1
|
Papadopoulos N, Nédélec A, Derenne A, Şulea TA, Pecquet C, Chachoua I, Vertenoeil G, Tilmant T, Petrescu AJ, Mazzucchelli G, Iorga BI, Vertommen D, Constantinescu SN. Oncogenic CALR mutant C-terminus mediates dual binding to the thrombopoietin receptor triggering complex dimerization and activation. Nat Commun 2023; 14:1881. [PMID: 37019903 PMCID: PMC10076285 DOI: 10.1038/s41467-023-37277-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 03/04/2023] [Indexed: 04/07/2023] Open
Abstract
Calreticulin (CALR) frameshift mutations represent the second cause of myeloproliferative neoplasms (MPN). In healthy cells, CALR transiently and non-specifically interacts with immature N-glycosylated proteins through its N-terminal domain. Conversely, CALR frameshift mutants turn into rogue cytokines by stably and specifically interacting with the Thrombopoietin Receptor (TpoR), inducing its constitutive activation. Here, we identify the basis of the acquired specificity of CALR mutants for TpoR and define the mechanisms by which complex formation triggers TpoR dimerization and activation. Our work reveals that CALR mutant C-terminus unmasks CALR N-terminal domain, rendering it more accessible to bind immature N-glycans on TpoR. We further find that the basic mutant C-terminus is partially α-helical and define how its α-helical segment concomitantly binds acidic patches of TpoR extracellular domain and induces dimerization of both CALR mutant and TpoR. Finally, we propose a model of the tetrameric TpoR-CALR mutant complex and identify potentially targetable sites.
Collapse
Affiliation(s)
- Nicolas Papadopoulos
- Ludwig Institute for Cancer Research Brussels, Brussels, Belgium
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium
| | - Audrey Nédélec
- Ludwig Institute for Cancer Research Brussels, Brussels, Belgium
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium
| | - Allison Derenne
- Spectralys Biotech SRL, rue Auguste Piccard 48, 6041, Gosselies, Belgium
| | - Teodor Asvadur Şulea
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Splaiul Independentei 296, Bucharest, 060031, Romania
| | - Christian Pecquet
- Ludwig Institute for Cancer Research Brussels, Brussels, Belgium
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium
| | - Ilyas Chachoua
- Ludwig Institute for Cancer Research Brussels, Brussels, Belgium
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium
- Department of Molecular Biology and Genetics, Bilkent University, Ankara, Turkey
| | - Gaëlle Vertenoeil
- Ludwig Institute for Cancer Research Brussels, Brussels, Belgium
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium
| | - Thomas Tilmant
- Mass Spectrometry Laboratory, MolSys Research Unit, Universiy of Liège, 4000, Liège, Belgium
| | - Andrei-Jose Petrescu
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Splaiul Independentei 296, Bucharest, 060031, Romania
| | - Gabriel Mazzucchelli
- Mass Spectrometry Laboratory, MolSys Research Unit, Universiy of Liège, 4000, Liège, Belgium
| | - Bogdan I Iorga
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, Gif-sur-Yvette, France
| | - Didier Vertommen
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium
- de Duve Institute and MASSPROT platform, Brussels, Belgium
| | - Stefan N Constantinescu
- Ludwig Institute for Cancer Research Brussels, Brussels, Belgium.
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium.
- Walloon Excelence in Life Sciences and Biotechnology, WELBIO, avenue Pasteur, 6, 1300, Wavre, Belgium.
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, Oxford University, Oxford, UK.
| |
Collapse
|
2
|
Rudolph M, Wang Y, Simolka T, Huc-Claustre E, Dai L, Grotenbreg G, Besra GS, Shevchenko A, Shevchenko A, Zeissig S. Sortase A-Cleavable CD1d Identifies Sphingomyelins as Major Class of CD1d-Associated Lipids. Front Immunol 2022; 13:897873. [PMID: 35874748 PMCID: PMC9301999 DOI: 10.3389/fimmu.2022.897873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 06/06/2022] [Indexed: 11/22/2022] Open
Abstract
CD1d is an atypical MHC class I molecule which binds endogenous and exogenous lipids and can activate natural killer T (NKT) cells through the presentation of lipid antigens. CD1d surveys different cellular compartments including the secretory and the endolysosomal pathway and broadly binds lipids through its two hydrophobic pockets. Purification of the transmembrane protein CD1d for the analysis of bound lipids is technically challenging as the use of detergents releases CD1d-bound lipids. To address these challenges, we have developed a novel approach based on Sortase A-dependent enzymatic release of CD1d at the cell surface of live mammalian cells, which allows for single step release and affinity tagging of CD1d for shotgun lipidomics. Using this system, we demonstrate that CD1d carrying the Sortase A recognition motif shows unimpaired subcellular trafficking through the secretory and endolysosomal pathway and is able to load lipids in these compartments and present them to NKT cells. Comprehensive shotgun lipidomics demonstrated that the spectrum and abundance of CD1d-associated lipids is not representative of the total cellular lipidome but rather characterized by preferential binding to long chain sphingolipids and glycerophospholipids. As such, sphingomyelin species recently identified as critical negative regulators of NKT cell activation, represented the vast majority of endogenous CD1d-associated lipids. Moreover, we observed that inhibition of endolysosomal trafficking of CD1d surprisingly did not affect the spectrum of CD1d-bound lipids, suggesting that the majority of endogenous CD1d-associated lipids load onto CD1d in the secretory rather than the endolysosomal pathway. In conclusion, we present a novel system for the analysis of CD1d-bound lipids in mammalian cells and provide new insight into the spectrum of CD1d-associated lipids, with important functional implications for NKT cell activation.
Collapse
Affiliation(s)
- Maren Rudolph
- Department of Medicine I, University Medical Center Dresden, Technische Universität (TU) Dresden, Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität (TU) Dresden, Dresden, Germany
| | - Yuting Wang
- Department of Medicine I, University Medical Center Dresden, Technische Universität (TU) Dresden, Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität (TU) Dresden, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Theresa Simolka
- Department of Medicine I, University Medical Center Dresden, Technische Universität (TU) Dresden, Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität (TU) Dresden, Dresden, Germany
| | - Emilie Huc-Claustre
- Department of Medicine I, University Medical Center Dresden, Technische Universität (TU) Dresden, Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität (TU) Dresden, Dresden, Germany
| | - Lingyun Dai
- Department of Geriatrics, First Affiliated Hospital of Southern University of Science and Technology (Shenzhen People’s Hospital), Shenzhen, China
| | | | | | - Anna Shevchenko
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Andrej Shevchenko
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Sebastian Zeissig
- Department of Medicine I, University Medical Center Dresden, Technische Universität (TU) Dresden, Dresden, Germany
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität (TU) Dresden, Dresden, Germany
- *Correspondence: Sebastian Zeissig,
| |
Collapse
|
3
|
Bakshi T, Pham D, Kaur R, Sun B. Hidden Relationships between N-Glycosylation and Disulfide Bonds in Individual Proteins. Int J Mol Sci 2022; 23:ijms23073742. [PMID: 35409101 PMCID: PMC8998389 DOI: 10.3390/ijms23073742] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 03/25/2022] [Accepted: 03/28/2022] [Indexed: 02/04/2023] Open
Abstract
N-Glycosylation (NG) and disulfide bonds (DBs) are two prevalent co/post-translational modifications (PTMs) that are often conserved and coexist in membrane and secreted proteins involved in a large number of diseases. Both in the past and in recent times, the enzymes and chaperones regulating these PTMs have been constantly discovered to directly interact with each other or colocalize in the ER. However, beyond a few model proteins, how such cooperation affects N-glycan modification and disulfide bonding at selective sites in individual proteins is largely unknown. Here, we reviewed the literature to discover the current status in understanding the relationships between NG and DBs in individual proteins. Our results showed that more than 2700 human proteins carry both PTMs, and fewer than 2% of them have been investigated in the associations between NG and DBs. We summarized both these proteins with the reported relationships in the two PTMs and the tools used to discover the relationships. We hope that, by exposing this largely understudied field, more investigations can be encouraged to unveil the hidden relationships of NG and DBs in the majority of membranes and secreted proteins for pathophysiological understanding and biotherapeutic development.
Collapse
Affiliation(s)
- Tania Bakshi
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada;
| | - David Pham
- Department of Computing Science, Simon Fraser University, Burnaby, BC V5A 1S6, Canada;
| | - Raminderjeet Kaur
- Faculty of Health Science, Simon Fraser University, Burnaby, BC V5A 1S6, Canada;
| | - Bingyun Sun
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada;
- Department of Chemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
- Correspondence:
| |
Collapse
|
4
|
Molecular design of the γδT cell receptor ectodomain encodes biologically fit ligand recognition in the absence of mechanosensing. Proc Natl Acad Sci U S A 2021; 118:2023050118. [PMID: 34172580 PMCID: PMC8256041 DOI: 10.1073/pnas.2023050118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
TCR mechanosensing is thought necessary for digital sensitivity of αβT cell response to scant pMHC antigens. We use bioinformatic analysis, molecular dynamics, single-molecule optical tweezers techniques, cellular activation, and RNA-seq analysis to explore this paradigm in the γδT cell lineage. We find that, in keeping with its role in recognizing abundant cell-surface ligands, the γδTCR lacks force-dependent hallmarks of mechanosensing in αβT cells. High-acuity αβT cell receptor (TCR) recognition of peptides bound to major histocompatibility complex molecules (pMHCs) requires mechanosensing, a process whereby piconewton (pN) bioforces exert physical load on αβTCR–pMHC bonds to dynamically alter their lifetimes and foster digital sensitivity cellular signaling. While mechanotransduction is operative for both αβTCRs and pre-TCRs within the αβT lineage, its role in γδT cells is unknown. Here, we show that the human DP10.7 γδTCR specific for the sulfoglycolipid sulfatide bound to CD1d only sustains a significant load and undergoes force-induced structural transitions when the binding interface-distal γδ constant domain (C) module is replaced with that of αβ. The chimeric γδ–αβTCR also signals more robustly than does the wild-type (WT) γδTCR, as revealed by RNA-sequencing (RNA-seq) analysis of TCR-transduced Rag2−/− thymocytes, consistent with structural, single-molecule, and molecular dynamics studies reflective of γδTCRs as mediating recognition via a more canonical immunoglobulin-like receptor interaction. Absence of robust, force-related catch bonds, as well as γδTCR structural transitions, implies that γδT cells do not use mechanosensing for ligand recognition. This distinction is consonant with the fact that their innate-type ligands, including markers of cellular stress, are expressed at a high copy number relative to the sparse pMHC ligands of αβT cells arrayed on activating target cells. We posit that mechanosensing emerged over ∼200 million years of vertebrate evolution to fulfill indispensable adaptive immune recognition requirements for pMHC in the αβT cell lineage that are unnecessary for the γδT cell lineage mechanism of non-pMHC ligand detection.
Collapse
|
5
|
Manica G, Ghenea S, Munteanu CVA, Martin EC, Butnaru C, Surleac M, Chiritoiu GN, Alexandru PR, Petrescu AJ, Petrescu SM. EDEM3 Domains Cooperate to Perform Its Overall Cell Functioning. Int J Mol Sci 2021; 22:2172. [PMID: 33671632 PMCID: PMC7926307 DOI: 10.3390/ijms22042172] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 02/15/2021] [Accepted: 02/19/2021] [Indexed: 01/20/2023] Open
Abstract
EDEM3 recognizes and directs misfolded proteins to the ER-associated protein degradation (ERAD) process. EDEM3 was predicted to act as lectin or as a mannosidase because of its homology with the GH47 catalytic domain of the Man1B1, but the contribution of the other regions remained unresolved. Here, we dissect the molecular determinants governing EDEM3 function and its cellular interactions. LC/MS analysis indicates very few stable ER interactors, suggesting EDEM3 availability for transient substrate interactions. Sequence analysis reveals that EDEM3 consists of four consecutive modules defined as GH47, intermediate (IMD), protease-associated (PA), and intrinsically disordered (IDD) domain. Using an EDEM3 knock-out cell line, we expressed EDEM3 and domain deletion mutants to address EDEM3 function. We find that the mannosidase domain provides substrate binding even in the absence of mannose trimming and requires the IMD domain for folding. The PA and IDD domains deletions do not impair the trimming, but specifically modulate the turnover of two misfolded proteins, NHK and the soluble tyrosinase mutant. Hence, we demonstrate that EDEM3 provides a unique ERAD timing to misfolded glycoproteins, not only by its mannose trimming activity, but also by the positive and negative feedback modulated by the protease-associated and intrinsically disordered domain, respectively.
Collapse
Affiliation(s)
- Georgiana Manica
- Department of Molecular Cell Biology, Institute of Biochemistry, Splaiul Independentei 296, 060031 Bucharest 17, Romania; (G.M.); (S.G.); (G.N.C.); (P.R.A.)
| | - Simona Ghenea
- Department of Molecular Cell Biology, Institute of Biochemistry, Splaiul Independentei 296, 060031 Bucharest 17, Romania; (G.M.); (S.G.); (G.N.C.); (P.R.A.)
| | - Cristian V. A. Munteanu
- Department of Bioinformatics and Structural Biochemistry, Splaiul Independentei 296, 060031 Bucharest 17, Romania; (C.V.A.M.); (E.C.M.); (C.B.); (M.S.); (A.-J.P.)
| | - Eliza C. Martin
- Department of Bioinformatics and Structural Biochemistry, Splaiul Independentei 296, 060031 Bucharest 17, Romania; (C.V.A.M.); (E.C.M.); (C.B.); (M.S.); (A.-J.P.)
| | - Cristian Butnaru
- Department of Bioinformatics and Structural Biochemistry, Splaiul Independentei 296, 060031 Bucharest 17, Romania; (C.V.A.M.); (E.C.M.); (C.B.); (M.S.); (A.-J.P.)
| | - Marius Surleac
- Department of Bioinformatics and Structural Biochemistry, Splaiul Independentei 296, 060031 Bucharest 17, Romania; (C.V.A.M.); (E.C.M.); (C.B.); (M.S.); (A.-J.P.)
- Research Institute of the University of Bucharest, 030018 Bucharest 17, Romania
| | - Gabriela N. Chiritoiu
- Department of Molecular Cell Biology, Institute of Biochemistry, Splaiul Independentei 296, 060031 Bucharest 17, Romania; (G.M.); (S.G.); (G.N.C.); (P.R.A.)
| | - Petruta R. Alexandru
- Department of Molecular Cell Biology, Institute of Biochemistry, Splaiul Independentei 296, 060031 Bucharest 17, Romania; (G.M.); (S.G.); (G.N.C.); (P.R.A.)
| | - Andrei-Jose Petrescu
- Department of Bioinformatics and Structural Biochemistry, Splaiul Independentei 296, 060031 Bucharest 17, Romania; (C.V.A.M.); (E.C.M.); (C.B.); (M.S.); (A.-J.P.)
| | - Stefana M. Petrescu
- Department of Molecular Cell Biology, Institute of Biochemistry, Splaiul Independentei 296, 060031 Bucharest 17, Romania; (G.M.); (S.G.); (G.N.C.); (P.R.A.)
| |
Collapse
|
6
|
Spiridon L, Şulea TA, Minh DDL, Petrescu AJ. Robosample: A rigid-body molecular simulation program based on robot mechanics. Biochim Biophys Acta Gen Subj 2020; 1864:129616. [PMID: 32298789 DOI: 10.1016/j.bbagen.2020.129616] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 03/18/2020] [Accepted: 04/08/2020] [Indexed: 11/26/2022]
Abstract
BACKGROUND Compared with all-atom molecular dynamics (MD), constrained MD methods allow for larger time steps, potentially reducing computational cost. For this reason, there has been continued interest in improving constrained MD algorithms to increase configuration space sampling in molecular simulations. METHODS Here, we introduce Robosample, a software package that implements high-performance constrained dynamics algorithms, originally developed for robotics, and applies them to simulations of biomolecular systems. As in the gMolmodel package developed by Spiridon and Minh in 2017, Robosample uses Constrained Dynamics Hamiltonian Monte Carlo (CDHMC) as a Gibbs sampling move - a type of Monte Carlo move where a subset of coordinates is allowed to change. In addition to the previously described Cartesian and torsional dynamics moves, Robosample implements spherical and cylindrical joints that can be distributed along the molecule by the user. RESULTS In alanine dipeptide simulations, the free energy surface is recovered by mixing fully flexible with torsional, cylindrical, or spherical dynamics moves. Ramachandran dynamics, where only the two key torsions are mobile, accelerate the slowest transition by an order of magnitude. We also show that simulations of a complex glycan cover significantly larger regions of the configuration space when mixed with constrained dynamics. MAJOR CONCLUSIONS Robosample is a tool of choice for efficient conformational sampling of large biomolecules. GENERAL SIGNIFICANCE Robosample is intended as a reliable and user-friendly simulation package for fast biomolecular sampling that does not require extensive expertise in mechanical engineering or in the statistical mechanics of reduced coordinates.
Collapse
Affiliation(s)
- Laurentiu Spiridon
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Splaiul Independentei 296, Bucharest 060031, Romania.
| | - Teodor Asvadur Şulea
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Splaiul Independentei 296, Bucharest 060031, Romania
| | - David D L Minh
- Department of Chemistry, Illinois Institute of Technology, Chicago, IL 60616, USA.
| | - Andrei-Jose Petrescu
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Splaiul Independentei 296, Bucharest 060031, Romania.
| |
Collapse
|
7
|
Shamin M, Benedyk TH, Graham SC, Deane JE. The lipid transfer protein Saposin B does not directly bind CD1d for lipid antigen loading. Wellcome Open Res 2019; 4:117. [PMID: 31667358 PMCID: PMC6807164 DOI: 10.12688/wellcomeopenres.15368.2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2019] [Indexed: 12/13/2022] Open
Abstract
Background: Lipid antigens are presented on the surface of cells by the CD1 family of glycoproteins, which have structural and functional similarity to MHC class I molecules. The hydrophobic lipid antigens are embedded in membranes and inaccessible to the lumenal lipid-binding domain of CD1 molecules. Therefore, CD1 molecules require lipid transfer proteins for lipid loading and editing. CD1d is loaded with lipids in late endocytic compartments, and lipid transfer proteins of the saposin family have been shown to play a crucial role in this process. However, the mechanism by which saposins facilitate lipid binding to CD1 molecules is not known and is thought to involve transient interactions between protein components to ensure CD1-lipid complexes can be efficiently trafficked to the plasma membrane for antigen presentation. Of the four saposin proteins, the importance of Saposin B (SapB) for loading of CD1d is the most well-characterised. However, a direct interaction between CD1d and SapB has yet to be described. Methods: In order to determine how SapB might load lipids onto CD1d, we used purified, recombinant CD1d and SapB and carried out a series of highly sensitive binding assays to monitor direct interactions. We performed equilibrium binding analysis, chemical cross-linking and co-crystallisation experiments, under a range of different conditions. Results: We could not demonstrate a direct interaction between SapB and CD1d using any of these binding assays. Conclusions: This work strongly indicates that the role of SapB in lipid loading does not involve direct binding to CD1d. We discuss the implication of this for our understanding of lipid loading of CD1d and propose several factors that may influence this process.
Collapse
Affiliation(s)
- Maria Shamin
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Tomasz H. Benedyk
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Stephen C. Graham
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Janet E. Deane
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK
| |
Collapse
|
8
|
Shamin M, Benedyk TH, Graham SC, Deane JE. The lipid transfer protein Saposin B does not directly bind CD1d for lipid antigen loading. Wellcome Open Res 2019; 4:117. [PMID: 31667358 PMCID: PMC6807164 DOI: 10.12688/wellcomeopenres.15368.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2019] [Indexed: 10/15/2023] Open
Abstract
Background: Lipid antigens are presented on the surface of cells by the CD1 family of glycoproteins, which have structural and functional similarity to MHC class I molecules. The hydrophobic lipid antigens are embedded in membranes and inaccessible to the lumenal lipid-binding domain of CD1 molecules. Therefore, CD1 molecules require lipid transfer proteins for lipid loading and editing. CD1d is loaded with lipids in late endocytic compartments, and lipid transfer proteins of the saposin family have been shown to play a crucial role in this process. However, the mechanism by which saposins facilitate lipid binding to CD1 molecules is not known and is thought to involve transient interactions between protein components to ensure CD1-lipid complexes can be efficiently trafficked to the plasma membrane for antigen presentation. Of the four saposin proteins, the importance of Saposin B (SapB) for loading of CD1d is the most well-characterised. However, a direct interaction between CD1d and SapB has yet to be described. Methods: In order to determine how SapB might load lipids onto CD1d, we used purified, recombinant CD1d and SapB and carried out a series of highly sensitive binding assays to monitor direct interactions. We performed equilibrium binding analysis, chemical cross-linking and co-crystallisation experiments, under a range of different conditions. Results: We could not demonstrate a direct interaction between SapB and CD1d using any of these binding assays. Conclusions: This work establishes comprehensively that the role of SapB in lipid loading does not involve direct binding to CD1d. We discuss the implication of this for our understanding of lipid loading of CD1d and propose several factors that may influence this process.
Collapse
Affiliation(s)
- Maria Shamin
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Tomasz H. Benedyk
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Stephen C. Graham
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Janet E. Deane
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK
| |
Collapse
|
9
|
Gram AM, Oosenbrug T, Lindenbergh MFS, Büll C, Comvalius A, Dickson KJI, Wiegant J, Vrolijk H, Lebbink RJ, Wolterbeek R, Adema GJ, Griffioen M, Heemskerk MHM, Tscharke DC, Hutt-Fletcher LM, Wiertz EJHJ, Hoeben RC, Ressing ME. The Epstein-Barr Virus Glycoprotein gp150 Forms an Immune-Evasive Glycan Shield at the Surface of Infected Cells. PLoS Pathog 2016; 12:e1005550. [PMID: 27077376 PMCID: PMC4831753 DOI: 10.1371/journal.ppat.1005550] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 03/14/2016] [Indexed: 12/15/2022] Open
Abstract
Cell-mediated immunity plays a key role in host control of viral infection. This is exemplified by life-threatening reactivations of e.g. herpesviruses in individuals with impaired T-cell and/or iNKT cell responses. To allow lifelong persistence and virus production in the face of primed immunity, herpesviruses exploit immune evasion strategies. These include a reduction in viral antigen expression during latency and a number of escape mechanisms that target antigen presentation pathways. Given the plethora of foreign antigens expressed in virus-producing cells, herpesviruses are conceivably most vulnerable to elimination by cell-mediated immunity during the replicative phase of infection. Here, we show that a prototypic herpesvirus, Epstein-Barr virus (EBV), encodes a novel, broadly acting immunoevasin, gp150, that is expressed during the late phase of viral replication. In particular, EBV gp150 inhibits antigen presentation by HLA class I, HLA class II, and the non-classical, lipid-presenting CD1d molecules. The mechanism of gp150-mediated T-cell escape does not depend on degradation of the antigen-presenting molecules nor does it require gp150’s cytoplasmic tail. Through its abundant glycosylation, gp150 creates a shield that impedes surface presentation of antigen. This is an unprecedented immune evasion mechanism for herpesviruses. In view of its likely broader target range, gp150 could additionally have an impact beyond escape of T cell activation. Importantly, B cells infected with a gp150-null mutant EBV displayed rescued levels of surface antigen presentation by HLA class I, HLA class II, and CD1d, supporting an important role for iNKT cells next to classical T cells in fighting EBV infection. At the same time, our results indicate that EBV gp150 prolongs the timespan for producing viral offspring at the most vulnerable stage of the viral life cycle. The human herpesvirus Epstein-Barr virus (EBV) is an important human pathogen involved in infectious mononucleosis and several malignant tumors, including lymphomas in the immunosuppressed. Upon primary infection, a balance between virus and host is established, to which EBV’s capacity to dodge T cell-mediated attack contributes. Here we identify the late protein EBV gp150 as a novel immunoevasin, frustrating antigen presentation by HLA class I, class II, and CD1d molecules. EBV gp150’s many sialoglycans create a shield impeding surface detection of presented antigen. Interestingly, exploiting glycan shielding as a mechanism to mask surface exposed proteins on infected cells could permit EBV to additionally modulate other aspects of host antiviral defense. B cells producing wild-type EBV escaped immune recognition more efficiently than those infected with a gp150-null virus, pointing towards a role for gp150 in natural infection. Our results reveal a novel, broadly active strategy by which a herpesvirus glycoprotein, EBV gp150, blocks antigen presentation to T cells through glycan shielding, a new paradigm in herpesvirus immune evasion.
Collapse
Affiliation(s)
- Anna M. Gram
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Timo Oosenbrug
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Christian Büll
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Anouskha Comvalius
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Kathryn J. I. Dickson
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Joop Wiegant
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Hans Vrolijk
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Robert Jan Lebbink
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Ron Wolterbeek
- Department of Medical Statistics & Bioinformatics, Leiden University Medical Center, Leiden, The Netherlands
| | - Gosse J. Adema
- Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Marieke Griffioen
- Department of Hematology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - David C. Tscharke
- John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Lindsey M. Hutt-Fletcher
- Department of Microbiology and Immunology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | | | - Rob C. Hoeben
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Maaike E. Ressing
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
- * E-mail:
| |
Collapse
|
10
|
Abstract
Over the past 15 years, investigators have shown that T lymphocytes can recognize not only peptides in the context of MHC class I and class II molecules but also foreign and self-lipids in association with the nonclassical MHC class I-like molecules, CD1 proteins. In this review, we describe the most recent events in the field, with particular emphasis on (a) structural and functional aspects of lipid presentation by CD1 molecules, (b) the development of CD1d-restricted invariant natural killer T (iNKT) cells and transcription factors required for their differentiation, (c) the ability of iNKT cells to modulate innate and adaptive immune responses through their cross talk with lymphoid and myeloid cells, and (d) MR1-restricted and group I (CD1a, CD1b, and CD1c)-restricted T cells.
Collapse
Affiliation(s)
- Mariolina Salio
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DU, United Kingdom;
| | | | | | | |
Collapse
|
11
|
Kunte A, Zhang W, Paduraru C, Veerapen N, Cox LR, Besra GS, Cresswell P. Endoplasmic reticulum glycoprotein quality control regulates CD1d assembly and CD1d-mediated antigen presentation. J Biol Chem 2013; 288:16391-16402. [PMID: 23615906 PMCID: PMC3675576 DOI: 10.1074/jbc.m113.474221] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The non-classical major histocompatibility complex (MHC) homologue CD1d presents lipid antigens to innate-like lymphocytes called natural-killer T (NKT) cells. These cells, by virtue of their broad cytokine repertoire, shape innate and adaptive immune responses. Here, we have assessed the role of endoplasmic reticulum glycoprotein quality control in CD1d assembly and function, specifically the role of a key component of the quality control machinery, the enzyme UDP glucose glycoprotein glucosyltransferase (UGT1). We observe that in UGT1-deficient cells, CD1d associates prematurely with β2-microglobulin (β2m) and is able to rapidly exit the endoplasmic reticulum. At least some of these CD1d-β2m heterodimers are shorter-lived and can be rescued by provision of a defined exogenous antigen, α-galactosylceramide. Importantly, we show that in UGT1-deficient cells the CD1d-β2m heterodimers have altered antigenicity despite the fact that their cell surface levels are unchanged. We propose that UGT1 serves as a quality control checkpoint during CD1d assembly and further suggest that UGT1-mediated quality control can shape the lipid repertoire of newly synthesized CD1d. The quality control process may play a role in ensuring stability of exported CD1d-β2m complexes, in facilitating presentation of low abundance high affinity antigens, or in preventing deleterious responses to self lipids.
Collapse
Affiliation(s)
- Amit Kunte
- Section of Infectious Diseases, Department of Internal Medicine, New Haven, Connecticut 06520-8011
| | - Wei Zhang
- Department of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520-8011
| | - Crina Paduraru
- Department of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520-8011
| | - Natacha Veerapen
- School of Biosciences, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Liam R Cox
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Gurdyal S Besra
- School of Biosciences, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Peter Cresswell
- Department of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520-8011.
| |
Collapse
|
12
|
Marin MB, Ghenea S, Spiridon LN, Chiritoiu GN, Petrescu AJ, Petrescu SM. Tyrosinase degradation is prevented when EDEM1 lacks the intrinsically disordered region. PLoS One 2012; 7:e42998. [PMID: 22905195 PMCID: PMC3414498 DOI: 10.1371/journal.pone.0042998] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 07/16/2012] [Indexed: 01/08/2023] Open
Abstract
EDEM1 is a mannosidase-like protein that recruits misfolded glycoproteins from the calnexin/calreticulin folding cycle to downstream endoplasmic reticulum associated degradation (ERAD) pathway. Here, we investigate the role of EDEM1 in the processing of tyrosinase, a tumour antigen overexpressed in melanoma cells. First, we analyzed and modeled EDEM1 major domains. The homology model raised on the crystal structures of human and Saccharomyces cerevisiae ER class I α1,2-mannosidases reveals that the major mannosidase domain located between aminoacids 121-598 fits with high accuracy. We have further identified an N-terminal region located between aminoacids 40-119, predicted to be intrinsically disordered (ID) and susceptible to adopt multiple conformations, hence facilitating protein-protein interactions. To investigate these two domains we have constructed an EDEM1 deletion mutant lacking the ID region and a triple mutant disrupting the glycan-binding domain and analyzed their association with tyrosinase. Tyrosinase is a glycoprotein partly degraded endogenously by ERAD and the ubiquitin proteasomal system. We found that the degradation of wild type and misfolded tyrosinase was enhanced when EDEM1 was overexpressed. Glycosylated and non-glycosylated mutants co-immunoprecipitated with EDEM1 even in the absence of its intact mannosidase-like domain, but not when the ID region was deleted. In contrast, calnexin and SEL 1L associated with the deletion mutant. Our data suggest that the ID region identified in the N-terminal end of EDEM1 is involved in the binding of glycosylated and non-glycosylated misfolded proteins. Accelerating tyrosinase degradation by EDEM1 overexpression may lead to an efficient antigen presentation and enhanced elimination of melanoma cells.
Collapse
Affiliation(s)
- Marioara B. Marin
- Department of Molecular Cell Biology, Institute of Biochemistry of Romanian Academy, Bucharest, Romania
| | - Simona Ghenea
- Department of Molecular Cell Biology, Institute of Biochemistry of Romanian Academy, Bucharest, Romania
| | - Laurentiu N. Spiridon
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of Romanian Academy, Bucharest, Romania
| | - Gabriela N. Chiritoiu
- Department of Molecular Cell Biology, Institute of Biochemistry of Romanian Academy, Bucharest, Romania
| | - Andrei-Jose Petrescu
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of Romanian Academy, Bucharest, Romania
- * E-mail: (SMP); (AJP)
| | - Stefana-Maria Petrescu
- Department of Molecular Cell Biology, Institute of Biochemistry of Romanian Academy, Bucharest, Romania
- * E-mail: (SMP); (AJP)
| |
Collapse
|
13
|
Ryan SO, Cobb BA. Roles for major histocompatibility complex glycosylation in immune function. Semin Immunopathol 2012; 34:425-41. [PMID: 22461020 DOI: 10.1007/s00281-012-0309-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 03/05/2012] [Indexed: 12/22/2022]
Abstract
The major histocompatibility complex (MHC) glycoprotein family, also referred to as human leukocyte antigens, present endogenous and exogenous antigens to T lymphocytes for recognition and response. These molecules play a central role in enabling the immune system to distinguish self from non-self, which is the basis for protective immunity against pathogenic infections and disease while at the same time representing a serious obstacle for tissue transplantation. All known MHC family members, like the majority of secreted, cell surface, and other immune-related molecules, carry asparagine (N)-linked glycans. The immune system has evolved increasing complexity in higher-order organisms along with a more complex pattern of protein glycosylation, a relationship that may contribute to immune function beyond the early protein quality control events in the endoplasmic reticulum that are commonly known. The broad MHC family maintains peptide sequence motifs for glycosylation at sites that are highly conserved across evolution, suggesting importance, yet functional roles for these glycans remain largely elusive. In this review, we will summarize what is known about MHC glycosylation and provide new insight for additional functional roles for this glycoprotein modification in mediating immune responses.
Collapse
Affiliation(s)
- Sean O Ryan
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | | |
Collapse
|
14
|
Shrestha D, Szöllosi J, Jenei A. Bare lymphocyte syndrome: an opportunity to discover our immune system. Immunol Lett 2011; 141:147-57. [PMID: 22027563 DOI: 10.1016/j.imlet.2011.10.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 09/30/2011] [Accepted: 10/11/2011] [Indexed: 11/27/2022]
Abstract
Bare lymphocyte syndrome (BLS) is a rare immunodeficiency disorder manifested by the partial or complete disappearance of major histocompatibility complex (MHC) proteins from the surface of the cells. Based on this specific feature, it is categorized into three different types depending on which type of MHC protein is affected. These proteins are mainly involved in generating the effective immune responses by differentiating 'self' from 'non-self' antigens through a process referred to as antigen presentation. Investigations on BLS have immensely contributed to our understanding of the transcriptional regulation of these molecules and have led to the discovery of several important proteins of the antigen presentation pathway. Reviews on this subject consistently project type II BLS, MHC II deficiency as BLS syndrome, although literatures' document cases of other types of BLS too. Therefore, in this article, we have assembled information on the BLS syndrome to produce a systematic narration while emphasizing the importance of BLS system in studying various aspects of immune biology.
Collapse
Affiliation(s)
- Dilip Shrestha
- Department of Biophysics and Cell Biology, Medical and Health Science Center, University of Debrecen, Nagyerdei krt 98, Debrecen 4032, Hungary
| | | | | |
Collapse
|
15
|
Herpes simplex virus 1 glycoprotein B and US3 collaborate to inhibit CD1d antigen presentation and NKT cell function. J Virol 2011; 85:8093-104. [PMID: 21653669 DOI: 10.1128/jvi.02689-10] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Herpes simplex viruses (HSVs) are prevalent human pathogens that establish latency in human neuronal cells and efficiently evade the immune system. It has been a major medical challenge to eradicate them and, despite intensive efforts, an effective vaccine is not available. We previously showed that upon infection of antigen-presenting cells, HSV type 1 (HSV-1) rapidly and efficiently downregulates the major histocompatibility complex class I-like antigen-presenting molecule, CD1d, and potently inhibits its recognition by CD1d-restricted natural killer T (NKT) cells. It suppresses CD1d expression primarily by inhibiting its recycling to the cell surface after endocytosis. We identify here the viral glycoprotein B (gB) as the predominant CD1d-interacting protein. gB initiates the interaction with CD1d in the endoplasmic reticulum and stably associates with it throughout CD1d trafficking. However, an additional HSV-1 component, the serine-threonine kinase US3, is required for optimal CD1d downregulation. US3 expression in infected cells leads to gB enrichment in the trans-Golgi network (TGN) and enhances the relocalization of both gB and CD1d to this compartment, suggesting that following internalization CD1d is translocated from the endocytic pathway to the TGN by its association with gB. Importantly, both US3 and gB are required for efficient inhibition of CD1d antigen presentation and NKT cell activation. In summary, our results suggest that HSV-1 uses gB and US3 to rapidly inhibit NKT cell function in the initial antiviral response.
Collapse
|
16
|
C-terminus glycans with critical functional role in the maturation of secretory glycoproteins. PLoS One 2011; 6:e19979. [PMID: 21625599 PMCID: PMC3097235 DOI: 10.1371/journal.pone.0019979] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 04/21/2011] [Indexed: 02/07/2023] Open
Abstract
The N-glycans of membrane glycoproteins are mainly exposed to the extracellular space. Human tyrosinase is a transmembrane glycoprotein with six or seven bulky N-glycans exposed towards the lumen of subcellular organelles. The central active site region of human tyrosinase is modeled here within less than 2.5 Å accuracy starting from Streptomyces castaneoglobisporus tyrosinase. The model accounts for the last five C-terminus glycosylation sites of which four are occupied and indicates that these cluster in two pairs--one in close vicinity to the active site and the other on the opposite side. We have analyzed and compared the roles of all tyrosinase N-glycans during tyrosinase processing with a special focus on the proximal to the active site N-glycans, s6:N337 and s7:N371, versus s3:N161 and s4:N230 which decorate the opposite side of the domain. To this end, we have constructed mutants of human tyrosinase in which its seven N-glycosylation sites were deleted. Ablation of the s6:N337 and s7:N371 sites arrests the post-translational productive folding process resulting in terminally misfolded mutants subjected to degradation through the mannosidase driven ERAD pathway. In contrast, single mutants of the other five N-glycans located either opposite to the active site or into the N-terminus Cys1 extension of tyrosinase are temperature-sensitive mutants and recover enzymatic activity at the permissive temperature of 31°C. Sites s3 and s4 display selective calreticulin binding properties. The C-terminus sites s7 and s6 are critical for the endoplasmic reticulum retention and intracellular disposal. Results herein suggest that individual N-glycan location is critical for the stability, regional folding control and secretion of human tyrosinase and explains some tyrosinase gene missense mutations associated with oculocutaneous albinism type I.
Collapse
|
17
|
Zhu Y, Zhang W, Veerapen N, Besra G, Cresswell P. Calreticulin controls the rate of assembly of CD1d molecules in the endoplasmic reticulum. J Biol Chem 2010; 285:38283-92. [PMID: 20861015 PMCID: PMC2992262 DOI: 10.1074/jbc.m110.170530] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
CD1d is an MHC class I-like molecule comprised of a transmembrane glycoprotein (heavy chain) associated with β2-microglobulin (β2m) that presents lipid antigens to NKT cells. Initial folding of the heavy chain involves its glycan-dependent association with calreticulin (CRT), calnexin (CNX), and the thiol oxidoreductase ERp57, and is followed by assembly with β2m to form the heterodimer. Here we show that in CRT-deficient cells CD1d heavy chains convert to β2m-associated dimers at an accelerated rate, indicating faster folding of the heavy chain, while the rate of intracellular transport after assembly is unaffected. Unlike the situation with MHC class I molecules, antigen presentation by CD1d is not impaired in the absence of CRT. Instead, there are elevated levels of stable and functional CD1d on the surface of CRT-deficient cells. Association of the heavy chains with the ER chaperones Grp94 and Bip is observed in the absence of CRT, and these may replace CRT in mediating CD1d folding and assembly. ER retention of free CD1d heavy chains is impaired in CRT-deficient cells, allowing their escape and subsequent expression on the plasma membrane. However, these free heavy chains are rapidly internalized and degraded in lysosomes, indicating that β2m association is required for the exceptional resistance of CD1d to lysosomal degradation that is normally observed.
Collapse
Affiliation(s)
- Yajuan Zhu
- Department of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520-8011, USA
| | | | | | | | | |
Collapse
|
18
|
Liu J, Shaji D, Cho S, Du W, Gervay-Hague J, Brutkiewicz RR. A threonine-based targeting signal in the human CD1d cytoplasmic tail controls its functional expression. THE JOURNAL OF IMMUNOLOGY 2010; 184:4973-81. [PMID: 20368272 DOI: 10.4049/jimmunol.0901448] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CD1d molecules are MHC class I-like molecules that present lipids to a unique subpopulation of T cells called NKT cells. The cytoplasmic tail of human CD1d possesses a tyrosine-based endosomal targeting motif (YXXZ). As such, these molecules traffic through the endocytic pathway, where it is believed that they are loaded with the antigenic lipid that stimulates NKT cells. In the current study, it was found that the T322 residue in the human CD1d tail is a major signal controlling transport to the cell surface and thus its functional expression. Mimicking the phosphorylation of this residue or removal of the entire cytoplasmic tail negates its ability to regulate CD1d trafficking, resulting in lysosomal targeting and degradation. These results demonstrate an important role of a heretofore unknown signal in the cytoplasmic tail of CD1d that may have relevance to other type I integral membrane proteins that traverse through the endocytic pathway.
Collapse
Affiliation(s)
- Jianyun Liu
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | | | | | | | | | | |
Collapse
|
19
|
De Libero G, Collmann A, Mori L. The cellular and biochemical rules of lipid antigen presentation. Eur J Immunol 2009; 39:2648-56. [PMID: 19728312 DOI: 10.1002/eji.200939425] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The recognition of both protein and lipid antigens follows similar strategies that rely on different molecular mechanisms. APC present lipid antigens exploiting the same mechanisms implicated in lipid translocation, lipoprotein assembly and lipid degradation. An important issue is how the lipid structure contributes to antigenicity. Lipid hydrophobicity influences the modes of internalization by APC, the trafficking through different membrane compartments, the binding to CD1 molecules and the stability of antigenic complexes. Some glycolipids with large hydrophilic parts require processing of the sugar moieties exerted by lysosomal hydrolases. Finally, extraction of lipids from membranes, their solubilization and loading on CD1 molecules are facilitated by the same lysosomal lipid-binding proteins that are also instrumental in lipid catabolism. More recent investigations reveal how lipid-specific immunity is regulated during infections. In this review we describe the main cellular and biochemical rules of lipid antigen presentation and discuss their implications in anti-microbial and autoimmune responses.
Collapse
Affiliation(s)
- Gennaro De Libero
- Experimental Immunology, Department of Biomedicine, University Hospital Basel, 4031 Basel, Switzerland.
| | | | | |
Collapse
|
20
|
Abstract
A crucial role has been suggested for invariant natural killer T cells (iNKT) in regulating the development of asthma, a complex and heterogeneous disease characterized by airway inflammation and airway hyperreactivity (AHR). iNKT cells constitute a unique subset of T cells responding to endogenous and exogenous lipid antigens, rapidly secreting a large amount of cytokines, which amplify both innate and adaptive immunity. Herein, we review recent studies showing a requirement for iNKT cells in various models of asthma in mice and monkeys as well as studies in human patients. Surprisingly, in several different murine models of asthma, distinct subsets of iNKT cells were required, suggesting that iNKT cells serve as a common critical pathogenic element for many different forms of asthma. The importance of iNKT cells in both allergic and non-allergic forms of asthma, which are independent of adaptive immunity and associated with airway neutrophils, may explain situations previously found to be incompatible with the Th2 paradigm of asthma.
Collapse
|
21
|
Sikder H, Zhao Y, Balato A, Chapoval A, Fishelevich R, Gade P, Singh IS, Kalvakolanu DV, Johnson PF, Gaspari AA. A central role for transcription factor C/EBP-beta in regulating CD1d gene expression in human keratinocytes. THE JOURNAL OF IMMUNOLOGY 2009; 183:1657-66. [PMID: 19592659 DOI: 10.4049/jimmunol.0900057] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CD1d is a nonclassical Ag-presenting molecule that presents glycolipid Ags to NKT cells that are involved in immune defense and tumor rejection. It also plays a role in immunoregulatory functions in the epidermis. The mechanisms controlling the expression of CD1d are not well understood. Therefore, we cloned the CD1d gene promoter and characterized its activities in primary human keratinocytes and other cell lines of epithelial origin. We found that a CCAAT box in the CD1d promoter is required for its expression in keratinocytes. We show here that transcription factor C/EBP-beta binds to the CCAAT box in the CD1d promoter in vitro and in vivo. Consistent with these observations, deletion of the gene encoding for C/EBP-beta caused a loss of CD1d expression. The in vivo regulation of CD1d has significant implications for the pathologic mechanisms of certain immunologic skin diseases in which NKT cells play a role, such as allergic contact dermatitis and psoriasis. Together, these data show a central role for C/EBP-beta in regulating CD1d transcription.
Collapse
Affiliation(s)
- Hashmat Sikder
- Department of Dermatology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Yuan W, Kang SJ, Evans JE, Cresswell P. Natural lipid ligands associated with human CD1d targeted to different subcellular compartments. THE JOURNAL OF IMMUNOLOGY 2009; 182:4784-91. [PMID: 19342656 DOI: 10.4049/jimmunol.0803981] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CD1d is an MHC class I-like membrane glycoprotein that presents lipid Ags to NKT cells. Despite intensive biochemical, genetic, and structural studies, the endogenous lipids associated with CD1d remain poorly defined because of the biochemical challenges posed by their hydrophobic nature. In this study, we report the generation of a protease-cleavable CD1d variant with a similar trafficking pattern to wild-type CD1d that can be purified in the absence of detergent and allows the characterization of the naturally associated lipids. In addition, we used soluble variants of CD1d that are secreted or retained in the endoplasmic reticulum (ER) to survey their acquired lipids. By using multiple mass spectrometry methods, we found that CD1d retained in the ER is predominantly loaded with the most abundant phospholipid in the cell, phosphatidyl choline, while the protease cleavable version of CD1d contains bound sphingomyelin and lysophospholipids in addition to phosphatidyl choline. The secreted soluble version of CD1d, in contrast, lacks detectable phosphatidyl choline and the only detectable associated lipid is sphingomyelin. The data suggest that, in the absence of infection or stress, CD1d molecules survey the ER, the secretory pathway, and the endocytic pathway, and accumulate the most abundantly available lipids present in these compartments.
Collapse
Affiliation(s)
- Weiming Yuan
- Department of Immunobiology and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520-8011, USA
| | | | | | | |
Collapse
|
23
|
|
24
|
Silk JD, Salio M, Brown J, Jones EY, Cerundolo V. Structural and functional aspects of lipid binding by CD1 molecules. Annu Rev Cell Dev Biol 2008; 24:369-95. [PMID: 18593354 DOI: 10.1146/annurev.cellbio.24.110707.175359] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Over the past ten years, investigators have shown that T lymphocytes can recognize not only peptides in the context of MHC class I and class II molecules but also foreign and self-lipids in association with the nonclassical MHC class I molecules the CD1 proteins. We describe the events that have led to the discovery of the role of CD1 molecules, their pattern of intracellular trafficking, and their ability to sample different intracellular compartments for self- and foreign lipids. Structural and functional aspects of lipid presentation by CD1 molecules are presented in the context of the function of CD1-restricted T cells in antimicrobial responses, antitumor immunity, and the regulation of the tolerance and autoimmunity immunoregulatory axis. Particular emphasis is on invariant NKT (iNKT) cells and their ability to modulate innate and adaptive immune responses.
Collapse
Affiliation(s)
- Jonathan D Silk
- Tumour Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | | | | | | | | |
Collapse
|
25
|
Yuan W, Qi X, Tsang P, Kang SJ, Illarionov PA, Besra GS, Gumperz J, Cresswell P. Saposin B is the dominant saposin that facilitates lipid binding to human CD1d molecules. Proc Natl Acad Sci U S A 2007; 104:5551-6. [PMID: 17372201 PMCID: PMC1838443 DOI: 10.1073/pnas.0700617104] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
CD1d molecules bind lipid antigens in the endocytic pathway, and access to the pathway is important for the development of CD1d-restricted natural killer T (NKT) cells. Saposins, derived from a common precursor, prosaposin, are small, heat-stable lysosomal glycoproteins required for lysosomal degradation of sphingolipids. Expression of prosaposin is required for efficient lipid binding and recognition of human CD1d molecules by NKT cells. Despite high sequence homology among the four saposins, they have different specificities for lipid substrates and different mechanisms of action. To determine the saposins involved in promoting lipid binding to CD1d, we expressed prosaposin deletion mutants lacking individual saposins in prosaposin-negative, CD1d-positive cells. No individual saposin proved to be absolutely essential, but the absence of saposin B resulted in the lowest recognition of alpha-galactosylceramide by NKT cells. When recombinant exogenous saposins were added to the prosaposin-negative cells, saposin B was the most efficient in restoring CD1d recognition. Saposin B was also the most efficient in mediating alpha-galactosylceramide binding to recombinant plate-bound CD1d and facilitating NKT cell activation. Saposin B could also mediate lipid binding to soluble CD1d molecules in a T cell-independent assay. The optimal pH for saposin B-mediated lipid binding to CD1d, pH 6, is higher than that of lysosomes, suggesting that saposin B may facilitate lipid binding to CD1d molecules throughout the endocytic pathway.
Collapse
Affiliation(s)
- Weiming Yuan
- *Department of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520-8011
| | - Xiaoyang Qi
- Division and Program in Human Genetics, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - Pansy Tsang
- *Department of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520-8011
| | - Suk-Jo Kang
- *Department of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520-8011
| | - Petr A. Illarionov
- Department of Microbial Physiology and Chemistry, School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom; and
| | - Gurdyal S. Besra
- Department of Microbial Physiology and Chemistry, School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom; and
| | - Jenny Gumperz
- Department of Medical Microbiology and Immunology, University of Wisconsin Medical School, 1300 University Avenue, Madison, WI 53706
| | - Peter Cresswell
- *Department of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520-8011
- To whom correspondence should be addressed at:
Howard Hughes Medical Institute, Department of Immunobiology, Yale University School of Medicine, P.O. Box 208011, New Haven, CT 06520-8011. E-mail:
| |
Collapse
|