-containing leukocyte phosphoprotein of 76kDa (SLP-76), B cell linker protein (BLNK), and cytokine-dependent hematopoietic cell linker (Clnk). These proteins are critical for integration of numerous signaling cascades downstream of immunotyrosine-based activation motif (ITAM)-bearing receptors and integrins in diverse hematopoietic cell types. Mutations in genes encoding SLP-76 family adapters result in severe phenotypes, underscoring the critical role these proteins play in cellular development and function by directing formation of signaling complexes in a temporally- and spatially-specific manner.
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Affiliation(s)
- Jennifer N Wu
- Department of Laboratory Medicine and Pathology, School of Medicine, Abramson Family Cancer Research Institute, University of Pennsylvania, 415 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104, USA
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Utting O, Sedgmen BJ, Watts TH, Shi X, Rottapel R, Iulianella A, Lohnes D, Veillette A. Immune functions in mice lacking Clnk, an SLP-76-related adaptor expressed in a subset of immune cells. Mol Cell Biol 2004; 24:6067-75. [PMID: 15199160 PMCID: PMC480883 DOI: 10.1128/mcb.24.13.6067-6075.2004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The SLP-76 family of immune cell-specific adaptors is composed of three distinct members named SLP-76, Blnk, and Clnk. They have been implicated in the signaling pathways coupled to immunoreceptors such as the antigen receptors and Fc receptors. Previous studies using gene-targeted mice and deficient cell lines showed that SLP-76 plays a central role in T-cell development and activation. Moreover, it is essential for normal mast cell and platelet activation. In contrast, Blnk is necessary for B-cell development and activation. While the precise function of Clnk is not known, it was reported that Clnk is selectively expressed in mast cells, natural killer (NK) cells, and previously activated T-cells. Moreover, ectopic expression of Clnk was shown to rescue T-cell receptor-mediated signal transduction in an SLP-76-deficient T-cell line, suggesting that, like its relatives, Clnk is involved in the positive regulation of immunoreceptor signaling. Stimulatory effects of Clnk on immunoreceptor signaling were also reported to occur in transfected B-cell and basophil leukemia cell lines. Herein, we attempted to address the physiological role of Clnk in immune cells by the generation of Clnk-deficient mice. The results of our studies demonstrated that Clnk is dispensable for normal differentiation and function of T cells, mast cells, and NK cells. Hence, unlike its relatives, Clnk is not essential for normal immune functions.
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Affiliation(s)
- Oliver Utting
- Laboratory of Molecular Oncology, Clinical Research Institute of Montreal, Montréal, Québec, Canada H2W 1R7
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