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Drake LA, Hahn AB, Dixon AM, Drake JR. Differential pairing of transmembrane domain GxxxG dimerization motifs defines two HLA-DR MHC class II conformers. J Biol Chem 2023; 299:104869. [PMID: 37247758 PMCID: PMC10320510 DOI: 10.1016/j.jbc.2023.104869] [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: 02/10/2023] [Revised: 05/19/2023] [Accepted: 05/22/2023] [Indexed: 05/31/2023] Open
Abstract
MHC class II molecules function to present exogenous antigen-derived peptides to CD4 T cells to both drive T cell activation and to provide signals back into the class II antigen-presenting cell. Previous work established the presence of multiple GxxxG dimerization motifs within the transmembrane domains of MHC class II α and β chains across a wide range of species and revealed a role for differential GxxxG motif pairing in the formation of two discrete mouse class II conformers with distinct functional properties (i.e., M1-and M2-paired I-Ak class II). Biochemical and mutagenesis studies detailed herein extend this model to human class II by identifying an anti-HLA-DR mAb (Tü36) that selectively binds M1-paired HLA-DR molecules. Analysis of the HLA-DR allele reactivity of the Tü36 mAb helped define other HLA-DR residues involved in mAb binding. In silico modeling of both TM domain interactions and whole protein structure is consistent with the outcome of biochemical/mutagenesis studies and provides insight into the possible structural differences between the two HLA-DR conformers. Cholesterol depletion studies indicate a role for cholesterol-rich membrane domains in the formation/maintenance of Tü36 mAb reactive DR molecules. Finally, phylogenetic analysis of the amino acid sequences of Tü36-reactive HLA-DR β chains reveals a unique pattern of both Tü36 mAb reactivity and key amino acid polymorphisms. In total, these studies bring the paradigm M1/M2-paired MHC class II molecules to the human HLA-DR molecule and suggest that the functional differences between these conformers defined in mouse class II extend to the human immune system.
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Affiliation(s)
- Lisa A Drake
- Department of Immunology and Microbial Disease, Albany Medical College, Albany, New York, USA
| | - Amy B Hahn
- Transplant Immunology Laboratory, Department of Surgery, Albany Medical College, Albany, New York, USA
| | - Ann M Dixon
- Department of Chemistry, University of Warwick, Coventry, United Kingdom
| | - James R Drake
- Department of Immunology and Microbial Disease, Albany Medical College, Albany, New York, USA.
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2
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Giltiay NV, Giordano D, Clark EA. The Plasticity of Newly Formed B Cells. THE JOURNAL OF IMMUNOLOGY 2020; 203:3095-3104. [PMID: 31818922 DOI: 10.4049/jimmunol.1900928] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 09/26/2019] [Indexed: 12/21/2022]
Abstract
Newly formed B cells (NF-B cells) that emerge from the bone marrow to the periphery have often been referred to as immature or transitional B cells. However, NF-B cells have several striking characteristics, including a distinct BCR repertoire, high expression of AID, high sensitivity to PAMPs, and the ability to produce cytokines. A number of findings do not support their designation as immature because NF-B cells have the potential to become Ab-producing cells and to undergo class-switch recombination. In this review, we provide a fresh perspective on NF-B cell functions and describe some of the signals driving their activation. We summarize growing evidence supporting a role for NF-B cells in protection against infections and as a potential source of autoantibody-producing cells in autoimmune diseases such as systemic lupus erythematosus.
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Affiliation(s)
- Natalia V Giltiay
- Division of Rheumatology, Department of Medicine, University of Washington, Seattle, WA 98109; and
| | - Daniela Giordano
- Department of Immunology, University of Washington, Seattle, WA 98109
| | - Edward A Clark
- Department of Immunology, University of Washington, Seattle, WA 98109
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3
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Roe K, Shu GL, Draves KE, Giordano D, Pepper M, Clark EA. Targeting Antigens to CD180 but Not CD40 Programs Immature and Mature B Cell Subsets to Become Efficient APCs. THE JOURNAL OF IMMUNOLOGY 2019; 203:1715-1729. [PMID: 31484732 DOI: 10.4049/jimmunol.1900549] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 07/29/2019] [Indexed: 12/16/2022]
Abstract
Targeting Ags to the CD180 receptor activates both B cells and dendritic cells (DCs) to become potent APCs. After inoculating mice with Ag conjugated to an anti-CD180 Ab, B cell receptors were rapidly internalized. Remarkably, all B cell subsets, including even transitional 1 B cells, were programed to process, present Ag, and stimulate Ag-specific CD4+ T cells. Within 24-48 hours, Ag-specific B cells were detectable at T-B borders in the spleen; there, they proliferated in a T cell-dependent manner and induced the maturation of T follicular helper (TFH) cells. Remarkably, immature B cells were sufficient for the maturation of TFH cells after CD180 targeting: TFH cells were induced in BAFFR-/- mice (with only transitional 1 B cells) and not in μMT mice (lacking all B cells) following CD180 targeting. Unlike CD180 targeting, CD40 targeting only induced DCs but not B cells to become APCs and thus failed to efficiently induce TFH cell maturation, resulting in slower and lower-affinity IgG Ab responses. CD180 targeting induces a unique program in Ag-specific B cells and to our knowledge, is a novel strategy to induce Ag presentation in both DCs and B cells, especially immature B cells and thus has the potential to produce a broad range of Ab specificities. This study highlights the ability of immature B cells to present Ag to and induce the maturation of cognate TFH cells, providing insights toward vaccination of mature B cell-deficient individuals and implications in treating autoimmune disorders.
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Affiliation(s)
- Kelsey Roe
- Department of Immunology, University of Washington, Seattle, WA 98109
| | - Geraldine L Shu
- Department of Immunology, University of Washington, Seattle, WA 98109
| | - Kevin E Draves
- Department of Immunology, University of Washington, Seattle, WA 98109
| | - Daniela Giordano
- Department of Immunology, University of Washington, Seattle, WA 98109
| | - Marion Pepper
- Department of Immunology, University of Washington, Seattle, WA 98109
| | - Edward A Clark
- Department of Immunology, University of Washington, Seattle, WA 98109
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4
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Dixon AM, Roy S. Role of membrane environment and membrane-spanning protein regions in assembly and function of the Class II Major Histocompatibility complex. Hum Immunol 2019; 80:5-14. [PMID: 30102939 DOI: 10.1016/j.humimm.2018.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/19/2018] [Accepted: 07/09/2018] [Indexed: 10/28/2022]
Abstract
Class II Major Histocompatibility complex (MHC-II) is a polymorphic heterodimer that binds antigen-derived peptides and presents them on the surface of antigen presenting cells. This mechanism of antigen presentation leads to recognition by CD4 T-cells and T-cell activation, making it a critical element of adaptive immune response. For this reason, the structural determinants of MHC-II function have been of great interest for the past 30 years, resulting in a robust structural understanding of the extracellular regions of the complex. However, the membrane-localized regions have also been strongly implicated in protein-protein and protein-lipid interactions that facilitate Class II assembly, transport and function, and it is these regions that are the focus of this review. Here we describe studies that reveal the strong and selective interactions between the transmembrane domains of the MHC α, and invariant chains which, when altered, have broad reaching impacts on antigen presentation and Class II function. We also summarize work that clearly demonstrates the link between membrane lipid composition (particularly the presence of cholesterol) and MHC-II conformation, subsequent peptide binding, and downstream T-cell activation. We have integrated these studies into a comprehensive view of Class II transmembrane domain biology.
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Affiliation(s)
- Ann M Dixon
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
| | - Syamal Roy
- National Institute of Pharmaceutical Education and Research-Kolkata, 4 Raja SC, Mullick Road, Kolkata 700032, India
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5
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Harton JA. Class II MHC cytoplasmic domain-mediated signaling in B cells: A tail of two signals. Hum Immunol 2018; 80:32-36. [PMID: 30056069 DOI: 10.1016/j.humimm.2018.07.232] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 07/09/2018] [Accepted: 07/25/2018] [Indexed: 01/25/2023]
Abstract
In addition to their role in antigen presentation, class II MHC molecules also transmit signals to B lymphocytes. Class II MHC-mediated signals initiate a range of events in B cells, including induction of cell surface proteins, initiation of cell-cycle progression/proliferation, activation of or protection from apoptosis, and antigen-dependent plasma cell differentiation. Although various transmembrane signaling proteins associate with class II MHC molecules, the class II MHC cytoplasmic domains are essential for signals leading to increased intracellular cAMP and activation of protein kinase C (PKC). Although truncation and mutagenesis studies have provided considerable information about the cytoplasmic domain sequences required, how class II MHC molecules elicit cAMP and PKC activation is not known. Further, appropriate T-dependent B cell responses require intact cAMP and PKC signaling, but the extent to which class II MHC signals are involved is also unknown. This review details our current knowledge of class II MHC cytoplasmic domain signaling in B cells with an emphasis on the likely importance of class II MHC signals for T-dependent antibody responses.
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Affiliation(s)
- Jonathan A Harton
- Department of Immunology & Microbial Disease, Albany Medical College, 47 New Scotland Avenue, MC-151, Albany, NY 12208, USA.
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6
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Drake JR. The immunobiology of ubiquitin-dependent B cell receptor functions. Mol Immunol 2018; 101:146-154. [PMID: 29940407 DOI: 10.1016/j.molimm.2018.05.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 04/29/2018] [Accepted: 05/24/2018] [Indexed: 02/01/2023]
Abstract
MHC class II-restricted antigen presentation by dendritic cells is necessary for activation of naïve CD4 T cells, whereas class II-restricted antigen presentation by B lymphocytes and macrophages is important for the recruitment of CD4+ helper and regulatory T cells. Antigen presentation by B cells is also important for induction of T cell tolerance. B cells are unique among these three types of MHC class II-expressing antigen presenting cells (APC) as they constitutively express high levels of cell surface class II molecules and express a clonally restricted antigen specific receptor, the B cell receptor (BCR). Here, I review our current understanding of three major steps that underlie the processing and presentation of BCR-bound cognate antigen: (1) endocytosis of antigen-BCR (Ag-BCR) complexes, (2) Ag-BCR trafficking to intracellular antigen processing compartments and (3) generation of antigenic peptide-MHC class II complexes, with a particular focus on the role of BCR ubiquitination in each. I will highlight potential topics for future research and briefly discuss the impact of the cell biology of BCR-mediated antigen processing on the response of the B cell and T cell to the cell-cell interactions mediated by B cell-expressed peptide-class II complexes.
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Affiliation(s)
- James R Drake
- Albany Medical College, Department of Immunology and Microbial Disease, 47 New Scotland Ave., MC-151, Albany, NY 12208-3479, United States.
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7
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Evolving Insights for MHC Class II Antigen Processing and Presentation in Health and Disease. ACTA ACUST UNITED AC 2017. [DOI: 10.1007/s40495-017-0097-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Adler LN, Jiang W, Bhamidipati K, Millican M, Macaubas C, Hung SC, Mellins ED. The Other Function: Class II-Restricted Antigen Presentation by B Cells. Front Immunol 2017; 8:319. [PMID: 28386257 PMCID: PMC5362600 DOI: 10.3389/fimmu.2017.00319] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/07/2017] [Indexed: 12/31/2022] Open
Abstract
Mature B lymphocytes (B cells) recognize antigens using their B cell receptor (BCR) and are activated to become antibody-producing cells. In addition, and integral to the development of a high-affinity antibodies, B cells utilize the specialized major histocompatibility complex class II (MHCII) antigen presentation pathway to process BCR-bound and internalized protein antigens and present selected peptides in complex with MHCII to CD4+ T cells. This interaction influences the fate of both types of lymphocytes and shapes immune outcomes. Specific, effective, and optimally timed antigen presentation by B cells requires well-controlled intracellular machinery, often regulated by the combined effects of several molecular events. Here, we delineate and summarize these events in four steps along the antigen presentation pathway: (1) antigen capture and uptake by B cells; (2) intersection of internalized antigen/BCRs complexes with MHCII in peptide-loading compartments; (3) generation and regulation of MHCII/peptide complexes; and (4) exocytic transport for presentation of MHCII/peptide complexes at the surface of B cells. Finally, we discuss modulation of the MHCII presentation pathway across B cell development and maturation to effector cells, with an emphasis on the shaping of the MHCII/peptide repertoire by two key antigen presentation regulators in B cells: HLA-DM and HLA-DO.
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Affiliation(s)
- Lital N Adler
- Department of Pediatrics, Stanford University, Stanford, CA, USA; Program in Immunology, Stanford University, Stanford, CA, USA
| | - Wei Jiang
- Department of Pediatrics, Stanford University, Stanford, CA, USA; Program in Immunology, Stanford University, Stanford, CA, USA
| | | | | | - Claudia Macaubas
- Department of Pediatrics, Stanford University, Stanford, CA, USA; Program in Immunology, Stanford University, Stanford, CA, USA
| | - Shu-Chen Hung
- Department of Pediatrics, Stanford University, Stanford, CA, USA; Program in Immunology, Stanford University, Stanford, CA, USA
| | - Elizabeth D Mellins
- Department of Pediatrics, Stanford University, Stanford, CA, USA; Program in Immunology, Stanford University, Stanford, CA, USA
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Roy K, Mandloi S, Chakrabarti S, Roy S. Cholesterol Corrects Altered Conformation of MHC-II Protein in Leishmania donovani Infected Macrophages: Implication in Therapy. PLoS Negl Trop Dis 2016; 10:e0004710. [PMID: 27214205 PMCID: PMC4877013 DOI: 10.1371/journal.pntd.0004710] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 04/23/2016] [Indexed: 12/20/2022] Open
Abstract
Background Previously we reported that Kala-azar patients show progressive decrease in serum cholesterol as a function of splenic parasite burden. Splenic macrophages (MΦ) of Leishmania donovani (LD) infected mice show decrease in membrane cholesterol, while LD infected macrophages (I-MΦ) show defective T cell stimulating ability that could be corrected by liposomal delivery of cholesterol. T helper cells recognize peptide antigen in the context of class II MHC molecule. It is known that the conformation of a large number of membrane proteins is dependent on membrane cholesterol. In this investigation we tried to understand the influence of decreased membrane cholesterol in I-MΦ on the conformation of MHC-II protein and peptide-MHC-II stability, and its bearing on the antigen specific T-cell activation. Methodology/Principal Findings MΦ of CBA/j mice were infected with Leishmania donovani (I-MΦ). Two different anti-Aκ mAbs were used to monitor the status of MHC-II protein under parasitized condition. One of them (11.5–2) was conformation specific, whereas the other one (10.2.16) was not. Under parasitized condition, the binding of 11.5–2 decreased significantly with respect to the normal counterpart, whereas that of 10.2.16 remained unaltered. The binding of 11.5–2 was restored to normal upon liposomal delivery of cholesterol in I-MΦ. By molecular dynamics (MD) simulation studies we found that there was considerable conformational fluctuation in the transmembrane domain of the MHC-II protein in the presence of membrane cholesterol than in its absence, which possibly influenced the distal peptide binding groove. This was evident from the faster dissociation of the cognate peptide from peptide-MHC complex under parasitized condition, which could be corrected by liposomal delivery of cholesterol in I-MΦ. Conclusion The decrease in membrane cholesterol in I-MΦ may lead to altered conformation of MHC II, and this may contribute to a faster dissociation of the peptide. Furthermore, liposomal delivery of cholesterol in I-MΦ restored its normal antigen presenting function. This observation brings strength to our previous observation on host directed therapeutic application of liposomal cholesterol in experimental visceral leishmaniasis. The disease visceral leishmaniasis is caused by the protozoan parasite Leishmania donovani (LD). One of the hallmarks of the disease is immune suppression. The parasites replicate within the macrophages and dendritic cells, and such cells are known as antigen presenting cells (APCs). APCs present peptide to T-helper cells in association with the transplantation antigen-II (MHC-II). The infected macrophages show decrease in membrane cholesterol leading to increase in membrane fluidity. The membrane cholesterol is important for maintaining conformation of membrane proteins. Here we show that conformation of MHC-II protein is altered in parasitized macrophages, which results faster dissociation of peptide from peptide-MHC-II complex as compared to normal counterpart. The conformational change in MHC-II protein is also supported by molecular dynamic simulation studies, as there is considerable structural fluctuation of MHC-II peptide binding domain in presence and absence of cholesterol. This observation indicated that cholesterol is important for maintaining conformation of MHC-II protein and stability of the peptide-MHC complex. Thus, Leishmania parasites by modulating membrane cholesterol influence above processes leading to defective T-cell stimulation in leishmaniasis. The above defects displayed by infected macrophages could be corrected by liposomal delivery of cholesterol indicating a possible therapeutic role of liposomal cholesterol in infection.
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Affiliation(s)
- Koushik Roy
- Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Sapan Mandloi
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Saikat Chakrabarti
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
- * E-mail: (SC); (SR)
| | - Syamal Roy
- Infectious Diseases and Immunology Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
- * E-mail: (SC); (SR)
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Drake LA, Drake JR. A triad of molecular regions contribute to the formation of two distinct MHC class II conformers. Mol Immunol 2016; 74:59-70. [PMID: 27148821 DOI: 10.1016/j.molimm.2016.04.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 04/18/2016] [Accepted: 04/18/2016] [Indexed: 02/07/2023]
Abstract
MHC class II molecules present antigen-derived peptides to CD4T cells to drive the adaptive immune response. Previous work has established that class II αβ dimers can adopt two distinct conformations, driven by the differential pairing of transmembrane domain GxxxG dimerization motifs. These class II conformers differ in their ability to be loaded with antigen-derived peptide and to effectively engage CD4T cells. Motif 1 (M1) paired I-A(k) class II molecules are efficiently loaded with peptides derived from the processing of B cell receptor-bound antigen, have unique B cell signaling properties and high T cell stimulation activity. The 11-5.2mAb selectively binds M1 paired I-A(k) class II molecules. However, the molecular determinants of 11-5.2 binding are currently unclear. Here, we report the ability of a human class II transmembrane domain to drive both M1 and M2 class II conformer formation. Protease sensitivity analysis further strengthens the idea that there are conformational differences between the extracellular domains of M1 and M2 paired class II. Finally, MHC class II chain alignments and site directed mutagenesis reveals a triad of molecular regions that contributes to 11-5.2mAb binding. In addition to transmembrane GxxxG motif domain pairing, 11-5.2 binding is influenced directly by α chain residue Glu-71 and indirectly by the region around the inter-chain salt bridge formed by α chain Arg-52 and β chain Glu-86. These findings provide insight into the complexity of 11-5.2mAb recognition of the M1 paired I-A(k) class II conformer and further highlight the molecular heterogeneity of peptide-MHC class II complexes that drive T cell antigen recognition.
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Affiliation(s)
- Lisa A Drake
- Center for Immunology and Microbial Disease, Albany Medical College, 47 New Scotland Ave, MC-151, Albany, NY 12208, United States
| | - James R Drake
- Center for Immunology and Microbial Disease, Albany Medical College, 47 New Scotland Ave, MC-151, Albany, NY 12208, United States.
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11
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Harton J, Jin L, Hahn A, Drake J. Immunological Functions of the Membrane Proximal Region of MHC Class II Molecules. F1000Res 2016; 5. [PMID: 27006762 PMCID: PMC4798158 DOI: 10.12688/f1000research.7610.1] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/10/2016] [Indexed: 12/30/2022] Open
Abstract
Major histocompatibility complex (MHC) class II molecules present exogenously derived antigen peptides to CD4 T cells, driving activation of naïve T cells and supporting CD4-driven immune functions. However, MHC class II molecules are not inert protein pedestals that simply bind and present peptides. These molecules also serve as multi-functional signaling molecules delivering activation, differentiation, or death signals (or a combination of these) to B cells, macrophages, as well as MHC class II-expressing T cells and tumor cells. Although multiple proteins are known to associate with MHC class II, interaction with STING (stimulator of interferon genes) and CD79 is essential for signaling. In addition, alternative transmembrane domain pairing between class II α and β chains influences association with membrane lipid sub-domains, impacting both signaling and antigen presentation. In contrast to the membrane-distal region of the class II molecule responsible for peptide binding and T-cell receptor engagement, the membrane-proximal region (composed of the connecting peptide, transmembrane domain, and cytoplasmic tail) mediates these "non-traditional" class II functions. Here, we review the literature on the function of the membrane-proximal region of the MHC class II molecule and discuss the impact of this aspect of class II immunobiology on immune regulation and human disease.
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Affiliation(s)
- Jonathan Harton
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, 12208-3479, USA
| | - Lei Jin
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, 12208-3479, USA
| | - Amy Hahn
- Transplantation Immunology Laboratory, Albany Medical College, Albany, New York, 12208-3479, USA
| | - Jim Drake
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, 12208-3479, USA
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Monos D, Maiers MJ. Progressing towards the complete and thorough characterization of the HLA genes by NGS (or single-molecule DNA sequencing): Consequences, opportunities and challenges. Hum Immunol 2015; 76:883-6. [PMID: 26455298 DOI: 10.1016/j.humimm.2015.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Dimitri Monos
- Immunogenetics Laboratory, The Children's Hospital of Philadelphia, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, 707A Abramson Research Bldg., 3615 Civic Center Blvd., Philadelphia, PA 19104, United States.
| | - Martin J Maiers
- Bioinformatics Research, National Marrow Donor Program
- Be The Match, Minneapolis, MN, United States
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Barroso M, Tucker H, Drake L, Nichol K, Drake JR. Antigen-B Cell Receptor Complexes Associate with Intracellular major histocompatibility complex (MHC) Class II Molecules. J Biol Chem 2015; 290:27101-27112. [PMID: 26400081 DOI: 10.1074/jbc.m115.649582] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Indexed: 01/09/2023] Open
Abstract
Antigen processing and MHC class II-restricted antigen presentation by antigen-presenting cells such as dendritic cells and B cells allows the activation of naïve CD4+ T cells and cognate interactions between B cells and effector CD4+ T cells, respectively. B cells are unique among class II-restricted antigen-presenting cells in that they have a clonally restricted antigen-specific receptor, the B cell receptor (BCR), which allows the cell to recognize and respond to trace amounts of foreign antigen present in a sea of self-antigens. Moreover, engagement of peptide-class II complexes formed via BCR-mediated processing of cognate antigen has been shown to result in a unique pattern of B cell activation. Using a combined biochemical and imaging/FRET approach, we establish that internalized antigen-BCR complexes associate with intracellular class II molecules. We demonstrate that the M1-paired MHC class II conformer, shown previously to be critical for CD4 T cell activation, is incorporated selectively into these complexes and loaded selectively with peptide derived from BCR-internalized cognate antigen. These results demonstrate that, in B cells, internalized antigen-BCR complexes associate with intracellular MHC class II molecules, potentially defining a site of class II peptide acquisition, and reveal a selective role for the M1-paired class II conformer in the presentation of cognate antigen. These findings provide key insights into the molecular mechanisms used by B cells to control the source of peptides charged onto class II molecules, allowing the immune system to mount an antibody response focused on BCR-reactive cognate antigen.
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Affiliation(s)
- Margarida Barroso
- Center for Cardiovascular Sciences, Albany Medical College, Albany, New York 12208
| | - Heidi Tucker
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208
| | - Lisa Drake
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208
| | - Kathleen Nichol
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208
| | - James R Drake
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208.
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Bhargava A, Bunkar N, Khare NK, Mishra D, Mishra PK. Nanoengineered strategies to optimize dendritic cells for gastrointestinal tumor immunotherapy: from biology to translational medicine. Nanomedicine (Lond) 2015; 9:2187-202. [PMID: 25405796 DOI: 10.2217/nnm.14.115] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Nanomedicine may play an important role in improving the clinical efficacy of dendritic cell-based immunotherapy against GI tract malignancies. Dendritic cell-based vaccines have proven their effectiveness against different established GI tract tumors, yet their success is mainly hindered by the strong tumor-induced suppressive microenvironment. The sustained and targeted release of tumor antigens to dendritic cells using different nanoengineered approaches would be an efficient strategy to overcome established immune tolerance. Encapsulation would result in low diffusivity, restricted movement, effective crosspresentation and enhanced T-cell responses. These nanotherapy-based approaches will certainly help with the designing of clinically translatable dendritic cell-based therapeutic vaccines and facilitate the selective removal of residual disease in gastrointestinal cancer patients following standard treatments.
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Affiliation(s)
- Arpit Bhargava
- Translational Research Laboratory, School of Biological Sciences, Dr H. S. Gour Central University, Sagar, India
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15
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Anderson HA, Roche PA. MHC class II association with lipid rafts on the antigen presenting cell surface. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:775-80. [PMID: 25261705 DOI: 10.1016/j.bbamcr.2014.09.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 09/16/2014] [Accepted: 09/17/2014] [Indexed: 12/29/2022]
Abstract
MHC class II (MHC-II) molecules function by binding peptides derived from either self or foreign proteins and expressing these peptides on the surface of antigen presenting cells (APCs) for recognition by CD4 T cells. MHC-II is known to exist on clusters on the surface of APCs, and a variety of biochemical and functional studies have suggested that these clusters represent lipid raft microdomain-associated MHC-II. This review will summarize data exploring the biosynthesis of raft-associated MHC-II and the role that lipid raft association plays in regulating T cell activation by APCs. This article is part of a Special Issue entitled: Nanoscale membrane organisation and signalling.
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Affiliation(s)
- Howard A Anderson
- Division of Therapeutic Proteins, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Paul A Roche
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Dixon AM, Drake L, Hughes KT, Sargent E, Hunt D, Harton JA, Drake JR. Differential transmembrane domain GXXXG motif pairing impacts major histocompatibility complex (MHC) class II structure. J Biol Chem 2014; 289:11695-11703. [PMID: 24619409 DOI: 10.1074/jbc.m113.516997] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Major histocompatibility complex (MHC) class II molecules exhibit conformational heterogeneity, which influences their ability to stimulate CD4 T cells and drive immune responses. Previous studies suggest a role for the transmembrane domain of the class II αβ heterodimer in determining molecular structure and function. Our previous studies identified an MHC class II conformer that is marked by the Ia.2 epitope. These Ia.2(+) class II conformers are lipid raft-associated and able to drive both tyrosine kinase signaling and efficient antigen presentation to CD4 T cells. Here, we establish that the Ia.2(+) I-A(k) conformer is formed early in the class II biosynthetic pathway and that differential pairing of highly conserved transmembrane domain GXXXG dimerization motifs is responsible for formation of Ia.2(+) versus Ia.2(-) I-A(k) class II conformers and controlling lipid raft partitioning. These findings provide a molecular explanation for the formation of two distinct MHC class II conformers that differ in their inherent ability to signal and drive robust T cell activation, providing new insight into the role of MHC class II in regulating antigen-presenting cell-T cell interactions critical to the initiation and control of multiple aspects of the immune response.
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Affiliation(s)
- Ann M Dixon
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Lisa Drake
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208
| | - Kelly T Hughes
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208
| | - Elizabeth Sargent
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208
| | - Danielle Hunt
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208
| | - Jonathan A Harton
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208
| | - James R Drake
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208.
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Roy K, Ghosh M, Pal TK, Chakrabarti S, Roy S. Cholesterol lowering drug may influence cellular immune response by altering MHC II function. J Lipid Res 2013; 54:3106-15. [PMID: 24038316 DOI: 10.1194/jlr.m041954] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Major histocompatibility complex class II (MHC II) expressed on the surface of antigen-presenting cells (APCs) displays peptides to CD4⁺ T cells. Depletion of membrane cholesterol from APCs by methyl β-cyclodextrin treatment compromises peptide-MHC II complex formation coupled with impaired binding of conformational antibody, which binds close to the peptide binding groove of MHC II. Interestingly, the total cell surface of MHC II remains unaltered. These defects can be corrected by restoring membrane cholesterol. In silico docking studies with a three-dimensional model showed the presence of a cholesterol binding site in the transmembrane domain of MHC II (TM-MHC-II). From the binding studies it was clear that cholesterol, indeed, interacts with the TM-MHC-II and alters its conformation. Mutation of cholesterol binding residues (F240, L243, and F246) in the TM-MHC-II decreased the affinity for cholesterol. Furthermore, transfection of CHO cells with full-length mutant MHC II, but not wild-type MHC II, failed to activate antigen-specific T cells coupled with decreased binding of conformation-specific antibodies. Thus, cholesterol-induced conformational change of TM-MHC-II may allosterically modulate the peptide binding groove of MHC II leading to T cell activation.
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Affiliation(s)
- Koushik Roy
- Infectious Diseases and Immunology and CSIR -Indian Institute of Chemical Biology, Jadavpur, Kolkata-700032, India
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Busman-Sahay K, Drake L, Sitaram A, Marks M, Drake JR. Cis and trans regulatory mechanisms control AP2-mediated B cell receptor endocytosis via select tyrosine-based motifs. PLoS One 2013; 8:e54938. [PMID: 23372794 PMCID: PMC3553015 DOI: 10.1371/journal.pone.0054938] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 12/18/2012] [Indexed: 12/20/2022] Open
Abstract
Following antigen recognition, B cell receptor (BCR)-mediated endocytosis is the first step of antigen processing and presentation to CD4+ T cells, a crucial component of the initiation and control of the humoral immune response. Despite this, the molecular mechanism of BCR internalization is poorly understood. Recently, studies of activated B cell-like diffuse large B cell lymphoma (ABC DLBCL) have shown that mutations within the BCR subunit CD79b leads to increased BCR surface expression, suggesting that CD79b may control BCR internalization. Adaptor protein 2 (AP2) is the major mediator of receptor endocytosis via clathrin-coated pits. The BCR contains five putative AP2-binding YxxØ motifs, including four that are present within two immunoreceptor tyrosine-based activation motifs (ITAMs). Using a combination of in vitro and in situ approaches, we establish that the sole mediator of AP2-dependent BCR internalization is the membrane proximal ITAM YxxØ motif in CD79b, which is a major target of mutation in ABC DLBCL. In addition, we establish that BCR internalization can be regulated at a minimum of two different levels: regulation of YxxØ AP2 binding in cis by downstream ITAM-embedded DCSM and QTAT regulatory elements and regulation in trans by the partner cytoplasmic domain of the CD79 heterodimer. Beyond establishing the basic rules governing BCR internalization, these results illustrate an underappreciated role for ITAM residues in controlling clathrin-dependent endocytosis and highlight the complex mechanisms that control the activity of AP2 binding motifs in this receptor system.
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Affiliation(s)
- Kathleen Busman-Sahay
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
| | - Lisa Drake
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
| | - Anand Sitaram
- Departments of Pathology and Laboratory Medicine and Physiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Michael Marks
- Departments of Pathology and Laboratory Medicine and Physiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - James R. Drake
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York, United States of America
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