1
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Lin H. Protein cysteine palmitoylation in immunity and inflammation. FEBS J 2021; 288:7043-7059. [PMID: 33506611 PMCID: PMC8872633 DOI: 10.1111/febs.15728] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/24/2020] [Accepted: 01/25/2021] [Indexed: 07/24/2023]
Abstract
Protein cysteine palmitoylation, or S-palmitoylation, has been known for about 40 years, and thousands of proteins in humans are known to be modified. Because of the large number of proteins modified, the importance and physiological functions of S-palmitoylation are enormous. However, most of the known physiological functions of S-palmitoylation can be broadly classified into two categories, neurological or immunological. This review provides a summary on the function of S-palmitoylation from the immunological perspective. Several important immune signaling pathways are discussed, including STING, NOD1/2, JAK-STAT in cytokine signaling, T-cell receptor signaling, chemotactic GPCR signaling, apoptosis, phagocytosis, and endothelial and epithelial integrity. This review is not meant to be comprehensive, but rather focuses on specific examples to highlight the versatility of palmitoylation in regulating immune signaling, as well as the potential and challenges of targeting palmitoylation to treat immune diseases.
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Affiliation(s)
- Hening Lin
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
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2
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Zhang Y, Qin Z, Sun W, Chu F, Zhou F. Function of Protein S-Palmitoylation in Immunity and Immune-Related Diseases. Front Immunol 2021; 12:661202. [PMID: 34557182 PMCID: PMC8453015 DOI: 10.3389/fimmu.2021.661202] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 08/23/2021] [Indexed: 02/04/2023] Open
Abstract
Protein S-palmitoylation is a covalent and reversible lipid modification that specifically targets cysteine residues within many eukaryotic proteins. In mammalian cells, the ubiquitous palmitoyltransferases (PATs) and serine hydrolases, including acyl protein thioesterases (APTs), catalyze the addition and removal of palmitate, respectively. The attachment of palmitoyl groups alters the membrane affinity of the substrate protein changing its subcellular localization, stability, and protein-protein interactions. Forty years of research has led to the understanding of the role of protein palmitoylation in significantly regulating protein function in a variety of biological processes. Recent global profiling of immune cells has identified a large body of S-palmitoylated immunity-associated proteins. Localization of many immune molecules to the cellular membrane is required for the proper activation of innate and adaptive immune signaling. Emerging evidence has unveiled the crucial roles that palmitoylation plays to immune function, especially in partitioning immune signaling proteins to the membrane as well as to lipid rafts. More importantly, aberrant PAT activity and fluctuations in palmitoylation levels are strongly correlated with human immunologic diseases, such as sensory incompetence or over-response to pathogens. Therefore, targeting palmitoylation is a novel therapeutic approach for treating human immunologic diseases. In this review, we discuss the role that palmitoylation plays in both immunity and immunologic diseases as well as the significant potential of targeting palmitoylation in disease treatment.
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3
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Dixon CL, Mekhail K, Fairn GD. Examining the Underappreciated Role of S-Acylated Proteins as Critical Regulators of Phagocytosis and Phagosome Maturation in Macrophages. Front Immunol 2021; 12:659533. [PMID: 33868308 PMCID: PMC8047069 DOI: 10.3389/fimmu.2021.659533] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 03/15/2021] [Indexed: 12/04/2022] Open
Abstract
Phagocytosis is a receptor-mediated process used by cells to engulf a wide variety of particulates, including microorganisms and apoptotic cells. Many of the proteins involved in this highly orchestrated process are post-translationally modified with lipids as a means of regulating signal transduction, membrane remodeling, phagosome maturation and other immunomodulatory functions of phagocytes. S-acylation, generally referred to as S-palmitoylation, is the post-translational attachment of fatty acids to a cysteine residue exposed topologically to the cytosol. This modification is reversible due to the intrinsically labile thioester bond between the lipid and sulfur atom of cysteine, and thus lends itself to a variety of regulatory scenarios. Here we present an overview of a growing number of S-acylated proteins known to regulate phagocytosis and phagosome biology in macrophages.
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Affiliation(s)
- Charneal L Dixon
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Katrina Mekhail
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Gregory D Fairn
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Department of Surgery, University of Toronto, Toronto, ON, Canada.,Department of Laboratory Medicine and Pathobiology, Toronto, ON, Canada
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4
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Abstract
S-palmitoylation is a reversible posttranslational lipid modification of proteins. It controls protein activity, stability, trafficking and protein–protein interactions. Recent global profiling of immune cells and targeted analysis have identified many S-palmitoylated immunity-associated proteins. Here, we review S-palmitoylated immune receptors and effectors, and their dynamic regulation at cellular membranes to generate specific and balanced immune responses. We also highlight how this understanding can drive therapeutic advances to pharmacologically modulate immune responses.
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Affiliation(s)
- Tandrila Das
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, NY 10065, USA
| | - Jacob S Yount
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210, USA
| | - Howard C Hang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, NY 10065, USA.,Departments of Immunology and Microbiology, Chemistry, Scripps Research, La Jolla, CA 92037, USA
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5
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Yang X, Chatterjee V, Ma Y, Zheng E, Yuan SY. Protein Palmitoylation in Leukocyte Signaling and Function. Front Cell Dev Biol 2020; 8:600368. [PMID: 33195285 PMCID: PMC7655920 DOI: 10.3389/fcell.2020.600368] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 09/30/2020] [Indexed: 12/12/2022] Open
Abstract
Palmitoylation is a post-translational modification (PTM) based on thioester-linkage between palmitic acid and the cysteine residue of a protein. This covalent attachment of palmitate is reversibly and dynamically regulated by two opposing sets of enzymes: palmitoyl acyltransferases containing a zinc finger aspartate-histidine-histidine-cysteine motif (PAT-DHHCs) and thioesterases. The reversible nature of palmitoylation enables fine-tuned regulation of protein conformation, stability, and ability to interact with other proteins. More importantly, the proper function of many surface receptors and signaling proteins requires palmitoylation-meditated partitioning into lipid rafts. A growing number of leukocyte proteins have been reported to undergo palmitoylation, including cytokine/chemokine receptors, adhesion molecules, pattern recognition receptors, scavenger receptors, T cell co-receptors, transmembrane adaptor proteins, and signaling effectors including the Src family of protein kinases. This review provides the latest findings of palmitoylated proteins in leukocytes and focuses on the functional impact of palmitoylation in leukocyte function related to adhesion, transmigration, chemotaxis, phagocytosis, pathogen recognition, signaling activation, cytotoxicity, and cytokine production.
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Affiliation(s)
- Xiaoyuan Yang
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Victor Chatterjee
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Yonggang Ma
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Ethan Zheng
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Sarah Y Yuan
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, United States.,Department of Surgery, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
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6
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Kara S, Amon L, Lühr JJ, Nimmerjahn F, Dudziak D, Lux A. Impact of Plasma Membrane Domains on IgG Fc Receptor Function. Front Immunol 2020; 11:1320. [PMID: 32714325 PMCID: PMC7344230 DOI: 10.3389/fimmu.2020.01320] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 05/26/2020] [Indexed: 12/13/2022] Open
Abstract
Lipid cell membranes not only represent the physical boundaries of cells. They also actively participate in many cellular processes. This contribution is facilitated by highly complex mixtures of different lipids and incorporation of various membrane proteins. One group of membrane-associated receptors are Fc receptors (FcRs). These cell-surface receptors are crucial for the activity of most immune cells as they bind immunoglobulins such as immunoglobulin G (IgG). Based on distinct mechanisms of IgG binding, two classes of Fc receptors are now recognized: the canonical type I FcγRs and select C-type lectin receptors newly referred to as type II FcRs. Upon IgG immune complex induced cross-linking, these receptors are known to induce a multitude of cellular effector responses in a cell-type dependent manner, including internalization, antigen processing, and presentation as well as production of cytokines. The response is also determined by specific intracellular signaling domains, allowing FcRs to either positively or negatively modulate immune cell activity. Expression of cell-type specific combinations and numbers of receptors therefore ultimately sets a threshold for induction of effector responses. Mechanistically, receptor cross-linking and localization to lipid rafts, i.e., organized membrane microdomains enriched in intracellular signaling proteins, were proposed as major determinants of initial FcR activation. Given that immune cell membranes might also vary in their lipid compositions, it is reasonable to speculate, that the cell membrane and especially lipid rafts serve as an additional regulator of FcR activity. In this article, we aim to summarize the current knowledge on the interplay of lipid rafts and IgG binding FcRs with a focus on the plasma membrane composition and receptor localization in immune cells, the proposed mechanisms underlying this localization and consequences for FcR function with respect to their immunoregulatory capacity.
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Affiliation(s)
- Sibel Kara
- Department of Biology, Institute of Genetics, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Lukas Amon
- Laboratory of Dendritic Cell Biology, Department of Dermatology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Jennifer J Lühr
- Laboratory of Dendritic Cell Biology, Department of Dermatology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany.,Division of Nano-Optics, Max-Planck Institute for the Science of Light, Erlangen, Germany
| | - Falk Nimmerjahn
- Department of Biology, Institute of Genetics, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany.,Medical Immunology Campus Erlangen (MICE), Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany.,Deutsches Zentrum Immuntherapie (DZI), Erlangen, Germany
| | - Diana Dudziak
- Laboratory of Dendritic Cell Biology, Department of Dermatology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany.,Medical Immunology Campus Erlangen (MICE), Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany.,Deutsches Zentrum Immuntherapie (DZI), Erlangen, Germany.,Comprehensive Cancer Center Erlangen-European Metropolitan Area of Nürnberg (CCC ER-EMN), Erlangen, Germany
| | - Anja Lux
- Department of Biology, Institute of Genetics, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany.,Medical Immunology Campus Erlangen (MICE), Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, Germany
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7
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Jiang H, Zhang X, Chen X, Aramsangtienchai P, Tong Z, Lin H. Protein Lipidation: Occurrence, Mechanisms, Biological Functions, and Enabling Technologies. Chem Rev 2018; 118:919-988. [PMID: 29292991 DOI: 10.1021/acs.chemrev.6b00750] [Citation(s) in RCA: 263] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Protein lipidation, including cysteine prenylation, N-terminal glycine myristoylation, cysteine palmitoylation, and serine and lysine fatty acylation, occurs in many proteins in eukaryotic cells and regulates numerous biological pathways, such as membrane trafficking, protein secretion, signal transduction, and apoptosis. We provide a comprehensive review of protein lipidation, including descriptions of proteins known to be modified and the functions of the modifications, the enzymes that control them, and the tools and technologies developed to study them. We also highlight key questions about protein lipidation that remain to be answered, the challenges associated with answering such questions, and possible solutions to overcome these challenges.
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Affiliation(s)
- Hong Jiang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Xiaoyu Zhang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Xiao Chen
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Pornpun Aramsangtienchai
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Zhen Tong
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Hening Lin
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
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8
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Membrane rafts in the erythrocyte membrane: a novel role of MPP1p55. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 842:61-78. [PMID: 25408337 DOI: 10.1007/978-3-319-11280-0_5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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9
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Endocytosis of soluble immune complexes leads to their clearance by FcγRIIIB but induces neutrophil extracellular traps via FcγRIIA in vivo. Blood 2012; 120:4421-31. [PMID: 22955924 DOI: 10.1182/blood-2011-12-401133] [Citation(s) in RCA: 151] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Soluble immune complexes (ICs) are abundant in autoimmune diseases, yet neutrophil responses to these soluble humoral factors remain uncharacterized. Moreover, the individual role of the uniquely human FcγRIIA and glycophosphatidylinositol (GPI)-linked FcγRIIIB in IC-mediated inflammation is still debated. Here we exploited mice and cell lines expressing these human neutrophil FcγRs to demonstrate that FcγRIIIB alone, in the absence of its known signaling partners FcγRIIA and the integrin Mac-1, internalizes soluble ICs through a mechanism used by GPI-anchored receptors and fluid-phase endocytosis. FcγRIIA also uses this pathway. As shown by intravital microscopy, FcγRIIA but not FcγRIIIB-mediated neutrophil interactions with extravascular soluble ICs results in the formation of neutrophil extracellular traps (NETs) in tissues. Unexpectedly, in wild-type mice, IC-induced NETosis does not rely on the NADPH oxidase, myeloperoxidase, or neutrophil elastase. In the context of soluble ICs present primarily within vessels, FcγRIIIB-mediated neutrophil recruitment requires Mac-1 and is associated with the removal of intravascular IC deposits. Collectively, our studies assign a new role for FcγRIIIB in the removal of soluble ICs within the vasculature that may serve to maintain homeostasis, whereas FcγRIIA engagement of tissue soluble ICs generates NETs, a proinflammatory process linked to autoimmunity.
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10
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FcγRIIa requires lipid rafts, but not co-localization into rafts, for effector function. Inflamm Res 2012; 62:37-43. [PMID: 22945762 DOI: 10.1007/s00011-012-0548-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 07/23/2012] [Accepted: 08/16/2012] [Indexed: 10/27/2022] Open
Abstract
OBJECTIVE To determine if receptor localization into lipid rafts, or the lipid rafts themselves, are important for FcγRIIa effector functions. MATERIAL Wild-type FcγRIIa or mutant FcγRIIa(C208A) that does not translocate to lipid rafts were transfected into Chinese hamster ovary (CHO) cells which have been shown to be reliable cells for studying FcγR function. TREATMENT Cells were treated with buffer or methyl-β-cyclodextrin (MβCD) to deplete cholesterol and dissolve the structure of lipid rafts. METHODS To evaluate lipid raft association, transfected CHO cells were lysed and centrifuged over a sucrose gradient. Fractions were run on SDS-PAGE and blotted for FcγRIIa or sphingolipid GM1 to illustrate the lipid raft fractions. Lateral mobility of GFP-tagged wild-type or mutant FcγRIIa was assessed using fluorescence recovery after photobleaching (FRAP) microscopy. Internalization of IgG-opsonized erythrocytes was assessed by fluorescence microscopy and uptake of heat-aggregated IgG (haIgG) was measured using flow cytometry. RESULTS We observed that FcγRIIa(C208A) did not localize into lipid rafts. However, the mutant FcγRIIa retained lateral mobility and effector function similar to wild-type FcγRIIa. However, mutant FcγRIIa function was abolished upon treatment with MβCD. CONCLUSIONS Lipid rafts provide an essential component required for effector activities independent of receptor localization.
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11
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Levental I, Grzybek M, Simons K. Greasing their way: lipid modifications determine protein association with membrane rafts. Biochemistry 2010; 49:6305-16. [PMID: 20583817 DOI: 10.1021/bi100882y] [Citation(s) in RCA: 299] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Increasing evidence suggests that biological membranes can be laterally subdivided into domains enriched in specific lipid and protein components and that these domains may be involved in the regulation of a number of vital cellular processes. An example is membrane rafts, which are lipid-mediated domains dependent on preferential association between sterols and sphingolipids and inclusive of a specific subset of membrane proteins. While the lipid and protein composition of rafts has been extensively characterized, the structural details determining protein partitioning to these domains remain unresolved. Here, we review evidence suggesting that post-translation modification by saturated lipids recruits both peripheral and transmembrane proteins to rafts, while short, unsaturated, and/or branched hydrocarbon chains prevent raft association. The most widely studied group of raft-associated proteins are glycophosphatidylinositol-anchored proteins (GPI-AP), and we review a variety of evidence supporting raft-association of these saturated lipid-anchored extracellular peripheral proteins. For transmembrane and intracellular peripheral proteins, S-acylation with saturated fatty acids mediates raft partitioning, and the dynamic nature of this modification presents an exciting possibility of enzymatically regulated raft association. The other common lipid modifications, that is, prenylation and myristoylation, are discussed in light of their likely role in targeting proteins to nonraft membrane regions. Finally, although the association between raft affinity and lipid modification is well-characterized, we discuss several open questions regarding regulation and remodeling of these post-translational modifications as well as their role in transbilayer coupling of membrane domains.
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Affiliation(s)
- Ilya Levental
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, Dresden, Germany
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12
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Vieth JA, Kim MK, Pan XQ, Schreiber AD, Worth RG. Differential requirement of lipid rafts for FcγRIIA mediated effector activities. Cell Immunol 2010; 265:111-9. [PMID: 20728077 PMCID: PMC2975250 DOI: 10.1016/j.cellimm.2010.07.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 05/11/2010] [Accepted: 07/28/2010] [Indexed: 01/18/2023]
Abstract
Immunoglobulin G (IgG) dependent activities are important in host defense and autoimmune diseases. Various cell types including macrophages and neutrophils contribute to pathogen destruction and tissue damage through binding of IgG to Fcγ receptors (FcγR). One member of this family, FcγRIIA, is a transmembrane glycoprotein known to mediate binding and internalization of IgG-containing targets. FcγRIIA has been observed to translocate into lipids rafts upon binding IgG-containing targets. We hypothesize that lipid rafts participate to different extents in binding and internalizing targets of different sizes. We demonstrate that disruption of lipid rafts with 8mM methyl-β-cyclodextrin (MβCD) nearly abolishes binding (91% reduction) and phagocytosis (60% reduction) of large IgG-coated targets. Conversely, binding and internalization of small IgG-complexes is less dependent on lipid rafts (49% and 17% inhibition at 8mM MβCD, respectively). These observations suggest that differences between phagocytosis and endocytosis may arise as early as the initial stages of ligand recognition.
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Affiliation(s)
- Joshua A. Vieth
- Department of Medical Microbiology & Immunology, University of Toledo College of Medicine, Toledo, OH 43614
| | - Moo-kyung Kim
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104
| | - Xiao Qing Pan
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104
| | - Alan D. Schreiber
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104
| | - Randall G. Worth
- Department of Medical Microbiology & Immunology, University of Toledo College of Medicine, Toledo, OH 43614
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13
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Moi ML, Lim CK, Takasaki T, Kurane I. Involvement of the Fc gamma receptor IIA cytoplasmic domain in antibody-dependent enhancement of dengue virus infection. J Gen Virol 2009; 91:103-11. [PMID: 19776239 DOI: 10.1099/vir.0.014829-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sub-neutralizing concentrations of antibody to dengue virus (DENV) enhance DENV infection of Fc gamma receptor-expressing cells. This phenomenon, referred to as antibody-dependent enhancement (ADE), has been hypothesized to be responsible for the severe form of DENV infection, including dengue haemorrhagic fever and dengue shock syndrome. To analyse further the mechanisms of ADE in vitro, this study introduced a series of cytoplasmic mutants into human Fc gammaRIIA. The mutated Fc gammaRIIA was then expressed on COS-7 cells to see whether these mutants could enhance DENV infection. Wild-type Fc gammaRIIA enhanced DENV infection, consistent with previous reports using Fc gammaR-positive monocytes. Disruption of the immune tyrosine activation motif (ITAM) in the cytoplasmic domain of Fc gammaRIIA or removing the sequences between the two ITAM regions eliminated ADE. These findings suggest that the specific structure of the Fc gammaRIIA cytoplasmic domain is essential for the ability of Fc gammaRIIA to mediate ADE.
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Affiliation(s)
- Meng Ling Moi
- Department of Virology I, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan
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14
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FcgammaRI ligation leads to a complex with BLT1 in lipid rafts that enhances rat lung macrophage antimicrobial functions. Blood 2009; 114:3316-24. [PMID: 19657115 PMCID: PMC2759654 DOI: 10.1182/blood-2009-01-199919] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Leukotriene (LT) B(4) is generated in response to engagement of the Fc gamma receptor (Fc gamma R) and potently contributes to Fc gamma R-mediated antimicrobial functions in pulmonary alveolar macrophages. In this study, we report that the LTB(4) receptor leukotriene B(4) receptor 1 (BLT1) redistributes from nonlipid raft (LR) to LR membrane microdomains upon immunoglobulin G-red blood cell, but not LTB(4), challenge. Cholesterol depletion to disrupt LRs abolished LTB(4)-induced enhancement of phagocytosis, microbicidal activity, and signaling. The dependence on LR integrity for BLT1 signaling correlated with formation of a complex consisting of BLT1, its primary coupled G protein G alpha i3, Src kinase, and Fc gamma RI within LRs. This association was dependent on Src-mediated phosphorylation of BLT1. These data identify a novel form of regulation in which engagement of a macrophage immunoreceptor recruits a stimulatory G protein-coupled receptor into a LR microdomain with resultant enhanced antimicrobial signaling.
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15
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Bournazos S, Hart SP, Chamberlain LH, Glennie MJ, Dransfield I. Association of FcgammaRIIa (CD32a) with lipid rafts regulates ligand binding activity. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2009; 182:8026-36. [PMID: 19494328 DOI: 10.4049/jimmunol.0900107] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Binding of Igs to myeloid cells via FcR is a key event in the control of innate and acquired immunity. FcgammaRIIa (CD32a) is a receptor for multivalent IgG expressed predominantly by myeloid cells, and its association with microdomains rich in cholesterol and sphingolipids, termed as lipid rafts, has been reported to be essential for efficient signaling. However, for many myeloid cell types, ligand binding to CD32a is suppressed by as yet undefined mechanisms. In this study, we have examined the role of CD32a-lipid raft interactions in the regulation of IgG binding to CD32a. Disruption of lipid raft structure following depletion or sequestration of membrane cholesterol greatly inhibited CD32a-mediated IgG binding. Furthermore, specific CD32a mutants, which show reduced association with lipid rafts (A224S and C241A), displayed decreased levels of IgG binding compared with wild-type CD32a. In contrast, constitutively lipid raft-associated CD32a (GPI-anchored CD32a) exhibited increased capacity for IgG binding compared with the full-length transmembrane CD32a. Our findings clearly suggest a major role for lipid rafts in the regulation of IgG binding and, more specifically, that suppression of CD32a-mediated IgG binding in myeloid cells is achieved by receptor exclusion from lipid raft membrane microdomains.
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Affiliation(s)
- Stylianos Bournazos
- University of Edinburgh/Medical Research Council Centre for Inflammation Research, Queen's Medical Research Institute, Edinburgh, UK
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16
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Abstract
The aggregation of cell surface Fc receptors by immune complexes induces a number of important antibody-dependent effector functions. It is becoming increasingly evident that the organization of key immune proteins has a significant impact on the function of these proteins. Comparatively little is known, however, about the nature of Fc receptor spatiotemporal organization. This review outlines the current literature concerning human Fc receptor spatial organization and physiological function.
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17
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Gonnord P, Delarasse C, Auger R, Benihoud K, Prigent M, Cuif MH, Lamaze C, Kanellopoulos JM. Palmitoylation of the P2X7 receptor, an ATP-gated channel, controls its expression and association with lipid rafts. FASEB J 2008; 23:795-805. [PMID: 18971257 DOI: 10.1096/fj.08-114637] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The P2X7 receptor (P2X7R) is an ATP-gated cationic channel expressed by hematopoietic, epithelial, and neuronal cells. Prolonged ATP exposure leads to the formation of a nonselective pore, which can result in cell death. We show that P2X7R is associated with detergent-resistant membranes (DRMs) in both transfected human embryonic kidney (HEK) cells and primary macrophages independently from ATP binding. The DRM association requires the posttranslational modification of P2X7R by palmitic acid. Treatment of cells with the palmitic acid analog 2-bromopalmitate as well as mutations of cysteine to alanine residues abolished P2X7R palmitoylation. Substitution of the 17 intracellular cysteines of P2X7R revealed that 4 regions of the carboxyl terminus domain are involved in palmitoylation. Palmitoylation-defective P2X7R mutants showed a dramatic decrease in cell surface expression because of their retention in the endoplasmic reticulum and proteolytic degradation. Taken together, our data demonstrate that P2X7R palmitoylation plays a critical role in its association with the lipid microdomains of the plasma membrane and in the regulation of its half-life.
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Affiliation(s)
- P Gonnord
- Institut de Biochimie et Biophysique Moléculaire et Cellulaire, CNRS UMR 8619, Université Paris Sud, F-91405 Orsay cedex, France
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Steinberg BE, Grinstein S. Pathogen destruction versus intracellular survival: the role of lipids as phagosomal fate determinants. J Clin Invest 2008; 118:2002-11. [PMID: 18523652 DOI: 10.1172/jci35433] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Phagocytosis is a key component of the innate immune response and of the clearance of apoptotic bodies. Phagosome formation and subsequent maturation require extensive cytoskeletal rearrangement and precisely choreographed vesicular fusion and fission events. The objectives of this review are to highlight the functional importance of lipids in the phagocytic process, to discuss how pathogenic microorganisms can in some cases manipulate host lipid metabolism to either co-opt or disrupt phagosome maturation and promote their own survival, and to describe how defective phagosomal lipid metabolism can result in disease.
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Affiliation(s)
- Benjamin E Steinberg
- Program in Cell Biology, Hospital for Sick Children, Institute of Medical Science and Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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Beekman JM, van der Linden JA, van de Winkel JGJ, Leusen JHW. FcgammaRI (CD64) resides constitutively in lipid rafts. Immunol Lett 2008; 116:149-55. [PMID: 18207250 DOI: 10.1016/j.imlet.2007.12.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 12/05/2007] [Accepted: 12/06/2007] [Indexed: 01/24/2023]
Abstract
Cellular membranes contain microdomains known as 'lipid rafts' or detergent-insoluble microdomains (DRM), enriched in cholesterol and sphingolipids. DRM can play an important role in many cellular processes, including signal transduction, cytoskeletal organization, and pathogen entry. Many receptors like T cell receptors, B cell receptors and IgE receptors have been shown to reside in DRM. The majority of these receptors depend on multivalent ligand interaction to associate with these microdomains. We, here, study association between the high affinity IgG receptor, FcgammaRI (CD64), and membrane microdomains. FcgammaRI is a 72kDa type I glycoprotein that can mediate phagocytosis of opsonized pathogens, but can also effectively capture small immune complexes, and facilitates antigen presentation. We found FcgammaRI to predominantly reside within detergent-insoluble buoyant membranes, together with FcRgamma-chain, but independent of cross-linking ligand. With the use of confocal imaging, FcgammaRI was found to co-patch with GM1, a microdomain-enriched glycolipid. Depletion of cellular cholesterol, furthermore, modulated FcgammaRI-ligand interactions. These data indicated FcgammaRI to reside within lipid rafts without prior triggering of the receptor.
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Affiliation(s)
- Jeffrey M Beekman
- Immunotherapy Laboratory, Department of Immunology, University Medical Center Utrecht, Utrecht, The Netherlands
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Abstract
Phagocytosis is an important component of innate and adaptive immunity. The formation of phagosomes and the subsequent maturation that capacitates them for pathogen elimination and antigen presentation are complex processes that involve signal transduction, cytoskeletal reorganization, and membrane remodeling. Lipids are increasingly appreciated to play a crucial role in these events. Sphingolipids, cholesterol, and glycerophospholipids, notably the phosphoinositides, are required for the segregation of signaling microdomains and for the generation of second messengers. They are also instrumental in the remodeling of the actin cytoskeleton and in directing membrane traffic. They accomplish these feats by congregating into liquid-ordered domains, by generating active metabolites that activate receptors, and by recruiting and anchoring specific protein ligands to the membrane, often altering their conformation and catalytic activity. A less appreciated role of acidic phospholipids is their contribution to the negative surface charge of the inner leaflet of the plasmalemma. The unique negativity of the inner aspect of the plasma membrane serves to attract and anchor key signaling and effector molecules that are required to initiate phagosome formation. Conversely, the loss of charge that accompanies phospholipid metabolism as phagosomes seal facilitates the dissociation of proteins and the termination of signaling and cytoskeleton assembly. In this manner, lipids provide a binary electrostatic switch to control phagocytosis.
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Affiliation(s)
- Tony Yeung
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
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Gardiner EE, Karunakaran D, Arthur JF, Mu FT, Powell MS, Baker RI, Hogarth PM, Kahn ML, Andrews RK, Berndt MC. Dual ITAM-mediated proteolytic pathways for irreversible inactivation of platelet receptors: de-ITAM-izing FcgammaRIIa. Blood 2007; 111:165-74. [PMID: 17848620 DOI: 10.1182/blood-2007-04-086983] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Collagen binding to glycoprotein VI (GPVI) induces signals critical for platelet activation in thrombosis. Both ligand-induced GPVI signaling through its coassociated Fc-receptor gamma-chain (FcRgamma) immunoreceptor tyrosine-activation motif (ITAM) and the calmodulin inhibitor, W7, dissociate calmodulin from GPVI and induce metalloproteinase-mediated GPVI ectodomain shedding. We investigated whether signaling by another ITAM-bearing receptor on platelets, FcgammaRIIa, also down-regulates GPVI expression. Agonists that signal through FcgammaRIIa, the mAbs VM58 or 14A2, potently induced GPVI shedding, inhibitable by the metalloproteinase inhibitor, GM6001. Unexpectedly, FcgammaRIIa also underwent rapid proteolysis in platelets treated with agonists for FcgammaRIIa (VM58/14A2) or GPVI/FcRgamma (the snake toxin, convulxin), generating an approximate 30-kDa fragment. Immunoprecipitation/pull-down experiments showed that FcgammaRIIa also bound calmodulin and W7 induced FcgammaRIIa cleavage. However, unlike GPVI, the approximate 30-kDa FcgammaRIIa fragment remained platelet associated, and proteolysis was unaffected by GM6001 but was inhibited by a membrane-permeable calpain inhibitor, E64d; consistent with this, micro-calpain cleaved an FcgammaRIIa tail-fusion protein at (222)Lys/(223)Ala and (230)Gly/(231)Arg, upstream of the ITAM domain. These findings suggest simultaneous activation of distinct extracellular (metalloproteinase-mediated) and intracellular (calpain-mediated) proteolytic pathways irreversibly inactivating platelet GPVI/FcRgamma and FcgammaRIIa, respectively. Activation of both pathways was observed with immunoglobulin from patients with heparin-induced thrombocytopenia (HIT), suggesting novel mechanisms for platelet dysfunction by FcgammaRIIa after immunologic insult.
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Martins de Lima T, Gorjão R, Hatanaka E, Cury-Boaventura MF, Portioli Silva EP, Procopio J, Curi R. Mechanisms by which fatty acids regulate leucocyte function. Clin Sci (Lond) 2007; 113:65-77. [PMID: 17555405 DOI: 10.1042/cs20070006] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Fatty acids (FAs) have been shown to alter leucocyte function and thus to modulate inflammatory and immune responses. In this review, the effects of FAs on several aspects of lymphocyte, neutrophil and macrophage function are discussed. The mechanisms by which FAs modulate the production of lipid mediators, activity of intracellular signalling pathways, activity of lipid-raft-associated proteins, binding to TLRs (Toll-like receptors), control of gene expression, activation of transcription factors, induction of cell death and production of reactive oxygen and nitrogen species are described in this review. The rationale for the use of specific FAs to treat patients with impaired immune function is explained. Substantial improvement in the therapeutic usage of FAs or FA derivatives may be possible based on an improvement in the understanding of the precise molecular mechanisms of action with respect to the different leucocyte types and outcome with respect to the inflammatory responses.
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Affiliation(s)
- Thais Martins de Lima
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
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García-García E, Brown EJ, Rosales C. Transmembrane Mutations to FcγRIIA Alter Its Association with Lipid Rafts: Implications for Receptor Signaling. THE JOURNAL OF IMMUNOLOGY 2007; 178:3048-58. [PMID: 17312151 DOI: 10.4049/jimmunol.178.5.3048] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Many immunoreceptors have been reported to associate with lipid rafts upon ligand binding. The way in which this association is regulated is still obscure. We investigated the roles for various domains of the human immunoreceptor FcgammaRIIA in regulating its association with lipid rafts by determining the resistance of unligated, or ligated and cross-linked, receptors to solubilization by the nonionic detergent Triton X-100, when expressed in RBL-2H3 cells. Deletion of the cytoplasmic domain, or destruction of the cytoplasmic palmitoylation site, had no effect on the association of the receptor with lipid rafts. A transmembrane mutant, A224S, lost the ability to associate with lipid rafts upon receptor cross-linking, whereas transmembrane mutants VA231-2MM and VVAL234-7GISF showed constitutive lipid raft association. Wild-type (WT) FcgammaRIIA and all transmembrane mutants activated Syk, regardless of their association with lipid rafts. WT FcgammaRIIA and mutants that associated with lipid rafts efficiently activated NF-kappaB, in an ERK-dependent manner. In contrast, WT FcgammaRIIA and the A224S mutant both presented efficient phagocytosis, while VA231-2MM and VVAL234-7GISF mutants presented lower phagocytosis, suggesting that phagocytosis may proceed independently of lipid raft association. These data identify the transmembrane domain of FcgammaRIIA as responsible for regulating its inducible association with lipid rafts and suggest that FcgammaRIIA-mediated responses, like NF-kappaB activation or phagocytosis, can be modulated by lipid raft association of the ligated receptor.
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Affiliation(s)
- Erick García-García
- Immunology Department, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City D.F.-04510, Mexico
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Abstract
Lipid rafts are liquid-ordered (lo) phase microdomains proposed to exist in biological membranes. Rafts have been widely studied by isolating lo-phase detergent-resistant membranes (DRMs) from cells. Recent findings have shown that DRMs are not the same as preexisting rafts, prompting a major revision of the raft model. Nevertheless, raft-targeting signals identified by DRM analysis are often required for protein function, implicating rafts in a variety of cell processes.
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Affiliation(s)
- Deborah A Brown
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, USA.
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Abstract
Palmitate, a 16-carbon saturated fatty acid, is attached to more than 100 proteins. Modification of proteins by palmitate has pleiotropic effects on protein function. Palmitoylation can influence membrane binding and membrane targeting of the modified proteins. In particular, many palmitoylated proteins concentrate in lipid rafts, and enrichment in rafts is required for efficient signal transduction. This Review focuses on the multiple effects of palmitoylation on the localization and function of ligands, receptors, and intracellular signaling proteins. Palmitoylation regulates the trafficking and function of transmembrane proteins such as ion channels, neurotransmitter receptors, heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors, and integrins. In addition, immune receptor signaling relies on protein palmitoylation at many levels, including palmitoylated co-receptors, Src family kinases, and adaptor or scaffolding proteins. The localization and signaling capacities of Ras and G proteins are modulated by dynamic protein palmitoylation. Cycles of palmitoylation and depalmitoylation allow H-Ras and G protein alpha subunits to reversibly bind to and signal from different intracellular cell membranes. Moreover, secreted ligands such as Hedgehog, Wingless, and Spitz use palmitoylation to regulate the extent of long- or short-range signaling. Finally, palmitoylation can alter signaling protein function by direct effects on enzymatic activity and substrate specificity. The identification of the palmitoyl acyltransferases has provided new insights into the biochemistry of this posttranslational process and permitted new substrates to be identified.
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Affiliation(s)
- Marilyn D Resh
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, Box 143, New York, NY 10021, USA.
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