1
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Tan C, Reilly B, Ma G, Murao A, Jha A, Aziz M, Wang P. Neutrophils disrupt B-1a cell homeostasis by targeting Siglec-G to exacerbate sepsis. Cell Mol Immunol 2024; 21:707-722. [PMID: 38789529 PMCID: PMC11214631 DOI: 10.1038/s41423-024-01165-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 04/11/2024] [Indexed: 05/26/2024] Open
Abstract
B-1a cells, an innate-like cell population, are crucial for pathogen defense and the regulation of inflammation through their release of natural IgM and IL-10. In sepsis, B-1a cell numbers are decreased in the peritoneal cavity as they robustly migrate to the spleen. Within the spleen, migrating B-1a cells differentiate into plasma cells, leading to alterations in their original phenotype and functionality. We discovered a key player, sialic acid-binding immunoglobulin-like lectin-G (Siglec-G), which is expressed predominantly on B-1a cells and negatively regulates B-1a cell migration to maintain homeostasis. Siglec-G interacts with CXCR4/CXCL12 to modulate B-1a cell migration. Neutrophils aid B-1a cell migration via neutrophil elastase (NE)-mediated Siglec-G cleavage. Human studies revealed increased NE expression in septic patients. We identified an NE cleavage sequence in silico, leading to the discovery of a decoy peptide that protects Siglec-G, preserves peritoneal B-1a cells, reduces inflammation, and enhances sepsis survival. The role of Siglec-G in inhibiting B-1a cell migration to maintain their inherent phenotype and function is compromised by NE in sepsis, offering valuable insights into B-1a cell homeostasis. Employing a small decoy peptide to prevent NE-mediated Siglec-G cleavage has emerged as a promising strategy to sustain peritoneal B-1a cell homeostasis, alleviate inflammation, and ultimately improve outcomes in sepsis patients.
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Affiliation(s)
- Chuyi Tan
- Center for Immunology and Inflammation, the Feinstein Institutes for Medical Research, Manhasset, New York, USA
- Department of Pathophysiology, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Bridgette Reilly
- Center for Immunology and Inflammation, the Feinstein Institutes for Medical Research, Manhasset, New York, USA
| | - Gaifeng Ma
- Center for Immunology and Inflammation, the Feinstein Institutes for Medical Research, Manhasset, New York, USA
| | - Atsushi Murao
- Center for Immunology and Inflammation, the Feinstein Institutes for Medical Research, Manhasset, New York, USA
| | - Alok Jha
- Center for Immunology and Inflammation, the Feinstein Institutes for Medical Research, Manhasset, New York, USA
| | - Monowar Aziz
- Center for Immunology and Inflammation, the Feinstein Institutes for Medical Research, Manhasset, New York, USA.
- Departments of Surgery and Molecular Medicine, Zucker School of Medicine at Hofstra/Northwell, Manhasset, New York, USA.
| | - Ping Wang
- Center for Immunology and Inflammation, the Feinstein Institutes for Medical Research, Manhasset, New York, USA.
- Departments of Surgery and Molecular Medicine, Zucker School of Medicine at Hofstra/Northwell, Manhasset, New York, USA.
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2
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Gutjahr JC, Crawford KS, Jensen DR, Naik P, Peterson FC, Samson GPB, Legler DF, Duchene J, Veldkamp CT, Rot A, Volkman BF. The dimeric form of CXCL12 binds to atypical chemokine receptor 1. Sci Signal 2021; 14:14/696/eabc9012. [PMID: 34404752 DOI: 10.1126/scisignal.abc9012] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The pleiotropic chemokine CXCL12 is involved in diverse physiological and pathophysiological processes, including embryogenesis, hematopoiesis, leukocyte migration, and tumor metastasis. It is known to engage the classical receptor CXCR4 and the atypical receptor ACKR3. Differential receptor engagement can transduce distinct cellular signals and effects as well as alter the amount of free, extracellular chemokine. CXCR4 binds both monomeric and the more commonly found dimeric forms of CXCL12, whereas ACKR3 binds monomeric forms. Here, we found that CXCL12 also bound to the atypical receptor ACKR1 (previously known as Duffy antigen/receptor for chemokines or DARC). In vitro nuclear magnetic resonance spectroscopy and isothermal titration calorimetry revealed that dimeric CXCL12 bound to the extracellular N terminus of ACKR1 with low nanomolar affinity, whereas the binding affinity of monomeric CXCL12 was orders of magnitude lower. In transfected MDCK cells and primary human Duffy-positive erythrocytes, a dimeric, but not a monomeric, construct of CXCL12 efficiently bound to and internalized with ACKR1. This interaction between CXCL12 and ACKR1 provides another layer of regulation of the multiple biological functions of CXCL12. The findings also raise the possibility that ACKR1 can bind other dimeric chemokines, thus potentially further expanding the role of ACKR1 in chemokine retention and presentation.
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Affiliation(s)
- Julia C Gutjahr
- Centre for Microvascular Research, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Kyler S Crawford
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Davin R Jensen
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Prachi Naik
- Centre for Microvascular Research, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Francis C Peterson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Guerric P B Samson
- Biotechnology Institute Thurgau (BITg), University of Konstanz, 8280 Kreuzlingen, Switzerland
| | - Daniel F Legler
- Biotechnology Institute Thurgau (BITg), University of Konstanz, 8280 Kreuzlingen, Switzerland.,Theodor Kocher Institute, University of Bern, 3012 Bern, Switzerland
| | - Johan Duchene
- Institute for Cardiovascular Prevention, Ludwig-Maximilians University, 80336 Munich, Germany
| | | | - Antal Rot
- Centre for Microvascular Research, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK. .,Institute for Cardiovascular Prevention, Ludwig-Maximilians University, 80336 Munich, Germany.,Centre for Inflammation and Therapeutic Innovation, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Brian F Volkman
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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3
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Patwardhan A, Cheng N, Trejo J. Post-Translational Modifications of G Protein-Coupled Receptors Control Cellular Signaling Dynamics in Space and Time. Pharmacol Rev 2020; 73:120-151. [PMID: 33268549 DOI: 10.1124/pharmrev.120.000082] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are a large family comprising >800 signaling receptors that regulate numerous cellular and physiologic responses. GPCRs have been implicated in numerous diseases and represent the largest class of drug targets. Although advances in GPCR structure and pharmacology have improved drug discovery, the regulation of GPCR function by diverse post-translational modifications (PTMs) has received minimal attention. Over 200 PTMs are known to exist in mammalian cells, yet only a few have been reported for GPCRs. Early studies revealed phosphorylation as a major regulator of GPCR signaling, whereas later reports implicated a function for ubiquitination, glycosylation, and palmitoylation in GPCR biology. Although our knowledge of GPCR phosphorylation is extensive, our knowledge of the modifying enzymes, regulation, and function of other GPCR PTMs is limited. In this review we provide a comprehensive overview of GPCR post-translational modifications with a greater focus on new discoveries. We discuss the subcellular location and regulatory mechanisms that control post-translational modifications of GPCRs. The functional implications of newly discovered GPCR PTMs on receptor folding, biosynthesis, endocytic trafficking, dimerization, compartmentalized signaling, and biased signaling are also provided. Methods to detect and study GPCR PTMs as well as PTM crosstalk are further highlighted. Finally, we conclude with a discussion of the implications of GPCR PTMs in human disease and their importance for drug discovery. SIGNIFICANCE STATEMENT: Post-translational modification of G protein-coupled receptors (GPCRs) controls all aspects of receptor function; however, the detection and study of diverse types of GPCR modifications are limited. A thorough understanding of the role and mechanisms by which diverse post-translational modifications regulate GPCR signaling and trafficking is essential for understanding dysregulated mechanisms in disease and for improving and refining drug development for GPCRs.
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Affiliation(s)
- Anand Patwardhan
- Department of Pharmacology and the Biomedical Sciences Graduate Program, School of Medicine, University of California, San Diego, La Jolla, California
| | - Norton Cheng
- Department of Pharmacology and the Biomedical Sciences Graduate Program, School of Medicine, University of California, San Diego, La Jolla, California
| | - JoAnn Trejo
- Department of Pharmacology and the Biomedical Sciences Graduate Program, School of Medicine, University of California, San Diego, La Jolla, California
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4
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Anderson CA, Patel P, Viney JM, Phillips RM, Solari R, Pease JE. A degradatory fate for CCR4 suggests a primary role in Th2 inflammation. J Leukoc Biol 2020; 107:455-466. [PMID: 32052476 PMCID: PMC7155072 DOI: 10.1002/jlb.2a0120-089rr] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 01/06/2020] [Accepted: 01/09/2020] [Indexed: 01/12/2023] Open
Abstract
CCR4 is the sole receptor for the chemokines CCL22 and CCL17. Clinical studies of asthmatic airways have shown levels of both ligands and CCR4+ Th2 cells to be elevated, suggestive of a role in disease. Consequently, CCR4 has aroused much interest as a potential therapeutic target and an understanding of how its cell surface expression is regulated is highly desirable. To this end, receptor expression, receptor endocytosis, and chemotaxis were assessed using transfectants expressing CCR4, CCR4+ human T cell lines, and human Th2 cells polarized in vitro. CCL17 and CCL22 drove rapid endocytosis of CCR4 in a dose-dependent manner. Replenishment at the cell surface was slow and sensitive to cycloheximide, suggestive of de novo synthesis of CCR4. Constitutive CCR4 endocytosis was also observed, with the internalized CCR4 found to be significantly degraded over a 6-h incubation. Truncation of the CCR4 C-terminus by 40 amino acids had no effect on cell surface expression, but resulted in significant impairment of ligand-induced endocytosis. Consequently, migration to both CCL17 and CCL22 was significantly enhanced. In contrast, truncation of CCR4 did not impair constitutive endocytosis or degradation, suggesting the use of alternative receptor motifs in these processes. We conclude that CCR4 cell surface levels are tightly regulated, with a degradative fate for endocytosed receptor. We postulate that this strict control is desirable, given that Th2 cells recruited by CCR4 can induce the further expression of CCR4 ligands in a positive feedback loop, thereby enhancing allergic inflammation.
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Affiliation(s)
- Caroline A Anderson
- National Heart & Lung Institute, Inflammation, Repair & Development Section, Imperial College London, London, UK.,Asthma UK Centre in Allergic Mechanisms of Asthma, London, UK
| | - Pallavi Patel
- National Heart & Lung Institute, Inflammation, Repair & Development Section, Imperial College London, London, UK.,Asthma UK Centre in Allergic Mechanisms of Asthma, London, UK
| | - Jonathan M Viney
- National Heart & Lung Institute, Inflammation, Repair & Development Section, Imperial College London, London, UK
| | - Rhian M Phillips
- National Heart & Lung Institute, Inflammation, Repair & Development Section, Imperial College London, London, UK
| | - Roberto Solari
- National Heart and Lung Institute, Airway Disease Infection Section, Imperial College London, London, UK.,Asthma UK Centre in Allergic Mechanisms of Asthma, London, UK
| | - James E Pease
- National Heart & Lung Institute, Inflammation, Repair & Development Section, Imperial College London, London, UK.,Asthma UK Centre in Allergic Mechanisms of Asthma, London, UK
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5
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Proost P, Struyf S, Van Damme J, Fiten P, Ugarte-Berzal E, Opdenakker G. Chemokine isoforms and processing in inflammation and immunity. J Autoimmun 2017; 85:45-57. [PMID: 28684129 DOI: 10.1016/j.jaut.2017.06.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 06/21/2017] [Indexed: 12/16/2022]
Abstract
The first dimension of chemokine heterogeneity is reflected by their discovery and purification as natural proteins. Each of those chemokines attracted a specific inflammatory leukocyte type. With the introduction of genomic technologies, a second wave of chemokine heterogeneity was established by the discovery of putative chemokine-like sequences and by demonstrating chemotactic activity of the gene products in physiological leukocyte homing. In the postgenomic era, the third dimension of chemokine heterogeneity is the description of posttranslational modifications on most chemokines. Proteolysis of chemokines, for instance by dipeptidyl peptidase IV (DPP IV/CD26) and by matrix metalloproteinases (MMPs) is already well established as a biological control mechanism to activate, potentiate, dampen or abrogate chemokine activities. Other posttranslational modifications are less known. Theoretical N-linked and O-linked attachment sites for chemokine glycosylation were searched with bio-informatic tools and it was found that most chemokines are not glycosylated. These findings are corroborated with a low number of experimental studies demonstrating N- or O-glycosylation of natural chemokine ligands. Because attached oligosaccharides protect proteins against proteolytic degradation, their absence may explain the fast turnover of chemokines in the protease-rich environments of infection and inflammation. All chemokines interact with G protein-coupled receptors (GPCRs) and glycosaminoglycans (GAGs). Whether lectin-like GAG-binding induces cellular signaling is not clear, but these interactions are important for leukocyte migration and have already been exploited to reduce inflammation. In addition to selective proteolysis, citrullination and nitration/nitrosylation are being added as biologically relevant modifications contributing to functional chemokine heterogeneity. Resulting chemokine isoforms with reduced affinity for GPCRs reduce leukocyte migration in various models of inflammation. Here, these third dimension modifications are compared, with reflections on the biological and pathological contexts in which these posttranslational modifications take place and contribute to the repertoire of chemokine functions and with an emphasis on autoimmune diseases.
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Affiliation(s)
- Paul Proost
- Laboratory of Molecular Immunology, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven, University of Leuven, Herestraat 49, B-3000, Leuven, Belgium.
| | - Sofie Struyf
- Laboratory of Molecular Immunology, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven, University of Leuven, Herestraat 49, B-3000, Leuven, Belgium.
| | - Jo Van Damme
- Laboratory of Molecular Immunology, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven, University of Leuven, Herestraat 49, B-3000, Leuven, Belgium.
| | - Pierre Fiten
- Laboratory of Immunobiology, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven, University of Leuven, Herestraat 49, B-3000, Leuven, Belgium.
| | - Estefania Ugarte-Berzal
- Laboratory of Immunobiology, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven, University of Leuven, Herestraat 49, B-3000, Leuven, Belgium.
| | - Ghislain Opdenakker
- Laboratory of Immunobiology, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven, University of Leuven, Herestraat 49, B-3000, Leuven, Belgium.
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6
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Sand LGL, Buckle T, van Leeuwen FWB, Corver WE, Kruisselbrink AB, Jochemsen AG, Hogendoorn PCW, Szuhai K. Fluorescent CXCR4 targeting peptide as alternative for antibody staining in Ewing sarcoma. BMC Cancer 2017; 17:383. [PMID: 28549419 PMCID: PMC5446759 DOI: 10.1186/s12885-017-3352-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 05/12/2017] [Indexed: 01/07/2023] Open
Abstract
Background Ewing sarcoma is an aggressive, highly metastatic primary bone and soft tissue tumor most frequently occurring in the bone of young adolescents. Patients, especially those diagnosed with a metastatic disease, have a poor overall survival. Chemokine receptor CXCR4 has a key pro-tumorigenic role in the tumor microenvironment of Ewing sarcoma and has been suggested to be involved in the increased metastatic propensity. Earlier studies on CXCR4 protein expression in Ewing sarcoma yielded contradictory results when compared to CXCR4 RNA expression studies. Previously, we demonstrated that CXCR4 expression could be detected in vivo using the fluorescently tagged CXCR4-specific peptide MSAP-Ac-TZ14011. Therefore, we studied the membranous CXCR4 expression in Ewing sarcoma cell lines using MSAP-Ac-TZ14011. Methods The CXCR4 membrane expression levels were studied in EWS cell lines by flow cytometry using the hybrid peptide MSAP-Ac-TZ14011 and were correlated to CXCR4 RNA expression levels. The measurements were compared to levels detected using the CXCR4 antibody ab2074 under various cell preparation conditions. In addition, the staining patterns were analyzed by confocal fluorescence microscopy over time. Results The hybrid peptide MSAP-Ac-TZ14011 levels showed a strong and better correlation of CXCR4 membrane expression with the CXCR4 RNA expression levels than observed with the anti-CXCR4 antibody ab2074. With the hybrid peptide MSAP-Ac-TZ14011 using live cell confocal microscopy CXCR4 membrane staining and internalization was detected and the signal intensity correlated well with CXCR4 mRNA expression levels. Conclusions The fluorescently labeled CXCR4 targeting peptide-based method provides a reliable alternative to antibody staining to study the CXCR4 membrane expression in live cells using either flow cytometry or live cell fluorescence microscopy. The fluorescently tagged CXCR4 targeting peptide could enable in vivo detection of CXCR4 expression in Ewing sarcoma which may help to stratify cases for anti-CXCR4 therapy. Electronic supplementary material The online version of this article (doi:10.1186/s12885-017-3352-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Laurens G L Sand
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | - Tessa Buckle
- Interventional Molecular Imaging Laboratory, Department of Radiology, Leiden, The Netherlands.,Division of Molecular Pathology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Fijs W B van Leeuwen
- Interventional Molecular Imaging Laboratory, Department of Radiology, Leiden, The Netherlands
| | - Willem E Corver
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Aart G Jochemsen
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, Postbus 9600, 2300 RC, The Netherlands
| | | | - Károly Szuhai
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, Postbus 9600, 2300 RC, The Netherlands.
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7
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Hauser MA, Kindinger I, Laufer JM, Späte AK, Bucher D, Vanes SL, Krueger WA, Wittmann V, Legler DF. Distinct CCR7 glycosylation pattern shapes receptor signaling and endocytosis to modulate chemotactic responses. J Leukoc Biol 2016; 99:993-1007. [PMID: 26819318 DOI: 10.1189/jlb.2vma0915-432rr] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 01/07/2016] [Indexed: 01/14/2023] Open
Abstract
The homeostatic chemokines CCL19 and CCL21 and their common cognate chemokine receptor CCR7 orchestrate immune cell trafficking by eliciting distinct signaling pathways. Here, we demonstrate that human CCR7 is N-glycosylated on 2 specific residues in the N terminus and the third extracellular loop. Conceptually, CCR7 glycosylation adds steric hindrance to the receptor N terminus and extracellular loop 3, acting as a "swinging door" to regulate receptor sensitivity and cell migration. We found that freshly isolated human B cells, as well as expanded T cells, but not naïve T cells, express highly sialylated CCR7. Moreover, we identified that human dendritic cells imprint T cell migration toward CCR7 ligands by secreting enzymes that deglycosylate CCR7, thereby boosting CCR7 signaling on T cells, permitting enhanced T cell locomotion, while simultaneously decreasing receptor endocytosis. In addition, dendritic cells proteolytically convert immobilized CCL21 to a soluble form that is more potent in triggering chemotactic movement and does not desensitize the receptor. Furthermore, we demonstrate that soluble CCL21 functionally resembles neither the CCL19 nor the CCL21 phenotype but acts as a chemokine with unique features. Thus, we advance the concept of dendritic cell-dependent generation of micromilieus and lymph node conditioning by demonstrating a novel layer of CCR7 regulation through CCR7 sialylation. In summary, we demonstrate that leukocyte subsets express distinct patterns of CCR7 sialylation that contribute to receptor signaling and fine-tuning chemotactic responses.
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Affiliation(s)
- Mark A Hauser
- Biotechnology Institute Thurgau at the University of Konstanz, University of Konstanz, Konstanz, Germany
| | - Ilona Kindinger
- Biotechnology Institute Thurgau at the University of Konstanz, University of Konstanz, Konstanz, Germany
| | - Julia M Laufer
- Biotechnology Institute Thurgau at the University of Konstanz, University of Konstanz, Konstanz, Germany
| | - Anne-Katrin Späte
- Department of Chemistry, Chair of Organic Chemistry/Bioorganic Chemistry, University of Konstanz, Konstanz, Germany; and
| | - Delia Bucher
- Biotechnology Institute Thurgau at the University of Konstanz, University of Konstanz, Konstanz, Germany
| | - Sarah L Vanes
- Biotechnology Institute Thurgau at the University of Konstanz, University of Konstanz, Konstanz, Germany
| | | | - Valentin Wittmann
- Department of Chemistry, Chair of Organic Chemistry/Bioorganic Chemistry, University of Konstanz, Konstanz, Germany; and
| | - Daniel F Legler
- Biotechnology Institute Thurgau at the University of Konstanz, University of Konstanz, Konstanz, Germany;
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8
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Sand LGL, Jochemsen AG, Beletkaia E, Schmidt T, Hogendoorn PCW, Szuhai K. Novel splice variants of CXCR4 identified by transcriptome sequencing. Biochem Biophys Res Commun 2015; 466:89-94. [PMID: 26321665 DOI: 10.1016/j.bbrc.2015.08.113] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 08/25/2015] [Indexed: 10/23/2022]
Abstract
Chemokine receptor CXCR4 is involved in tumor growth, angiogenesis and metastasis. Its function is regulated in many ways and one of them is alternative splicing. We identified two novel coding splice variants (CXCR4-3 and CXCR4-4) of CXCR4 in Ewing sarcoma (EWS) cell lines by whole transcriptome sequencing and validated these with reverse transcriptase- PCR and Sanger sequencing. The novel splice variants were expressed at RNA level in Ewing sarcoma samples and in other tumor cell lines and placenta, but not in lung. Due to inclusion of an additional exon the new isoforms have a 70 and 33 amino acid elongation of the N-terminal end of CXCR4. For validation at protein and functional level, the identified isoforms and normal CXCR4 were cloned into an EYFP tagged vector and ectopically expressed in HEK293T cell line and EWS cell line A673. Of the novel isoforms CXCR4-3 showed cell membrane localization and a functional response after addition of CXCR4 ligand CXCL12a. CXCR4-4 showed strong cytoplasmic accumulation and no response to ligand treatment. The role of the newly discovered isoforms in CXCR4 signaling is likely to be limited. Our data stresses the importance of functional validation of newly identified isoforms.
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Affiliation(s)
- L G L Sand
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | - A G Jochemsen
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - E Beletkaia
- Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
| | - T Schmidt
- Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
| | - P C W Hogendoorn
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | - K Szuhai
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
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9
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Sartim MA, Riul TB, Del Cistia-Andrade C, Stowell SR, Arthur CM, Sorgi CA, Faccioli LH, Cummings RD, Dias-Baruffi M, Sampaio SV. Galatrox is a C-type lectin in Bothrops atrox snake venom that selectively binds LacNAc-terminated glycans and can induce acute inflammation. Glycobiology 2014; 24:1010-21. [PMID: 24973254 DOI: 10.1093/glycob/cwu061] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Previous studies indicate that snake venom contains glycan-binding proteins (GBPs), although the binding specificity and biological activities of many of these GBPs is unclear. Here we report our studies on the glycan binding specificity and activities of galatrox, a Bothrops atrox snake venom-derived GBP. Glycan microarray analysis indicates that galatrox binds most strongly to glycans expressing N-acetyllactosamine (LacNAc), with a significant preference for Galβ1-4GlcNAcβ over Galβ1-3GlcNAcβ compounds. Galatrox also bound immobilized laminin, a LacNAc-dense extracellular matrix component, suggesting that this GBP can bind LacNAc-bearing glycoproteins. As several endogenous mammalian GBPs utilize a similar binding LacNAc binding preference to regulate neutrophil and monocyte activity, we hypothesized that galatrox may mediate B. atrox toxicity through regulation of leukocyte activity. Indeed, galatrox bound neutrophils and promoted leukocyte chemotaxis in a carbohydrate-dependent manner. Similarly, galatrox administration into the mouse peritoneal cavity induced significant neutrophil migration and the release of pro-inflammatory cytokines IL-1α and IL-6. Exposure of bone marrow-derived macrophages to galatrox induced generation of pro-inflammatory mediators IL-6, TNF-α, and keratinocyte-derived chemokine. This signaling by galatrox was mediated via its carbohydrate recognition domain by activation of the TLR4-mediated MyD88-dependent signaling pathway. These results indicate that galatrox has pro-inflammatory activity through its interaction with LacNAc-bearing glycans on neutrophils, macrophages and extracellular matrix proteins and induce the release of pro-inflammatory mediators.
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Affiliation(s)
- Marco A Sartim
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040903 São Paulo, Brazil
| | - Thalita B Riul
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040903 São Paulo, Brazil
| | - Camillo Del Cistia-Andrade
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040903 São Paulo, Brazil
| | - Sean R Stowell
- Department of Pathology and Laboratory Medicine, Center for Transfusion and Cellular Therapies, Emory University School of Medicine, Atlanta 30322, GA, USA
| | - Connie M Arthur
- Department of Pathology and Laboratory Medicine, Center for Transfusion and Cellular Therapies, Emory University School of Medicine, Atlanta 30322, GA, USA
| | - Carlos A Sorgi
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040903 São Paulo, Brazil
| | - Lucia H Faccioli
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040903 São Paulo, Brazil
| | - Richard D Cummings
- Department of Biochemistry and The Glycomics Center, Emory University School of Medicine, Atlanta 30322, GA, USA
| | - Marcelo Dias-Baruffi
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040903 São Paulo, Brazil
| | - Suely V Sampaio
- Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040903 São Paulo, Brazil
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10
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Boulais PE, Escher E, Leduc R. Analysis by substituted cysteine scanning mutagenesis of the fourth transmembrane domain of the CXCR4 receptor in its inactive and active state. Biochem Pharmacol 2012; 85:541-50. [PMID: 23219524 DOI: 10.1016/j.bcp.2012.11.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 11/23/2012] [Accepted: 11/27/2012] [Indexed: 11/28/2022]
Abstract
The chemokine SDF-1 (CXCL12) selectively binds to CXCR4, a member of the G protein-coupled receptor (GPCR) superfamily. In this study, we used the substituted-cysteine accessibility method (SCAM) to identify specific residues of the fourth transmembrane domain (TM4) that contribute to the formation of the binding pocket of CXCR4 in its inactive and active state. We successively substituted each residue from E179((4.68)) to K154((4.43)) with cysteine and expressed the mutants in COS-7 cells. Mutant receptors were then alkylated with methanethiosulfonate-ethylammonium (MTSEA), and binding inhibition was monitored using the CXCR4 antagonist FC131 [cyclo(-D-Tyr(1)-Arg(2)-Arg(3)-Nal(4)-Gly(5)-)], which displays anti-HIV activity. MTSEA treatment resulted in a significant reduction of FC131 binding to D171C((4.60)) and P170C((4.59)). To assess TM4 accessibility in an active state of CXCR4, TM4 cysteine mutants were transposed within the constitutively active mutant N119S((3.35)). MTSEA treatment of TM4 mutants N119S-S178C((4.67)), N119S-V177C((4.66)) and N119S-I173C((4.62)) resulted in a significant reduction in FC131 binding. Protection assays using FC131 prior to MTSEA treatment significantly reduced the alkylation of all MTSEA-sensitive mutants. The accessibility of the D171C((4.60)) and P170C((4.59)) residues suggests that they are oriented towards a water-accessible area of the binding pocket of CXCR4. S178C((4.67)), V177C((4.66)) and I173C((4.62)) showed binding inhibition only in an N119S((3.35)) background. Taken together our results suggest that TM4 and ECL2 undergo conformational changes during CXCR4 activation and also demonstrate how TM4 is an important feature for the binding of anti-HIV compounds.
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Affiliation(s)
- Philip E Boulais
- Department of Pharmacology, Institut de Pharmacologie de Sherbrooke, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec J1H5N4, Canada
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11
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Szpakowska M, Fievez V, Arumugan K, van Nuland N, Schmit JC, Chevigné A. Function, diversity and therapeutic potential of the N-terminal domain of human chemokine receptors. Biochem Pharmacol 2012; 84:1366-80. [PMID: 22935450 DOI: 10.1016/j.bcp.2012.08.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Revised: 08/08/2012] [Accepted: 08/09/2012] [Indexed: 11/16/2022]
Abstract
Chemokines and their receptors play fundamental roles in many physiological and pathological processes such as leukocyte trafficking, inflammation, cancer and HIV-1 infection. Chemokine-receptor interactions are particularly intricate and therefore require precise orchestration. The flexible N-terminal domain of human chemokine receptors has regularly been demonstrated to hold a crucial role in the initial recognition and selective binding of the receptor ligands. The length and the amino acid sequences of the N-termini vary considerably among different receptors but they all show a high content of negatively charged residues and are subject to post-translational modifications such as O-sulfation and N- or O-glycosylation. In addition, a conserved cysteine that is most likely engaged in a receptor-stabilizing disulfide bond delimits two functionally distinct parts in the N-terminus, characterized by specific molecular signatures. Structural analyses have shown that the N-terminus of chemokine receptors recognizes a groove on the chemokine surface and that this interaction is stabilized by high-affinity binding to a conserved sulfotyrosine-binding pocket. Altogether, these data provide new insights on the chemokine-receptor molecular interplay and identify the receptor N-terminus-binding site as a new target for the development of therapeutic molecules. This review presents and discusses the diversity and function of human chemokine receptor N-terminal domains and provides a comprehensive annotated inventory of their sequences, laying special emphasis on the presence of post-translational modifications and functional features. Finally, it identifies new molecular signatures and proposes a computational model for the positioning and the conformation of the CXCR4 N-terminus grafted on the first chemokine receptor X-ray structure.
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Affiliation(s)
- Martyna Szpakowska
- Laboratory of Retrovirology, Public Research Center for Health, Luxembourg, Luxembourg.
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12
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Tagliamonte M, Tornesello ML, Buonaguro FM, Buonaguro L. Conformational HIV-1 envelope on particulate structures: a tool for chemokine coreceptor binding studies. J Transl Med 2011; 9 Suppl 1:S1. [PMID: 21284899 PMCID: PMC3105500 DOI: 10.1186/1479-5876-9-s1-s1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) external envelope glycoprotein gp120 presents conserved binding sites for binding to the primary virus receptor CD4 as well as the major HIV chemokine coreceptors, CCR5 and CXCR4. Concerted efforts are underway to understand the specific interactions between gp120 and coreceptors as well as their contribution to the subsequent membrane fusion process. The present review summarizes the current knowledge on this biological aspect, which represents one of the key and essential points of the HIV-host cell interplay and HIV life cycle. The relevance of conformational HIV-1 Envelope proteins presented on Virus-like Particles for appropriate assessment of this molecular interaction, is also discussed.
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Affiliation(s)
- Maria Tagliamonte
- Lab, of Molecular Biology and Viral Oncogenesis & AIDS Reference Center, Istituto Nazionale Tumori Fond, G, Pascale, Naples, Italy
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13
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Zhang H, Tully DC, Zhang T, Moriyama H, Thompson J, Wood C. Molecular determinants of HIV-1 subtype C coreceptor transition from R5 to R5X4. Virology 2010; 407:68-79. [PMID: 20797755 DOI: 10.1016/j.virol.2010.07.047] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 06/01/2010] [Accepted: 07/28/2010] [Indexed: 11/18/2022]
Abstract
The molecular mechanism(s) underlying transition from CCR5 to CXCR4 usage of subtype C viruses remain largely unknown. We previously identified a subtype C HIV-1 infected child whose virus demonstrated CXCR4 usage along with CCR5 upon longitudinal follow-up. Here we delineated the molecular determinants of Env involved in expanded coreceptor usage. Residue changes in three positions of Env V3 domain are critical for the dual tropic phenotype. These include: substitution of arginine at position 11, MG or LG insertion between positions 13 and 14, and substitution of threonine at the position immediately downstream of the GPGQ crown. Introducing these mutations into V3 region of a heterologous R5 virus also conferred dual tropism. Molecular modeling of V3 revealed a possible structural basis for the dual tropic phenotype. Determining what defines a subtype C X4 virus will lead to a better understanding of subtype C HIV-1 pathogenesis, and will provide important information relevant to anti-retroviral therapy.
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Affiliation(s)
- Hong Zhang
- Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583-0900, USA
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14
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LI L, HE T, MO XM, LI XY, ZHANG G, SUN HX. Biological Functions, Screen and Identify Research on Chemokine Receptor Antagonist Encoded by US28 of Human Cytomegalovirus*. PROG BIOCHEM BIOPHYS 2010. [DOI: 10.3724/sp.j.1206.2009.00771] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Bestebroer J, de Haas CJ, van Strijp JA. How microorganisms avoid phagocyte attraction. FEMS Microbiol Rev 2010; 34:395-414. [DOI: 10.1111/j.1574-6976.2009.00202.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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16
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Wong JP, Reboul E, Molday RS, Kast J. A carboxy-terminal affinity tag for the purification and mass spectrometric characterization of integral membrane proteins. J Proteome Res 2009; 8:2388-96. [PMID: 19236039 DOI: 10.1021/pr801008c] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
G-protein-coupled receptors (GPCRs) and other structurally and functionally related membrane proteins represent particularly attractive targets for drug discovery. Integral membrane proteins are often difficult to purify from native contexts, and lack of sufficient quantities hampers subsequent structural and functional proteomic studies. We describe here an optimized enrichment strategy involving a membrane protein-compatible 1D4 affinity tag that is derived from the carboxy-terminal nine amino residues of bovine rhodopsin, and its corresponding tag-specific, high-affinity monoclonal antibody. When two GPCRs as well as two related ATP binding cassette (ABC) transporters are expressed in their functional forms in human cell lines, we have shown that a single detergent and wash condition can be employed for the purification of all said membrane proteins. Subsequent in-gel digestion with trypsin and mass spectrometric peptide analysis resulted in high sequence coverage for the ABC transporters ABCA1-1D4 and ABCA4-1D4. In contrast, digestion by various enzymatic combinations was necessary to obtain the best sequence coverage for affinity-enriched GPCRs CXCR4-1D4 and CCR5-1D4 as compared against other entries in an annotated spectrum library. Furthermore, specific enzyme combinations were necessary to produce suitable peptides for deducing N-glycosylation sites on CXCR4. Our results demonstrate that the 1D4-tag enrichment strategy is a versatile tool for the characterization of integral membrane proteins that can be employed for functional proteomic studies.
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Affiliation(s)
- Julie P Wong
- Biomedical Research Centre, Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
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17
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Abstract
Staphylococcus aureus secretes several virulence factors modulating immune responses. Staphylococcal superantigen-like (SSL) proteins are a family of 14 exotoxins with homology to superantigens, but with generally unknown function. Recently, we showed that SSL5 binds to P-selectin glycoprotein ligand 1 dependently of sialyl Lewis X and inhibits P-selectin-dependent neutrophil rolling. Here, we show that SSL5 potently and specifically inhibits leukocyte activation by anaphylatoxins and all classes of chemokines. SSL5 inhibited calcium mobilization, actin polymerization, and chemotaxis induced by chemokines and anaphylatoxins but not by other chemoattractants. Antibody competition experiments showed that SSL5 targets several chemokine and anaphylatoxin receptors. In addition, transfection studies showed that SSL5 binds glycosylated N-termini of all G protein-coupled receptors (GPCRs) but only inhibits stimuli of protein nature that require the receptor N-terminus for activation. Furthermore, SSL5 increased binding of chemokines to cells independent of chemokine receptors through their common glycosaminoglycan-binding site. Importance of glycans was shown for both GPCR and chemokine binding. Thus, SSL5 is an important immunomodulatory protein of S aureus that targets several crucial, initial stages of leukocyte extravasation. It is therefore a potential new antiinflammatory compound for diseases associated with chemoattractants and their receptors and disorders characterized by excessive recruitment of leukocytes.
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18
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Brass AL, Dykxhoorn DM, Benita Y, Yan N, Engelman A, Xavier RJ, Lieberman J, Elledge SJ. Identification of host proteins required for HIV infection through a functional genomic screen. Science 2008; 319:921-6. [PMID: 18187620 DOI: 10.1126/science.1152725] [Citation(s) in RCA: 1109] [Impact Index Per Article: 69.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
HIV-1 exploits multiple host proteins during infection. We performed a large-scale small interfering RNA screen to identify host factors required by HIV-1 and identified more than 250 HIV-dependency factors (HDFs). These proteins participate in a broad array of cellular functions and implicate new pathways in the viral life cycle. Further analysis revealed previously unknown roles for retrograde Golgi transport proteins (Rab6 and Vps53) in viral entry, a karyopherin (TNPO3) in viral integration, and the Mediator complex (Med28) in viral transcription. Transcriptional analysis revealed that HDF genes were enriched for high expression in immune cells, suggesting that viruses evolve in host cells that optimally perform the functions required for their life cycle. This effort illustrates the power with which RNA interference and forward genetics can be used to expose the dependencies of human pathogens such as HIV, and in so doing identify potential targets for therapy.
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Affiliation(s)
- Abraham L Brass
- Department of Genetics, Center for Genetics and Genomics, Brigham and Women's Hospital, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
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19
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Parris GE. 2-Deoxy-d-glucose as a potential drug against fusogenic viruses including HIV. Med Hypotheses 2008; 70:776-82. [DOI: 10.1016/j.mehy.2007.08.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 08/05/2007] [Indexed: 01/08/2023]
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20
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Kubo Y, Yokoyama M, Yoshii H, Mitani C, Tominaga C, Tanaka Y, Sato H, Yamamoto N. Inhibitory role of CXCR4 glycan in CD4-independent X4-tropic human immunodeficiency virus type 1 infection and its abrogation in CD4-dependent infection. J Gen Virol 2007; 88:3139-3144. [PMID: 17947541 DOI: 10.1099/vir.0.83202-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
CXCR4 functions as an infection receptor of X4 human immunodeficiency virus type 1 (HIV-1) . CXCR4 is glycosylated at the N-terminal extracellular region, which is important for viral envelope (Env) protein binding. We compared the effects of CXCR4 glycan on the CD4-dependent and -independent infections in human cells by X4 viruses. We found that transduction mediated by Env proteins of CD4-independent HIV-1 strains increased up to 5.5-fold in cells expressing unglycosylated CXCR4, suggesting that the CXCR4 glycan inhibits CD4-independent X4 virus infection. Co-expression of CD4 on the target cell surface or pre-incubation of virus particles with soluble CD4 abrogates the glycan-mediated inhibition of X4 virus infection, suggesting that interaction of Env protein with CD4 counteracts the inhibition. These findings indicate that it will be advantageous for X4 HIV-1 to remain CD4-dependent. A structural model that explains the glycan-mediated inhibition is discussed.
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Affiliation(s)
- Yoshinao Kubo
- Department of AIDS Research, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Masaru Yokoyama
- Laboratory of Viral Genomics, Center for Pathogen Genomics, National Institute of Infectious Diseases, Tokyo, Japan.,Department of AIDS Research, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Hiroaki Yoshii
- Department of AIDS Research, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Chiho Mitani
- Department of AIDS Research, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Chika Tominaga
- Department of AIDS Research, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Yuetsu Tanaka
- Department of Immunology, Graduate School and Faculty of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Hironori Sato
- Laboratory of Viral Genomics, Center for Pathogen Genomics, National Institute of Infectious Diseases, Tokyo, Japan.,Department of AIDS Research, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Naoki Yamamoto
- Department of Molecular Virology, Tokyo Medical and Dental University, Tokyo, Japan.,AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan.,Department of AIDS Research, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
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21
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Xu C, Sui J, Tao H, Zhu Q, Marasco WA. Human anti-CXCR4 antibodies undergo VH replacement, exhibit functional V-region sulfation, and define CXCR4 antigenic heterogeneity. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2007; 179:2408-18. [PMID: 17675502 DOI: 10.4049/jimmunol.179.4.2408] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The chemokine receptor CXCR4 and its ligand stromal-derived factor-1 (SDF-1/CXCL12) are essential for many biological processes and various pathological conditions. However, the relationship between CXCR4 antigenic structure and SDF-1-mediated biological responses is poorly understood. In this report, a panel of human anti-CXCR4 Abs were isolated and used to explore CXCR4 antigenic heterogeneity and function. Multiple fixed CXCR4 antigenic isoforms were detected on the surface of hemopoietic cells. Epitope mapping studies demonstrated the complex nature of the surface-exposed CXCR4 epitopes. Ab-mediated inhibition of chemotaxis correlated strongly with binding affinity, epitope recognition, as well as the level of CXCR4 isoform expression. In addition, detailed genetic analyses of these Abs showed evidence of V(H) replacement. Importantly, structural and biochemical studies demonstrated tyrosine sulfation in novel regions of the V genes that contributed bidirectionally to the binding activity of the Abs. These data provide the first evidence that functional tyrosine sulfation occurs in self-reactive Abs and suggest a potential new mechanism that may contribute to the pathogenesis of Ab-mediated autoimmune disease. These Abs also provide valuable tools to explore the selective in vivo targeting of CXCR4 isoforms that may be preferentially expressed in certain disease states and involved in steady-state CXCR4-SDF-1 homeostasis.
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Affiliation(s)
- Chen Xu
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, MA, USA
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22
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Lin G, Bertolotti-Ciarlet A, Haggarty B, Romano J, Nolan KM, Leslie GJ, Jordan APO, Huang CC, Kwong PD, Doms RW, Hoxie JA. Replication-competent variants of human immunodeficiency virus type 2 lacking the V3 loop exhibit resistance to chemokine receptor antagonists. J Virol 2007; 81:9956-66. [PMID: 17609282 PMCID: PMC2045409 DOI: 10.1128/jvi.00385-07] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Entry of human immunodeficiency virus type 1 (HIV-1) and HIV-2 requires interactions between the envelope glycoprotein (Env) on the virus and CD4 and a chemokine receptor, either CCR5 or CXCR4, on the cell surface. The V3 loop of the HIV gp120 glycoprotein plays a critical role in this process, determining tropism for CCR5- or CXCR4-expressing cells, but details of how V3 interacts with these receptors have not been defined. Using an iterative process of deletion mutagenesis and in vitro adaptation of infectious viruses, variants of HIV-2 were derived that could replicate without V3, either with or without a deletion of the V1/V2 variable loops. The generation of these functional but markedly minimized Envs required adaptive changes on the gp120 core and gp41 transmembrane glycoprotein. V3-deleted Envs exhibited tropism for both CCR5- and CXCR4-expressing cells, suggesting that domains on the gp120 core were mediating interactions with determinants shared by both coreceptors. Remarkably, HIV-2 Envs with V3 deletions became resistant to small-molecule inhibitors of CCR5 and CXCR4, suggesting that these drugs inhibit wild-type viruses by disrupting a specific V3 interaction with the coreceptor. This study represents a proof of concept that HIV Envs lacking V3 alone or in combination with V1/V2 that retain functional domains required for viral entry can be derived. Such minimized Envs may be useful in understanding Env function, screening for new inhibitors of gp120 core interactions with chemokine receptors, and designing novel immunogens for vaccines.
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Affiliation(s)
- George Lin
- Department of Medicine, University of Pennsylvania, 421 Curie Blvd., Philadelphia, PA 19104, USA
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23
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McReynolds KD, Gervay-Hague J. Chemotherapeutic Interventions Targeting HIV Interactions with Host-Associated Carbohydrates. Chem Rev 2007; 107:1533-52. [PMID: 17439183 DOI: 10.1021/cr0502652] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Katherine D McReynolds
- Department of Chemistry, California State University, Sacramento, Sacramento, California 95819, USA.
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24
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Busillo JM, Benovic JL. Regulation of CXCR4 signaling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1768:952-63. [PMID: 17169327 PMCID: PMC1952230 DOI: 10.1016/j.bbamem.2006.11.002] [Citation(s) in RCA: 451] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Accepted: 11/04/2006] [Indexed: 12/31/2022]
Abstract
The chemokine receptor CXCR4 belongs to the large superfamily of G protein-coupled receptors, and is directly involved in a number of biological processes including organogenesis, hematopoiesis, and immune response. Recent evidence has highlighted the role of CXCR4 in a variety of diseases including HIV, cancer, and WHIM syndrome. Importantly, the involvement of CXCR4 in cancer metastasis and WHIM syndrome appears to be due to dysregulation of the receptor leading to enhanced signaling. Herein we review what is currently known regarding the regulation of CXCR4 and how dysregulation contributes to disease progression.
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Affiliation(s)
- John M. Busillo
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Jeffrey L. Benovic
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107
- To whom correspondence should be addressed:
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25
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Dukkipati A, Vaclavikova J, Waghray D, Garcia KC. In vitro reconstitution and preparative purification of complexes between the chemokine receptor CXCR4 and its ligands SDF-1alpha, gp120-CD4 and AMD3100. Protein Expr Purif 2006; 50:203-14. [PMID: 16962791 DOI: 10.1016/j.pep.2006.07.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Revised: 07/13/2006] [Accepted: 07/23/2006] [Indexed: 01/18/2023]
Abstract
CXCR4 belongs to the family of G protein-coupled receptors and mediates the various developmental and regulatory effects of the chemokine SDF-1alpha. In addition, CXCR4 acts as a co-receptor along with CD4 for the HIV-1 viral glycoprotein gp120. Recently, there has also been a small molecule described that antagonizes both SDF-1 and gp120 binding to CXCR4. The structural and mechanistic basis for this dual recognition ability of CXCR4 is unknown largely due to the technical challenges of biochemically producing the components of the various complexes. We expressed the human CXCR4 receptor using a modified baculovirus expression vector that facilitates a single step antibody affinity purification of CXCR4 to >80% purity from Hi5 cells. The recombinant receptor undergoes N-linked glycosylation, tyrosine sulfation and is recognized by the 12G5 conformation specific antibody against human CXCR4. We are able to purify CXCR4 alone as well as complexed with its endogenous ligand SDF-1, its viral ligand gp120, and a small molecule antagonist AMD3100 by ion-exchange chromatography. We anticipate that the expression and purification scheme described in this paper will facilitate structure-function studies aimed at elucidating the molecular basis for CXCR4 recognition of its endogenous chemokine and viral ligands.
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Affiliation(s)
- Abhiram Dukkipati
- Department of Microbiology and Immunology, Stanford University School of Medicine, 299 Campus Drive, Stanford, CA 94305, USA
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26
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Veldkamp CT, Seibert C, Peterson FC, Sakmar TP, Volkman BF. Recognition of a CXCR4 sulfotyrosine by the chemokine stromal cell-derived factor-1alpha (SDF-1alpha/CXCL12). J Mol Biol 2006; 359:1400-9. [PMID: 16725153 PMCID: PMC2670582 DOI: 10.1016/j.jmb.2006.04.052] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2006] [Revised: 04/20/2006] [Accepted: 04/24/2006] [Indexed: 11/20/2022]
Abstract
Tyrosine sulfation of the chemokine receptor CXCR4 enhances its interaction with the chemokine SDF-1alpha. Given similar post-translational modification of other receptors, including CCR5, CX3CR1 and CCR2b, tyrosine sulfation may be of universal importance in chemokine signaling. N-terminal domains from seven transmembrane chemokine receptors have been employed for structural studies of chemokine-receptor interactions, but never in the context of proper post-translational modifications known to affect function. A CXCR4 peptide modified at position 21 by expressed tyrosylprotein sulfotransferase-1 and unmodified peptide are both disordered in solution, but bind SDF-1alpha with low micromolar affinities. NMR and fluorescence polarization measurements showed that the CXCR4 peptide stabilizes dimeric SDF-1alpha, and that sulfotyrosine 21 binds a specific site on the chemokine that includes arginine 47. We conclude that the SDF-1alpha dimer preferentially interacts with receptor peptide, and residues beyond the extreme N-terminal region of CXCR4, including sulfotyrosine 21, make specific contacts with the chemokine ligand.
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27
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Rojek JM, Spiropoulou CF, Kunz S. Characterization of the cellular receptors for the South American hemorrhagic fever viruses Junin, Guanarito, and Machupo. Virology 2006; 349:476-91. [PMID: 16574183 DOI: 10.1016/j.virol.2006.02.033] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 12/19/2005] [Accepted: 02/23/2006] [Indexed: 12/01/2022]
Abstract
The New World arenaviruses Junin, Machupo, and Guanarito are the causative agents of hemorrhagic fevers (HF) with high mortality in humans. The cellular receptor for Old World arenaviruses and one subgroup of the New World arenaviruses (Clade C) have been identified as alpha-dystroglycan (alpha-DG). In contrast, the receptor(s) of the South American HF viruses, which belong to the Clade B New World arenaviruses, are currently unknown. To begin to characterize the cellular receptors used by these pathogens, we generated recombinant retroviral pseudotypes with the glycoproteins of Guanarito, Junin, and Machupo. Infection with the South American HF viruses is independent of alpha-DG and functional receptors for Guanarito, Junin, and Machupo were found on most human cell types and cells derived from non-human primate and rodents. Guanarito, Junin, and Machupo share a common receptor, which is distinct from the receptor(s) used by the closely related non-pathogenic Clade B virus Amapari, and the genetically more distant Clade A and C New World arenaviruses. We show that the cellular receptor(s) for the South American HF viruses are proteins or protein-linked entities and that infection is not dependent on protein-linked N-glycans, O-glycans, or glycosaminoglycans.
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Affiliation(s)
- Jillian M Rojek
- Molecular and Integrative Neuroscience Department (MIND), The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
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28
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Imperiali M, Thoma C, Pavoni E, Brancaccio A, Callewaert N, Oxenius A. O Mannosylation of alpha-dystroglycan is essential for lymphocytic choriomeningitis virus receptor function. J Virol 2006; 79:14297-308. [PMID: 16254364 PMCID: PMC1280192 DOI: 10.1128/jvi.79.22.14297-14308.2005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Alpha-dystroglycan (alpha-DG) was identified as a common receptor for lymphocytic choriomeningitis virus (LCMV) and several other arenaviruses including the human pathogenic Lassa fever virus. Initial work postulated that interactions between arenavirus glycoproteins and alpha-DG are based on protein-protein interactions. We found, however, that susceptibility toward LCMV infection differed in various cell lines despite them expressing comparable levels of DG, suggesting that posttranslational modifications of alpha-DG would be involved in viral receptor function. Here, we demonstrate that glycosylation of alpha-DG, and in particular, O mannosylation, which is a rare type of O-linked glycosylation in mammals, is essential for LCMV receptor function. Cells that are defective in components of the O-mannosylation pathway showed strikingly reduced LCMV infectibility. As defective O mannosylation is associated with severe clinical symptoms in mammals such as congenital muscular dystrophies, it is likely that LCMV and potentially other arenaviruses may have selected this conserved and crucial posttranslational modification as the primary target structure for cell entry and infection.
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Affiliation(s)
- Mauro Imperiali
- Institute for Microbiology, ETH Zurich, 8093 Zürich, Switzerland
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29
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Kunz S, Rojek JM, Kanagawa M, Spiropoulou CF, Barresi R, Campbell KP, Oldstone MBA. Posttranslational modification of alpha-dystroglycan, the cellular receptor for arenaviruses, by the glycosyltransferase LARGE is critical for virus binding. J Virol 2006; 79:14282-96. [PMID: 16254363 PMCID: PMC1280193 DOI: 10.1128/jvi.79.22.14282-14296.2005] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The receptor for lymphocytic choriomeningitis virus (LCMV), the human pathogenic Lassa fever virus (LFV), and clade C New World arenaviruses is alpha-dystroglycan (alpha-DG), a cell surface receptor for proteins of the extracellular matrix (ECM). Specific posttranslational modification of alpha-DG by the glycosyltransferase LARGE is critical for its function as an ECM receptor. In the present study, we show that LARGE-dependent modification is also crucial for alpha-DG's function as a cellular receptor for arenaviruses. Virus binding involves the mucin-type domain of alpha-DG and depends on modification by LARGE. A crucial role of the LARGE-dependent glycosylation of alpha-DG for virus binding is found for several isolates of LCMV, LFV, and the arenaviruses Mobala and Oliveros. Since the posttranslational modification by LARGE is crucial for alpha-DG recognition by both arenaviruses and the host-derived ligand laminin, it also influences competition between virus and laminin for alpha-DG. Hence, LARGE-dependent glycosylation of alpha-DG has important implications for the virus-host cell interaction and the pathogenesis of LFV in humans.
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Affiliation(s)
- Stefan Kunz
- Department of Neuropharmacology, The Scripps Research Institute, La Jolla, California 92037, USA.
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30
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Parker SL, Parker MS, Sah R, Sallee F. Angiogenesis and rhodopsin-like receptors: a role for N-terminal acidic residues? Biochem Biophys Res Commun 2005; 335:983-92. [PMID: 16023616 DOI: 10.1016/j.bbrc.2005.06.158] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Accepted: 06/23/2005] [Indexed: 12/22/2022]
Abstract
Numerous rhodopsin-like G-protein coupling receptors induce or inhibit angiogenesis. The active human receptors include several chemokine receptors, apelin APJ receptor, neuropeptide Y Y2 receptor, Duffy antigen, and herpes virus-8 receptor. A common and striking feature of these receptors is the large fraction (up to 42%) of residues with anionic sidechains (Asp, Glu, and benzene anions Tyr, Trp, and Phe) in the N-terminal extracellular domain. These residues (which are frequently clustered) can assist the binding of ligand peptides, but should also support interactions that help tubular arraying of cells, e.g., via cationic bridges and/or hydrogen bonding with cell-connecting receptors such as integrins, or with proteins of the extracellular matrix.
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Affiliation(s)
- Steven L Parker
- Department of Pharmacology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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31
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Neel NF, Schutyser E, Sai J, Fan GH, Richmond A. Chemokine receptor internalization and intracellular trafficking. Cytokine Growth Factor Rev 2005; 16:637-58. [PMID: 15998596 PMCID: PMC2668263 DOI: 10.1016/j.cytogfr.2005.05.008] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Accepted: 05/03/2005] [Indexed: 01/25/2023]
Abstract
The internalization and intracellular trafficking of chemokine receptors have important implications for the cellular responses elicited by chemokine receptors. The major pathway by which chemokine receptors internalize is the clathrin-mediated pathway, but some receptors may utilize lipid rafts/caveolae-dependent internalization routes. This review discusses the current knowledge and controversies regarding these two different routes of endocytosis. The functional consequences of internalization and the regulation of chemokine receptor recycling will also be addressed. Modifications of chemokine receptors, such as palmitoylation, ubiquitination, glycosylation, and sulfation, may also impact trafficking, chemotaxis and signaling. Finally, this review will cover the internalization and trafficking of viral and decoy chemokine receptors.
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Affiliation(s)
- Nicole F Neel
- Department of Veterans Affairs Medical Center, Vanderbilt University School of Medicine, 432 PRB, 23rd Avenue South at Pierce, Nashville, TN 37232, USA.
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32
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Abstract
The third variable region, V3, of the gp120 surface envelope glycoprotein is an approximately 35-residue-long, frequently glycosylated, highly variable, disulfide-bonded structure that has a major influence on HIV-1 tropism. Thus the sequence of V3, directly or indirectly, can determine which coreceptor (CCR5 or CXCR4) is used to trigger the fusion potential of the Env complex, and hence which cells the virus can infect. V3 also influences HIV-1's sensitivity to, and ability to escape from, entry inhibitors that are being developed as antiviral drugs. For some strains, V3 is a prominent target for HIV-1 neutralizing antibodies (NAbs); indeed, for many years it was considered to be the "principal neutralization determinant" (PND). Some efforts to use V3 as a vaccine target continue to this day, despite disappointing progress over more than a decade. Recent findings on the structure, function, antigenicity, and immunogenicity of V3 cast new doubts on the value of this vaccine approach. Here, we review recent advances in the understanding of V3 as a determinant of viral tropism, and discuss how this new knowledge may inform the development of HIV-1 drugs and vaccines.
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Affiliation(s)
- Oliver Hartley
- Department of Structural Biology and Bioinformatics, Centre Medical Universitaire, Geneva, Switzerland
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