1
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Feng Y, Huang C, Wang Y, Chen J. SIRPα: A key player in innate immunity. Eur J Immunol 2023; 53:e2350375. [PMID: 37672390 DOI: 10.1002/eji.202350375] [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: 03/01/2023] [Revised: 07/15/2023] [Accepted: 09/05/2023] [Indexed: 09/08/2023]
Abstract
Signal regulatory protein alpha (SIRPα) is a crucial inhibitory regulator expressed on the surface of myeloid cells, including macrophages, dendritic cells, monocytes, neutrophils, and microglia. SIRPα plays an indispensable role in innate immune and adoptive immune responses in cancer immunology, tissue homeostasis, and other physiological or phycological conditions. This review provides an overview of the research history, ligands, signal transduction pathways, and functional mechanisms associated with SIRPα. Additionally, we summarize the therapeutic implications of targeting SIRPα as a promising novel strategy in immuno-oncology.
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Affiliation(s)
- Yongyi Feng
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Chunliu Huang
- Molecular Imaging Center, Guangdong Provincial Key Laboratory of Biomedical Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, China
| | - Yingzhao Wang
- Department of Gastrointestinal Surgery, The First Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Jun Chen
- Department of Immunology and Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Guangdong Engineering & Technology Research Center for Disease-Model Animals, Laboratory Animal Center, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Key Laboratory of Tropical Disease Control of the Ministry of Education, Sun Yat-sen University, Guangzhou, China
- Jinfeng Laboratory, Chongqing, China
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2
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Montero E, Isenberg JS. The TSP1-CD47-SIRPα interactome: an immune triangle for the checkpoint era. Cancer Immunol Immunother 2023; 72:2879-2888. [PMID: 37217603 PMCID: PMC10412679 DOI: 10.1007/s00262-023-03465-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 05/09/2023] [Indexed: 05/24/2023]
Abstract
The use of treatments, such as programmed death protein 1 (PD1) or cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) antibodies, that loosen the natural checks upon immune cell activity to enhance cancer killing have shifted clinical practice and outcomes for the better. Accordingly, the number of antibodies and engineered proteins that interact with the ligand-receptor components of immune checkpoints continue to increase along with their use. It is tempting to view these molecular pathways simply from an immune inhibitory perspective. But this should be resisted. Checkpoint molecules can have other cardinal functions relevant to the development and use of blocking moieties. Cell receptor CD47 is an example of this. CD47 is found on the surface of all human cells. Within the checkpoint paradigm, non-immune cell CD47 signals through immune cell surface signal regulatory protein alpha (SIRPα) to limit the activity of the latter, the so-called trans signal. Even so, CD47 interacts with other cell surface and soluble molecules to regulate biogas and redox signaling, mitochondria and metabolism, self-renewal factors and multipotency, and blood flow. Further, the pedigree of checkpoint CD47 is more intricate than supposed. High-affinity interaction with soluble thrombospondin-1 (TSP1) and low-affinity interaction with same-cell SIRPα, the so-called cis signal, and non-SIRPα ectodomains on the cell membrane suggests that multiple immune checkpoints converge at and through CD47. Appreciation of this may provide latitude for pathway-specific targeting and intelligent therapeutic effect.
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Affiliation(s)
- Enrique Montero
- Department of Diabetes Immunology, City of Hope National Medical Center, 1500 Duarte Road, Duarte, CA, 91010, USA
- Arthur Riggs Diabetes and Metabolism Research Institute, City of Hope National Medical Center, 1500 Duarte Road, Duarte, CA, 91010, USA
| | - Jeffrey S Isenberg
- Department of Diabetes Complications and Metabolism, City of Hope National Medical Center, 1500 Duarte Road, Duarte, CA, 91010, USA.
- Arthur Riggs Diabetes and Metabolism Research Institute, City of Hope National Medical Center, 1500 Duarte Road, Duarte, CA, 91010, USA.
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3
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Zhao Y, Fang L, Guo P, Fang Y, Wu J. A MD Simulation Prediction for Regulation of N-Terminal Modification on Binding of CD47 to CD172a in a Force-Dependent Manner. Molecules 2023; 28:molecules28104224. [PMID: 37241964 DOI: 10.3390/molecules28104224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 05/12/2023] [Accepted: 05/18/2023] [Indexed: 05/28/2023] Open
Abstract
Cancer cells can evade immune surveillance through binding of its transmembrane receptor CD47 to CD172a on myeloid cells. CD47 is recognized as a promising immune checkpoint for cancer immunotherapy inhibiting macrophage phagocytosis. N-terminal post-translated modification (PTM) via glutaminyl cyclase is a landmark event in CD47 function maturation, but the molecular mechanism underlying the mechano-chemical regulation of the modification on CD47/CD172a remains unclear. Here, we performed so-called "ramp-clamp" steered molecular dynamics (SMD) simulations, and found that the N-terminal PTM enhanced interaction of CD172a with CD47 by inducing a dynamics-driven contraction of the binding pocket of the bound CD172a, an additional constraint on CYS15 on CD47 significantly improved the tensile strength of the complex with or without PTM, and a catch bond phenomenon would occur in complex dissociation under tensile force of 25 pN in a PTM-independent manner too. The residues GLN52 and SER66 on CD172a reinforced the H-bonding with their partners on CD47 in responding to PTM, while ARG69 on CD172 with its partner on CD47 might be crucial in the structural stability of the complex. This work might serve as molecular basis for the PTM-induced function improvement of CD47, should be helpful for deeply understanding CD47-relevant immune response and cancer development, and provides a novel insight in developing of new strategies of immunotherapy targeting this molecule interaction.
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Affiliation(s)
- Yang Zhao
- Institute of Biomechanics, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Liping Fang
- Institute of Biomechanics, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Pei Guo
- Institute of Biomechanics, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Ying Fang
- Institute of Biomechanics, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
| | - Jianhua Wu
- Institute of Biomechanics, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
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4
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Hao Y, Zhou X, Li Y, Li B, Cheng L. The CD47-SIRPα axis is a promising target for cancer immunotherapies. Int Immunopharmacol 2023; 120:110255. [PMID: 37187126 DOI: 10.1016/j.intimp.2023.110255] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/22/2023] [Accepted: 04/27/2023] [Indexed: 05/17/2023]
Abstract
Cluster of differentiation 47(CD47) is a transmembrane protein that is ubiquitously found on the surface of many cells in the body and uniquely overexpressed by both solid and hematologic malignant cells. CD47 interacts with signal-regulatory protein α (SIRPα), to trigger a "don't eat me" signal and thereby achieve cancer immune escape by inhibiting macrophage-mediated phagocytosis. Thus, blocking the CD47-SIRPα phagocytosis checkpoint, for release of the innate immune system, is a current research focus. Indeed, targeting the CD47-SIRPα axis as a cancer immunotherapy has shown promising efficacies in pre-clinical outcomes. Here, we first reviewed the origin, structure, and function of the CD47-SIRPα axis. Then, we reviewed its role as a target for cancer immunotherapies, as well as the factors regulating CD47-SIRPα axis-based immunotherapies. We specifically focused on the mechanism and progress of CD47-SIRPα axis-based immunotherapies and their combination with other treatment strategies. Finally, we discussed the challenges and directions for future research and identified potential CD47-SIRPα axis-based therapies that are suitable for clinical application.
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Affiliation(s)
- Yu Hao
- State Key Laboratory of Oral Diseases & West China Hospital of Stomatology & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu 610041, China; Department of Operative Dentistry and Endodontics, West China School of Stomatology, Sichuan University, Chengdu 610041, China
| | - Xinxuan Zhou
- State Key Laboratory of Oral Diseases & West China Hospital of Stomatology & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu 610041, China
| | - Yiling Li
- State Key Laboratory of Oral Diseases & West China Hospital of Stomatology & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu 610041, China; Department of Operative Dentistry and Endodontics, West China School of Stomatology, Sichuan University, Chengdu 610041, China
| | - Bolei Li
- State Key Laboratory of Oral Diseases & West China Hospital of Stomatology & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu 610041, China; Department of Operative Dentistry and Endodontics, West China School of Stomatology, Sichuan University, Chengdu 610041, China.
| | - Lei Cheng
- State Key Laboratory of Oral Diseases & West China Hospital of Stomatology & National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu 610041, China; Department of Operative Dentistry and Endodontics, West China School of Stomatology, Sichuan University, Chengdu 610041, China.
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5
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Pennington LF, Gasser P, Kleinboelting S, Zhang C, Skiniotis G, Eggel A, Jardetzky TS. Directed evolution of and structural insights into antibody-mediated disruption of a stable receptor-ligand complex. Nat Commun 2021; 12:7069. [PMID: 34862384 PMCID: PMC8642555 DOI: 10.1038/s41467-021-27397-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 11/11/2021] [Indexed: 11/15/2022] Open
Abstract
Antibody drugs exert therapeutic effects via a range of mechanisms, including competitive inhibition, allosteric modulation, and immune effector mechanisms. Facilitated dissociation is an additional mechanism where antibody-mediated “disruption” of stable high-affinity macromolecular complexes can potentially enhance therapeutic efficacy. However, this mechanism is not well understood or utilized therapeutically. Here, we investigate and engineer the weak disruptive activity of an existing therapeutic antibody, omalizumab, which targets IgE antibodies to block the allergic response. We develop a yeast display approach to select for and engineer antibody disruptive efficiency and generate potent omalizumab variants that dissociate receptor-bound IgE. We determine a low resolution cryo-EM structure of a transient disruption intermediate containing the IgE-Fc, its partially dissociated receptor and an antibody inhibitor. Our results provide a conceptual framework for engineering disruptive inhibitors for other targets, insights into the failure in clinical trials of the previous high affinity omalizumab HAE variant and anti-IgE antibodies that safely and rapidly disarm allergic effector cells. Facilitated dissociation is a mechanism where antibody-mediated disruption of high-affinity complexes can enhance the therapeutic effects of a drug. Here the authors present a yeast display approach to select and engineer omalizumab variants that dissociate receptor-bound IgE to accelerate its inhibition of the allergic response.
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Affiliation(s)
- Luke F Pennington
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA.,Progam in Immunology, Stanford University School of Medicine, Stanford, CA, 94305, USA.,Sean N. Parker Center for Allergy Research at Stanford University, Stanford, CA, 94305, USA
| | - Pascal Gasser
- Department of Rheumatology and Immunology, University Hospital Bern, Bern, Switzerland.,Department of BioMedical Research, University of Bern, Bern, Switzerland
| | - Silke Kleinboelting
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Chensong Zhang
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Georgios Skiniotis
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA.,Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Alexander Eggel
- Department of Rheumatology and Immunology, University Hospital Bern, Bern, Switzerland.,Department of BioMedical Research, University of Bern, Bern, Switzerland
| | - Theodore S Jardetzky
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA. .,Progam in Immunology, Stanford University School of Medicine, Stanford, CA, 94305, USA. .,Sean N. Parker Center for Allergy Research at Stanford University, Stanford, CA, 94305, USA.
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6
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Sasikumar PG, Ramachandra M. Peptide and peptide-inspired checkpoint inhibitors: Protein fragments to cancer immunotherapy. MEDICINE IN DRUG DISCOVERY 2020. [DOI: 10.1016/j.medidd.2020.100073] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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7
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Jalil AR, Andrechak JC, Discher DE. Macrophage checkpoint blockade: results from initial clinical trials, binding analyses, and CD47-SIRPα structure-function. Antib Ther 2020; 3:80-94. [PMID: 32421049 PMCID: PMC7206415 DOI: 10.1093/abt/tbaa006] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/07/2020] [Accepted: 04/14/2020] [Indexed: 12/11/2022] Open
Abstract
The macrophage checkpoint is an anti-phagocytic interaction between signal regulatory protein alpha (SIRPα) on a macrophage and CD47 on all types of cells - ranging from blood cells to cancer cells. This interaction has emerged over the last decade as a potential co-target in cancer when combined with other anti-cancer agents, with antibodies against CD47 and SIRPα currently in preclinical and clinical development for a variety of hematological and solid malignancies. Monotherapy with CD47 blockade is ineffective in human clinical trials against many tumor types tested to date, except for rare cutaneous and peripheral lymphomas. In contrast, pre-clinical results show efficacy in multiple syngeneic mouse models of cancer, suggesting that many of these tumor models are more immunogenic and likely artificial compared to human tumors. However, combination therapies in humans of anti-CD47 with agents such as the anti-tumor antibody rituximab do show efficacy against liquid tumors (lymphoma) and are promising. Here, we review such trials as well as key interaction and structural features of CD47-SIRPα.
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Affiliation(s)
- AbdelAziz R Jalil
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
- Biophysical Engineering Labs, University of Pennsylvania, Philadelphia, PA, USA
| | - Jason C Andrechak
- Biophysical Engineering Labs, University of Pennsylvania, Philadelphia, PA, USA
- Graduate Group in Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Dennis E Discher
- Biophysical Engineering Labs, University of Pennsylvania, Philadelphia, PA, USA
- Graduate Group in Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
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8
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Epithelial CD47 is critical for mucosal repair in the murine intestine in vivo. Nat Commun 2019; 10:5004. [PMID: 31676794 PMCID: PMC6825175 DOI: 10.1038/s41467-019-12968-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 10/07/2019] [Indexed: 02/07/2023] Open
Abstract
CD47 is a ubiquitously expressed transmembrane glycoprotein that regulates inflammatory responses and tissue repair. Here, we show that normal mice treated with anti-CD47 antibodies, and Cd47-null mice have impaired intestinal mucosal wound healing. Furthermore, intestinal epithelial cell (IEC)-specific loss of CD47 does not induce spontaneous immune-mediated intestinal barrier disruption but results in defective mucosal repair after biopsy-induced colonic wounding or Dextran Sulfate Sodium (DSS)-induced mucosal damage. In vitro analyses using primary cultures of CD47-deficient murine colonic IEC or human colonoid-derived IEC treated with CD47-blocking antibodies demonstrate impaired epithelial cell migration in wound healing assays. Defective wound repair after CD47 loss is linked to decreased epithelial β1 integrin and focal adhesion signaling, as well as reduced thrombospondin-1 and TGF-β1. These results demonstrate a critical role for IEC-expressed CD47 in regulating mucosal repair and raise important considerations for possible alterations in wound healing secondary to therapeutic targeting of CD47. The role of the transmembrane glycoprotein CD47 in healing injured intestinal mucosa is unclear. Here, the authors show that selective loss of CD47 in the murine intestinal epithelium results in defective mucosal repair after colonic wounding, with suggested impaired cell migration in vitro.
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9
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Boettcher AN, Cunnick JE, Powell EJ, Egner TK, Charley SE, Loving CL, Tuggle CK. Porcine signal regulatory protein alpha binds to human CD47 to inhibit phagocytosis: Implications for human hematopoietic stem cell transplantation into severe combined immunodeficient pigs. Xenotransplantation 2018; 26:e12466. [PMID: 30311702 DOI: 10.1111/xen.12466] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 08/10/2018] [Accepted: 09/18/2018] [Indexed: 12/27/2022]
Abstract
BACKGROUND Severe combined immunodeficient (SCID) pigs are an emerging animal model being developed for biomedical and regenerative medicine research. SCID pigs can successfully engraft human-induced pluripotent stem cells and cancer cell lines. The development of a humanized SCID pig through xenotransplantation of human hematopoietic stem cells (HSCs) would be a further demonstration of the value of such a large animal SCID model. Xenotransplantation success with HSCs into non-obese diabetic (NOD)-derived SCID mice is dependent on the ability of NOD mouse signal regulatory protein alpha (SIRPA) to bind human CD47, inducing higher phagocytic tolerance than other mouse strains. Therefore, we investigated whether porcine SIRPA binds human CD47 in the context of developing a humanized SCID pig. METHODS Peripheral blood mononuclear cells (PBMCs) were collected from SCID and non-SCID pigs. Flow cytometry was used to assess whether porcine monocytes could bind to human CD47. Porcine monocytes were isolated from PBMCs and were subjected to phagocytosis assays with pig, human, and mouse red blood cell (RBC) targets. Blocking phagocytosis assays were performed by incubating human RBCs with anti-human CD47 blocking antibody B6H12, non-blocking antibody 2D3, and nonspecific IgG1 antibody and exposing to human or porcine monocytes. RESULTS We found that porcine SIRPA binds to human CD47 in vitro by flow cytometric assays. Additionally, phagocytosis assays were performed, and we found that porcine monocytes phagocytose human and porcine RBCs at significantly lower levels than mouse RBCs. When human RBCs were preincubated with CD47 antibodies B6H12 or 2D3, phagocytosis was induced only after B6H12 incubation, indicating the lower phagocytic activity of porcine monocytes with human cells requires interaction between porcine SIRPA and human CD47. CONCLUSIONS We have shown the first evidence that porcine monocytes can bind to human CD47 and are phagocytically tolerant to human cells, suggesting that porcine SCID models have the potential to support engraftment of human HSCs.
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Affiliation(s)
| | - Joan E Cunnick
- Department of Animal Science, Iowa State University, Ames, Iowa
| | - Ellis J Powell
- Department of Animal Science, Iowa State University, Ames, Iowa.,National Animal Disease Center, Ruminant Diseases and Immunology Unit, US Department of Agriculture, Agricultural Research Service, Ames, Iowa
| | | | - Sara E Charley
- Department of Animal Science, Iowa State University, Ames, Iowa
| | - Crystal L Loving
- National Animal Disease Center, Food Safety and Enteric Pathogens Unit, US Department of Agriculture, Agricultural Research Service, Ames, Iowa
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10
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Azcutia V, Bassil R, Herter JM, Engelbertsen D, Newton G, Autio A, Mayadas T, Lichtman AH, Khoury SJ, Parkos CA, Elyaman W, Luscinskas FW. Defects in CD4+ T cell LFA-1 integrin-dependent adhesion and proliferation protect Cd47-/- mice from EAE. J Leukoc Biol 2016; 101:493-505. [PMID: 27965383 DOI: 10.1189/jlb.3a1215-546rr] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Revised: 08/26/2016] [Accepted: 08/29/2016] [Indexed: 11/24/2022] Open
Abstract
CD47 is known to play an important role in CD4+ T cell homeostasis. We recently reported a reduction in mice deficient in the Cd47 gene (Cd47-/-) CD4+ T cell adhesion and transendothelial migration (TEM) in vivo and in vitro as a result of impaired expression of high-affinity forms of LFA-1 and VLA-4 integrins. A prior study concluded that Cd47-/- mice were resistant to experimental autoimmune encephalomyelitis (EAE) as a result of complete failure in CD4+ T cell activation after myelin oligodendrocyte glycoprotein peptide 35-55 aa (MOG35-55) immunization. As the prior EAE study was published before our report, authors could not have accounted for defects in T cell integrin function as a mechanism to protect Cd47-/- in EAE. Thus, we hypothesized that failure of T cell activation involved defects in LFA-1 and VLA-4 integrins. We confirmed that Cd47-/- mice were resistant to MOG35-55-induced EAE. Our data, however, supported a different mechanism that was not a result of failure of CD4+ T cell activation. Instead, we found that CD4+ T cells in MOG35-55-immunized Cd47-/- mice were activated, but clonal expansion contracted within 72 h after immunization. We used TCR crosslinking and mitogen activation in vitro to investigate the underlying mechanism. We found that naïve Cd47-/- CD4+ T cells exhibited a premature block in proliferation and survival because of impaired activation of LFA-1, despite effective TCR-induced activation. These results identify CD47 as an important regulator of LFA-1 and VLA-4 integrin-adhesive functions in T cell proliferation, as well as recruitment, and clarify the roles played by CD47 in MOG35-55-induced EAE.
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Affiliation(s)
- Veronica Azcutia
- Center for Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Ribal Bassil
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Jan M Herter
- Center for Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Daniel Engelbertsen
- Center for Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Gail Newton
- Center for Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Anu Autio
- Center for Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Tanya Mayadas
- Center for Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Andrew H Lichtman
- Center for Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Samia J Khoury
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.,Abou Haidar Neuroscience Institute, American University of Beirut, Lebanon; and
| | - Charles A Parkos
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA
| | - Wassim Elyaman
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA;
| | - Francis W Luscinskas
- Center for Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA;
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11
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Weber DA, Sumagin R, McCall IC, Leoni G, Neumann PA, Andargachew R, Brazil JC, Medina-Contreras O, Denning TL, Nusrat A, Parkos CA. Neutrophil-derived JAML inhibits repair of intestinal epithelial injury during acute inflammation. Mucosal Immunol 2014; 7:1221-32. [PMID: 24621992 PMCID: PMC4340686 DOI: 10.1038/mi.2014.12] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 01/20/2014] [Accepted: 02/04/2014] [Indexed: 02/04/2023]
Abstract
Neutrophil transepithelial migration (TEM) during acute inflammation is associated with mucosal injury. Using models of acute mucosal injury in vitro and in vivo, we describe a new mechanism by which neutrophils infiltrating the intestinal mucosa disrupt epithelial homeostasis. We report that junctional adhesion molecule-like protein (JAML) is cleaved from neutrophil surface by zinc metalloproteases during TEM. Neutrophil-derived soluble JAML binds to the epithelial tight junction protein coxsackie-adenovirus receptor (CAR) resulting in compromised barrier and inhibition of wound repair, through decreased epithelial proliferation. The deleterious effects of JAML on barrier and wound repair are reversed with an anti-JAML monoclonal antibody that inhibits JAML-CAR binding. JAML released from transmigrating neutrophils across inflamed epithelia may thus promote recruitment of leukocytes and aid in clearance of invading microorganisms. However, sustained release of JAML under pathologic conditions associated with persistence of large numbers of infiltrated neutrophils would compromise intestinal barrier and inhibit mucosal healing. Thus, targeting JAML-CAR interactions may improve mucosal healing responses under conditions of dysregulated neutrophil recruitment.
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Affiliation(s)
- Dominique A. Weber
- Epithelial Pathobiology and Mucosal Inflammation Unit, Department of Pathology and Laboratory Medicine
| | - Ronen Sumagin
- Epithelial Pathobiology and Mucosal Inflammation Unit, Department of Pathology and Laboratory Medicine
| | - Ingrid C. McCall
- Epithelial Pathobiology and Mucosal Inflammation Unit, Department of Pathology and Laboratory Medicine
| | - Giovanna Leoni
- Epithelial Pathobiology and Mucosal Inflammation Unit, Department of Pathology and Laboratory Medicine
| | - Philipp A. Neumann
- Epithelial Pathobiology and Mucosal Inflammation Unit, Department of Pathology and Laboratory Medicine
| | - Rakieb Andargachew
- Epithelial Pathobiology and Mucosal Inflammation Unit, Department of Pathology and Laboratory Medicine
| | - Jennifer C. Brazil
- Epithelial Pathobiology and Mucosal Inflammation Unit, Department of Pathology and Laboratory Medicine,Department of Pediatrics, Emory University, Atlanta, Georgia 30322
| | - Oscar Medina-Contreras
- Epithelial Pathobiology and Mucosal Inflammation Unit, Department of Pathology and Laboratory Medicine,Department of Pediatrics, Emory University, Atlanta, Georgia 30322
| | - Timothy L. Denning
- Epithelial Pathobiology and Mucosal Inflammation Unit, Department of Pathology and Laboratory Medicine,Department of Pediatrics, Emory University, Atlanta, Georgia 30322
| | - Asma Nusrat
- Epithelial Pathobiology and Mucosal Inflammation Unit, Department of Pathology and Laboratory Medicine
| | - Charles A. Parkos
- Epithelial Pathobiology and Mucosal Inflammation Unit, Department of Pathology and Laboratory Medicine,Department of Pediatrics, Emory University, Atlanta, Georgia 30322
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12
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Iwamoto C, Takenaka K, Urata S, Yamauchi T, Shima T, Kuriyama T, Daitoku S, Saito Y, Miyamoto T, Iwasaki H, Kitabayashi I, Itoh K, Kishimoto J, Kohda D, Matozaki T, Akashi K. The BALB/c-specific polymorphic SIRPA enhances its affinity for human CD47, inhibiting phagocytosis against human cells to promote xenogeneic engraftment. Exp Hematol 2013; 42:163-171.e1. [PMID: 24269920 DOI: 10.1016/j.exphem.2013.11.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 11/05/2013] [Accepted: 11/07/2013] [Indexed: 02/04/2023]
Abstract
It has been shown that in xenotransplantation of human cells into immunodeficient mice, the mouse strain background is critical. For example, the nonobese diabetic (NOD) strain is most efficient, the BALB/c is moderate, and the C57BL/6 is inefficient for human cell engraftment. We have shown that the NOD-specific polymorphism of the signal regulatory protein-alpha (Sirpa) allows NOD SIRPA to bind human CD47, and the resultant "don't eat me" signaling by this binding prevents host macrophages to engulf human grafts, thereby inhibiting rejection. Here we tested whether the efficient xenotransplantation capability of the BALB/c strain is also mediated by the SIRPA-CD47 self-recognition system. BALB/c SIRPA was capable of binding to human CD47 at an intermediate level between those of C57BL/6 SIRPA and NOD SIRPA. Consistent with its binding activity, BALB/c-derived macrophages exhibited a moderate inhibitory effect on human long-term culture-initiating cells in in vitro cultures, and showed moderate phagocytic activity against human hematopoietic stem cells. The increased affinity of BALB/c SIRPA for human CD47 was mounted at least through the BALB/c-specific L29V SNP within the IgV domain. Thus, the mouse strain effect on xenogeneic engraftment might be ascribed mainly to the binding affinity of strain-specific polymorphic SIRPA with human CD47. This information should be useful for developing a novel immunodeficient strain with superior efficiency for xenogeneic transplantation of human cells.
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Affiliation(s)
- Chika Iwamoto
- Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Katsuto Takenaka
- Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Shingo Urata
- Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Takuji Yamauchi
- Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Takahiro Shima
- Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Takuro Kuriyama
- Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Shinya Daitoku
- Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Yasuyuki Saito
- Laboratory of Biosignal Sciences, Institute for Molecular and Cellular Regulation, Gunma University, Gunma, Japan
| | - Toshihiro Miyamoto
- Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Hiromi Iwasaki
- Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Issay Kitabayashi
- Division of Hematological Malignancy, National Cancer Center Research Institute, Tokyo, Japan
| | - Katsuhiko Itoh
- Department of Clinical Molecular Biology, Faculty of Medicine, Kyoto University, Kyoto, Japan
| | - Junji Kishimoto
- Digital Medicine Initiative, Kyushu University, Fukuoka, Japan
| | - Daisuke Kohda
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Takashi Matozaki
- Laboratory of Biosignal Sciences, Institute for Molecular and Cellular Regulation, Gunma University, Gunma, Japan; Division of Molecular and Cellular Signaling, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Koichi Akashi
- Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
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13
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Toledano N, Gur-Wahnon D, Ben-Yehuda A, Rachmilewitz J. Novel CD47: SIRPα dependent mechanism for the activation of STAT3 in antigen-presenting cell. PLoS One 2013; 8:e75595. [PMID: 24073274 PMCID: PMC3779186 DOI: 10.1371/journal.pone.0075595] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 08/15/2013] [Indexed: 12/16/2022] Open
Abstract
Cell surface CD47 interacts with its receptor, signal-regulatory-protein α (SIRPα) that is expressed predominantly on macrophages, to inhibit phagocytosis of normal, healthy cells. This “don’t eat me” signal is mediated through tyrosine phosphorylation of SIRPα at the cytoplasmic ITIM motifs and the recruitment of the phosphatase, SHP-1. We previously revealed a novel mechanism for the activation of the STAT3 pathway and the regulation of human APC maturation and function that is based on cell:cell interaction. In this study, we present evidence supporting the notion that CD47:SIRPα serves as a cell surface receptor: ligand pair involved in this contact-dependent STAT3 activation and regulation of APC maturation. We show that upon co-culturing APC with various primary and tumor cell lines STAT3 phosphorylation and IL-10 expression are induced, and such regulation could be suppressed by specific CD47 siRNAs and shRNAs. Significantly, >50% reduction in CD47 expression abolished the contact-dependent inhibition of T cell activation. Furthermore, co-immunoprecipitation experiments revealed a physical association between SIRPα and STAT3. Thus, we suggest that in addition to signaling through the ITIM-SHP-1 complex that transmit an anti-phagocytotic, CD47:SIRPα also triggers STAT3 signaling that is linked to an immature APC phenotype and peripheral tolerance under steady state and pathological conditions.
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Affiliation(s)
- Natan Toledano
- Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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14
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Nettleship JE, Ren J, Scott DJ, Rahman N, Hatherley D, Zhao Y, Stuart DI, Barclay AN, Owens RJ. Crystal structure of signal regulatory protein gamma (SIRPγ) in complex with an antibody Fab fragment. BMC STRUCTURAL BIOLOGY 2013; 13:13. [PMID: 23826770 PMCID: PMC3716694 DOI: 10.1186/1472-6807-13-13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 06/24/2013] [Indexed: 11/28/2022]
Abstract
BACKGROUND Signal Regulatory Protein γ (SIRPγ) is a member of a closely related family of three cell surface receptors implicated in modulating immune/inflammatory responses. SIRPγ is expressed on T lymphocytes where it appears to be involved in the integrin-independent adhesion of lymphocytes to antigen-presenting cells. Here we describe the first full length structure of the extracellular region of human SIRPγ. RESULTS We obtained crystals of SIRPγ by making a complex of the protein with the Fab fragment of the anti-SIRP antibody, OX117, which also binds to SIRPα and SIRPβ. We show that the epitope for FabOX117 is formed at the interface of the first and second domains of SIRPγ and comprises residues which are conserved between all three SIRPs. The FabOX117 binding site is distinct from the region in domain 1 which interacts with CD47, the physiological ligand for both SIRPγ and SIRPα but not SIRPβ. Comparison of the three domain structures of SIRPγ and SIRPα showed that these receptors can adopt different overall conformations due to the flexibility of the linker between the first two domains. SIRPγ in complex with FabOX117 forms a dimer in the crystal. Binding to the Fab fixes the position of domain 1 relative to domains 2/3 exposing a surface which favours formation of a homotypic dimer. However, the interaction appears to be relatively weak since only monomers of SIRPγ were observed in sedimentation velocity analytical ultracentrifugation of the protein alone. Studies of complex formation by equilibrium ultracentrifugation showed that only a 1:1 complex of SIRPγ: FabOX117 was formed with a dissociation constant in the low micromolar range (Kd = 1.2 +/- 0.3 μM). CONCLUSION The three-domain extracellular regions of SIRPs are structurally conserved but show conformational flexibility in the disposition of the amino terminal ligand-binding Ig domain relative to the two membrane proximal Ig domains. Binding of a cross-reactive anti-SIRP Fab fragment to SIRPγ stabilises a conformation that favours SIRP dimer formation in the crystal structure, though this interaction does not appear sufficiently stable to be observed in solution.
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MESH Headings
- Antigen-Antibody Complex/chemistry
- Antigen-Antibody Complex/metabolism
- Antigens, Differentiation/chemistry
- Antigens, Differentiation/genetics
- Antigens, Differentiation/metabolism
- Binding Sites
- Crystallography, X-Ray
- Dimerization
- HEK293 Cells
- Humans
- Immunoglobulin Fab Fragments/chemistry
- Immunoglobulin Fab Fragments/genetics
- Immunoglobulin Fab Fragments/immunology
- Immunoglobulin Fab Fragments/metabolism
- Protein Structure, Tertiary
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Receptors, Immunologic/chemistry
- Receptors, Immunologic/genetics
- Receptors, Immunologic/metabolism
- Recombinant Proteins/biosynthesis
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Ultracentrifugation
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Affiliation(s)
- Joanne E Nettleship
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
- OPPF-UK, The Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Oxfordshire OX11 0FA, UK
| | - Jingshan Ren
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - David J Scott
- The Research Complex at Harwell and ISIS Neutron and Muon source, Rutherford Appleton Laboratory, Harwell Oxford, Oxfordshire OX11 0FA, UK
- The School of Biosciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Leicestershire LE12 5RD, UK
| | - Nahid Rahman
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
- OPPF-UK, The Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Oxfordshire OX11 0FA, UK
| | - Deborah Hatherley
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Yuguang Zhao
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - David I Stuart
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
- Diamond Light Sources, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | - A Neil Barclay
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Raymond J Owens
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
- OPPF-UK, The Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Oxfordshire OX11 0FA, UK
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15
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Crosstalk between colon cancer cells and macrophages via inflammatory mediators and CD47 promotes tumour cell migration. Eur J Cancer 2013; 49:3320-34. [PMID: 23810249 DOI: 10.1016/j.ejca.2013.06.005] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 05/08/2013] [Accepted: 06/02/2013] [Indexed: 12/17/2022]
Abstract
Tumour-associated macrophages (TAMs) of the M2 phenotype are present in the stroma of many tumours and are frequently associated with the progression of several types of cancer. We investigated the role of M2 macrophages in colon cancer progression and found that human colon cancer tissue had elevated numbers of CD68(+) (macrophage marker) cells and CD206(+) (M2 macrophage marker) cells and increased CD47 expression. To explore potential interplay between colon cancer cells and M2 macrophages, we differentiated the monocyte cell line THP-1 into M1 and M2 macrophages (CD206(high) and Th2 cytokine-secreting cells), respectively. M2 macrophages migrated faster than M1 macrophages towards SW480-conditioned medium. Similarly, M2 macrophage-conditioned medium induced SW480 cell migration and CD47 expression. Factors released by macrophages were involved in this induction. In addition, SW480 cells migrated faster when co-cultured with M2 macrophages. Inhibition of CD47 with blocking antibodies or siRNA significantly reduced the migration of SW480 cells in the presence of M2 macrophages. This effect was further decreased via blocking antibodies against the CD47 ligand signal-regulatory protein α (SIRPα). Additionally, cancer cells also secreted significant levels of IL-10, thereby promoting M2 macrophage differentiation. These findings indicate that a TAM-enriched tumour microenvironment promotes colon cancer cell migration and metastasis.
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16
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van Beek E, Zarate J, van Bruggen R, Schornagel K, Tool A, Matozaki T, Kraal G, Roos D, van den Berg T. SIRPα Controls the Activity of the Phagocyte NADPH Oxidase by Restricting the Expression of gp91phox. Cell Rep 2012; 2:748-55. [DOI: 10.1016/j.celrep.2012.08.027] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 07/20/2012] [Accepted: 08/27/2012] [Indexed: 12/27/2022] Open
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17
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Lin Y, Yan XQ, Yang F, Yang XW, Jiang X, Zhao XC, Zhu BK, Liu L, Qin HY, Liang YM, Han H. Soluble extracellular domains of human SIRPα and CD47 expressed in Escherichia coli enhances the phagocytosis of leukemia cells by macrophages in vitro. Protein Expr Purif 2012; 85:109-16. [DOI: 10.1016/j.pep.2012.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 07/01/2012] [Accepted: 07/02/2012] [Indexed: 02/04/2023]
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18
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Fournier B, Andargachew R, Robin AZ, Laur O, Voelker DR, Lee WY, Weber D, Parkos CA. Surfactant protein D (Sp-D) binds to membrane-proximal domain (D3) of signal regulatory protein α (SIRPα), a site distant from binding domain of CD47, while also binding to analogous region on signal regulatory protein β (SIRPβ). J Biol Chem 2012; 287:19386-98. [PMID: 22511785 DOI: 10.1074/jbc.m111.324533] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Signal regulatory protein α (SIRPα), a highly glycosylated type-1 transmembrane protein, is composed of three immunoglobulin-like extracellular loops as well as a cytoplasmic tail containing three classical tyrosine-based inhibitory motifs. Previous reports indicate that SIRPα binds to humoral pattern recognition molecules in the collectin family, namely surfactant proteins D and A (Sp-D and Sp-A, respectively), which are heavily expressed in the lung and constitute one of the first lines of innate immune defense against pathogens. However, little is known about molecular details of the structural interaction of Sp-D with SIRPs. In the present work, we examined the molecular basis of Sp-D binding to SIRPα using domain-deleted mutant proteins. We report that Sp-D binds to the membrane-proximal Ig domain (D3) of SIRPα in a calcium- and carbohydrate-dependent manner. Mutation of predicted N-glycosylation sites on SIRPα indicates that Sp-D binding is dependent on interactions with specific N-glycosylated residues on the membrane-proximal D3 domain of SIRPα. Given the remarkable sequence similarity of SIRPα to SIRPβ and the lack of known ligands for the latter, we examined Sp-D binding to SIRPβ. Here, we report specific binding of Sp-D to the membrane-proximal D3 domain of SIRPβ. Further studies confirmed that Sp-D binds to SIRPα expressed on human neutrophils and differentiated neutrophil-like cells. Because the other known ligand of SIRPα, CD47, binds to the membrane-distal domain D1, these findings indicate that multiple, distinct, functional ligand binding sites are present on SIRPα that may afford differential regulation of receptor function.
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Affiliation(s)
- Bénédicte Fournier
- Epithelial Pathobiology Research Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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19
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Lee WY, Weber DA, Laur O, Stowell SR, McCall I, Andargachew R, Cummings RD, Parkos CA. The role of cis dimerization of signal regulatory protein alpha (SIRPalpha) in binding to CD47. J Biol Chem 2010; 285:37953-63. [PMID: 20826801 DOI: 10.1074/jbc.m110.180018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Interaction of SIRPα with its ligand, CD47, regulates leukocyte functions, including transmigration, phagocytosis, oxidative burst, and cytokine secretion. Recent progress has provided significant insights into the structural details of the distal IgV domain (D1) of SIRPα. However, the structural roles of proximal IgC domains (D2 and D3) have been largely unstudied. The high degree of conservation of D2 and D3 among members of the SIRP family as well as the propensity of known IgC domains to assemble in cis has led others to hypothesize that SIRPα forms higher order structures on the cell surface. Here we report that SIRPα forms noncovalently linked cis homodimers. Treatment of SIRPα-expressing cells with a membrane-impermeable cross-linker resulted in the formation of SDS-stable SIRPα dimers and oligomers. Biochemical analyses of soluble recombinant extracellular regions of SIRPα, including domain truncation mutants, revealed that each of the three extracellular immunoglobulin loops of SIRPα formed dimers in solution. Co-immunoprecipitation experiments using cells transfected with different affinity-tagged SIRPα molecules revealed that SIRPα forms cis dimers. Interestingly, in cells treated with tunicamycin, SIRPα dimerization but not CD47 binding was inhibited, suggesting that a SIRPα dimer is probably bivalent. Last, we demonstrate robust dimerization of SIRPa in adherent, stimulated human neutrophils. Collectively, these data are consistent with SIRPα being expressed on the cell surface as a functional cis-linked dimer.
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Affiliation(s)
- Winston Y Lee
- Epithelial Pathobiology Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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20
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Barclay AN. Signal regulatory protein alpha (SIRPalpha)/CD47 interaction and function. Curr Opin Immunol 2009; 21:47-52. [PMID: 19223164 PMCID: PMC3128989 DOI: 10.1016/j.coi.2009.01.008] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Accepted: 01/20/2009] [Indexed: 12/12/2022]
Abstract
SIRPalpha is an inhibitory receptor present on myeloid cells that interacts with a widely distributed membrane protein CD47. The activating member SIRPbeta, despite extensive sequence similarity to SIRPalpha in the extracellular region, shows negligible binding to CD47. The SIRPalpha/CD47 interaction is unusual in that it can lead to bidirectional signalling through both SIRPalpha and CD47. This review concentrates on the interactions of SIRPalpha with CD47 where recent data have shed light on the structure of the proteins including determining why the activating SIRPbeta does not bind CD47, evidence of extensive polymorphisms and implication for the evolution and function of this protein and paired receptors in general. The interaction may be modified by endocytosis of the receptors, cleavage by proteolysis and through interactions of surfactant proteins.
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Affiliation(s)
- A Neil Barclay
- Sir William Dunn School of Pathology, University of Oxford, United Kingdom.
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21
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Thrombospondin-1 and CD47 regulate blood pressure and cardiac responses to vasoactive stress. Matrix Biol 2009; 28:110-9. [PMID: 19284971 DOI: 10.1016/j.matbio.2009.01.002] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 12/17/2008] [Accepted: 01/05/2009] [Indexed: 12/11/2022]
Abstract
Nitric oxide (NO) locally regulates vascular resistance and blood pressure by modulating blood vessel tone. Thrombospondin-1 signaling via its receptor CD47 locally limits the ability of NO to relax vascular smooth muscle cells and increase regional blood flow in ischemic tissues. To determine whether thrombospondin-1 plays a broader role in central cardiovascular physiology, we examined vasoactive stress responses in mice lacking thrombospondin-1 or CD47. Mice lacking thrombospondin-1 exhibit activity-associated increases in heart rate, central diastolic and mean arterial blood pressure and a constant decrease in pulse pressure. CD47-deficient mice have normal central pulse pressure but elevated resting peripheral blood pressure. Both null mice show exaggerated decreases in peripheral blood pressure and increased cardiac output and ejection fraction in response to NO. Autonomic blockade also induces exaggerated hypotensive responses in awake thrombospondin-1 null and CD47 null mice. Both null mice exhibit a greater hypotensive response to isoflurane, and autonomic blockage under isoflurane anesthesia leads to premature death of thrombospondin-1 null mice. Conversely, the hypertensive response to epinephrine is attenuated in thrombospondin-1 null mice. Thus, the matricellular protein thrombospondin-1 and its receptor CD47 serve as acute physiological regulators of blood pressure and exert a vasopressor activity to maintain global hemodynamics under stress.
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22
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Matozaki T, Murata Y, Okazawa H, Ohnishi H. Functions and molecular mechanisms of the CD47-SIRPalpha signalling pathway. Trends Cell Biol 2009; 19:72-80. [PMID: 19144521 DOI: 10.1016/j.tcb.2008.12.001] [Citation(s) in RCA: 340] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 12/01/2008] [Accepted: 12/02/2008] [Indexed: 12/30/2022]
Abstract
Signal regulatory protein (SIRP)alpha, also known as SHPS-1 or SIRPA, is a transmembrane protein that binds to the protein tyrosine phosphatases SHP-1 and SHP-2 through its cytoplasmic region and is predominantly expressed in neurons, dendritic cells and macrophages. CD47, a widely expressed transmembrane protein, is a ligand for SIRPalpha, with the two proteins constituting a cell-cell communication system. The interaction of SIRPalpha with CD47 is important for the regulation of migration and phagocytosis. Recent studies have implicated the CD47-SIRPalpha signalling pathway in immune homeostasis and in regulation of neuronal networks. Advances in the structural and functional analyses of the CD47-SIRPalpha signalling pathway now provide exciting hints of the therapeutic benefits of manipulating this signalling system in autoimmune diseases and neurological disorders.
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Affiliation(s)
- Takashi Matozaki
- Laboratory of Biosignal Sciences, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-Machi, Maebashi, Gunma, Japan.
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23
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Paired Receptor Specificity Explained by Structures of Signal Regulatory Proteins Alone and Complexed with CD47. Mol Cell 2008; 31:266-77. [DOI: 10.1016/j.molcel.2008.05.026] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Revised: 03/13/2008] [Accepted: 05/13/2008] [Indexed: 11/20/2022]
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24
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CD47-Fc fusion proteins as putative immunotherapeutic agents for the treatment of immunological and inflammatory diseases. Expert Opin Ther Pat 2008. [DOI: 10.1517/13543776.18.5.555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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25
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van den Berg TK, van der Schoot CE. Innate immune 'self' recognition: a role for CD47-SIRPalpha interactions in hematopoietic stem cell transplantation. Trends Immunol 2008; 29:203-6. [PMID: 18394962 DOI: 10.1016/j.it.2008.02.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 01/22/2008] [Accepted: 02/06/2008] [Indexed: 10/22/2022]
Abstract
Self-nonself discrimination is a central property of the immune system. This paradigm was originally established in the context of tissue transplantation, leading to the discovery of major histocompatibility complex molecules as signals of 'self'. However, accumulating evidence has shown that innate immune cells are regulated in a similar fashion. Recent evidence has suggested that interactions between the 'self' molecule CD47 and the innate inhibitory receptor signal regulatory protein-alpha expressed on macrophages may be a critical determinant of transplant engraftment, supporting the concept that 'self'-awareness is a general property of all immune cells.
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Affiliation(s)
- Timo K van den Berg
- Sanquin Research and Landsteiner Laboratory, Academic Medical Center, 1066 CX Amsterdam, The Netherlands.
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