1
|
Bozelli JC, Yune J, Takahashi D, Sakane F, Epand RM. Membrane morphology determines diacylglycerol kinase α substrate acyl chain specificity. FASEB J 2021; 35:e21602. [PMID: 33977628 DOI: 10.1096/fj.202100264r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/22/2021] [Accepted: 04/01/2021] [Indexed: 01/06/2023]
Abstract
Diacylglycerol kinases catalyze the ATP-dependent phosphorylation of diacylglycerol (DAG) to produce phosphatidic acid (PA). In humans, the alpha isoform (DGKα) has emerged as a potential target in the treatment of cancer due to its anti-tumor and pro-immune responses. However, its mechanism of action at a molecular level is not fully understood. In this work, a systematic investigation of the role played by the membrane in the regulation of the enzymatic properties of human DGKα is presented. By using a cell-free system with purified DGKα and model membranes of variable physical and chemical properties, it is shown that membrane physical properties determine human DGKα substrate acyl chain specificity. In model membranes with a flat morphology; DGKα presents high enzymatic activity, but it is not able to differentiate DAG molecular species. Furthermore, DGKα enzymatic properties are insensitive to membrane intrinsic curvature. However, in the presence of model membranes with altered morphology, specifically the presence of physically curved membrane structures, DGKα bears substrate acyl chain specificity for palmitic acid-containing DAG. The present results identify changes in membrane morphology as one possible mechanism for the depletion of specific pools of DAG as well as the production of specific pools of PA by DGKα, adding an extra layer of regulation on the interconversion of these two potent lipid-signaling molecules. It is proposed that the interplay between membrane physical (shape) and chemical (lipid composition) properties guarantee a fine-tuned signal transduction system dependent on the levels and molecular species of DAG and PA.
Collapse
Affiliation(s)
- José Carlos Bozelli
- Department of Biochemistry and Biomedical Sciences, McMaster University, Health Sciences Centre, Hamilton, ON, Canada
| | - Jenny Yune
- Department of Biochemistry and Biomedical Sciences, McMaster University, Health Sciences Centre, Hamilton, ON, Canada
| | - Daisuke Takahashi
- Department of Pharmaceutical Health Care and Sciences, Kyushu University, Fukuoka, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Richard M Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, Health Sciences Centre, Hamilton, ON, Canada
| |
Collapse
|
2
|
Li Y, Tunbridge HM, Britton GJ, Hill EV, Sinai P, Cirillo S, Thompson C, Fallah-Arani F, Dovedi SJ, Wraith DC, Wülfing C. A LAT-Based Signaling Complex in the Immunological Synapse as Determined with Live Cell Imaging Is Less Stable in T Cells with Regulatory Capability. Cells 2021; 10:418. [PMID: 33671236 PMCID: PMC7921939 DOI: 10.3390/cells10020418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/12/2021] [Accepted: 02/12/2021] [Indexed: 12/03/2022] Open
Abstract
Peripheral immune regulation is critical for the maintenance of self-tolerance. Here we have investigated signaling processes that distinguish T cells with regulatory capability from effector T cells. The murine Tg4 T cell receptor recognizes a peptide derived from the self-antigen myelin basic protein. T cells from Tg4 T cell receptor transgenic mice can be used to generate effector T cells and three types of T cells with regulatory capability, inducible regulatory T cells, T cells tolerized by repeated in vivo antigenic peptide exposure or T cells treated with the tolerogenic drug UCB9608 (a phosphatidylinositol 4 kinase IIIβ inhibitor). We comparatively studied signaling in all of these T cells by activating them with the same antigen presenting cells presenting the same myelin basic protein peptide. Supramolecular signaling structures, as efficiently detected by large-scale live cell imaging, are critical mediators of T cell activation. The formation of a supramolecular signaling complex anchored by the adaptor protein linker for activation of T cells (LAT) was consistently terminated more rapidly in Tg4 T cells with regulatory capability. Such termination could be partially reversed by blocking the inhibitory receptors CTLA-4 and PD-1. Our work suggests that attenuation of proximal signaling may favor regulatory over effector function in T cells.
Collapse
Affiliation(s)
- Yikui Li
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK
| | - Helen M Tunbridge
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK
| | - Graham J Britton
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK
- Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Elaine V Hill
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK
| | - Parisa Sinai
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK
| | - Silvia Cirillo
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK
| | | | | | - Simon J Dovedi
- R&D Oncology, AstraZeneca, Granta Park, Cambridge, CB21 6GH, UK
| | - David C Wraith
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, B15 2TT, UK
| | - Christoph Wülfing
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK
| |
Collapse
|
3
|
Chuang E, Augustine M, Jung M, Schwartz RH, Singh NJ. Density dependent re-tuning of autoreactive T cells alleviates their pathogenicity in a lymphopenic environment. Immunol Lett 2017; 192:61-71. [PMID: 29111199 DOI: 10.1016/j.imlet.2017.10.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 10/04/2017] [Accepted: 10/09/2017] [Indexed: 10/18/2022]
Abstract
Peripheral T cell tolerance is challenging to induce in partially lymphopenic hosts and this is relevant for clinical situations involving transplant tolerance. While the shortage of regulatory cells is thought to be one reason for this, T cell-intrinsic tolerance processes such as anergy are also poorly triggered in such hosts. In order to understand the latter, we used a T cell deficient mouse model system where adoptively transferred autoreactive T cells are significantly tolerized in a cell intrinsic fashion, without differentiation to regulatory T cells. Intriguingly these T cells often retain sufficient effector functions to trigger autoimmune pathology. Here we find that the high population density of the autoreactive T cells that accumulated in such a host limits the progression of the cell-intrinsic tolerance process in T cells. Accordingly, reducing the cell density during a second transfer allowed T cells to further tune down their responsiveness to antigenic stimulation. The retuning of T cells was reflected by a loss of the T cell's abilities to proliferate, produces cytokines or help B cells. We further suggest, based on altering the levels of chronic antigen using miniosmotic pumps, that the effects of cell-density on T cell re-tuning may reflect the effective changes in the antigen dose perceived by individual T cells. This could proportionally elicit more negative feedback downstream of the TCR. Consistent with this, the retuned T cells showed signaling defects both proximal and distal to the TCR. Therefore, similar to the immunogenic activation of T cells, cell-intrinsic T cell tolerance may also involve a quantitative and progressive process of tuning down its antigen-responsiveness. The progress of such tuning seems to be stabilized at multiple intermediate stages by factors such as cell density, rather than just absolute antigen levels.
Collapse
Affiliation(s)
- Eleanore Chuang
- Laboratory of Cellular & Molecular Immunology, National Institute of Allergy & Infectious Diseases (NIAID), National Institutes of Health (NIH), 4/211, Center Drive, Bethesda, MD 20892-0420, United States; John A. Burns School of Medicine, Department of Tropical Medicine, Hawaii Center for AIDS, University of Hawaii, Honolulu, HI 96813, United States
| | - Marilyn Augustine
- Laboratory of Cellular & Molecular Immunology, National Institute of Allergy & Infectious Diseases (NIAID), National Institutes of Health (NIH), 4/211, Center Drive, Bethesda, MD 20892-0420, United States; University of Pittsburgh, Division of Endocrinology and Metabolism, 200 Lothrop Street, E1140 BST, Pittsburgh, PA 15261, United States
| | - Matthew Jung
- Laboratory of Cellular & Molecular Immunology, National Institute of Allergy & Infectious Diseases (NIAID), National Institutes of Health (NIH), 4/211, Center Drive, Bethesda, MD 20892-0420, United States; Washington University School of Medicine, Deptartment of Otolaryngology Head and Neck Surgery, 660 South Euclid Ave, St. Louis, MO 63110, United States
| | - Ronald H Schwartz
- Laboratory of Cellular & Molecular Immunology, National Institute of Allergy & Infectious Diseases (NIAID), National Institutes of Health (NIH), 4/211, Center Drive, Bethesda, MD 20892-0420, United States
| | - Nevil J Singh
- Laboratory of Cellular & Molecular Immunology, National Institute of Allergy & Infectious Diseases (NIAID), National Institutes of Health (NIH), 4/211, Center Drive, Bethesda, MD 20892-0420, United States; Department of Microbiology and Immunology, University of Maryland School of Medicine, HH 320A, 660 W Baltimore Street, Baltimore, MD 21201, United States.
| |
Collapse
|
4
|
Nassef Kadry Naguib Roufaiel M, Wells JW, Steptoe RJ. Impaired T-Cell Function in B-Cell Lymphoma: A Direct Consequence of Events at the Immunological Synapse? Front Immunol 2015; 6:258. [PMID: 26082776 PMCID: PMC4451642 DOI: 10.3389/fimmu.2015.00258] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 05/11/2015] [Indexed: 12/21/2022] Open
Abstract
Tumors can escape immune destruction through the development of antigen loss variants and loss of antigen processing/presentation pathways, thereby rendering them invisible to T cells. Alternatively, mechanisms of peripheral T-cell tolerance that would normally be important for protection from the development of autoimmunity may also be co-opted to (i) generate an immuno-inhibitory tumor environment, (ii) promote development of regulatory cell populations, or (iii) cell-intrinsically inactivate tumor-specific T cells. Emerging evidence suggests that T-cell function is impaired in hematological malignancies, which may manifest from cognate interactions between T cells and the tumor. The immunological synapse forms the cognate T-cell and antigen-presenting cell interaction and is the site where key signalling events, including those delivered by co-inhibitory receptors, that determine the fate of T cells occur. Here, we review evidence that events at the immune synapse between T cells and malignant B cells and alterations in immune synapse function may contribute to loss of T-cell function in B-cell malignancies.
Collapse
Affiliation(s)
- Marian Nassef Kadry Naguib Roufaiel
- The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute , Brisbane, QLD , Australia
| | - James W Wells
- The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute , Brisbane, QLD , Australia
| | - Raymond J Steptoe
- The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute , Brisbane, QLD , Australia
| |
Collapse
|
5
|
Abstract
Dynamic tuning of cellular responsiveness as a result of repeated stimuli improves the ability of cells to distinguish physiologically meaningful signals from each other and from noise. In particular, lymphocyte activation thresholds are subject to tuning, which contributes to maintaining tolerance to self-antigens and persisting foreign antigens, averting autoimmunity and immune pathogenesis, but allowing responses to strong, structured perturbations that are typically associated with acute infection. Such tuning is also implicated in conferring flexibility to positive selection in the thymus, in controlling the magnitude of the immune response, and in generating memory cells. Additional functional properties are dynamically and differentially tuned in parallel via subthreshold contact interactions between developing or mature lymphocytes and self-antigen-presenting cells. These interactions facilitate and regulate lymphocyte viability, maintain their functional integrity, and influence their responses to foreign antigens and accessory signals, qualitatively and quantitatively. Bidirectional tuning of T cells and antigen-presenting cells leads to the definition of homeostatic set points, thus maximizing clonal diversity.
Collapse
Affiliation(s)
- Zvi Grossman
- Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892; ,
| | | |
Collapse
|
6
|
Chappert P. Role of SFB in autoimmune arthritis: an example of regulation of autoreactive T cell sensitivity in the gut. Gut Microbes 2014; 5:259-64. [PMID: 24637598 PMCID: PMC4063855 DOI: 10.4161/gmic.28134] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
A key role for segmented filamentous bacteria (SFB) has recently been demonstrated in several mouse models of autoimmune diseases, including autoimmune arthritis and multiple sclerosis. The mechanism governing the activation of systemic autoreactive T cell responses by such commensals in the gut, however, remained elusive. In this addendum, we discuss recent results addressing the local regulation of autoreactive T cell sensitivity by these unique bacteria. We found that the presence of SFB in the gut microbiota was sufficient to promote a local inflammatory microenvironment altering the T cell-intrinsic desensitization process normally occurring in response to chronic self-antigen stimulation. In the absence of this key tolerance checkpoint, sustained chronic T cell proliferation, IFNγ production, and B cell activation eventually led to the development of enhanced pathologies in a Th1-driven T cell-transfer model of autoimmune arthritis.
Collapse
|
7
|
Chappert P, Bouladoux N, Naik S, Schwartz RH. Specific gut commensal flora locally alters T cell tuning to endogenous ligands. Immunity 2013; 38:1198-210. [PMID: 23809163 DOI: 10.1016/j.immuni.2013.06.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 03/25/2013] [Indexed: 02/07/2023]
Abstract
Differences in gut commensal flora can dramatically influence autoimmune responses, but the mechanisms behind this are still unclear. We report, in a Th1-cell-driven murine model of autoimmune arthritis, that specific gut commensals, such as segmented filamentous bacteria, have the ability to modulate the activation threshold of self-reactive T cells. In the local microenvironment of gut-associated lymphoid tissues, inflammatory cytokines elicited by the commensal flora dynamically enhanced the antigen responsiveness of T cells that were otherwise tuned down to a systemic self-antigen. Together with subtle differences in early lineage differentiation, this ultimately led to an enhanced recruitment of pathogenic Th1 cells and the development of a more severe form of autoimmune arthritis. These findings define a key role for the gut commensal flora in sustaining ongoing autoimmune responses through the local fine tuning of T-cell-receptor-proximal activation events in autoreactive T cells.
Collapse
Affiliation(s)
- Pascal Chappert
- Laboratory of Cellular and Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | | | | | | |
Collapse
|