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Fiske BE, Wemlinger SM, Crute BW, Getahun A. The Src-family kinase Lyn plays a critical role in establishing and maintaining B cell anergy by suppressing PI3K-dependent signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.21.595208. [PMID: 38826354 PMCID: PMC11142063 DOI: 10.1101/2024.05.21.595208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Although the Src family kinase (SFK) Lyn is known to be involved in induction and maintenance of peripheral B cell tolerance, the molecular basis of its action in this context remains unclear. This question has been approached using conventional as well as B cell-targeted knockouts of Lyn, with varied conclusions likely confused by collateral loss of Lyn functions in B cell and myeloid cell development and activation. Here we utilized a system in which Lyn gene deletion is tamoxifen inducible and B cell restricted. This system allows acute elimination of Lyn in B cells without off-target effects. This genetic tool was employed in conjunction with immunoglobulin transgenic mice in which peripheral B cells are autoreactive. DNA reactive Ars/A1 B cells require continuous inhibitory signaling, mediated by the inositol phosphatase SHIP-1 and the tyrosine phosphatase SHP-1, to maintain an unresponsive (anergic) state. Here we show that Ars/A1 B cells require Lyn to establish and maintain B cell unresponsiveness. Lyn primarily functions by restricting PI3K-dependent signaling pathways. This Lyn-dependent mechanism complements the impact of reduced mIgM BCR expression to restrict BCR signaling in Ars/A1 B cells. Our findings suggest that a subset of autoreactive B cells requires Lyn to become anergic and that the autoimmunity associated with dysregulated Lyn function may, in part, be due to an inability of these autoreactive B cells to become tolerized.
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2
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Olufunmilayo EO, Holsinger RMD. INPP5D/SHIP1: Expression, Regulation and Roles in Alzheimer's Disease Pathophysiology. Genes (Basel) 2023; 14:1845. [PMID: 37895194 PMCID: PMC10606568 DOI: 10.3390/genes14101845] [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: 08/17/2023] [Revised: 09/20/2023] [Accepted: 09/20/2023] [Indexed: 10/29/2023] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia, accounting for approximately 38.5 million cases of all-cause dementia. Over 60% of these individuals live in low- and middle-income countries and are the worst affected, especially by its deleterious effects on the productivity of both patients and caregivers. Numerous risk factors for the disease have been identified and our understanding of gene-environment interactions have shed light on several gene variants that contribute to the most common, sporadic form of AD. Microglial cells, the innate immune cells of the central nervous system (CNS), have long been established as guardians of the brain by providing neuroprotection and maintaining cellular homeostasis. A protein with a myriad of effects on various important signaling pathways that is expressed in microglia is the Src Homology 2 (SH2) domain-containing Inositol 5' Phosphatase 1 (SHIP1) protein. Encoded by the INPP5D (Inositol Polyphosphate-5-Phosphatase D) gene, SHIP1 has diminutive effects on most microglia signaling processes. Polymorphisms of the INPP5D gene have been found to be associated with a significantly increased risk of AD. Several studies have elucidated mechanistic processes by which SHIP1 exerts its perturbations on signaling processes in peripheral immune cells. However, current knowledge of the controllers of INPP5D/SHIP1 expression and the idiosyncrasies of its influences on signaling processes in microglia and their relevance to AD pathophysiology is limited. In this review, we summarize these discoveries and discuss the potential of leveraging INPP5D/SHIP1 as a therapeutic target for Alzheimer's disease.
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Affiliation(s)
- Edward O. Olufunmilayo
- Laboratory of Molecular Neuroscience and Dementia, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW 2050, Australia;
- Department of Medicine, University College Hospital, Queen Elizabeth Road, Oritamefa, Ibadan 2002012, Nigeria
| | - R. M. Damian Holsinger
- Laboratory of Molecular Neuroscience and Dementia, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW 2050, Australia;
- Neuroscience, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia
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3
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Waddell GL, Drew EE, Rupp HP, Hansen SD. Mechanisms controlling membrane recruitment and activation of the autoinhibited SHIP1 inositol 5-phosphatase. J Biol Chem 2023; 299:105022. [PMID: 37423304 PMCID: PMC10448276 DOI: 10.1016/j.jbc.2023.105022] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 06/28/2023] [Accepted: 07/01/2023] [Indexed: 07/11/2023] Open
Abstract
Signal transduction downstream of growth factor and immune receptor activation relies on the production of phosphatidylinositol-(3,4,5)-trisphosphate (PI(3,4,5)P3) lipids by PI3K. Regulating the strength and duration of PI3K signaling in immune cells, Src homology 2 domain-containing inositol 5-phosphatase 1 (SHIP1) controls the dephosphorylation of PI(3,4,5)P3 to generate phosphatidylinositol-(3,4)-bisphosphate. Although SHIP1 has been shown to regulate neutrophil chemotaxis, B-cell signaling, and cortical oscillations in mast cells, the role that lipid and protein interactions serve in controlling SHIP1 membrane recruitment and activity remains unclear. Using single-molecule total internal reflection fluorescence microscopy, we directly visualized membrane recruitment and activation of SHIP1 on supported lipid bilayers and the cellular plasma membrane. We find that localization of the central catalytic domain of SHIP1 is insensitive to dynamic changes in PI(3,4,5)P3 and phosphatidylinositol-(3,4)-bisphosphate both in vitro and in vivo. Very transient SHIP1 membrane interactions were detected only when membranes contained a combination of phosphatidylserine and PI(3,4,5)P3 lipids. Molecular dissection reveals that SHIP1 is autoinhibited with the N-terminal Src homology 2 domain playing a critical role in suppressing phosphatase activity. Robust SHIP1 membrane localization and relief of autoinhibition can be achieved through interactions with immunoreceptor-derived phosphopeptides presented either in solution or conjugated to a membrane. Overall, this work provides new mechanistic details concerning the dynamic interplay between lipid-binding specificity, protein-protein interactions, and the activation of autoinhibited SHIP1.
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Affiliation(s)
- Grace L Waddell
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, USA; Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Emma E Drew
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, USA; Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Henry P Rupp
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, USA; Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Scott D Hansen
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon, USA; Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA.
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4
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Waddell GL, Drew EE, Rupp HP, Hansen SD. Mechanisms controlling membrane recruitment and activation of autoinhibited SHIP1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.30.538895. [PMID: 37205499 PMCID: PMC10187190 DOI: 10.1101/2023.04.30.538895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Signal transduction downstream of growth factor and immune receptor activation relies on the production of phosphatidylinositol-(3,4,5)-trisphosphate (PI(3,4,5)P 3 ) lipids by phosphoinositide-3-kinase (PI3K). Regulating the strength and duration of PI3K signaling in immune cells, Src homology 2 domain-containing inositol 5-phosphatase 1 (SHIP1) controls the dephosphorylation of PI(3,4,5)P 3 to generate PI(3,4)P 2 . Although SHIP1 has been shown to regulate neutrophil chemotaxis, B-cell signaling, and cortical oscillations in mast cells, the role that lipid and protein interactions serve in controlling SHIP1 membrane recruitment and activity remains unclear. Using single molecule TIRF microscopy, we directly visualized membrane recruitment and activation of SHIP1 on supported lipid bilayers and the cellular plasma membrane. We find that SHIP1's interactions with lipids are insensitive to dynamic changes in PI(3,4,5)P 3 both in vitro and in vivo. Very transient SHIP1 membrane interactions were detected only when membranes contained a combination of phosphatidylserine (PS) and PI(3,4,5)P 3 lipids. Molecular dissection reveals that SHIP1 is autoinhibited with the N-terminal SH2 domain playing a critical role in suppressing phosphatase activity. Robust SHIP1 membrane localization and relief of autoinhibition can be achieved through interactions with immunoreceptor derived phosphopeptides presented either in solution or conjugated to supported membranes. Overall, this work provides new mechanistic details concerning the dynamic interplay between lipid binding specificity, protein-protein interactions, and activation of autoinhibited SHIP1.
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5
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Jin K, Qiu S, Chen B, Zhang Z, Zhang C, Zhou X, Yang L, Ai J, Wei Q. DOK3 promotes proliferation and inhibits apoptosis of prostate cancer via the NF-κB signaling pathway. Chin Med J (Engl) 2023; 136:423-432. [PMID: 36867541 PMCID: PMC10106266 DOI: 10.1097/cm9.0000000000002251] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Indexed: 03/04/2023] Open
Abstract
BACKGROUND DOK3 (Downstream of kinase 3) is involved primarily with immune cell infiltration. Recent research reported the role of DOK3 in tumor progression, with opposite effects in lung cancer and gliomas; however, its role in prostate cancer (PCa) remains elusive. This study aimed to explore the role of DOK3 in PCa and to determine the mechanisms involved. METHODS To investigate the functions and mechanisms of DOK3 in PCa, we performed bioinformatic and biofunctional analyses. Samples from patients with PCa were collected from West China Hospital, and 46 were selected for the final correlation analysis. A lentivirus-based short hairpin ribonucleic acid (shRNA) carrier was established for silencing DOK3. A series of experiments involving the cell counting kit-8, bromodeoxyuridine, and flow cytometry assays were performed to identify cell proliferation and apoptosis. Changes in biomarkers from the nuclear factor kappa B (NF-κB) signaling pathway were detected to verify the relationship between DOK3 and the NF-κB pathway. A subcutaneous xenograft mouse model was performed to examine phenotypes after knocking down DOK3 in vivo . Rescue experiments with DOK3 knockdown and NF-κB pathway activation were designed to verify regulating effects. RESULTS DOK3 was up-regulated in PCa cell lines and tissues. In addition, a high level of DOK3 was predictive of higher pathological stages and worse prognoses. Similar results were observed with PCa patient samples. After silencing DOK3 in PCa cell lines 22RV1 and PC3, cell proliferation was significantly inhibited while apoptosis was promoted. Gene set enrichment analysis revealed that DOK3 function was enriched in the NF-κB pathway. Mechanism experiments determined that knockdown of DOK3 suppressed activation of the NF-κB pathway, increased the expressions of B-cell lymphoma-2 like 11 (BIM) and B-cell lymphoma-2 associated X (BAX), and decreased the expression of phosphorylated-P65 and X-linked inhibitor of apoptosis (XIAP). In the rescue experiments, pharmacological activation of NF-κB by tumor necrosis factor-α (TNF-α) partially recovered cell proliferation after the knockdown of DOK3. CONCLUSION Our findings suggest that overexpression of DOK3 promotes PCa progression by activating the NF-κB signaling pathway.
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Affiliation(s)
- Kun Jin
- Department of Urology and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Shi Qiu
- Center of Biomedical Big Data, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Bo Chen
- Department of Urology and Institute of Urology, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Zilong Zhang
- Department of Urology and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Chichen Zhang
- Department of Urology and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Xianghong Zhou
- Department of Urology and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Lu Yang
- Department of Urology and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Jianzhong Ai
- Department of Urology and Institute of Urology, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Qiang Wei
- Department of Urology and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
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Andreani V, Ramamoorthy S, Fässler R, Grosschedl R. Integrin β1 regulates marginal zone B cell differentiation and PI3K signaling. J Exp Med 2022; 220:213672. [PMID: 36350325 PMCID: PMC9814157 DOI: 10.1084/jem.20220342] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 08/03/2022] [Accepted: 09/23/2022] [Indexed: 11/10/2022] Open
Abstract
Marginal zone (MZ) B cells represent innate-like B cells that mediate a fast immune response. The adhesion of MZ B cells to the marginal sinus of the spleen is governed by integrins. Here, we address the question of whether β1-integrin has additional functions by analyzing Itgb1fl/flCD21Cre mice in which the β1-integrin gene is deleted in mature B cells. We find that integrin β1-deficient mice have a defect in the differentiation of MZ B cells and plasma cells. We show that integrin β1-deficient transitional B cells, representing the precursors of MZ B cells, have enhanced B cell receptor (BCR) signaling, altered PI3K and Ras/ERK pathways, and an enhanced interaction of integrin-linked kinase (ILK) with the adaptor protein Grb2. Moreover, the MZ B cell defect of integrin β1-deficient mice could, at least in part, be restored by a pharmacological inhibition of the PI3K pathway. Thus, β1-integrin has an unexpected function in the differentiation and function of MZ B cells.
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Affiliation(s)
- Virginia Andreani
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany,Institute for Immunodeficiency, Center for Chronic Immunodeficiency, Medical Center, University of Freiburg, Freiburg, Germany,Virginia Andreani:
| | - Senthilkumar Ramamoorthy
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany,Institute of Medical Bioinformatics and Systems Medicine, Medical Center, University of Freiburg, Freiburg, Germany,Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Medical Center, University of Freiburg, Freiburg, Germany
| | | | - Rudolf Grosschedl
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany,Correspondence to Rudolf Grosschedl:
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7
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Corneth OBJ, Neys SFH, Hendriks RW. Aberrant B Cell Signaling in Autoimmune Diseases. Cells 2022; 11:cells11213391. [PMID: 36359789 PMCID: PMC9654300 DOI: 10.3390/cells11213391] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/15/2022] [Accepted: 10/24/2022] [Indexed: 11/30/2022] Open
Abstract
Aberrant B cell signaling plays a critical in role in various systemic and organ-specific autoimmune diseases. This is supported by genetic evidence by many functional studies in B cells from patients or specific animal models and by the observed efficacy of small-molecule inhibitors. In this review, we first discuss key signal transduction pathways downstream of the B cell receptor (BCR) that ensure that autoreactive B cells are removed from the repertoire or functionally silenced. We provide an overview of aberrant BCR signaling that is associated with inappropriate B cell repertoire selection and activation or survival of peripheral B cell populations and plasma cells, finally leading to autoantibody formation. Next to BCR signaling, abnormalities in other signal transduction pathways have been implicated in autoimmune disease. These include reduced activity of several phosphates that are downstream of co-inhibitory receptors on B cells and increased levels of BAFF and APRIL, which support survival of B cells and plasma cells. Importantly, pathogenic synergy of the BCR and Toll-like receptors (TLR), which can be activated by endogenous ligands, such as self-nucleic acids, has been shown to enhance autoimmunity. Finally, we will briefly discuss therapeutic strategies for autoimmune disease based on interfering with signal transduction in B cells.
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8
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Getahun A. Role of inhibitory signaling in peripheral B cell tolerance*. Immunol Rev 2022; 307:27-42. [PMID: 35128676 PMCID: PMC8986582 DOI: 10.1111/imr.13070] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 12/16/2022]
Abstract
At least 20% of B cells in the periphery expresses an antigen receptor with a degree of self-reactivity. If activated, these autoreactive B cells pose a risk as they can contribute to the development of autoimmune diseases. To prevent their activation, both B cell-intrinsic and extrinsic tolerance mechanisms are in place in healthy individuals. In this review article, I will focus on B cell-intrinsic mechanisms that prevent the activation of autoreactive B cells in the periphery. I will discuss how inhibitory signaling circuits are established in autoreactive B cells, focusing on the Lyn-SHIP-1-SHP-1 axis, how they contribute to peripheral immune tolerance, and how disruptions of these circuits can contribute to the development of autoimmunity.
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Affiliation(s)
- Andrew Getahun
- Department of Immunology and Microbiology University of Colorado SOM Aurora Colorado USA
- Department of Immunology and Genomic Medicine National Jewish Health Denver Colorado USA
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9
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Carroll DJ, Cao Y, Bochner BS, O’Sullivan JA. Siglec-8 Signals Through a Non-Canonical Pathway to Cause Human Eosinophil Death In Vitro. Front Immunol 2021; 12:737988. [PMID: 34721399 PMCID: PMC8549629 DOI: 10.3389/fimmu.2021.737988] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 09/14/2021] [Indexed: 12/19/2022] Open
Abstract
Sialic acid-binding immunoglobulin-like lectin (Siglec)-8 is a glycan-binding receptor bearing immunoreceptor tyrosine-based inhibitory and switch motifs (ITIM and ITSM, respectively) that is selectively expressed on eosinophils, mast cells, and, to a lesser extent, basophils. Previous work has shown that engagement of Siglec-8 on IL-5-primed eosinophils causes cell death via CD11b/CD18 integrin-mediated adhesion and NADPH oxidase activity and identified signaling molecules linking adhesion, reactive oxygen species (ROS) production, and cell death. However, the proximal signaling cascade activated directly by Siglec-8 engagement has remained elusive. Most members of the Siglec family possess similar cytoplasmic signaling motifs and recruit the protein tyrosine phosphatases SHP-1/2, consistent with ITIM-mediated signaling, to dampen cellular activation. However, the dependence of Siglec-8 function in eosinophils on these phosphatases has not been studied. Using Siglec-8 antibody engagement and pharmacological inhibition in conjunction with assays to measure cell-surface upregulation and conformational activation of CD11b integrin, ROS production, and cell death, we sought to identify molecules involved in Siglec-8 signaling and determine the stage of the process in which each molecule plays a role. We demonstrate here that the enzymatic activities of Src family kinases (SFKs), Syk, SHIP1, PAK1, MEK1, ERK1/2, PLC, PKC, acid sphingomyelinase/ceramidase, and Btk are all necessary for Siglec-8-induced eosinophil cell death, with no apparent role for SHP-1/2, SHIP2, or c-Raf. While most of these signaling molecules are necessary for Siglec-8-induced upregulation of CD11b integrin at the eosinophil cell surface, Btk is phosphorylated and activated later in the signaling cascade and is instead necessary for CD11b activation. In contrast, SFKs and ERK1/2 are phosphorylated far earlier in the process, consistent with their role in augmenting cell-surface levels of CD11b. In addition, pretreatment of eosinophils with latrunculin B or jasplakinolide revealed that actin filament disassembly is necessary and sufficient for surface CD11b integrin upregulation and that actin polymerization is necessary for downstream ROS production. These results show that Siglec-8 signals through an unanticipated set of signaling molecules in IL-5-primed eosinophils to induce cell death and challenges the expectation that ITIM-bearing Siglecs signal through inhibitory pathways involving protein tyrosine phosphatases to achieve their downstream functions.
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Affiliation(s)
| | | | | | - Jeremy A. O’Sullivan
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
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10
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Gao WS, Qu YJ, Huai J, Wei H, Zhang Y, Yue SW. DOK3 is involved in microglial cell activation in neuropathic pain by interacting with GPR84. Aging (Albany NY) 2020; 13:389-410. [PMID: 33281117 PMCID: PMC7835011 DOI: 10.18632/aging.202144] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 09/09/2020] [Indexed: 01/12/2023]
Abstract
Adaptor molecule downstream of kinase-3 (DOK3) is a vital regulator of innate immune responses in macrophages and B cells, and G-protein-coupled receptor 84 (GPR84) is significant in mediating the biosynthesis and maintenance of inflammatory mediators that are induced by neuropathic pain in microglia. In the present study, we determined the role of DOK3 in activating microglia-induced neuropathic pain and investigated the underlying mechanisms associated with GPR84. We found that knockdown of DOK3 in microglial cells dramatically reduced the levels of inflammatory factors, and we uncovered a physical association between DOK3 and GPR84 in the induction of inflammatory responses. We also observed that neuropathic pain and inflammatory responses induced by chronic constriction injury (CCI) of the sciatic nerve or intrathecal injection of a GPR84 agonist were compromised in DOK3-/- mice in vivo. Finally, enforced expression of DOK3 provoked inflammatory responses, and administration of pregabalin relieved neuropathic pain via inhibition of DOK3 expression. In conclusion, DOK3 induced neuropathic pain in mice by interacting with GPR84 in microglia. We hypothesize that targeting the adaptor protein DOK3 may open new avenues for pharmaceutical approaches to the alleviation of neuropathic pain in the spinal cord.
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Affiliation(s)
- Wen-Shuang Gao
- Rehabilitation Center, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Yu-Juan Qu
- Rehabilitation Center, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Juan Huai
- Rehabilitation Center, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Hui Wei
- Rehabilitation Center, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Yang Zhang
- Rehabilitation Center, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Shou-Wei Yue
- Rehabilitation Center, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
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11
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Loh JT, Teo JKH, Lim HH, Lam KP. Emerging Roles of Downstream of Kinase 3 in Cell Signaling. Front Immunol 2020; 11:566192. [PMID: 33133079 PMCID: PMC7550416 DOI: 10.3389/fimmu.2020.566192] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 09/10/2020] [Indexed: 11/18/2022] Open
Abstract
Downstream of kinase (Dok) 3 is a member of the Dok family of adaptor proteins known to regulate signaling pathways downstream of various immunoreceptors. As Dok-3 lacks intrinsic catalytic activity, it functions primarily as a molecular scaffold to facilitate the nucleation of protein complexes in a regulated manner and hence, achieve specificity in directing signaling cascades. Since its discovery, considerable progress has been made toward defining the role of Dok-3 in limiting B cell-receptor signaling. Nonetheless, Dok-3 has since been implicated in the signaling of Toll-like and C-type lectin receptors. Emerging data further demonstrate that Dok-3 can act both as an activator and inhibitor, in lymphoid and non-lymphoid cell types, suggesting Dok-3 involvement in a plethora of signal transduction pathways. In this review, we will focus on the structure and expression profile of Dok-3 and highlight its role during signal transduction in B cells, innate cells as well as in bone and lung tissues.
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Affiliation(s)
- Jia Tong Loh
- Bioprocessing Technology Institute, Agency for Science, Technology and Research, Singapore, Singapore.,Singapore Immunology Network, Agency for Science, Technology and Research, Singapore, Singapore
| | - Joey Kay Hui Teo
- Bioprocessing Technology Institute, Agency for Science, Technology and Research, Singapore, Singapore.,Singapore Immunology Network, Agency for Science, Technology and Research, Singapore, Singapore
| | - Hong-Hwa Lim
- Bioprocessing Technology Institute, Agency for Science, Technology and Research, Singapore, Singapore.,Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore
| | - Kong-Peng Lam
- Bioprocessing Technology Institute, Agency for Science, Technology and Research, Singapore, Singapore.,Singapore Immunology Network, Agency for Science, Technology and Research, Singapore, Singapore.,Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,School of Biological Sciences, College of Science, Nanyang Technological University, Singapore, Singapore
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12
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Crute BW, Sheraden R, Ott VL, Harley ITW, Getahun A, Cambier JC. Inhibitory Receptor Trap: A Platform for Discovery of Inhibitory Receptors That Utilize Inositol Lipid and Phosphotyrosine Phosphatase Effectors. Front Immunol 2020; 11:592329. [PMID: 33193438 PMCID: PMC7641642 DOI: 10.3389/fimmu.2020.592329] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 09/29/2020] [Indexed: 01/06/2023] Open
Abstract
Among the areas of most impactful recent progress in immunology is the discovery of inhibitory receptors and the subsequent translation of this knowledge to the clinic. Although the original and canonical member of this family is FcγRIIB, more recent studies defined PD1 as an inhibitory receptor that constrains T cell immunity to tumors. These studies led to development of “checkpoint blockade” immunotherapies (CBT) for cancers in which PD1 interactions with its ligand are blocked. Unfortunately, although very effective in some patients, only a small proportion respond to this therapy. This suggests that additional as yet undescribed inhibitory receptors exist, which could be exploited. Here, we describe a new platform, termed inhibitory receptor trap (IRT), for discovery of members of this family. The approach takes advantage of the fact that many of the known inhibitory receptors mediate signaling by phospho-immunoreceptor tyrosine-based inhibition motif (ITIM) mediated recruitment of Src Homology 2 (SH2) domain-containing phosphatases including the SH2 domain-containing inositol phosphatase SHIP1 encoded by the INPP5D gene and the SH2 domain-containing phosphotyrosine phosphatases SHP1 and SHP2 encoded by the PTPN6 and PTPN11 genes respectively. Here, we describe the IRT discovery platform in which the SH2 domains of inhibitory phosphatases are used for affinity-based isolation and subsequent identification of candidate effectors via immunoblotting and high sensitivity liquid chromatography–mass spectrometry. These receptors may represent alternative targets that can be exploited for improved CBT. Salient observations from these studies include the following: SH2 domains derived from the respective phosphatases bind distinct sets of candidates from different cell types. Thus, cells of different identity and different activation states express partially distinct repertoires of up and downstream phosphatase effectors. Phosphorylated PD1 binds not only SHP2 but also SHIP1, thus the latter may be important in its inhibitory function. B cell antigen receptor signaling leads predominantly to CD79 mono-phosphorylation as indicated by much greater binding to LynSH2 than Syk(SH2)2. This balance of ITAM mono- versus bi-phosphorylation likely tunes signaling by varying activation of inhibitory (Lyn) and stimulatory (Syk) pathways.
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Affiliation(s)
- Bergren W Crute
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Rachel Sheraden
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Vanessa L Ott
- Department of Biomedical Sciences, National Jewish Health, Denver, CO, United States
| | - Isaac T W Harley
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States.,Division of Rheumatology, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - Andrew Getahun
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States.,Department of Biomedical Sciences, National Jewish Health, Denver, CO, United States
| | - John C Cambier
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States.,Department of Biomedical Sciences, National Jewish Health, Denver, CO, United States
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Lemm EA, Valle-Argos B, Smith LD, Richter J, Gebreselassie Y, Carter MJ, Karolova J, Svaton M, Helman K, Weston-Bell NJ, Karydis L, Williamson CT, Lenz G, Pettigrew J, Harwig C, Stevenson FK, Cragg M, Forconi F, Steele AJ, Cross J, Mackenzie L, Klener P, Packham G. Preclinical Evaluation of a Novel SHIP1 Phosphatase Activator for Inhibition of PI3K Signaling in Malignant B Cells. Clin Cancer Res 2020; 26:1700-1711. [PMID: 31831562 PMCID: PMC7124891 DOI: 10.1158/1078-0432.ccr-19-2202] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 10/23/2019] [Accepted: 12/09/2019] [Indexed: 01/09/2023]
Abstract
PURPOSE PI3K signaling is a common feature of B-cell neoplasms, including chronic lymphocytic leukemia (CLL) and diffuse large B-cell lymphoma (DLBCL), and PI3K inhibitors have been introduced into the clinic. However, there remains a clear need to develop new strategies to target PI3K signaling. PI3K activity is countered by Src homology domain 2-containing inositol-5'-phosphatase 1 (SHIP1) and, here, we have characterized the activity of a novel SHIP1 activator, AQX-435, in preclinical models of B-cell malignancies. EXPERIMENTAL DESIGN In vitro activity of AQX-435 was evaluated using primary CLL cells and DLBCL-derived cell lines. In vivo activity of AQX-435, alone or in combination with the Bruton's tyrosine kinase (BTK) inhibitor ibrutinib, was assessed using DLBCL cell line and patient-derived xenograft models. RESULTS Pharmacologic activation of SHIP1 using AQX-435 was sufficient to inhibit anti-IgM-induced PI3K-mediated signaling, including induction of AKT phosphorylation and MYC expression, without effects on upstream SYK phosphorylation. AQX-435 also cooperated with the BTK inhibitor ibrutinib to enhance inhibition of anti-IgM-induced AKT phosphorylation. AQX-435 induced caspase-dependent apoptosis of CLL cells preferentially as compared with normal B cells, and overcame in vitro survival-promoting effects of microenvironmental stimuli. Finally, AQX-435 reduced AKT phosphorylation and growth of DLBCL in vivo and cooperated with ibrutinib for tumor growth inhibition. CONCLUSIONS Our results using AQX-435 demonstrate that SHIP1 activation may be an effective novel therapeutic strategy for treatment of B-cell neoplasms, alone or in combination with ibrutinib.
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MESH Headings
- Animals
- Antineoplastic Agents/pharmacology
- Apoptosis/drug effects
- Cell Line, Tumor
- Enzyme Activators/pharmacology
- Female
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy
- Leukemia, Lymphocytic, Chronic, B-Cell/metabolism
- Leukemia, Lymphocytic, Chronic, B-Cell/pathology
- Lymphoma, Large B-Cell, Diffuse/drug therapy
- Lymphoma, Large B-Cell, Diffuse/metabolism
- Lymphoma, Large B-Cell, Diffuse/pathology
- Mice
- Mice, Inbred NOD
- Phosphatidylinositol 3-Kinases/chemistry
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases/genetics
- Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases/metabolism
- Sesquiterpenes/pharmacology
- Signal Transduction
- Xenograft Model Antitumor Assays
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Affiliation(s)
- Elizabeth A Lemm
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Beatriz Valle-Argos
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Lindsay D Smith
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Johanna Richter
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Yohannes Gebreselassie
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Matthew J Carter
- Centre for Cancer Immunology, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Jana Karolova
- Institute of Pathological Physiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
- CLIP - Childhood Leukaemia Investigation Prague, Second Faculty of Medicine and Charles University Hospital in Motol, Prague, Czech Republic
| | - Michael Svaton
- Institute of Pathological Physiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
- CLIP - Childhood Leukaemia Investigation Prague, Second Faculty of Medicine and Charles University Hospital in Motol, Prague, Czech Republic
| | - Karel Helman
- Faculty of Informatics and Statistics, University of Economics, Prague, Czech Republic
| | - Nicola J Weston-Bell
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Laura Karydis
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Chris T Williamson
- Aquinox Pharmaceuticals (Canada) Inc., Vancouver, British Columbia, Canada
| | - Georg Lenz
- Department of Medicine A for Hematology, Oncology, and Pneumology, University Hospital Münster, Münster, Germany
| | - Jeremy Pettigrew
- Aquinox Pharmaceuticals (Canada) Inc., Vancouver, British Columbia, Canada
| | - Curtis Harwig
- Aquinox Pharmaceuticals (Canada) Inc., Vancouver, British Columbia, Canada
| | - Freda K Stevenson
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Mark Cragg
- Centre for Cancer Immunology, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Francesco Forconi
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Andrew J Steele
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Jennifer Cross
- Aquinox Pharmaceuticals (Canada) Inc., Vancouver, British Columbia, Canada
| | - Lloyd Mackenzie
- Aquinox Pharmaceuticals (Canada) Inc., Vancouver, British Columbia, Canada
| | - Pavel Klener
- Institute of Pathological Physiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
- CLIP - Childhood Leukaemia Investigation Prague, Second Faculty of Medicine and Charles University Hospital in Motol, Prague, Czech Republic
| | - Graham Packham
- Cancer Research UK Centre, Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.
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Ibañez-Vega J, Del Valle Batalla F, Saez JJ, Soza A, Yuseff MI. Proteasome Dependent Actin Remodeling Facilitates Antigen Extraction at the Immune Synapse of B Cells. Front Immunol 2019; 10:225. [PMID: 30873155 PMCID: PMC6401660 DOI: 10.3389/fimmu.2019.00225] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 01/28/2019] [Indexed: 12/24/2022] Open
Abstract
Engagement of the B cell receptor (BCR) with surface-tethered antigens leads to the formation of an immune synapse (IS), where cell signaling and antigen uptake are tightly coordinated. Centrosome re-orientation to the immune synapse has emerged as a critical regulatory step to guide the local recruitment and secretion of lysosomes, which can facilitate the extraction of immobilized antigens. This process is coupled to actin remodeling at the centrosome and at the immune synapse, which is crucial to promote cell polarity. How B cells balance both pools of actin cytoskeleton to achieve a polarized phenotype during the formation of an immune synapse is not fully understood. Here, we reveal that B cells rely on proteasome activity to achieve this task. The proteasome is a multi-catalytic protease that degrades cytosolic and nuclear proteins and its dysfunction is associated with diseases, such as cancer and autoimmunity. Our results show that resting B cells contain an active proteasome pool at the centrosome, which is required for efficient actin clearance at this level. As a result of proteasome inhibition, activated B cells do not deplete actin at the centrosome and are unable to separate the centrosome from the nucleus and thus display impaired polarity. Consequently, lysosome recruitment to the immune synapse, antigen extraction and presentation are severely compromised in B cells with diminished proteasome activity. Additionally, we found that proteasome inhibition leads to impaired actin remodeling at the immune synapse, where B cells display defective spreading responses and distribution of key signaling molecules at the synaptic membrane. Overall, our results reveal a new role for the proteasome in regulating the immune synapse of B cells, where the intracellular compartmentalization of proteasome activity controls cytoskeleton remodeling between the centrosome and synapse, with functional repercussions in antigen extraction and presentation.
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Affiliation(s)
- Jorge Ibañez-Vega
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Felipe Del Valle Batalla
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan José Saez
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Andrea Soza
- Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Facultad de Ciencias, Universidad San Sebastián, Santiago, Chile
- Centro de Envejecimiento y Regeneración (CARE), Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Maria-Isabel Yuseff
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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15
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Dobranowski P, Sly LM. SHIP negatively regulates type II immune responses in mast cells and macrophages. J Leukoc Biol 2018; 103:1053-1064. [PMID: 29345374 DOI: 10.1002/jlb.3mir0817-340r] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 12/11/2017] [Accepted: 12/14/2017] [Indexed: 12/13/2022] Open
Abstract
SHIP is a hematopoietic-specific lipid phosphatase that dephosphorylates PI3K-generated PI(3,4,5)-trisphosphate. SHIP removes this second messenger from the cell membrane blunting PI3K activity in immune cells. Thus, SHIP negatively regulates mast cell activation downstream of multiple receptors. SHIP has been referred to as the "gatekeeper" of mast cell degranulation as loss of SHIP dramatically increases degranulation or permits degranulation in response to normally inert stimuli. SHIP also negatively regulates Mϕ activation, including both pro-inflammatory cytokine production downstream of pattern recognition receptors, and alternative Mϕ activation by the type II cytokines, IL-4, and IL-13. In the SHIP-deficient (SHIP-/- ) mouse, increased mast cell and Mϕ activation leads to spontaneous inflammatory pathology at mucosal sites, which is characterized by high levels of type II inflammatory cytokines. SHIP-/- mast cells and Mϕs have both been implicated in driving inflammation in the SHIP-/- mouse lung. SHIP-/- Mϕs drive Crohn's disease-like intestinal inflammation and fibrosis, which is dependent on heightened responses to innate immune stimuli generating IL-1, and IL-4 inducing abundant arginase I. Both lung and gut pathology translate to human disease as low SHIP levels and activity have been associated with allergy and with Crohn's disease in people. In this review, we summarize seminal literature and recent advances that provide insight into SHIP's role in mast cells and Mϕs, the contribution of these cell types to pathology in the SHIP-/- mouse, and describe how these findings translate to human disease and potential therapies.
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Affiliation(s)
- Peter Dobranowski
- Division of Gastroenterology, Department of Pediatrics, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
- Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Laura M Sly
- Division of Gastroenterology, Department of Pediatrics, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
- Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada
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16
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Reth M, Gold MR. What goes up must come down: A tripartite Dok-3/Grb2/SHIP1 inhibitory module limits BCR signaling. Eur J Immunol 2017; 46:2507-2511. [PMID: 27813071 DOI: 10.1002/eji.201646705] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 09/20/2016] [Accepted: 09/27/2016] [Indexed: 01/30/2023]
Abstract
Properly regulated immunity requires precise integration of activating and inhibitory signals. As for other lymphocytes, B cells express an antigen-specific activating receptor, the B-cell antigen receptor (BCR), and inhibitory receptors (e.g. FcγRIIb) that exercise checkpoint control on B-cell activation. Moreover, following BCR engagement, CD19 recruits proteins that amplify BCR signaling, while CD22 initiates a negative feedback loop by recruiting proteins that inhibit BCR signaling. Initial BCR signaling is mediated by protein tyrosine kinases and lipid kinases; inhibitory receptors directly antagonize the actions of these enzymes by recruiting protein tyrosine phosphatases and lipid phosphatases and positioning them close to actively signaling BCRs. Previously it was thought that inhibitory receptors such as FcγRIIb and CD22 were essential for bringing these phosphatases near the BCR. In this issue of the European Journal of Immunology, Manno et al. show that a tripartite inhibitory module consisting of the adaptor proteins Dok-3 and Grb2 and the lipid phosphatase SHIP1 binds directly to activated BCRs and limits the Ca2+ mobilization that is required for B lymphocyte activation. This reveals that the BCR can be both an activating and inhibitory receptor, one that activates signaling enzymes while initiating a negative feedback loop that prevents excessive signaling.
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Affiliation(s)
- Michael Reth
- BIOSS Centre for Biological Signaling Studies, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany.,Department of Molecular Immunology, Biology III, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany.,Max Planck Institute for Immunobiology and Epigenetics, Freiburg, Germany
| | - Michael R Gold
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada.
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17
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Pauls SD, Marshall AJ. Regulation of immune cell signaling by SHIP1: A phosphatase, scaffold protein, and potential therapeutic target. Eur J Immunol 2017; 47:932-945. [PMID: 28480512 DOI: 10.1002/eji.201646795] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 03/06/2017] [Accepted: 05/03/2017] [Indexed: 02/06/2023]
Abstract
The phosphoinositide phosphatase SHIP is a critical regulator of immune cell activation. Despite considerable study, the mechanisms controlling SHIP activity to ensure balanced cell activation remain incompletely understood. SHIP dampens BCR signaling in part through its association with the inhibitory coreceptor Fc gamma receptor IIB, and serves as an effector for other inhibitory receptors in various immune cell types. The established paradigm emphasizes SHIP's inhibitory receptor-dependent function in regulating phosphoinositide 3-kinase signaling by dephosphorylating the phosphoinositide PI(3,4,5)P3 ; however, substantial evidence indicates that SHIP can be activated independently of inhibitory receptors and can function as an intrinsic brake on activation signaling. Here, we integrate historical and recent reports addressing the regulation and function of SHIP in immune cells, which together indicate that SHIP acts as a multifunctional protein controlled by multiple regulatory inputs, and influences downstream signaling via both phosphatase-dependent and -independent means. We further summarize accumulated evidence regarding the functions of SHIP in B cells, T cells, NK cells, dendritic cells, mast cells, and macrophages, and data suggesting defective expression or activity of SHIP in autoimmune and malignant disorders. Lastly, we discuss the biological activities, therapeutic promise, and limitations of small molecule modulators of SHIP enzymatic activity.
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Affiliation(s)
- Samantha D Pauls
- Department of Immunology, University of Manitoba, Winnipeg, Canada
| | - Aaron J Marshall
- Department of Immunology, University of Manitoba, Winnipeg, Canada
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