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Wang Z, Qu S, Yuan J, Tian W, Xu J, Tao R, Sun S, Lu T, Tang W, Zhu Y. Review and prospects of targeted therapies for Spleen tyrosine kinase (SYK). Bioorg Med Chem 2023; 96:117514. [PMID: 37984216 DOI: 10.1016/j.bmc.2023.117514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 10/30/2023] [Accepted: 10/31/2023] [Indexed: 11/22/2023]
Abstract
Spleen tyrosine kinase (SYK) is a non-receptor tyrosine kinase. The dysregulation of SYK is closely related to the occurrence and development of allergic diseases, autoimmune diseases and cancer. SYK has become an attractive target for drug discovery due to its important biological functions. This article reviews the biological function of SYK, the relationship between SYK and disease, and therapies targeting SYK. In addition, inspired by new technologies such as proteolysis targeting chimeras (PROTACs) and phosphatase recruiting chimeras (PHORCs), we propose the development of new therapeutic approaches for targeting SYK, such as SYK PROTACs and SYK PHORCs, which may overcome deficiencies of existing methods.
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Affiliation(s)
- Zhaozhao Wang
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing 211198, PR China
| | - Shu Qu
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing 211198, PR China
| | - Jiahao Yuan
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing 211198, PR China
| | - Wen Tian
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing 211198, PR China
| | - Jinglei Xu
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing 211198, PR China
| | - Rui Tao
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing 211198, PR China
| | - Shilong Sun
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing 211198, PR China
| | - Tao Lu
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing 211198, PR China; State Key Laboratory of Natural Medicines, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, PR China
| | - Weifang Tang
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing 211198, PR China.
| | - Yong Zhu
- School of Science, China Pharmaceutical University, 639 Longmian Avenue, Nanjing 211198, PR China.
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2
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Zhong J, Qiu M, Meng Y, Wang P, Chen S, Wang L. Single-cell multi-omics sequencing reveals the immunological disturbance underlying STAT3-V637M Hyper-IgE syndrome. Int Immunopharmacol 2023; 122:110624. [PMID: 37480751 DOI: 10.1016/j.intimp.2023.110624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 06/29/2023] [Accepted: 07/06/2023] [Indexed: 07/24/2023]
Abstract
Hyper-IgE syndrome (HIES) is a primary immunodeficiency characterized by, among others, the excessive production of IgE and repetitive bacterial/fungal infections. Mutations in STAT3, a transcription factor that orchestrates immune responses, may cause HIES, but the underlying mechanisms are not fully understood. Here, we used multi-omic approaches to comprehensively decipher the immune disturbance in a male HIES patient harboring STAT3-V637M. In his peripheral blood mononuclear cell (PBMC) we found significant clonal expansion of CD8 T cells (with increased CD8 subunits expression, potentially enhancing responsiveness to MHC I molecules), but not in his CD4 T cells and B cells. Although his B cells exhibited a higher potential in producing immunoglobulin, elevated SPIC binding might bias the products toward IgE isotype. Immune checkpoint inhibitors, including CTLA4, LAG3, were overexpressed in his PBMC-CD4 T cells, accompanied by reduced CD28 and IL6ST (gp130) expression. In his CD4 T cells, integrative analyses predicted upstream transcription factors (including ETV6, KLF13, and RORA) for LAG3, IL6ST, and CD28, respectively. The down-regulation of phagocytosis and nitric oxide synthesis-related genes in his PBMC-monocytes seem to be the culprit of his disseminated bacterial/fungal infection. Counterintuitively, in his PBMC we predicted increased STAT3 binding in both naïve and mature CD4 compartments, although this was not observed in most of his PBMC. In his bronchoalveolar lavage fluid (BALF), we found two macrophage subtypes with anti-bacterial properties, which were identified by CXCL8/S100A8/S100A9, or SOD2, respectively. Together, we described how the immune cell landscape was disturbed in STAT3-V637M HIES, providing a resource for further studies.
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Affiliation(s)
- Jiacheng Zhong
- Shenzhen Institute of Respiratory Diseases, Department of Respiratory and Critical Care Medicine, Shenzhen People's Hospital, Shenzhen 518055, Guangdong, China; Shenzhen Key Laboratory of Respiratory Diseases, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University, The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen 518055, Guangdong, China
| | - Minzhi Qiu
- Health Management Center, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University, the First Affiliated Hospital, Southern University of Science and Technology), Shenzhen 518020, China
| | - Yu Meng
- Department of Quality Control, Shenzhen People's Hospital, Shenzhen 518055, Guangdong, China
| | - Peizhong Wang
- Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
| | - Shanze Chen
- Shenzhen Institute of Respiratory Diseases, Department of Respiratory and Critical Care Medicine, Shenzhen People's Hospital, Shenzhen 518055, Guangdong, China; Shenzhen Key Laboratory of Respiratory Diseases, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University, The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen 518055, Guangdong, China.
| | - Lingwei Wang
- Shenzhen Institute of Respiratory Diseases, Department of Respiratory and Critical Care Medicine, Shenzhen People's Hospital, Shenzhen 518055, Guangdong, China; Shenzhen Key Laboratory of Respiratory Diseases, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University, The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen 518055, Guangdong, China.
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3
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Chellappan DK, Yee LW, Xuan KY, Kunalan K, Rou LC, Jean LS, Ying LY, Wie LX, Chellian J, Mehta M, Satija S, Singh SK, Gulati M, Dureja H, Da Silva MW, Tambuwala MM, Gupta G, Paudel KR, Wadhwa R, Hansbro PM, Dua K. Targeting neutrophils using novel drug delivery systems in chronic respiratory diseases. Drug Dev Res 2020; 81:419-436. [PMID: 32048757 DOI: 10.1002/ddr.21648] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 01/21/2020] [Accepted: 01/25/2020] [Indexed: 12/29/2022]
Abstract
Neutrophils are essential effector cells of immune system for clearing the extracellular pathogens during inflammation and immune reactions. Neutrophils play a major role in chronic respiratory diseases. In respiratory diseases such as asthma, chronic obstructive pulmonary disease, cystic fibrosis, lung cancer and others, there occurs extreme infiltration and activation of neutrophils followed by a cascade of events like oxidative stress and dysregulated cellular proteins that eventually result in apoptosis and tissue damage. Dysregulation of neutrophil effector functions including delayed neutropil apoptosis, increased neutrophil extracellular traps in the pathogenesis of asthma, and chronic obstructive pulmonary disease enable neutrophils as a potential therapeutic target. Accounting to their role in pathogenesis, neutrophils present as an excellent therapeutic target for the treatment of chronic respiratory diseases. This review highlights the current status and the emerging trends in novel drug delivery systems such as nanoparticles, liposomes, microspheres, and other newer nanosystems that can target neutrophils and their molecular pathways, in the airways against infections, inflammation, and cancer. These drug delivery systems are promising in providing sustained drug delivery, reduced therapeutic dose, improved patient compliance, and reduced drug toxicity. In addition, the review also discusses emerging strategies and the future perspectives in neutrophil-based therapy.
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Affiliation(s)
- Dinesh K Chellappan
- Department of Life Sciences, School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Lim W Yee
- School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Kong Y Xuan
- School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Kishen Kunalan
- School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Lim C Rou
- School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Leong S Jean
- School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Lee Y Ying
- School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Lee X Wie
- School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Jestin Chellian
- Department of Life Sciences, School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Meenu Mehta
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara, Punjab, India
| | - Saurabh Satija
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara, Punjab, India
| | - Sachin K Singh
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara, Punjab, India
| | - Monica Gulati
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara, Punjab, India
| | - Harish Dureja
- Department of Pharmaceutical Sciences, Maharishi Dayanand University, Rohtak, Haryana, India
| | - Mateus Webba Da Silva
- School of Pharmacy and Pharmaceutical Sciences, Ulster University, County Londonderry, Northern Ireland, United Kingdom
| | - Murtaza M Tambuwala
- School of Pharmacy and Pharmaceutical Sciences, Ulster University, County Londonderry, Northern Ireland, United Kingdom
| | - Gaurav Gupta
- School of Phamacy, Suresh Gyan Vihar University, Jaipur, India
| | - Keshav R Paudel
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, Australia.,Centre for Inflammation, Centenary Institute, Sydney, New South Wales, Australia
| | - Ridhima Wadhwa
- Centre for Inflammation, Centenary Institute, Sydney, New South Wales, Australia.,Discipline of Pharmacy, Graduate School of Health, University of Technology Sydney, Ultimo, New South Wales, Australia
| | - Philip M Hansbro
- School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, Australia.,Centre for Inflammation, Centenary Institute, Sydney, New South Wales, Australia.,Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute (HMRI) & School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia
| | - Kamal Dua
- Centre for Inflammation, Centenary Institute, Sydney, New South Wales, Australia.,Discipline of Pharmacy, Graduate School of Health, University of Technology Sydney, Ultimo, New South Wales, Australia.,Priority Research Centre for Healthy Lungs, Hunter Medical Research Institute (HMRI) & School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia.,School of Pharmaceutical Sciences, Shoolini University, Solan, Himachal Pradesh, India
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4
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NF-κB activation mediates LPS-or zymosan-induced hypotension and inflammation reversed by BAY61-3606, a selective Syk inhibitor, in rat models of septic and non-septic shock. Clin Exp Pharmacol Physiol 2019; 46:173-182. [DOI: 10.1111/1440-1681.13045] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 10/16/2018] [Accepted: 10/16/2018] [Indexed: 11/26/2022]
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5
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Unsal D, Kacan M, Temiz-Resitoglu M, Guden DS, Korkmaz B, Sari AN, Buharalioglu CK, Yildirim-Yaroglu H, Tamer-Gumus L, Tunctan B, Malik KU, Sahan-Firat S. The role of Syk/IĸB-α/NF-ĸB pathway activation in the reversal effect of BAY 61-3606, a selective Syk inhibitor, on hypotension and inflammation in a rat model of zymosan-induced non-septic shock. Clin Exp Pharmacol Physiol 2017; 45:155-165. [DOI: 10.1111/1440-1681.12864] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 07/31/2017] [Accepted: 09/19/2017] [Indexed: 01/22/2023]
Affiliation(s)
- Demet Unsal
- Department of Pharmacology; Faculty of Pharmacy; Mersin University; Mersin Turkey
| | - Meltem Kacan
- Department of Pharmacology; Faculty of Pharmacy; Mersin University; Mersin Turkey
| | | | - Demet S Guden
- Department of Pharmacology; Faculty of Pharmacy; Mersin University; Mersin Turkey
| | - Belma Korkmaz
- Department of Pharmacology; Faculty of Pharmacy; Mersin University; Mersin Turkey
| | - Ayse N Sari
- Department of Pharmacology; Faculty of Pharmacy; Mersin University; Mersin Turkey
| | - Cuneyt K Buharalioglu
- Department of Pharmacology; Faculty of Pharmacy International; Cyprus University; Nicosia Cyprus
| | | | - Lulufer Tamer-Gumus
- Department of Biochemistry; Faculty of Medicine; Mersin University; Mersin Turkey
| | - Bahar Tunctan
- Department of Pharmacology; Faculty of Pharmacy; Mersin University; Mersin Turkey
| | - Kafait U Malik
- Department of Pharmacology; College of Medicine; Center for Health Sciences; University of Tennessee; Memphis TN USA
| | - Seyhan Sahan-Firat
- Department of Pharmacology; Faculty of Pharmacy; Mersin University; Mersin Turkey
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Zhu X, Ng HP, Lai YC, Craigo JK, Nagilla PS, Raghani P, Nagarajan S. Scavenger receptor function of mouse Fcγ receptor III contributes to progression of atherosclerosis in apolipoprotein E hyperlipidemic mice. THE JOURNAL OF IMMUNOLOGY 2014; 193:2483-95. [PMID: 25038257 DOI: 10.4049/jimmunol.1303075] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Recent studies showed loss of CD36 or scavenger receptor-AI/II (SR-A) does not ameliorate atherosclerosis in a hyperlipidemic mouse model, suggesting receptors other than CD36 and SR-A may also contribute to atherosclerosis. In this report, we show that apolipoprotein E (apoE)-CD16 double knockout (DKO; apoE-CD16 DKO) mice have reduced atherosclerotic lesions compared with apoE knockout mice. In vivo and in vitro foam cell analyses showed apoE-CD16 DKO macrophages accumulated less neutral lipids. Reduced foam cell formation in apoE-CD16 DKO mice is not due to change in expression of CD36, SR-A, and LOX-1. This led to a hypothesis that CD16 may have scavenger receptor activity. We presented evidence that a soluble form of recombinant mouse CD16 (sCD16) bound to malondialdehyde-modified low-density lipoprotein (MDALDL), and this binding is blocked by molar excess of MDA- modified BSA and anti-MDA mAbs, suggesting CD16 specifically recognizes MDA epitopes. Interestingly, sCD16 inhibited MDALDL binding to macrophage cell line, as well as soluble forms of recombinant mouse CD36, SR-A, and LOX-1, indicating CD16 can cross-block MDALDL binding to other scavenger receptors. Anti-CD16 mAb inhibited immune complex binding to sCD16, whereas it partially inhibited MDALDL binding to sCD16, suggesting MDALDL binding site may be in close proximity to the immune complex binding site in CD16. Loss of CD16 expression resulted in reduced levels of MDALDL-induced proinflammatory cytokine expression. Finally, CD16-deficient macrophages showed reduced MDALDL-induced Syk phosphorylation. Collectively, our findings suggest scavenger receptor activity of CD16 may, in part, contribute to the progression of atherosclerosis.
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Affiliation(s)
- Xinmei Zhu
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261; Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Hang Pong Ng
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261; Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Yen-Chun Lai
- Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Jodi K Craigo
- Center for Vaccine Research, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261; Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Pruthvi S Nagilla
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261; Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Pooja Raghani
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261; Summer Undergraduate Research Program, University of Pittsburgh, Pittsburgh, PA 15261; and Arizona State University, Tempe, AZ 85287
| | - Shanmugam Nagarajan
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261; Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261; Center for Vaccine Research, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261;
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7
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Uckun FM, Qazi S. Spleen tyrosine kinase as a molecular target for treatment of leukemias and lymphomas. Expert Rev Anticancer Ther 2014; 10:1407-18. [DOI: 10.1586/era.10.112] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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8
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Abstract
Endocytosis is an essential process of eukaryotic cells that facilitates numerous cellular and organismal functions. The formation of vesicles from the plasma membrane serves the internalization of ligands and receptors and leads to their degradation or recycling. A number of distinct mechanisms have been described over the years, several of which are only partially characterized in terms of mechanism and function. These are often referred to as novel endocytic pathways. The pathways differ in their mode of uptake and in their intracellular destination. Here, an overview of the set of cellular proteins that facilitate the different pathways is provided. Further, the approaches to distinguish between the pathways by different modes of perturbation are critically discussed, emphasizing the use of genetic tools such as dominant negative mutant proteins.
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Affiliation(s)
- Lena Kühling
- Emmy Noether Group: Virus Endocytosis, Institutes of Molecular Virology and Medical Biochemistry, ZMBE, Westphalian Wilhelms University of Münster, Von-Esmarch-Str. 56, Münster, 48149, Germany
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Greuber EK, Pendergast AM. Abl family kinases regulate FcγR-mediated phagocytosis in murine macrophages. THE JOURNAL OF IMMUNOLOGY 2012; 189:5382-92. [PMID: 23100514 DOI: 10.4049/jimmunol.1200974] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Phagocytosis of Ab-coated pathogens is mediated through FcγRs, which activate intracellular signaling pathways to drive actin cytoskeletal rearrangements. Abl and Arg define a family of nonreceptor tyrosine kinases that regulate actin-dependent processes in a variety of cell types, including those important in the adaptive immune response. Using pharmacological inhibition as well as dominant negative and knockout approaches, we demonstrate a role for the Abl family kinases in phagocytosis by macrophages and define a mechanism whereby Abl kinases regulate this process. Bone marrow-derived macrophages from mice lacking Abl and Arg kinases exhibit inefficient phagocytosis of sheep erythrocytes and zymosan particles. Treatment with the Abl kinase inhibitors imatinib and GNF-2 or overexpression of kinase-inactive forms of the Abl family kinases also impairs particle internalization in murine macrophages, indicating Abl kinase activity is required for efficient phagocytosis. Further, Arg kinase is present at the phagocytic cup, and Abl family kinases are activated by FcγR engagement. The regulation of phagocytosis by Abl family kinases is mediated in part by the spleen tyrosine kinase (Syk). Loss of Abl and Arg expression or treatment with Abl inhibitors reduced Syk phosphorylation in response to FcγR ligation. The link between Abl family kinases and Syk may be direct, as purified Arg kinase phosphorylates Syk in vitro. Further, overexpression of membrane-targeted Syk in cells treated with Abl kinase inhibitors partially rescues the impairment in phagocytosis. Together, these findings reveal that Abl family kinases control the efficiency of phagocytosis in part through the regulation of Syk function.
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Affiliation(s)
- Emileigh K Greuber
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA
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10
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Park H, Ishihara D, Cox D. Regulation of tyrosine phosphorylation in macrophage phagocytosis and chemotaxis. Arch Biochem Biophys 2011; 510:101-11. [PMID: 21356194 PMCID: PMC3114168 DOI: 10.1016/j.abb.2011.02.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 02/15/2011] [Accepted: 02/18/2011] [Indexed: 12/22/2022]
Abstract
Macrophages display a large variety of surface receptors that are critical for their normal cellular functions in host defense, including finding sites of infection (chemotaxis) and removing foreign particles (phagocytosis). However, inappropriate regulation of these processes can lead to human diseases. Many of these receptors utilize tyrosine phosphorylation cascades to initiate and terminate signals leading to cell migration and clearance of infection. Actin remodeling dominates these processes and many regulators have been identified. This review focuses on how tyrosine kinases and phosphatases regulate actin dynamics leading to macrophage chemotaxis and phagocytosis.
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Affiliation(s)
- Haein Park
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Dan Ishihara
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Dianne Cox
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
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11
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Lu Y, Wang W, Mao H, Hu H, Wu Y, Chen BG, Liu Z. Antibody-mediated platelet phagocytosis by human macrophages is inhibited by siRNA specific for sequences in the SH2 tyrosine kinase, Syk. Cell Immunol 2011; 268:1-3. [DOI: 10.1016/j.cellimm.2011.02.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 02/14/2011] [Accepted: 02/15/2011] [Indexed: 12/15/2022]
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Abstract
BACKGROUND The non-receptor spleen tyrosine kinase (Syk; EC 2.7.10.2) is involved in signal transduction in a variety of cell types. In particular, it is a key mediator of immune receptors signaling in host inflammatory cells (B cells, mast cells, macrophages and neutrophils), important for both allergic and antibody-mediated autoimmune diseases. Deregulated Syk kinase activity also allows growth factor-independent proliferation and transforms bone marrow-derived pre-B cells that are able to induce leukemia. Consequently, the development of Syk kinase inhibitors could conceivably treat these disorders and so they have became a major focus in the pharmaceutical and biotech industry. OBJECTIVE In this review, we analyze the structure and role of Syk kinase, the use of small molecules, interacting with ATP-binding site, as inhibitors of kinase activity and finally the potential of using inhibitors of Syk kinase expression to attenuate pathological conditions. CONCLUSION Syk kinase inhibition is suggested as a powerful tool for the therapy of different pathologies.
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Affiliation(s)
- Paolo Ruzza
- Institute of Biomolecular Chemistry of CNR, Padova Unit, c/o Dept. Chemical Sciences, University of Padova, via Marzolo 1, Padua, Italy.
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Singh D, Rani R, Rajendran R, Kaur NJ, Pandey A, Chopra P, Jain T, Jain MK, Grover S, Arya R, Saini KS. Human spleen tyrosine kinase (Syk) recombinant expression systems for high-throughput assays. Biotechnol J 2009; 5:201-12. [DOI: 10.1002/biot.200900139] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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14
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Adachi R, Suzuki K. Lyn, one of the Src-family tyrosine kinases expressed in phagocytes, plays an important role in beta2 integrin-signalling pathways in opsonized zymosan-activated macrophage-like U937 cells. Cell Biochem Funct 2007; 25:323-33. [PMID: 17173331 DOI: 10.1002/cbf.1393] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We have investigated the contribution of Hck, Lyn and Fgr, highly expressed Src family tyrosine kinases (SFKs) in signalling pathways in opsonized zymosan (OZ)-activated phagocytes by using short interfering RNAs (siRNAs). Treatment of macrophage-like U937 cells with the siRNAs targeted to these transcripts decreased the protein content of each kinase to less than half that of untreated cells. Among these siRNAs, siRNA targeted to Lyn was the most effective in diminishing two kinds of phagocyte functions, that is oxidative burst and phagocytosis. Phosphorylation of c-Cbl, a multidomain adaptor protein in the beta2 integrin-signalling pathway, was also largely inhibited by treatment with siRNA to Lyn. Thus, the results with siRNAs highly specific for Hck, Lyn and Fgr suggested that, among these three SFKs, Lyn plays the most important role in signalling pathways downstream of beta2 integrins in OZ-stimulated phagocytes.
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Affiliation(s)
- Reiko Adachi
- Division of Biosignaling, National Institute of Health Sciences, Setagaya-ku, Tokyo, Japan.
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Ulanova M, Asfaha S, Stenton G, Lint A, Gilbertson D, Schreiber A, Befus D. Involvement of Syk protein tyrosine kinase in LPS-induced responses in macrophages. ACTA ACUST UNITED AC 2007; 13:117-25. [PMID: 17621553 DOI: 10.1177/0968051907079125] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Syk kinase is best known as a critical component of immunoreceptor signaling in leukocytes. Activation of Syk following cross-linking of Fcgamma and Fcepsilon receptors on macrophages, mast cells, and other cells induces various inflammatory events. We hypothesized that Syk is involved in inflammatory responses induced by the lipopolysaccharide (LPS). We studied the role of Syk using its inhibition by antisense oligonucleotides, or small interfering RNA. Our data demonstrated that in vivo inhibition of Syk caused down-regulation of LPS-induced responses in rat alveolar macrophages. In in vitro experiments, inhibition of Syk in rat peritoneal macrophages, as well as in human myelomonocyte cell line THP-1 also caused a decrease in LPS-induced cytokine release. Our data support the hypothesis that, in macrophages, Syk is involved in LPS-induced intracellular signaling pathways leading to the release of pro-inflammatory mediators. Understanding the role of Syk in LPS-induced signaling may help in developing new therapeutic tools for inflammatory disorders.
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MESH Headings
- Animals
- Blotting, Western
- Cell Line
- Cytokines/immunology
- Cytokines/metabolism
- Enzyme-Linked Immunosorbent Assay
- Humans
- Inflammation Mediators/metabolism
- Intracellular Signaling Peptides and Proteins/antagonists & inhibitors
- Intracellular Signaling Peptides and Proteins/immunology
- Intracellular Signaling Peptides and Proteins/metabolism
- Lipopolysaccharides/immunology
- Lipopolysaccharides/metabolism
- Liposomes
- Macrophages, Alveolar/enzymology
- Macrophages, Alveolar/immunology
- Macrophages, Alveolar/metabolism
- Macrophages, Peritoneal/enzymology
- Macrophages, Peritoneal/immunology
- Macrophages, Peritoneal/metabolism
- Male
- Monocytes/immunology
- Monocytes/metabolism
- Nitric Oxide/metabolism
- Oligonucleotides, Antisense/metabolism
- Oligonucleotides, Antisense/pharmacology
- Protein-Tyrosine Kinases/antagonists & inhibitors
- Protein-Tyrosine Kinases/immunology
- Protein-Tyrosine Kinases/metabolism
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Rats
- Rats, Sprague-Dawley
- Reverse Transcriptase Polymerase Chain Reaction
- Syk Kinase
- Transfection
- Tumor Necrosis Factor-alpha/metabolism
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Affiliation(s)
- Marina Ulanova
- Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.
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Ulanova M, Duta F, Puttagunta L, Schreiber AD, Befus AD. Spleen tyrosine kinase (Syk) as a novel target for allergic asthma and rhinitis. Expert Opin Ther Targets 2007; 9:901-21. [PMID: 16185147 DOI: 10.1517/14728222.9.5.901] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Allergic asthma and rhinitis are prevalent diseases in the modern world, both marked by inflammation of the airways. The spleen tyrosine kinase (Syk) plays a critical role in the regulation of such immune and inflammatory responses. Although Syk is best known as a key component of immunoreceptor signalling complexes in leukocytes, recent studies demonstrated Syk expression in cells outside the haematopoietic lineage. Moreover, in recent years, it has been established that Syk is involved in various signalling cascades including those originating from integrin and cytokine receptors. Thus, Syk likely has a much wider biological role than previously recognised. Specific inhibition of Syk using aerosolised antisense oligonucleotides in liposome complexes significantly decreased lung inflammatory responses in experimental asthma and acute lung injury models. In addition, pharmacological inhibitors of Syk have been recently developed with potential for use as therapeutics. However, in the development and the rational delivery of drugs targeting Syk, it is important to consider the multiple cell types that express this kinase and the potential effects of its inhibition on various physiological functions. This review focuses on the recent data and the emerging ideas about Syk as a therapeutic target.
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Affiliation(s)
- Marina Ulanova
- University of Alberta, Department of Medicine, Edmonton, Alberta, T6G 2S2, Canada
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17
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Joshi T, Butchar JP, Tridandapani S. Fcgamma receptor signaling in phagocytes. Int J Hematol 2006; 84:210-216. [PMID: 17050193 DOI: 10.1532/ijh97.06140] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Accepted: 07/05/2006] [Indexed: 01/16/2023]
Abstract
Fcgamma receptors are among the best-studied phagocytic receptors. The key features of Fcgamma receptor-mediated phagocytosis include phagocytic cup formation by extensive actin cytoskeletal rearrangements, particle engulfment, and the release of proinflammatory mediators such as cytokines and reactive oxygen species. These events are elegantly regulated by the simultaneous engagement of activating and inhibitory Fcgamma receptors and by intracellular signaling molecules. Extensive studies in the past several years have defined the molecular mechanisms of the phagocytic process. The purpose of this review is to revisit some of the well-established signaling pathways as well as to summarize the new findings in this field.
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Affiliation(s)
- Trupti Joshi
- Department of Internal Medicine, Dorothy M. Davis Heart and Lung Research Institute and Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, USA
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18
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Ulanova M, Schreiber AD, Befus AD. The future of antisense oligonucleotides in the treatment of respiratory diseases. BioDrugs 2006; 20:1-11. [PMID: 16573347 PMCID: PMC7100773 DOI: 10.2165/00063030-200620010-00001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Antisense oligonucleotides (ASO) are short synthetic DNA molecules designed to inhibit translation of a targeted gene to protein via interaction with messenger RNA. More recently, small interfering (si)RNA have been developed as potent tools to specifically inhibit gene expression. ASO directed against signaling molecules, cytokine receptors, and transcription factors involved in allergic immune and inflammatory responses, have been applied in experimental models of asthma and demonstrate potential as therapeutics. Several ASO-based drugs directed against oncogenes have been developed for therapy of lung cancer, and some have recently reached clinical trials. ASO and siRNA to respiratory syncytial virus infection have demonstrated good potential to treat this condition, particularly in combination with an antiviral drug. Although ASO-based therapeutics are promising for lung diseases, issues of specificity, identification of correct molecular targets, delivery and carrier systems, as well as potential adverse effects must be carefully evaluated before clinical application.
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Affiliation(s)
- Marina Ulanova
- Department of Medicine, Pulmonary Research Group, University of Alberta, Room 550A HMRC, Edmonton, AB T6G 2S2 Canada
- Northern Ontario School of Medicine, Thunder Bay, Ontario Canada
| | - Alan D. Schreiber
- University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania USA
| | - A. Dean Befus
- Department of Medicine, Pulmonary Research Group, University of Alberta, Room 550A HMRC, Edmonton, AB T6G 2S2 Canada
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19
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Huang ZY, Barreda DR, Worth RG, Indik ZK, Kim MK, Chien P, Schreiber AD. Differential kinase requirements in human and mouse Fc-gamma receptor phagocytosis and endocytosis. J Leukoc Biol 2006; 80:1553-62. [PMID: 16921024 DOI: 10.1189/jlb.0106019] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Fc gamma receptors (FcgammaRs) contribute to the internalization of large and small immune complexes through phagocytosis and endocytosis, respectively. The molecular processes underlying these internalization mechanisms differ dramatically and have distinct outcomes in immune clearance and modulation of cell function. However, it is unclear how the same receptors (FcgammaR) binding to identical ligands (IgG) can elicit such distinct responses. We and others have shown that Syk kinase, Src-related tyrosine kinases (SRTKs) and phosphatidyl inositol 3-kinases (PI3K) play important roles in FcgammaR phagocytosis. Herein, we demonstrate that these kinases are not required for FcgammaR endocytosis. Endocytosis of heat-aggregated IgG (HA-IgG) by COS-1 cells stably transfected with FcgammaRIIA or chimeric FcgammaRI-gamma-gamma (EC-TM-CYT) was not significantly altered by PP2, piceatannol, or wortmannin. In contrast, phagocytosis of large opsonized particles (IgG-sensitized sheep erythrocytes, EA) was markedly reduced by these inhibitors. These results were confirmed in primary mouse bone marrow-derived macrophages and freshly isolated human monocytes. Levels of receptor phosphorylation were similar when FcgammaRIIA was cross-linked using HA-IgG or EA. However, inhibition of FcgammaR phosphorylation prevented only FcgammaR phagocytosis. Finally, biochemical analyses of PI3K(p85)-Syk binding indicated that direct interactions between native Syk and PI3K proteins are differentially regulated during FcgammaR phagocytosis and endocytosis. Overall, our results indicate that FcgammaR endocytosis and phagocytosis differ dramatically in their requirement for Syk, SRTKs, and PI3K, pointing to striking differences in their signal transduction mechanisms. We propose a competitive inhibition-based model in which PI3K and c-Cbl play contrasting roles in the induction of phagocytosis or endocytosis signaling cascades.
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Affiliation(s)
- Zhen-Yu Huang
- University of Pennsylvania School of Medicine, Hematology and Oncology Division, 421 Curie Blvd., Philadelphia, PA 19104, USA
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20
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Bajpai AK, Park JH, Moon IJ, Kang H, Lee YH, Doh KO, Suh SI, Chang BC, Park JG. Rapid blockade of telomerase activity and tumor cell growth by the DPL lipofection of ribbon antisense to hTR. Oncogene 2005; 24:6492-501. [PMID: 16170384 DOI: 10.1038/sj.onc.1208731] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ribbon antisense (RiAS) to the hTR RNA, a component of the telomerase complex, was employed to inhibit telomerase activity and cancer cell growth. The antisense molecule, hTR-RiAS, combined with enhanced cellular uptake was shown to effectively inhibit telomerase activity and cause rapid cell death in various cancer cell lines. When cancer cells were treated with hTR-RiAS, the level of hTR RNA was reduced by more than 90% accompanied with reduction in telomerase activity. When checked for cancer cell viability, cancer cell lines treated with hTR-RiAS using DNA+Peptide+Lipid complex showed 70-80% growth inhibition in 3 days. The reduced cell viability was due to apoptosis as the percentage of cells exhibiting the sub-G0 arrest and DNA fragmentation increased after antisense treatment. Further, when subcutaneous tumors of a colon cancer cell line (SW480) were treated intratumorally with hTR-RiAS, tumor growth was markedly suppressed with almost total ablation of hTR RNA in the tumor tissue. Cells in the tumor tissue were also found to undergo apoptosis after hTR-RiAS treatment. These results suggest that hTR-RiAS is an effective anticancer reagent, with a potential for broad efficacy to diverse malignant tumors.
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Affiliation(s)
- Arun K Bajpai
- WelGENE Inc. 71B-4L, Hightech sector 2, Sungseo Industrial Park III, Dalseogu, Daegu 704-230, Republic of Korea
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21
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Hallal-Calleros C, Agramonte-Hevia J, Garay-Canales C, Oliver JM, Guerra-Araiza C, Heras D, Camacho-Arroyo I, Soto-Cruz I, Ortega E. Syk and Lyn phosphorylation induced by FcγRI and FγRII crosslinking is determined by the differentiation state of U-937 monocytic cells. Immunol Lett 2005; 99:169-79. [PMID: 16009267 DOI: 10.1016/j.imlet.2005.02.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2004] [Revised: 12/16/2004] [Accepted: 02/15/2005] [Indexed: 10/25/2022]
Abstract
Fcgamma receptor (FcgammaR)-mediated phagocytosis by mononuclear phagocytes is an essential function in host defense. This process is initiated by crosslinking of membrane FcgammaRs, which induces phosphorylation and activation of Src and Syk tyrosine kinases. Activation of these enzymes is essential for initiating the biochemical cascade that results in the cytoskeletal and membrane changes involved in phagocytosis. Phagocytic capacity and other effector functions of mononuclear phagocytes change during differentiation/maturation of these cells. This is a complex process governed by different soluble and micro-environmental factors, giving rise to populations of cells with distinct phenotypic characteristics. Several agents, including calcitriol, have been shown to induce in vitro differentiation-related phenotypic changes in monocytic cell lines. In this paper, we characterized the changes in the initial biochemical signals associated with the increase in FcgammaR-mediated phagocytosis induced by calcitriol in monocytic U-937 cells. The 10-fold increase in phagocytic capacity is not accompanied by an increase in FcgammaR expression. However, the phosphorylation levels of Lyn and Syk after FcgammaRI or FcgammaRII crosslinking are increased after calcitriol treatment. Our results suggest that signaling induced by FcgammaR in mononuclear phagocytes is not only dependent on the quantity of FcgammaRs aggregated by a stimulus, but it is highly dependent on the cell's differentiation state.
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Affiliation(s)
- Claudia Hallal-Calleros
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México - UNAM, D.F
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22
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Lee YH, Moon IJ, Hur B, Park JH, Han KH, Uhm SY, Kim YJ, Kang KJ, Park JW, Seu YB, Kim YH, Park JG. Gene knockdown by large circular antisense for high-throughput functional genomics. Nat Biotechnol 2005; 23:591-9. [PMID: 15867911 DOI: 10.1038/nbt1089] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Accepted: 03/14/2005] [Indexed: 11/08/2022]
Abstract
Single-stranded genomic DNA of recombinant M13 phages was tested as an antisense molecule and examined for its usefulness in high-throughput functional genomics. cDNA fragments of various genes (TNF-alpha, c-myc, c-myb, cdk2 and cdk4) were independently cloned into phagemid vectors. Using the life cycle of M13 bacteriophages, large circular (LC)-molecules, antisense to their respective genes, were prepared from the culture supernatant of bacterial transformants. LC-antisense molecules exhibited enhanced stability, target specificity and no need for target-site searches. High-throughput functional genomics was then attempted with an LC-antisense library, which was generated by using a phagemid vector that incorporated a unidirectional subtracted cDNA library derived from liver cancer tissue. We identified 56 genes involved in the growth of these cells. These results indicate that an antisense sequence as a part of single-stranded LC-genomic DNA of recombinant M13 phages exhibits effective antisense activity, and may have potential for high-throughput functional genomics.
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Affiliation(s)
- Yun-Han Lee
- WelGENE Inc., 71B 4L, Development Sector 2-3, Sungseo Industrial Park, Dalseogu, Daegu, 704-230, South Korea
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23
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Lee YH, Kim YH, Park JG. Identification of genes involved in liver cancer cell growth using an antisense library of phage genomic DNA. Cancer Res Treat 2004; 36:246-54. [PMID: 20368842 DOI: 10.4143/crt.2004.36.4.246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2004] [Accepted: 07/22/2004] [Indexed: 11/21/2022] Open
Abstract
PURPOSE Genes involved in liver cancer cell growth have been identified using an antisense library of large circular (LC-) genomic DNA of a recombinant M13 phage. MATERIALS AND METHODS A subtracted cDNA library was constructed by combining procedures of suppression subtractive hybridization (SSH) and unidirectional cloning of the subtracted cDNA into an M13 phagemid vector. Utilizing the life cycle of M13 bacteriophages, LC-antisense molecules derived from 1,200 random cDNA clones selected by size were prepared from the culture supernatant of bacterial transformants. The antisense molecules were arrayed for transfection on 96-well plates preseeded with HepG2. RESULTS When examined for growth inhibition after antisense transfection, 153 out of 1,200 LC-antisense molecules showed varying degrees of growth inhibitory effect to HepG2 cells. Sequence comparison of the 153 clones identified 58 unique genes. The observations were further extended by other cell-based assays. CONCLUSION These results suggest that the LC-antisense library offers potential for unique high-throughput screening to find genes involved in a specific biological function, and may prove to be an effective target validation system for gene-based drug discovery.
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Huang ZY, Hunter S, Kim MK, Chien P, Worth RG, Indik ZK, Schreiber AD. The monocyte Fcgamma receptors FcgammaRI/gamma and FcgammaRIIA differ in their interaction with Syk and with Src-related tyrosine kinases. J Leukoc Biol 2004; 76:491-499. [PMID: 15136586 DOI: 10.1189/jlb.1103562] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2003] [Revised: 03/03/2004] [Accepted: 04/06/2004] [Indexed: 11/24/2022] Open
Abstract
There are important differences in signaling between the Fc receptor for immunoglobulin G (IgG) FcgammaRIIA, which uses the Ig tyrosine-activating motif (ITAM) within its own cytoplasmic domain, and FcgammaRI, which transmits signals by means of an ITAM located within the cytoplasmic domain of its associated gamma-chain. For example, in transfected epithelial cells and COS-1 cells, FcgammaRIIA mediates phagocytosis of IgG-coated red blood cells more efficiently than does FcgammaRI/gamma, and enhancement of phagocytosis by Syk kinase is more pronounced for FcgammaRI/gamma than for FcgammaRIIA. In addition, structure/function studies indicate that the gamma-chain ITAM and the FcgammaRIIA ITAM have different requirements for mediating the phagocytic signal. To study the differences between FcgammaRIIA and FcgammaRI/gamma, we examined the interaction of FcgammaRIIA and the FcgammaRI/gamma chimera FcgammaRI-gamma-gamma (extracellular domain-transmembrane domain-cytoplasmic domain) with Syk kinase and with the Src-related tyrosine kinases (SRTKs) Hck and Lyn in transfected COS-1 cells. Our data indicate that FcgammaRIIA interacts more readily with Syk than does FcgammaRI-gamma-gamma and suggest that one consequence may be the greater phagocytic efficiency of FcgammaRIIA compared with FcgammaRI/gamma. Furthermore, individual SRTKs affect the efficiency of phagocytosis differently for FcgammaRI-gamma-gamma and FcgammaRIIA and also influence the ability of these receptors to interact with Syk kinase. Taken together, the data suggest that differences in signaling by FcgammaRIIA and FcgammaRI-gamma-gamma are related in part to interaction with Syk and Src kinases and that individual SRTKs play different roles in FcgammaR-mediated phagocytosis.
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Affiliation(s)
- Zhen-Yu Huang
- University of Pennsylvania, School of Medicine, Hematology and Oncology Division, Biomedical Research Building II/III, Room 705, 421 Curie Blvd., Philadelphia, PA 19104, USA
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25
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Abstract
Abstract
Hemolytic anemia due to immune function is one of the major causes of acquired hemolytic anemia. In recent years, as more is known about the immune system, these entities have become better understood and their treatment improved. In this section, we will discuss three areas in which this progress has been apparent.
In Section I, Dr. Peter Hillmen outlines the recent findings in the pathogenesis of paroxysmal nocturnal hemoglobinuria (PNH), relating the biochemical defect (the lack of glycosylphosphatidylinositol [GPI]-linked proteins on the cell surface) to the clinical manifestations, particularly hemolysis (and its effects) and thrombosis. He discusses the pathogenesis of the disorder in the face of marrow dysfunction insofar as it is known. His major emphasis is on innovative therapies that are designed to decrease the effectiveness of complement activation, since the lack of cellular modulation of this system is the primary cause of the pathology of the disease. He recounts his considerable experience with a humanized monoclonal antibody against C5, which has a remarkable effect in controlling the manifestations of the disease. Other means of controlling the action of complement include replacing the missing modulatory proteins on the cell surface; these studies are not as developed as the former agent.
In Section II, Dr. Alan Schreiber describes the biochemistry, genetics, and function of the Fcγ receptors and their role in the pathobiology of autoimmune hemolytic anemia and idiopathic thrombocytopenic purpura due to IgG antibodies. He outlines the complex varieties of these molecules, showing how they vary in genetic origin and in function. These variations can be related to three-dimensional topography, which is known in some detail. Liganding IgG results in the transduction of a signal through the tyrosine-based activation motif and Syk signaling. The role of these receptors in the pathogenesis of hematological diseases due to IgG antibodies is outlined and the potential of therapy of these diseases by regulation of these receptors is discussed.
In Section III, Dr. Wendell Rosse discusses the forms of autoimmune hemolytic anemia characterized by antibodies that react preferentially in the cold–cold agglutinin disease and paroxysmal cold hemoglobinuria (PCH). The former is due to IgM antibodies with a common but particular structure that reacts primarily with carbohydrate or carbohydrate-containing antigens, an interaction that is diminished at body temperature. PCH is a less common but probably underdiagnosed illness due to an IgG antibody reacting with a carbohydrate antigen; improved techniques for the diagnosis of PCH are described. Therapy for the two disorders differs somewhat because of the differences in isotype of the antibody. Since the hemolysis in both is primarily due to complement activation, the potential role of its control, as by the monoclonal antibody described by Dr. Hillmen, is discussed.
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MESH Headings
- Anemia, Hemolytic, Autoimmune/diagnosis
- Anemia, Hemolytic, Autoimmune/immunology
- Anemia, Hemolytic, Autoimmune/therapy
- Antigen-Antibody Complex/immunology
- Autoantibodies/immunology
- Hemoglobinuria, Paroxysmal/diagnosis
- Hemoglobinuria, Paroxysmal/physiopathology
- Hemoglobinuria, Paroxysmal/therapy
- Humans
- Receptors, IgG/immunology
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Affiliation(s)
- Wendell F Rosse
- Duke University, Department of Medicine, Durham, NC 27707, USA
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Yamamoto N, Takeshita K, Shichijo M, Kokubo T, Sato M, Nakashima K, Ishimori M, Nagai H, Li YF, Yura T, Bacon KB. The orally available spleen tyrosine kinase inhibitor 2-[7-(3,4-dimethoxyphenyl)-imidazo[1,2-c]pyrimidin-5-ylamino]nicotinamide dihydrochloride (BAY 61-3606) blocks antigen-induced airway inflammation in rodents. J Pharmacol Exp Ther 2003; 306:1174-81. [PMID: 12766258 DOI: 10.1124/jpet.103.052316] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Spleen tyrosine kinase (Syk) tyrosine kinase plays essential roles in receptors for Fc portion of immunoglobulins and B cell receptor complex signaling in various inflammatory cells; therefore, inhibitors of Syk kinase may show potential as antiasthmatic/allergic therapeutics. We identified 2-[7-(3,4-dimethoxyphenyl)-imidazo[1,2-c]pyrimidin-5-ylamino]-nicotinamide dihydrochloride (BAY 61-3606), a potent (Ki = 7.5 nM) and selective inhibitor of Syk kinase. BAY 61-3606 inhibited not only degranulation (IC50 values between 5 and 46 nM) but also lipid mediator and cytokine synthesis in mast cells. BAY 61-3606 was highly efficacious in basophils obtained from healthy human subjects (IC50 = 10 nM) and seems to be at least as potent in basophils obtained from atopic (high serum IgE) subjects (IC50 = 8.1 nM). B cell receptor activation and receptors for Fc portion of IgG signaling in eosinophils and monocytes were also potently suppressed by BAY 61-3606. Oral administration of BAY 61-3606 to rats significantly suppressed antigen-induced passive cutaneous anaphylactic reaction, bronchoconstriction, and bronchial edema at 3 mg/kg. Furthermore, BAY 61-3606 attenuated antigen-induced airway inflammation in rats. Based on these anti-inflammatory effects of BAY 61-3606 both in vitro and in vivo, it was demonstrated that Syk may play a very critical role in the pathogenesis of allergic reactions.
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Canetti C, Hu B, Curtis JL, Peters-Golden M. Syk activation is a leukotriene B4-regulated event involved in macrophage phagocytosis of IgG-coated targets but not apoptotic cells. Blood 2003; 102:1877-83. [PMID: 12730109 DOI: 10.1182/blood-2003-02-0534] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Macrophages are called upon to ingest both IgG-coated targets and apoptotic cells. Important roles for tyrosine kinase Syk and leukotriene B4 (LTB4) are recognized in FcgammaR-mediated phagocytosis. Here we evaluated the roles of Syk and LTB4 in macrophage phagocytosis of apoptotic thymocytes versus IgG-coated erythrocytes. Macrophage ingestion of apoptotic thymocytes was not influenced by exogenous or endogenous LTB4 nor associated with Syk activation (phosphorylation). By contrast, LTB4 dose-dependently amplified FcgammaR-mediated phagocytosis as well as Syk activation. Furthermore, a role for endogenous LTB4 in Syk activation during FcgammaR-mediated phagocytosis was demonstrated using pharmacologic and genetic abrogation of 5-lipoxygenase. LTB4 was unique among 5-lipoxygenase products in this regard, since LTD4 and 5-hydroxyeicosatetraenoic acid (HETE) were unable to amplify Syk activation in response to FcgammaR engagement. Ca2+ chelation studies revealed that FcgammaR-mediated Syk activation as well as LTB4 amplification thereof was Ca2+ regulated. These 2 parallel phagocytic processes therefore exhibit initial divergence in signal transduction events, with Syk activation being an LTB4-regulated event in FcgammaR-mediated but not apoptotic cell ingestion. As LTB4 is an important proinflammatory product of macrophages, we speculate that this divergence evolved to permit FcgammaR-mediated phagocytosis to proceed in an inflammatory milieu, while apoptotic cell clearance is noninflammatory.
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Affiliation(s)
- Claudio Canetti
- Division of Pulmonary and Critical Care Medicine, 6301 MSRB III, University of Michigan Medical Center, Ann Arbor, MI 48109-0642, USA
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28
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Agramonte-Hevia J, Hallal C, Garay-Canales C, Guerra-Araiza C, Camacho-Arroyo I, Ortega Soto E. 1alpha, 25-dihydroxy-vitamin D3 alters Syk activation through FcgammaRII in monocytic THP-1 cells. J Cell Biochem 2003; 89:1056-76. [PMID: 12874838 DOI: 10.1002/jcb.10575] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In monocytes and macrophages, activation of the tyrosine kinase Syk is an essential step in the biochemical cascade linking aggregation of receptors for immunoglobulin G (FcgammaR) to initiation of effector functions. An increase in Syk activation during differentiation of myeloid cells by different agents has been reported. We studied the activation state of Syk in response to FcgammaRII crosslinking in monocytic cells before and after in vitro differentiation with 1alpha, 25-dihydroxy-vitamin D3. We show here that while in undifferentiated THP-1 cells clustering of FcgammaRII induces significant phosphorylation and activation of Syk, in THP-1 cells differentiated in vitro by 1alpha, 25-dihydroxy-vitamin D3, FcgammaRII crosslinking induced a decrease in Syk activity. In vitro differentiation did not induce changes in the expression of FcgammaRII isoforms. The observed effect on Syk activation though FcgammaRII could be mediated by differentiation-induced changes in the expression and basal activation level of Syk, as well as changes in the association of Syk with the tyrosine phosphatase SHP-1. These results suggest that the biochemical signaling pathways induced by FcgammaRII could be dependent on the differentiation state of the cell.
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Affiliation(s)
- José Agramonte-Hevia
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Cuidad Universitaria, D. F., 04510 México
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29
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Santini V, Scappini B, Indik ZK, Gozzini A, Ferrini PR, Schreiber AD. The carboxy-terminal region of the granulocyte colony-stimulating factor receptor transduces a phagocytic signal. Blood 2003; 101:4615-22. [PMID: 12586631 DOI: 10.1182/blood-2002-07-2271] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Granulocyte colony-stimulating factor (G-CSF) induces proliferation, maturation, and functional activities of myeloid progenitors and mature neutrophils through a specific receptor, the G-CSF-R. Different signals are mediated by distinct regions of the cytoplasmic domain of G-CSF-R, but the precise role of each region has not yet been fully clarified. We evaluated the involvement of Syk kinase, essential in mediating phagocytic signals by Fcgamma receptors, in G-CSF-induced phagocytosis, using murine myeloid 32D cells transfected with wild-type (WT) human G-CSF-R (hG-CSF-R) or with a G-CSF-R mutant truncated at cytoplasmic amino acid 715. The G-CSF-R mutant lacks the immunoreceptor tyrosine-based activation motif (ITAM), putative binding site for Syk. Following treatment of WT hG-CSF-R transfectants with IgG-coated particles, there was a significant increase in phagocytosis in G-CSF-stimulated cells, in which Syk tyrosine phosphorylation occurred, paralleled by enhancement of its tyrosine kinase activity. In the mutant transfectants, no significant increase in phagocytosis or Syk tyrosine phosphorylation occurred after stimulation with G-CSF. We also demonstrated that tyrosine phosphorylation of the Src kinases Hck and Lyn occurs following G-CSF stimulation of cells expressing WT G-CSF-R, but that Hck is not phosphorylated in mutant G-CSF-R transfectants. The increase in phagocytosis following G-CSF stimulation cannot be attributed to a rapid de novo increase in expression of Fcgamma receptors. G-CSF induced expression of Fcgamma receptors only after prolonged stimulation. Our data provide evidence that the carboxy-terminal region of G-CSF-R plays a role in the phagocytosis of IgG-coated particles and that Syk and Hck kinase tyrosine phosphorylation is involved.
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Affiliation(s)
- Valeria Santini
- Department of Hematology, University of Florence, Florence, Italy.
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30
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Yamamoto N, Hasegawa H, Seki H, Ziegelbauer K, Yasuda T. Development of a high-throughput fluoroimmunoassay for Syk kinase and Syk kinase inhibitors. Anal Biochem 2003; 315:256-61. [PMID: 12689835 DOI: 10.1016/s0003-2697(03)00026-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Syk is a tyrosine kinase which is indispensable in immunoglobulin Fc receptor- and B cell receptor-mediated signal transduction in various immune cells. This pathway is important in the pathophysiology of allergy. In this study we established a quantitative nonradioactive kinase assay to identify inhibitors of Syk. We used recombinant GST-tagged Syk purified from baculovirus-infected insect cells. As a substrate, biotinylated peptide corresponding to the activation loop domain of Syk, whose tyrosine residues are autophosphorylated upon activation, was employed to screen both ATP- and substrate-competitive inhibitors. After the kinase reaction in solution phase, substrate was trapped on a streptavidin-coated plate, followed by detection of the phosphorylated tyrosine with europium-labeled anti-phosphotyrosine antibody. The kinase reaction in solution phase greatly enhanced phosphorylation of substrate compared to that of plate-coated substrate. High signal-to-background ratio and low data scattering were obtained in the optimized high-throughput screening (HTS) format. Further, several kinase inhibitors showed concentration-dependent inhibition of recombinant Syk kinase activity with almost the same efficacy for immunoprecipitated Syk from a human cell line. These data suggest that this assay is useful to screen Syk kinase inhibitors in HTS.
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Affiliation(s)
- Noriyuki Yamamoto
- Research Center Kyoto, Bayer Yakuhin, Ltd, 6-5-1-3, Kunimidai, Kizu-cho, Soraku-gun, Kyoto 619-0216, Japan.
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Kwiatkowska K, Frey J, Sobota A. Phosphorylation of FcgammaRIIA is required for the receptor-induced actin rearrangement and capping: the role of membrane rafts. J Cell Sci 2003; 116:537-50. [PMID: 12508114 DOI: 10.1242/jcs.00254] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Activation of Fcgamma receptor II (FcgammaRII) induces rearrangement of the actin-based cytoskeleton that serves as a driving force for FcgammaRII-mediated phagocytosis and FcgammaRII capping. To get insight into the signaling events that lead to the actin reorganization we investigated the role of raft-associated Src family tyrosine kinases in capping of FcgammaRII in U937 cells. After crosslinking, FcgammaRII was found to be recruited to detergent-resistant membrane domains (DRMs), rafts, where it coexisted with Lyn kinase and underwent tyrosine phosphorylation. Lyn was displaced from DRMs under the influence of DL-alpha-hydroxymyristic acid and 2-bromopalmitic acid, agents blocking N-terminal myristoylation and palmitoylation of proteins, respectively, and after disruption of DRM integrity by depletion of plasma membrane cholesterol with beta-cyclodextrin. Under these conditions, phosphorylation of the crosslinked FcgammaRII was diminished and assembly of FcgammaRII caps was blocked. The similar reduction of FcgammaRII cap formation correlated with inhibition of receptor phosphorylation was achieved with the use of PP1 and herbimycin A, specific inhibitors of Src family tyrosine kinases. Phosphorylation of FcgammaRIIA expressed in BHK cells, lacking endogenous FcgammaRs, was abolished by substitution of tyrosine 298 by phenylalanine in the ITAM of the receptor. The mutant receptor did not undergo translocation towards cap-like structures and failed to promote the receptor-mediated spreading of the cells, as compared to BHK cells transfected with the wild-type FcgammaRIIA. On the basis of these data, we suggest that tyrosine phosphorylation of activated FcgammaRIIA by raft-residing tyrosine kinases of the Src family triggers signaling pathways that control the rearrangement of the actin cytoskeleton required for FcgammaRII-mediated motility.
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Affiliation(s)
- Katarzyna Kwiatkowska
- Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland. Universität Bielefeld, Fakultät für Chemie, Biochemie II, 33615 Bielefeld, Germany
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32
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Hinkovska-Galcheva V, Boxer L, Mansfield PJ, Schreiber AD, Shayman JA. Enhanced phagocytosis through inhibition of de novo ceramide synthesis. J Biol Chem 2003; 278:974-82. [PMID: 12424251 DOI: 10.1074/jbc.m206199200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fcgamma receptors are important mediators of the binding of IgG to and induction of phagocytosis in neutrophils. COS-1 cells provide a potentially useful model for studying these receptors because transfection with the FcgammaRIIA renders these cells phagocytic. During FcgammaRIIA-mediated phagocytosis in COS-1 cells, endogenous ceramide levels increased 52% by 20 min (p < 0.01). Phospholipase D activity increased by 62% (p < 0.01). Correspondingly, the phagocytic index increased by 3.7-fold by 20 min. Two inhibitors of ceramide formation were used to assess the consequences of reduced ceramide generation. l-Cycloserine, an inhibitor that blocks serine palmitoyltransferase activity, lowered both sphingosine and ceramide levels. Under these conditions, the phagocytic index increased 100% in the presence of 2 mm l-cycloserine. The formation of ceramide resulting from the N-acylation of dihydrosphingosine or sphingosine by ceramide synthase is inhibited by the fungal toxin fumonisin B(1). When cells were treated with 5-50 microm fumonisin B(1), the cellular level of ceramide decreased in a concentration-dependent manner, while simultaneously the phagocytic index increased by 52%. Concomitantly, three indirect measures of FcgammaRIIA activity were altered with the fall in ceramide levels. Syk phosphorylation, phospholipase D activity, and mitogen-activated protein (MAP) kinase phosphorylation were increased at 30 min. When Syk phosphorylation was blocked with piceatannol and cells were similarly challenged, phosphatidylinositol 3-kinase activation was blocked, but no changes in either ceramide accumulation or MAP kinase activation were observed. Ceramide formation and MAP kinase activation are therefore not dependent on Syk kinase activity in this system. These results indicate that COS-1 cells provide a useful model for the recapitulation of sphingolipid signaling in the study of phagocytosis. Ceramide formed by de novo synthesis may represent an important mechanism in the regulation of phagocytosis.
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Affiliation(s)
- Vania Hinkovska-Galcheva
- Department of Pediatrics, Division of Hematology Oncology, University of Michigan, Ann Arbor 48109, USA
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33
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Strzelecka-Kiliszek A, Kwiatkowska K, Sobota A. Lyn and Syk kinases are sequentially engaged in phagocytosis mediated by Fc gamma R. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:6787-94. [PMID: 12471110 DOI: 10.4049/jimmunol.169.12.6787] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recent data indicate that phagocytosis mediated by FcgammaRs is controlled by the Src and Syk families of protein tyrosine kinases. In this study, we demonstrate a sequential involvement of Lyn and Syk in the phagocytosis of IgG-coated particles. The particles isolated at the stage of their binding to FcgammaRs (4 degrees C) were accompanied by high amounts of Lyn, in addition to the signaling gamma-chain of FcgammaRs. Simultaneously, the particle binding induced rapid tyrosine phosphorylation of numerous proteins. During synchronized internalization of the particles induced by shifting the cell to 37 degrees C, Syk kinase and Src homology 2-containing tyrosine phosphatase-1 (SHP-1) were associated with the formed phagosomes. At this step, most of the proteins were dephosphorylated, although some underwent further tyrosine phosphorylation. Quantitative immunoelectron microscopy studies confirmed that Lyn accumulated under the plasma membrane beneath the bound particles. High amounts of the gamma-chain and tyrosine-phosphorylated proteins were also observed under the bound particles. When the particles were internalized, the gamma-chain was still detected in the region of the phagosomes, while amounts of Lyn were markedly reduced. In contrast, the vicinity of the phagosomes was heavily decorated with anti-Syk and anti-SHP-1 Abs. The local level of protein tyrosine phosphorylation was reduced. The data indicate that the accumulation of Lyn during the binding of IgG-coated particles to FcgammaRs correlated with strong tyrosine phosphorylation of numerous proteins, suggesting an initiating role for Lyn in protein phosphorylation at the onset of the phagocytosis. Syk kinase and SHP-1 phosphatase are mainly engaged at the stage of particle internalization.
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34
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García‐García E, Rosales C. Signal transduction during Fc receptor‐mediated phagocytosis. J Leukoc Biol 2002. [DOI: 10.1189/jlb.72.6.1092] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Erick García‐García
- Immunology Department, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City
| | - Carlos Rosales
- Immunology Department, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City
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35
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Yamamoto N, Shichijo M, Kokubo T. Establishment of the superoxide production assay with human monocytic cell line, U937, for the evaluation of Syk kinase inhibitors. J Immunol Methods 2002; 268:123-30. [PMID: 12215380 DOI: 10.1016/s0022-1759(02)00188-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Protein tyrosine kinase Syk is known to play critical roles in the signal transduction from receptors for Fc portion of immunoglobulins (FcRs) and B cell receptor complex (BCR). Its importance was well studied in Fc epsilon RI-induced activation of mast cells; therefore, Syk inhibitors are expected to have anti-allergic effects and to be novel therapy for allergic diseases, such as asthma, allergic rhinitis and atopic dermatitis. We previously developed an enzyme assay of recombinant human Syk kinase for the high throughput screening. In order to evaluate the Syk kinase inhibitors in a human cell system, we have developed an assay with human monocytic cell line, U937, to monitor FcgammaRI-mediated superoxide production. We treated cells with IFN-gamma to enhance the expression of FcgammaRI and to obtain enough production of superoxide. Engagement of FcgammaRI stimulated superoxide production, which was accompanied with Syk phosphorylation. PMA, an activator of protein kinase C, also evoked superoxide production, but Syk was not phosphorylated. Moreover, the treatment of cells with antisense oligonucleotide against syk attenuated Syk protein expression and suppressed superoxide production induced by FcgammaRI-engagement, but not by PMA. These results confirm that Syk is involved in the signal transduction from FcgammaRI upstream of PKC in U937 cells and we can evaluate the efficacy and the selectivity of Syk inhibitors with this assay system.
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Affiliation(s)
- Noriyuki Yamamoto
- Research Center Kyoto, Bayer Yakuhin, Ltd., 6-5-1-3, Kunimidai, Kizu-cho, Soraku-gun, Japan.
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36
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Kasono K, Nishida J, Tamemoto H, Fudaka K, Namai K, Kajio H, Masatoshi K, Kanazawa Y, Kawakami M. Thiazolidinediones increase the number of platelets in immune thrombocytopenic purpura mice via inhibition of phagocytic activity of the reticulo-endothelial system. Life Sci 2002; 71:2037-52. [PMID: 12175897 DOI: 10.1016/s0024-3205(02)01950-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Thiazolidinediones (TZDs) have broad spectrum of actions, including immunomodulating effects that are dependent or independent of the target nuclear receptor, peroxisome proliferator activated receptor-gamma (PPAR-gamma). In this study, we investigated the effect of TZDs on the platelet numbers in male immune thrombocytopenic purpura (ITP) model mice, (NZW x BXSB)F(1) (W/BF(1)) in vivo, and attempted to clarify the mechanism of action. Seven-day treatment with troglitazone increased platelet counts by 66% compared with those of controls. Within two weeks after the termination of the treatment period, the numbers of platelets were decreased to the level in controls. Pioglitazone showed only weak increasing effect on platelet counts in short-term experiment. However, long-term treatment with the drug resulted in a more pronounced up-regulation of platelets. We next assayed the platelet-associated antibodies (PAA) and the survival rate of antibody-sensitized mouse erythrocytes (Ab-mRBC) in W/BF1 mice. Pioglitazone slightly decreased the production of PAA and significantly elongated the survival period of Ab-mRBC in vivo. These drugs showed dose-dependent inhibitory effects on the cell proliferation and Fcgamma receptor (FcgammaR)-mediated phagocytic activity of macrophage-like cells in vitro. These results suggest that TZDs improve platelet counts in this mouse model mainly by suppressing systemic reticulo-endothelial phagocytic function.
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MESH Headings
- Animals
- Antibody-Dependent Cell Cytotoxicity/drug effects
- Autoantibodies/analysis
- Blood Platelets/drug effects
- Blood Platelets/immunology
- COS Cells
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Erythrocytes/immunology
- Hybridization, Genetic
- Hypoglycemic Agents/pharmacology
- Macrophages/immunology
- Male
- Mice
- Mice, Inbred Strains
- Mononuclear Phagocyte System/drug effects
- Mononuclear Phagocyte System/immunology
- Phagocytosis/drug effects
- Pioglitazone
- Platelet Count
- Purpura, Thrombocytopenic, Idiopathic/blood
- Purpura, Thrombocytopenic, Idiopathic/drug therapy
- Purpura, Thrombocytopenic, Idiopathic/immunology
- Receptors, Fc/immunology
- Thiazoles/pharmacology
- Thiazolidinediones
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Affiliation(s)
- Keizo Kasono
- Department of Endocrinology and Metabolism, Jichi Medical School, Omiya Medical Center, 1-847 Amanuma-cho, Saitama 330-8503, Japan
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37
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Stenton GR, Ulanova M, Déry RE, Merani S, Kim MK, Gilchrist M, Puttagunta L, Musat-Marcu S, James D, Schreiber AD, Befus AD. Inhibition of allergic inflammation in the airways using aerosolized antisense to Syk kinase. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:1028-36. [PMID: 12097411 DOI: 10.4049/jimmunol.169.2.1028] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Activation of the protein tyrosine kinase Syk is an early event that follows cross-linking of Fc gamma R and Fc epsilon R, leading to the release of biologically active molecules in inflammation. We reported previously that aerosolized Syk antisense oligodeoxynucleotides (ASO) depresses Syk expression in inflammatory cells, the release of mediators from alveolar macrophages, and pulmonary inflammation. To study the effect of Syk ASO in allergic inflammation and airway hyperresponsiveness, we used the Brown Norway rat model of OVA-induced allergic asthma. Syk ASO, delivered in a liposome, carrier/lipid complex by aerosol to rats, significantly inhibited the Ag-induced inflammatory cell infiltrate in the bronchoalveolar space, decreasing both neutrophilia and eosinophilia. The number of eosinophils in the lung parenchyma was also diminished. Syk ASO also depressed up-regulation of the expression of beta(2) integrins, alpha(4) integrin, and ICAM-1 in bronchoalveolar lavage leukocytes and reversed the Ag-induced decrease in CD62L expression on neutrophils. Furthermore, the increase in TNF levels in bronchoalveolar lavage following Ag challenge was significantly inhibited. Syk ASO also suppressed Ag-mediated contraction of the trachea in a complementary model. Thus, aerosolized Syk ASO suppresses many of the central components of allergic asthma and inflammation and may provide a new therapeutic approach.
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Affiliation(s)
- Grant R Stenton
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
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38
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Pricop L, Salmon JE. Redox regulation of Fcgamma receptor-mediated phagocytosis: implications for host defense and tissue injury. Antioxid Redox Signal 2002; 4:85-95. [PMID: 11970846 DOI: 10.1089/152308602753625889] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent advances in our understanding of the mechanisms that regulate acute and chronic inflammatory responses have revealed a key role for reactive oxygen intermediates in modulating the activation of neutrophils. Opsonized microbes and immune complexes initiate the oxidative burst by the engagement of receptors for immunoglobulin G, termed Fcgamma receptors. The regulation of phagocytic cell function by oxidant-sensitive signaling pathways optimizes host defense capabilities, but it also amplifies tissue damage. This review will focus on the cross-talk between Fcgamma receptors and reactive oxygen intermediates at sites of inflammation and its role in microbial immunity.
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Affiliation(s)
- Luminita Pricop
- Hospital for Special Surgery and Weill Medical College of Cornell University, Department of Medicine, New York, NY 10021, USA
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39
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Bulanova E, Budagian V, Pohl T, Krause H, Dürkop H, Paus R, Bulfone-Paus S. The IL-15R alpha chain signals through association with Syk in human B cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:6292-302. [PMID: 11714793 DOI: 10.4049/jimmunol.167.11.6292] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The alpha-chain of the IL-15R (IL-15Ralpha) serves as the specific, high-affinity receptor for IL-15. It is expressed by lymphoid and nonlymphoid cells, including B cell lymphoma lines. In this study, we have further explored IL-15Ralpha-mediated signaling in activated primary B cells and in Raji cells, a human B-lymphoblastoid cell line which expresses the IL-15Ralpha and IL-2Rgamma chains, but lacks the IL-2Rbeta chain. Stimulation of Raji cells with IL-15 induces their proliferation and rescues them from C2-ceramide-induced apoptosis. By immunoprecipitation and Western blotting, we show that treatment of Raji cells and activated primary B cells with IL-15 induces coprecipitation of Syk kinase with the IL-15Ralpha chain. Upon association, the activated Syk kinase phosphorylates the IL-15Ralpha chain as well as phospholipase Cgamma, which coprecipitates with Syk. Furthermore, transfection of Raji cells with stem-loop Syk antisense oligonucleotides prevents IL-15Ralpha and phospholipase Cgamma phosphorylation as well as the inhibition of apoptosis by IL-15. Mutation of a defined region of the intracellular signaling portion of IL-15Ralpha (Tyr227) abrogates both the IL-15Ralpha/Syk association and IL-15Ralpha phosphorylation. Taken together, this suggests that Syk kinase physically and functionally associates with the IL-15Ralpha chain in B cells and that Syk plays a key role in mediating IL-15-induced signal transduction, thus accounting for the distinct functional consequences of IL-15 vs IL-2 binding to B cells.
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Affiliation(s)
- E Bulanova
- Department of Immunology and Cell Biology, Research Center Borstel, Borstel, Germany
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40
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Worth RG, Mayo-Bond L, Kim MK, van de Winkel JG, Todd RF, Petty HR, Schreiber AD. The cytoplasmic domain of FcgammaRIIA (CD32) participates in phagolysosome formation. Blood 2001; 98:3429-34. [PMID: 11719384 DOI: 10.1182/blood.v98.12.3429] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Signaling motifs located within the cytoplasmic domain of certain receptors contribute to lysosome fusion. Most studies have described lysosome fusion with respect to endocytic receptors. Phagolysosome fusion has not been extensively studied. To test the hypothesis that the tail of FcgammaRIIA participates in phagolysosomal fusion, a "reverse" genetic complementation system was used. It was previously shown that complement receptor type 3 (CR3) can rescue the phagocytic activity of a mutant FcgammaRIIA lacking its cytoplasmic domain (tail-minus form). This system has allowed us to study Fcgamma receptor-dependent phagocytosis and phagolysosome fusion in the presence and absence of the cytoplasmic domain of FcgammaRIIA. Fluorescent dextran was used to label lysosomes. After target internalization, wild-type FcgammaRIIA-mediated phagolysosome formation was observed as indicated by colocalization of fluorescent dextran and the phagosome. In addition, when studying mutants of FcgammaRIIA containing a full-length cytoplasmic tail with the 2 ITAM tyrosines mutated to phenylalanine, (1) phagocytosis was abolished, (2) CR3 restored phagocytosis, and (3) lysosomal fusion was similar to that observed with the wild-type receptor. In contrast, in the presence of CR3 and the tail-minus form of FcgammaRIIA, internalized particles did not colocalize with dextran. Electron microscopy revealed that the lysosomal enzyme acid phosphatase colocalized with immunoglobulin G-coated targets internalized by wild-type FcgammaRIIA but not by tail-minus FcgammaRIIA and CR3. Thus, the tail of FcgammaRIIA contributes to phagolysosome fusion by a mechanism that does not require a functional ITAM sequence.
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Affiliation(s)
- R G Worth
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
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41
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Cox D, Greenberg S. Phagocytic signaling strategies: Fc(gamma)receptor-mediated phagocytosis as a model system. Semin Immunol 2001; 13:339-45. [PMID: 11708889 DOI: 10.1006/smim.2001.0330] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Phagocytosis is a phylogenetically ancient process by which eukaryotic cells engulf insoluble substances whose size exceeds approximately 0.5 microm. The engulfment process requires the concerted action of several fundamental cellular pathways and is governed by multiple transmembrane signaling events. Here we focus on phagocytosis mediated by a well-studied class of phagocytic receptors that recognize the Fc portion of IgG (Fc(gamma)Rs ).
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Affiliation(s)
- D Cox
- Department of Medicine, Columbia University, 630 West 168th Street, New York, NY 10032, USA.
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42
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Fernandez R, Sarma V, Younkin E, Hirschl RB, Ward PA, Younger JG. Exposure to perflubron is associated with decreased Syk phosphorylation in human neutrophils. J Appl Physiol (1985) 2001; 91:1941-7. [PMID: 11641328 DOI: 10.1152/jappl.2001.91.5.1941] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Liquid ventilation with perflubron is associated with reduced neutrophil recruitment into the lung during acute injury. Perflubron also reduces chemotactic responses, the respiratory burst, and cytokine production in neutrophils and in alveolar macrophages in vitro. In the current studies, the effect of perflubron on neutrophil chemotaxis to formyl-Met-Leu-Phe (fMLP) and phagocytosis of opsonized sheep erythrocytes (EA) correlated with decreased phosphorylation of Syk, an important intracellular second messenger in pathways regulating neutrophil functional responses. Brief (5 min) exposure of neutrophils to perflubron resulted in a dose-dependent reduction in chemotaxis to fMLP and reduced phagocytosis of EA but no apparent morphological changes as seen by electron microscopy. Concurrently, there was a reduction in both total cytosolic tyrosine phosphorylation and Syk phosphorylation. Binding studies indicated that this effect was neither a result of impaired ligand-receptor affinity nor a change in the number of fMLP receptors available on the neutrophil surface. These results suggest that perflubron nonspecifically affects cellular activation as measured by tyrosine phosphorylation perhaps by interfering with transmembrane signal transduction.
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Affiliation(s)
- R Fernandez
- Department of Emergency Medicine, University of Michigan, Ann Arbor, Michigan 48109-0303, USA
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43
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Majeed M, Caveggion E, Lowell CA, Berton G. Role of Src kinases and Syk in Fcγ receptor‐mediated phagocytosis and phagosome‐lysosome fusion. J Leukoc Biol 2001. [DOI: 10.1189/jlb.70.5.801] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Meytham Majeed
- Department of Pathology, Section of General Pathology, University of Verona, Verona, Italy, and
| | - Elena Caveggion
- Department of Pathology, Section of General Pathology, University of Verona, Verona, Italy, and
| | - Clifford A. Lowell
- Department of Laboratory Medicine, University of California San Francisco, San Francisco
| | - Giorgio Berton
- Department of Pathology, Section of General Pathology, University of Verona, Verona, Italy, and
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44
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Forsberg M, Löfgren R, Zheng L, Stendahl O. Tumour necrosis factor-alpha potentiates CR3-induced respiratory burst by activating p38 MAP kinase in human neutrophils. Immunology 2001; 103:465-72. [PMID: 11529937 PMCID: PMC1783267 DOI: 10.1046/j.1365-2567.2001.01270.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CR3 and Fc gamma Rs are the main receptors involved in the phagocytic process leading to engulfment and killing of microbes by production of reactive oxygen intermediates (ROI) and degranulation. Various inflammatory mediators, such as tumour necrosis factor-alpha (TNF-alpha) and lipopolysaccharide (LPS), are known to prime neutrophils leading to increased bactericidal responses, but the underlying mechanism of priming has only been partially elucidated. The purpose of this study was to investigate how TNF-alpha primes neutrophils for subsequent stimuli via either CR3 or Fc gamma R. The receptors were specifically activated with pansorbins (protein-A-positive Staphylococcus aureus) coated with anti-CR3, anti-Fc gamma RIIa, or anti-Fc gamma RIIIb monoclonal antibody. Activation of neutrophils with these particles resulted in ROI production as measured by chemiluminescence. Anti-CR3 pansorbins induced the most prominent ROI production in neutrophils. TNF-alpha potentiated the CR3-mediated respiratory burst but had little effect on that mediated by Fc gamma Rs. The priming effect of TNF-alpha on CR3-mediated ROI production is associated with an increased activation of p38 MAPK as well as tyrosine phosphorylation of p72(syk). Pretreatment of neutrophils with the inhibitors for p38 MAPK and p72(syk) markedly suppressed the respiratory burst induced by CR3. Furthermore, TNF-alpha induced about a three-fold increase in the expression of CR3 in neutrophils, an effect which is blocked by the p38 MAPK inhibitor. Taken together, these results showed that TNF-alpha potentiates the CR3-mediated respiratory burst in neutrophils not only by triggering a p38 MAPK-dependent up-regulation of CD11b/CD18 but also by modulating the signalling pathways.
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Affiliation(s)
- M Forsberg
- Division of Medical Microbiology, Department of Health and Care, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden.
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45
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Kedzierska K, Vardaxis NJ, Jaworowski A, Crowe SM. FcγR‐mediated phagocytosis by human macrophages involves Hck, Syk, and Pyk2 and is augmented by GM‐CSF. J Leukoc Biol 2001. [DOI: 10.1189/jlb.70.2.322] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Katherine Kedzierska
- AIDS Pathogenesis Research Unit, Macfarlane Burnet Centre for Medical Research, and National Centre for HIV Virology Research, Fairfield
- Department of Medicine, Monash University, Prahran; and
| | - Nicholas J. Vardaxis
- Department of Medical Laboratory Science, Royal Melbourne Institute of Technology, Bundoora, Australia
| | - Anthony Jaworowski
- AIDS Pathogenesis Research Unit, Macfarlane Burnet Centre for Medical Research, and National Centre for HIV Virology Research, Fairfield
- Department of Medicine, Monash University, Prahran; and
- Department of Medical Laboratory Science, Royal Melbourne Institute of Technology, Bundoora, Australia
| | - Suzanne M. Crowe
- AIDS Pathogenesis Research Unit, Macfarlane Burnet Centre for Medical Research, and National Centre for HIV Virology Research, Fairfield
- Department of Medicine, Monash University, Prahran; and
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46
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Abstract
The process of engulfing a foreign particle - phagocytosis - is of fundamental importance for a wide diversity of organisms. From simple unicellular organisms that use phagocytosis to obtain their next meal, to complex metazoans in which phagocytic cells represent an essential branch of the immune system, evolution has armed cells with a fantastic repertoire of molecules that serve to bring about this complex event. Regardless of the organism or specific molecules concerned, however, all phagocytic processes are driven by a finely controlled rearrangement of the actin cytoskeleton. A variety of signals can converge to locally reorganise the actin cytoskeleton at a phagosome, and there are significant similarities and differences between different organisms and between different engulfment processes within the same organism. Recent advances have demonstrated the complexity of phagocytic signalling, such as the involvement of phosphoinostide lipids and multicomponent signalling complexes in transducing signals from phagocytic receptors to the cytoskeleton. Similarly, a wide diversity of ‘effector molecules’ are now implicated in actin-remodelling downstream of these receptors.
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Affiliation(s)
- R C May
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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47
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Yamada T, Fujieda S, Yanagi S, Yamamura H, Inatome R, Sunaga H, Saito H. Protein-tyrosine kinase Syk expressed in human nasal fibroblasts and its effect on RANTES production. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:538-43. [PMID: 11123334 DOI: 10.4049/jimmunol.166.1.538] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Fibroblasts, a rich source of chemokines, interact with eosinophils and play a key role in the pathogenesis of airway disease. RANTES is produced by fibroblasts to attract and activate eosinophils. LPS is known to induce RANTES and cause protein tyrosine phosphorylation. Nonreceptor protein tyrosine kinase Syk is widely expressed and an important role in intracellular signal transduction in hemopoietic cells. In the present study, we examined whether Syk was expressed in a number of primary human nasal polyp tissue-derived fibroblast lines and whether it played some role in cellular function. Syk proteins were expressed in human nasal fibroblasts, but the expression level varied. There were positive correlations between the level of Syk expression and RANTES production induced by LPS. Overexpression of wild-type Syk by gene transfer enhanced RANTES production from nasal fibroblasts stimulated with LPS. The decrease of Syk expression by the administration of Syk antisense inhibited RANTES production. These results suggest that Syk expression affects RANTES production in fibroblasts of nasal polyps.
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Affiliation(s)
- T Yamada
- Department of Otorhinolaryngology, Fukui Medical University, Fukui, Japan
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Kim MK, Pan XQ, Huang ZY, Hunter S, Hwang PH, Indik ZK, Schreiber AD. Fc gamma receptors differ in their structural requirements for interaction with the tyrosine kinase Syk in the initial steps of signaling for phagocytosis. Clin Immunol 2001; 98:125-32. [PMID: 11141335 DOI: 10.1006/clim.2000.4955] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Receptors for the constant region of IgG, Fc gamma receptors, are expressed on the surface of hematopoietic cells, where they mediate signaling events, such as phagocytosis, essential for host defense. Fc gamma receptors also play a role in the pathophysiology of autoimmune diseases. We have demonstrated that members of each of the three classes of human Fc gamma receptors, Fc gamma RI, Fc gamma RII, and Fc gamma RIII, mediate phagocytosis, but that important differences exist in their requirements for phagocytic signaling. For example, the Fc gamma receptors Fc gamma RI and Fc gamma RIIIA induce signaling largely by association with a gamma subunit containing a conserved cytoplasmic motif (ITAM) whose tyrosines are phosphorylated following receptor stimulation. Fc gamma RIIA contains a similar motif in its own cytoplasmic domain and does not require the gamma chain for phagocytic signaling. The tyrosine kinase Syk associates with the cytoplasmic domain of both the Fc gamma receptor gamma chain and Fc gamma RIIA and is required for phagocytosis by both Fc gamma receptor systems. To elucidate the differences in phagocytic signaling by the gamma chain and Fc gamma RIIA, we investigated the requirements for Fc gamma receptor/Syk co-immunoprecipitation, tyrosine phosphorylation, and phagocytosis. Both Fc gamma RIIA and the human gamma chain contain a tyrosine seven amino acids upstream of the ITAM motif. We observed that the upstream tyrosine plays a role in Fc gamma RIIA phagocytic signaling but is not involved in phagocytic signaling by the human gamma chain. Our data also indicate that the two ITAM tyrosines of the human gamma chain and Fc gamma RIIA do not contribute equally to Fc gamma receptor association with Syk kinase and phagocytic signaling. The data indicate that the carboxy-terminal tyrosine of the receptor cytoplasmic domain is especially important both for the interaction with Syk kinase and for phagocytosis. Elucidating such differences in gamma chain and Fc gamma RIIA signaling may be valuable in designing strategies for therapeutic intervention in hematopoietic and immunological disorders.
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Affiliation(s)
- M K Kim
- Division of Hematology/Oncology, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Nonopsonic monocyte/macrophage phagocytosis of Plasmodium falciparum–parasitized erythrocytes: a role for CD36 in malarial clearance. Blood 2000. [DOI: 10.1182/blood.v96.9.3231] [Citation(s) in RCA: 191] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractPlasmodium falciparum is the most lethal form of malaria and is increasing both in incidence and in its resistance to antimalarial agents. An improved understanding of the mechanisms of malarial clearance may facilitate the development of new therapeutic interventions. We postulated that the scavenger receptor CD36, an important factor in cytoadherence of P falciparum–parasitized erythrocytes (PEs), might also play a role in monocyte- and macrophage-mediated malarial clearance. Exposure of nonopsonized PEs to Fc receptor–blocked monocytes resulted in significant PE phagocytosis, accompanied by intense clustering of CD36 around the PEs. Phagocytosis was blocked 60% to 70% by monocyte pretreatment with monoclonal anti-CD36 antibodies but not by antibodies to αvβ3, thrombospondin, intercellular adhesion molecule-1, or platelet/endothelial cell adhesion molecule-1. Antibody-induced CD36 cross-linking did result in the early increase of surface CD11b expression, but there was no increase in, or priming for, tumor necrosis factor (TNF)-α secretion following either CD36 cross-linking or PE phagocytosis. CD36 clustering does support intracellular signaling: Antibody-induced cross-linking initiated intracellular tyrosine phosphorylation as well as extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) phosphorylation. Both broad-spectrum tyrosine kinase inhibition (genistein) and selective ERK and p38 MAPK inhibition (PD98059 and SB203580, respectively) reduced PE uptake to almost the same extent as CD36 blockade. Thus, CD36-dependent binding and signaling appears to be crucial for the nonopsonic clearance of PEs and does not appear to contribute to the increase in TNF-α that is prognostic of poor outcome in clinical malaria.
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50
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Nonopsonic monocyte/macrophage phagocytosis of Plasmodium falciparum–parasitized erythrocytes: a role for CD36 in malarial clearance. Blood 2000. [DOI: 10.1182/blood.v96.9.3231.h8003231_3231_3240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmodium falciparum is the most lethal form of malaria and is increasing both in incidence and in its resistance to antimalarial agents. An improved understanding of the mechanisms of malarial clearance may facilitate the development of new therapeutic interventions. We postulated that the scavenger receptor CD36, an important factor in cytoadherence of P falciparum–parasitized erythrocytes (PEs), might also play a role in monocyte- and macrophage-mediated malarial clearance. Exposure of nonopsonized PEs to Fc receptor–blocked monocytes resulted in significant PE phagocytosis, accompanied by intense clustering of CD36 around the PEs. Phagocytosis was blocked 60% to 70% by monocyte pretreatment with monoclonal anti-CD36 antibodies but not by antibodies to αvβ3, thrombospondin, intercellular adhesion molecule-1, or platelet/endothelial cell adhesion molecule-1. Antibody-induced CD36 cross-linking did result in the early increase of surface CD11b expression, but there was no increase in, or priming for, tumor necrosis factor (TNF)-α secretion following either CD36 cross-linking or PE phagocytosis. CD36 clustering does support intracellular signaling: Antibody-induced cross-linking initiated intracellular tyrosine phosphorylation as well as extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) phosphorylation. Both broad-spectrum tyrosine kinase inhibition (genistein) and selective ERK and p38 MAPK inhibition (PD98059 and SB203580, respectively) reduced PE uptake to almost the same extent as CD36 blockade. Thus, CD36-dependent binding and signaling appears to be crucial for the nonopsonic clearance of PEs and does not appear to contribute to the increase in TNF-α that is prognostic of poor outcome in clinical malaria.
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