1
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Acuto O. T-cell virtuosity in ''knowing thyself". Front Immunol 2024; 15:1343575. [PMID: 38415261 PMCID: PMC10896960 DOI: 10.3389/fimmu.2024.1343575] [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: 11/23/2023] [Accepted: 01/17/2024] [Indexed: 02/29/2024] Open
Abstract
Major Histocompatibility Complex (MHC) I and II and the αβ T-cell antigen receptor (TCRαβ) govern fundamental traits of adaptive immunity. They form a membrane-borne ligand-receptor system weighing host proteome integrity to detect contamination by nonself proteins. MHC-I and -II exhibit the "MHC-fold", which is able to bind a large assortment of short peptides as proxies for self and nonself proteins. The ensuing varying surfaces are mandatory ligands for Ig-like TCRαβ highly mutable binding sites. Conserved molecular signatures guide TCRαβ ligand binding sites to focus on the MHC-fold (MHC-restriction) while leaving many opportunities for its most hypervariable determinants to contact the peptide. This riveting molecular strategy affords many options for binding energy compatible with specific recognition and signalling aimed to eradicated microbial pathogens and cancer cells. While the molecular foundations of αβ T-cell adaptive immunity are largely understood, uncertainty persists on how peptide-MHC binding induces the TCRαβ signals that instruct cell-fate decisions. Solving this mystery is another milestone for understanding αβ T-cells' self/nonself discrimination. Recent developments revealing the innermost links between TCRαβ structural dynamics and signalling modality should help dissipate this long-sought-after enigma.
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Affiliation(s)
- Oreste Acuto
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
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2
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Chen K, Luo M, Lv Y, Luo Z, Yang H. Undervalued and novel roles of heterogeneous nuclear ribonucleoproteins in autoimmune diseases: Resurgence as potential biomarkers and targets. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1806. [PMID: 37365887 DOI: 10.1002/wrna.1806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 06/28/2023]
Abstract
Autoimmune diseases are mainly characterized by the abnormal autoreactivity due to the loss of tolerance to specific autoantigens, though multiple pathways associated with the homeostasis of immune responses are involved in initiating or aggravating the conditions. The heterogeneous nuclear ribonucleoproteins (hnRNPs) are a major category of RNA-binding proteins ubiquitously expressed in a multitude of cells and have attracted great attentions especially with their distinctive roles in nucleic acid metabolisms and the pathogenesis in diseases like neurodegenerative disorders and cancers. Nevertheless, the interplay between hnRNPs and autoimmune disorders has not been fully elucidated. Virtually various family members of hnRNPs are increasingly identified as immune players and are pertinent to all kinds of immune-related processes including immune system development and innate or adaptive immune responses. Specifically, hnRNPs have been extensively recognized as autoantigens within and even beyond a myriad of autoimmune diseases, yet their diagnostic and prognostic values are seemingly underestimated. Molecular mimicry, epitope spreading and bystander activation may represent major putative mechanisms underlying the presence of autoantibodies to hnRNPs. Besides, hnRNPs play critical parts in regulating linchpin genes expressions that control genetic susceptibility, disease-linked functional pathways, or immune responses by interacting with other components particularly like microRNAs and long non-coding RNAs, thereby contributing to inflammation and autoimmunity as well as specific disease phenotypes. Therefore, comprehensive unraveling of the roles of hnRNPs is conducive to establishing potential biomarkers and developing better intervention strategies by targeting these hnRNPs in the corresponding disorders. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Kangzhi Chen
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Mengchuan Luo
- Department of Geriatrics, Xiangya Hospital, Central South University, Changsha, China
| | - Yuanzhi Lv
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Zhaohui Luo
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Huan Yang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
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3
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Lambert S, Cao W, Zhang H, Colville A, Liu JY, Weyand CM, Goronzy JJ, Gustafson CE. The influence of three-dimensional structure on naïve T cell homeostasis and aging. FRONTIERS IN AGING 2022; 3:1045648. [PMID: 36419548 PMCID: PMC9676450 DOI: 10.3389/fragi.2022.1045648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 10/24/2022] [Indexed: 11/09/2022]
Abstract
A breakdown in cellular homeostasis is thought to drive naïve T cell aging, however the link between naïve T cell homeostasis and aging in humans is poorly understood. To better address this, we developed a lymphoid organoid system that maintains resting naïve T cells for more than 2 weeks, in conjunction with high CD45RA expression. Deep phenotypic characterization of naïve T cells across age identified reduced CD45RA density as a hallmark of aging. A conversion from CD45RAhigh naive cells to a CD45RAlow phenotype was reproduced within our organoid system by structural breakdown, but not by stromal cell aging or reduced lymphocyte density, and mediated by alternative CD45 splicing. Together, these data suggest that external influences within the lymph node microenvironment may cause phenotypic conversion of naïve T cells in older adults.
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Affiliation(s)
- Simon Lambert
- Department of Medicine, Veterans Administration Healthcare System, Palo Alto, CA, United States
| | - Wenqiang Cao
- Department of Medicine, Veterans Administration Healthcare System, Palo Alto, CA, United States,Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA, United States,Health Sciences Institute, Key Laboratory of Major Chronic Diseases of Nervous System of Liaoning Province, China Medical University, Shenyang, China
| | - Huimin Zhang
- Department of Medicine, Veterans Administration Healthcare System, Palo Alto, CA, United States,Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA, United States
| | - Alex Colville
- Paul F. Glenn Center for Biology of Aging and Department of Neurology and Neurological Science, Stanford University School of Medicine, Stanford, CA, United States
| | - Jie-Yu Liu
- Paul F. Glenn Center for Biology of Aging and Department of Neurology and Neurological Science, Stanford University School of Medicine, Stanford, CA, United States
| | - Cornelia M. Weyand
- Department of Medicine, Veterans Administration Healthcare System, Palo Alto, CA, United States,Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA, United States
| | - Jorg J. Goronzy
- Department of Medicine, Veterans Administration Healthcare System, Palo Alto, CA, United States,Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA, United States
| | - Claire E. Gustafson
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA, United States,Allen Institute for Immunology, Seattle, WA, United States,*Correspondence: Claire E. Gustafson,
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4
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Blake D, Lynch KW. The three as: Alternative splicing, alternative polyadenylation and their impact on apoptosis in immune function. Immunol Rev 2021; 304:30-50. [PMID: 34368964 DOI: 10.1111/imr.13018] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/19/2021] [Accepted: 07/28/2021] [Indexed: 12/13/2022]
Abstract
The latest advances in next-generation sequencing studies and transcriptomic profiling over the past decade have highlighted a surprising frequency of genes regulated by RNA processing mechanisms in the immune system. In particular, two control steps in mRNA maturation, namely alternative splicing and alternative polyadenylation, are now recognized to occur in the vast majority of human genes. Both have the potential to alter the identity of the encoded protein, as well as control protein abundance or even protein localization or association with other factors. In this review, we will provide a summary of the general mechanisms by which alternative splicing (AS) and alternative polyadenylation (APA) occur, their regulation within cells of the immune system, and their impact on immunobiology. In particular, we will focus on how control of apoptosis by AS and APA is used to tune cell fate during an immune response.
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Affiliation(s)
- Davia Blake
- Immunology Graduate Group and the Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kristen W Lynch
- Immunology Graduate Group and the Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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5
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Lau CI, Rowell J, Yanez DC, Solanki A, Ross S, Ono M, Crompton T. The pioneer transcription factors Foxa1 and Foxa2 regulate alternative RNA splicing during thymocyte positive selection. Development 2021; 148:dev199754. [PMID: 34323272 PMCID: PMC8353164 DOI: 10.1242/dev.199754] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 06/28/2021] [Indexed: 02/02/2023]
Abstract
During positive selection at the transition from CD4+CD8+ double-positive (DP) to single-positive (SP) thymocyte, TCR signalling results in appropriate MHC restriction and signals for survival and progression. We show that the pioneer transcription factors Foxa1 and Foxa2 are required to regulate RNA splicing during positive selection of mouse T cells and that Foxa1 and Foxa2 have overlapping/compensatory roles. Conditional deletion of both Foxa1 and Foxa2 from DP thymocytes reduced positive selection and development of CD4SP, CD8SP and peripheral naïve CD4+ T cells. Foxa1 and Foxa2 regulated the expression of many genes encoding splicing factors and regulators, including Mbnl1, H1f0, Sf3b1, Hnrnpa1, Rnpc3, Prpf4b, Prpf40b and Snrpd3. Within the positively selecting CD69+DP cells, alternative RNA splicing was dysregulated in the double Foxa1/Foxa2 conditional knockout, leading to >850 differentially used exons. Many genes important for this stage of T-cell development (Ikzf1-3, Ptprc, Stat5a, Stat5b, Cd28, Tcf7) and splicing factors (Hnrnpab, Hnrnpa2b1, Hnrnpu, Hnrnpul1, Prpf8) showed multiple differentially used exons. Thus, Foxa1 and Foxa2 are required during positive selection to regulate alternative splicing of genes essential for T-cell development, and, by also regulating splicing of splicing factors, they exert widespread control of alternative splicing.
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Affiliation(s)
- Ching-In Lau
- UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Jasmine Rowell
- UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Diana C. Yanez
- UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Anisha Solanki
- UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Susan Ross
- UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Masahiro Ono
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Tessa Crompton
- UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
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6
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Yabas M, Yazicioglu YF, Hoyne GF, Goodnow CC, Enders A. Loss of hnRNPLL-dependent splicing of Ptprc has no impact on B-cell development, activation and terminal differentiation into antibody-secreting cells. Immunol Cell Biol 2021; 99:532-541. [PMID: 33331104 DOI: 10.1111/imcb.12433] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 12/10/2020] [Accepted: 12/14/2020] [Indexed: 01/03/2023]
Abstract
The RNA-binding protein heterogeneous nuclear ribonucleoprotein L-like (hnRNPLL) controls alternative splicing of protein tyrosine phosphatase receptor type C (Ptprc) which encodes CD45. hnRNPLL deficiency leads to a failure in silencing Ptprc exons 4-6 causing aberrant expression of the corresponding CD45 isoforms, namely, CD45RA, RB and RC. While an N-ethyl-N-nitrosourea-induced point mutation in murine Hnrnpll results in loss of peripheral naïve T cells, its role in B-cell biology remains unclear. Here, we demonstrate that B-cell development in the bone marrow of Hnrnpllthu/thu mice is normal and the number of mature B-cell subsets in the spleen and peritoneal cavity is comparable to control littermates. In response to in vivo immunization, Hnrnpllthu/thu mice were deficient in generating germinal center (GC) B cells, and analysis of mixed bone marrow chimeras revealed that the GC B-cell deficiency was a B-cell extrinsic effect of the hnRNPLL mutation. Mature Hnrnpllthu/thu B cells proliferated normally in response to various B-cell receptor- and Toll-like receptor-mediated stimuli. Similarly, in vitro stimulation of mutant B cells led to normal generation of plasmablasts, but mutant plasmablasts failed to downregulate B220 expression because of the inability of cells to undergo proper CD45 pre-messenger RNA alternative splicing. These findings collectively suggest that, like in T and natural killer T cells, the mutation disrupts hnRNPLL-mediated alternative splicing of the Ptprc gene in plasmablasts, but this dysregulation of Ptprc alternative splicing does not affect the development and function of B cells.
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Affiliation(s)
- Mehmet Yabas
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia.,Department of Genetics and Bioengineering, Trakya University, Edirne, Turkey
| | - Yavuz F Yazicioglu
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Gerard F Hoyne
- School of Health Sciences, Institute of Health Science Research, The University of Notre Dame Australia, Fremantle, WA, Australia
| | - Christopher C Goodnow
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia.,The Garvan Institute of Medical Research, The University of New South Wales, Darlinghurst, NSW, Australia.,Department of Medicine, St Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW, Australia
| | - Anselm Enders
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
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7
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van den Buuse M, Halley P, Hoyne GF. Behavioural phenotyping of thunder mice with a hypomorphic mutation of heterogeneous nuclear ribonuclear protein L-like (hnRNPLL) and reduced T cell function. Neurosci Lett 2020; 740:135469. [PMID: 33152455 DOI: 10.1016/j.neulet.2020.135469] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 09/23/2020] [Accepted: 10/27/2020] [Indexed: 02/01/2023]
Abstract
Heterogeneous nuclear ribonuclear protein l-like (hnRNPLL) is an RNA binding protein that regulates alternative splicing of mRNA and is abundantly expressed in memory T lymphocytes of the immune system and in the brain. A hypomorphic allele of the gene encoding hnRNPLL (Hnrpllthunder) selectively reduces T cell accumulation in lymphoid tissues, but little is known about its effects in the brain. Therefore, we exposed Hnrpllthunder mice to a test battery with relevance for a range of psychiatric illnesses. Thunder mice showed enhanced immobility in the tail-suspension test for depression-related behaviours, impaired short-term spatial memory in the Y-maze and reduced avoidance learning in the active avoidance test. Thus, in addition to its reported effects on immune function, the hnRNPLL mutation in thunder mice selectively affected aspects of behaviour.
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Affiliation(s)
- Maarten van den Buuse
- Mental Health Research Institute of Victoria, Parkville, VIC, Australia; School of Psychology and Public Health, La Trobe University, Melbourne, VIC, Australia.
| | - Paul Halley
- Mental Health Research Institute of Victoria, Parkville, VIC, Australia
| | - Gerard F Hoyne
- Immunology Program, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia; School of Health Sciences, University of Notre Dame Australia, Fremantle, WA, Australia
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Silva SL, Fonseca M, Pereira MLM, Silva SP, Barbosa RR, Serra-Caetano A, Blanco E, Rosmaninho P, Pérez-Andrés M, Sousa AB, Raposo AASF, Gama-Carvalho M, Victorino RMM, Hammarstrom L, Sousa AE. Monozygotic Twins Concordant for Common Variable Immunodeficiency: Strikingly Similar Clinical and Immune Profile Associated With a Polygenic Burden. Front Immunol 2019; 10:2503. [PMID: 31824477 PMCID: PMC6882918 DOI: 10.3389/fimmu.2019.02503] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 10/07/2019] [Indexed: 01/10/2023] Open
Abstract
Monozygotic twins provide a unique opportunity to better understand complex genetic diseases and the relative contribution of heritable factors in shaping the immune system throughout life. Common Variable Immunodeficiency Disorders (CVID) are primary antibody defects displaying wide phenotypic and genetic heterogeneity, with monogenic transmission accounting for only a minority of the cases. Here, we report a pair of monozygotic twins concordant for CVID without a family history of primary immunodeficiency. They featured a remarkably similar profile of clinical manifestations and immunological alterations at diagnosis (established at age 37) and along the subsequent 15 years of follow-up. Interestingly, whole-exome sequencing failed to identify a monogenic cause for CVID, but unraveled a combination of heterozygous variants, with a predicted deleterious impact. These variants were found in genes involved in relevant immunological pathways, such as JUN, PTPRC, TLR1, ICAM1, and JAK3. The potential for combinatorial effects translating into the observed disease phenotype is inferred from their roles in immune pathways, namely in T and B cell activation. The combination of these genetic variants is also likely to impose a significant constraint on environmental influences, resulting in a similar immunological phenotype in both twins, despite exposure to different living conditions. Overall, these cases stress the importance of integrating NGS data with clinical and immunological phenotypes at the single-cell level, as provided by multi-dimensional flow-cytometry, in order to understand the complex genetic landscape underlying the vast majority of patients with CVID, as well as those with other immunodeficiencies.
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Affiliation(s)
- Susana L Silva
- Faculdade de Medicina, Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisbon, Portugal.,Centro de Imunodeficiências Primárias, Centro Académico de Medicina de Lisboa, Centro Hospitalar Universitário Lisboa Norte and Faculdade de Medicina da Universidade de Lisboa and Instituto de Medicina Molecular, Lisbon, Portugal.,Centro Hospitalar Universitário Lisboa Norte, Hospital de Santa Maria, Lisbon, Portugal
| | - Mariana Fonseca
- Faculdade de Medicina, Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisbon, Portugal.,Centro de Imunodeficiências Primárias, Centro Académico de Medicina de Lisboa, Centro Hospitalar Universitário Lisboa Norte and Faculdade de Medicina da Universidade de Lisboa and Instituto de Medicina Molecular, Lisbon, Portugal
| | - Marcelo L M Pereira
- Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, University of Lisboa, Lisbon, Portugal
| | - Sara P Silva
- Faculdade de Medicina, Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisbon, Portugal.,Centro de Imunodeficiências Primárias, Centro Académico de Medicina de Lisboa, Centro Hospitalar Universitário Lisboa Norte and Faculdade de Medicina da Universidade de Lisboa and Instituto de Medicina Molecular, Lisbon, Portugal.,Centro Hospitalar Universitário Lisboa Norte, Hospital de Santa Maria, Lisbon, Portugal
| | - Rita R Barbosa
- Faculdade de Medicina, Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisbon, Portugal
| | - Ana Serra-Caetano
- Faculdade de Medicina, Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisbon, Portugal.,Centro de Imunodeficiências Primárias, Centro Académico de Medicina de Lisboa, Centro Hospitalar Universitário Lisboa Norte and Faculdade de Medicina da Universidade de Lisboa and Instituto de Medicina Molecular, Lisbon, Portugal
| | - Elena Blanco
- Department of Medicine, Cancer Research Centre (IBMCC, USAL-CSIC), Cytometry Service (NUCLEUS), Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca (USAL), Salamanca, Spain.,Biomedical Research Networking Centre on Cancer-CIBER-CIBERONC, Number CB16/12/00400, Institute of Health Carlos III, Madrid, Spain
| | - Pedro Rosmaninho
- Faculdade de Medicina, Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisbon, Portugal.,Centro de Imunodeficiências Primárias, Centro Académico de Medicina de Lisboa, Centro Hospitalar Universitário Lisboa Norte and Faculdade de Medicina da Universidade de Lisboa and Instituto de Medicina Molecular, Lisbon, Portugal
| | - Martin Pérez-Andrés
- Department of Medicine, Cancer Research Centre (IBMCC, USAL-CSIC), Cytometry Service (NUCLEUS), Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca (USAL), Salamanca, Spain.,Biomedical Research Networking Centre on Cancer-CIBER-CIBERONC, Number CB16/12/00400, Institute of Health Carlos III, Madrid, Spain
| | - Ana Berta Sousa
- Faculdade de Medicina, Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisbon, Portugal.,Centro de Imunodeficiências Primárias, Centro Académico de Medicina de Lisboa, Centro Hospitalar Universitário Lisboa Norte and Faculdade de Medicina da Universidade de Lisboa and Instituto de Medicina Molecular, Lisbon, Portugal.,Centro Hospitalar Universitário Lisboa Norte, Hospital de Santa Maria, Lisbon, Portugal
| | - Alexandre A S F Raposo
- Faculdade de Medicina, Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisbon, Portugal.,Centro de Imunodeficiências Primárias, Centro Académico de Medicina de Lisboa, Centro Hospitalar Universitário Lisboa Norte and Faculdade de Medicina da Universidade de Lisboa and Instituto de Medicina Molecular, Lisbon, Portugal
| | - Margarida Gama-Carvalho
- Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, University of Lisboa, Lisbon, Portugal
| | - Rui M M Victorino
- Faculdade de Medicina, Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisbon, Portugal.,Centro de Imunodeficiências Primárias, Centro Académico de Medicina de Lisboa, Centro Hospitalar Universitário Lisboa Norte and Faculdade de Medicina da Universidade de Lisboa and Instituto de Medicina Molecular, Lisbon, Portugal.,Centro Hospitalar Universitário Lisboa Norte, Hospital de Santa Maria, Lisbon, Portugal
| | | | - Ana E Sousa
- Faculdade de Medicina, Instituto de Medicina Molecular João Lobo Antunes, Universidade de Lisboa, Lisbon, Portugal.,Centro de Imunodeficiências Primárias, Centro Académico de Medicina de Lisboa, Centro Hospitalar Universitário Lisboa Norte and Faculdade de Medicina da Universidade de Lisboa and Instituto de Medicina Molecular, Lisbon, Portugal
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9
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Díaz-Muñoz MD, Turner M. Uncovering the Role of RNA-Binding Proteins in Gene Expression in the Immune System. Front Immunol 2018; 9:1094. [PMID: 29875770 PMCID: PMC5974052 DOI: 10.3389/fimmu.2018.01094] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/02/2018] [Indexed: 12/29/2022] Open
Abstract
Fighting external pathogens requires an ever-changing immune system that relies on tight regulation of gene expression. Transcriptional control is the first step to build efficient responses while preventing immunodeficiencies and autoimmunity. Post-transcriptional regulation of RNA editing, location, stability, and translation are the other key steps for final gene expression, and they are all controlled by RNA-binding proteins (RBPs). Nowadays we have a deep understanding of how transcription factors control the immune system but recent evidences suggest that post-transcriptional regulation by RBPs is equally important for both development and activation of immune responses. Here, we review current knowledge about how post-transcriptional control by RBPs shapes our immune system and discuss the perspective of RBPs being the key players of a hidden immune cell epitranscriptome.
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Affiliation(s)
- Manuel D Díaz-Muñoz
- Centre de Physiopathologie Toulouse-Purpan, INSERM UMR1043/CNRS U5282, Toulouse, France
| | - Martin Turner
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
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10
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Yurova KA, Sokhonevich NA, Khaziakhmatova OG, Litvinova LS. [Cytokine-mediated regulation of expression of Gfi1 and U2afll4 genes activated by T-cells with different differentiation status in vitro]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2016; 62:180-6. [PMID: 27143377 DOI: 10.18097/pbmc20166202180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The dose-dependent effects of cytokines (IL-2, IL-7, and IL-15), which have a common g-chain, on mRNA expression of U2afll4 and GFi1 genes involved in regulation of alternative splicing of the Ptprc gene, have been investigated in vitro using T-lymphocyte cultures with different degrees of differentiation. IL-2, IL-7, and IL-15 caused a similar unidirectional inhibitory effect of various severity on restimulated CD45RO+ T-cells exposed to an antigen-independent activation; they caused a dose-dependent decrease of the U2af1l4 gene expression, and an increase of Gfi1 gene expression. This may suggest formation of active forms of the CD45 receptor, and also limitation of the formation of low-molecular short splice variants of the CD45RO receptor. Under conditions of antigen-independent stimulation of naive CD45RA+-cells rIL-7 and IL-15 exhibited opposite effects on U2af1l4 and Gfi1 gene expression. The increase of IL-7 concentrations in the incubation medium of naive cells was accompanied by a decrease in expression of both genes. IL-15 IL-7 exhibited opposite effects. Cytokines possessing a common g-chain (IL-2, IL-7, and IL-15) prevented antigen-independent differentiation of naive T-cells, by preventing the formation of polyclonal "surrogate" cells. In general, the study of the molecular mechanisms of genetic control determining homeostatic processes of T-cells in response to exposure to antigenic or non-antigenic treatments may be important for construction of a general model of self-maintenance and differentiation of immune cells.
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Affiliation(s)
- K A Yurova
- Kant Baltic Federal University, Kaliningrad, Russia
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11
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Chang X. RNA-binding protein hnRNPLL as a critical regulator of lymphocyte homeostasis and differentiation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:295-302. [PMID: 26821996 DOI: 10.1002/wrna.1335] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 12/18/2015] [Indexed: 12/24/2022]
Abstract
RNA-binding proteins orchestrate posttranscriptional regulation of gene expression, such as messenger RNA (mRNA) splicing, RNA stability regulation, and translation regulation. Heterogeneous nuclear RNA-binding proteins (hnRNPs) refer to a collection of unrelated RNA-binding proteins predominantly located in the nucleus (Han et al. Biochem J 2010, 430:379-392). Although canonical functions of hnRNPs are to promote pre-mRNA splicing, they are involved in all the processes of RNA metabolism through recognizing specific cis-elements on RNA (Dreyfuss et al. Annu Rev Biochem 1993, 62:289-321; Huelga et al. Cell Rep 2012, 1:167-178; Krecic and Swanson. Curr Opin Cell Biol 1999, 11:363-371). Heterogeneous nuclear RNA-binding protein L like (hnRNPLL) is a tissue-specific hnRNP, which was identified as a regulator of CD45RA to CD45RO switching during memory T-cell development (Oberdoerffer et al. Science 2008, 321:686-691; Topp et al. RNA 2008, 14:2038-2049; Wu et al. Immunity 2008, 29:863-875). Since then, hnRNPLL has emerged as a critical regulator of lymphocyte homeostasis and terminal differentiation, controlling alternative splicing or expression of critical genes for the lymphocytes development (Wu et al. Immunity 2008, 29:863-875; Chang et al. Proc Natl Acad Sci USA 2015, 112:E1888-E1897). This review will summarize recent advances in understanding the functions of hnRNPLL, focusing on its biochemical functions and physiological roles in lymphocyte differentiation and homeostasis. WIREs RNA 2016, 7:295-302. doi: 10.1002/wrna.1335 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Xing Chang
- La Jolla Institute for Allergy and Immunology, La Jolla, CA, USA
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The Role of Alternative Splicing in the Control of Immune Homeostasis and Cellular Differentiation. Int J Mol Sci 2015; 17:ijms17010003. [PMID: 26703587 PMCID: PMC4730250 DOI: 10.3390/ijms17010003] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 12/11/2015] [Accepted: 12/15/2015] [Indexed: 12/21/2022] Open
Abstract
Alternative splicing of pre-mRNA helps to enhance the genetic diversity within mammalian cells by increasing the number of protein isoforms that can be generated from one gene product. This provides a great deal of flexibility to the host cell to alter protein function, but when dysregulation in splicing occurs this can have important impact on health and disease. Alternative splicing is widely used in the mammalian immune system to control the development and function of antigen specific lymphocytes. In this review we will examine the splicing of pre-mRNAs yielding key proteins in the immune system that regulate apoptosis, lymphocyte differentiation, activation and homeostasis, and discuss how defects in splicing can contribute to diseases. We will describe how disruption to trans-acting factors, such as heterogeneous nuclear ribonucleoproteins (hnRNPs), can impact on cell survival and differentiation in the immune system.
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Effects of Immunoregulatory Cytokines (IL-2, IL-7, and IL-15) on Expression of Gfi1 and U2afll4 Genes in T Cells at Different Stages of Differentiation. Bull Exp Biol Med 2015; 159:236-9. [PMID: 26085358 DOI: 10.1007/s10517-015-2931-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Indexed: 10/23/2022]
Abstract
Opposite effects of common γ-chain cytokines (IL-2, IL-7, and IL-15) on the expression of Gfi1 and U2af1l4 genes regulating alternative splicing of Ptprc gene in T cells at different stages of differentiation were demonstrated in vitro. Generally, produced a dose-dependent activating effect on T cells, while to the effects of rIL-7 and rIL-15 on T cells at different stages of differentiation were opposite to that of rIL-2: maximum concentrations of recombinant cytokines IL-7 and IL-15 produced the most pronounced inhibitory effect on U2af1l4 and to a lesser extent on Gfi1 gene expression, thus limiting activation of resting cells. This is consistent with their biological effects on T cells. In general, common γ-chain cytokines IL-2, IL-7, and IL-15 prevent differentiation of naïve T cells in vitro and limit activation of primed T cells in the absence of antigenic stimulus, which can contribute to the formation of cytokine imbalance.
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Siggs OM. Dissecting mammalian immunity through mutation. Immunol Cell Biol 2014; 92:392-9. [PMID: 24518983 PMCID: PMC4038135 DOI: 10.1038/icb.2014.8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 01/15/2014] [Accepted: 01/15/2014] [Indexed: 12/27/2022]
Abstract
Although mutation and natural selection have given rise to our immune system, a well-placed mutation can also cripple it, and within an expanding population we are recognizing more and more cases of single-gene mutations that compromise immunity. These mutations are an ideal tool for understanding human immunology, and there are more ways than ever to measure their physiological effects. There are also more ways to create mutations in the laboratory, and to use these resources to systematically define the function of every gene in our genome. This review focuses on the discovery and creation of mutations in the context of mammalian immunity, with an emphasis on the use of genome-wide chemical and CRISPR/Cas9 mutagenesis to reveal gene function.
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Affiliation(s)
- Owen M Siggs
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
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Cho V, Mei Y, Sanny A, Chan S, Enders A, Bertram EM, Tan A, Goodnow CC, Andrews TD. The RNA-binding protein hnRNPLL induces a T cell alternative splicing program delineated by differential intron retention in polyadenylated RNA. Genome Biol 2014; 15:R26. [PMID: 24476532 PMCID: PMC4053824 DOI: 10.1186/gb-2014-15-1-r26] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 01/29/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Retention of a subset of introns in spliced polyadenylated mRNA is emerging as a frequent, unexplained finding from RNA deep sequencing in mammalian cells. RESULTS Here we analyze intron retention in T lymphocytes by deep sequencing polyadenylated RNA. We show a developmentally regulated RNA-binding protein, hnRNPLL, induces retention of specific introns by sequencing RNA from T cells with an inactivating Hnrpll mutation and from B lymphocytes that physiologically downregulate Hnrpll during their differentiation. In Ptprc mRNA encoding the tyrosine phosphatase CD45, hnRNPLL induces selective retention of introns flanking exons 4 to 6; these correspond to the cassette exons containing hnRNPLL binding sites that are skipped in cells with normal, but not mutant or low, hnRNPLL. We identify similar patterns of hnRNPLL-induced differential intron retention flanking alternative exons in 14 other genes, representing novel elements of the hnRNPLL-induced splicing program in T cells. Retroviral expression of a normally spliced cDNA for one of these targets, Senp2, partially corrects the survival defect of Hnrpll-mutant T cells. We find that integrating a number of computational methods to detect genes with differentially retained introns provides a strategy to enrich for alternatively spliced exons in mammalian RNA-seq data, when complemented by RNA-seq analysis of purified cells with experimentally perturbed RNA-binding proteins. CONCLUSIONS Our findings demonstrate that intron retention in mRNA is induced by specific RNA-binding proteins and suggest a biological significance for this process in marking exons that are poised for alternative splicing.
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Orrù V, Steri M, Sole G, Sidore C, Virdis F, Dei M, Lai S, Zoledziewska M, Busonero F, Mulas A, Floris M, Mentzen WI, Urru SAM, Olla S, Marongiu M, Piras MG, Lobina M, Maschio A, Pitzalis M, Urru MF, Marcelli M, Cusano R, Deidda F, Serra V, Oppo M, Pilu R, Reinier F, Berutti R, Pireddu L, Zara I, Porcu E, Kwong A, Brennan C, Tarrier B, Lyons R, Kang HM, Uzzau S, Atzeni R, Valentini M, Firinu D, Leoni L, Rotta G, Naitza S, Angius A, Congia M, Whalen MB, Jones CM, Schlessinger D, Abecasis GR, Fiorillo E, Sanna S, Cucca F. Genetic variants regulating immune cell levels in health and disease. Cell 2013; 155:242-56. [PMID: 24074872 DOI: 10.1016/j.cell.2013.08.041] [Citation(s) in RCA: 244] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 07/11/2013] [Accepted: 08/20/2013] [Indexed: 12/14/2022]
Abstract
The complex network of specialized cells and molecules in the immune system has evolved to defend against pathogens, but inadvertent immune system attacks on "self" result in autoimmune disease. Both genetic regulation of immune cell levels and their relationships with autoimmunity are largely undetermined. Here, we report genetic contributions to quantitative levels of 95 cell types encompassing 272 immune traits, in a cohort of 1,629 individuals from four clustered Sardinian villages. We first estimated trait heritability, showing that it can be substantial, accounting for up to 87% of the variance (mean 41%). Next, by assessing ∼8.2 million variants that we identified and confirmed in an extended set of 2,870 individuals, 23 independent variants at 13 loci associated with at least one trait. Notably, variants at three loci (HLA, IL2RA, and SH2B3/ATXN2) overlap with known autoimmune disease associations. These results connect specific cellular phenotypes to specific genetic variants, helping to explicate their involvement in disease.
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Affiliation(s)
- Valeria Orrù
- Istituto di Ricerca Genetica e Biomedica (IRGB), CNR, Monserrato 09042, Italy
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17
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Genetic variants regulating immune cell levels in health and disease. Cell 2013. [PMID: 24074872 DOI: 10.1016/j.cell.2013.08.041.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The complex network of specialized cells and molecules in the immune system has evolved to defend against pathogens, but inadvertent immune system attacks on "self" result in autoimmune disease. Both genetic regulation of immune cell levels and their relationships with autoimmunity are largely undetermined. Here, we report genetic contributions to quantitative levels of 95 cell types encompassing 272 immune traits, in a cohort of 1,629 individuals from four clustered Sardinian villages. We first estimated trait heritability, showing that it can be substantial, accounting for up to 87% of the variance (mean 41%). Next, by assessing ∼8.2 million variants that we identified and confirmed in an extended set of 2,870 individuals, 23 independent variants at 13 loci associated with at least one trait. Notably, variants at three loci (HLA, IL2RA, and SH2B3/ATXN2) overlap with known autoimmune disease associations. These results connect specific cellular phenotypes to specific genetic variants, helping to explicate their involvement in disease.
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18
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Caignard G, Leiva-Torres GA, Leney-Greene M, Charbonneau B, Dumaine A, Fodil-Cornu N, Pyzik M, Cingolani P, Schwartzentruber J, Dupaul-Chicoine J, Guo H, Saleh M, Veillette A, Lathrop M, Blanchette M, Majewski J, Pearson A, Vidal SM. Genome-wide mouse mutagenesis reveals CD45-mediated T cell function as critical in protective immunity to HSV-1. PLoS Pathog 2013; 9:e1003637. [PMID: 24068938 PMCID: PMC3771889 DOI: 10.1371/journal.ppat.1003637] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 07/24/2013] [Indexed: 01/15/2023] Open
Abstract
Herpes simplex encephalitis (HSE) is a lethal neurological disease resulting from infection with Herpes Simplex Virus 1 (HSV-1). Loss-of-function mutations in the UNC93B1, TLR3, TRIF, TRAF3, and TBK1 genes have been associated with a human genetic predisposition to HSE, demonstrating the UNC93B-TLR3-type I IFN pathway as critical in protective immunity to HSV-1. However, the TLR3, UNC93B1, and TRIF mutations exhibit incomplete penetrance and represent only a minority of HSE cases, perhaps reflecting the effects of additional host genetic factors. In order to identify new host genes, proteins and signaling pathways involved in HSV-1 and HSE susceptibility, we have implemented the first genome-wide mutagenesis screen in an in vivo HSV-1 infectious model. One pedigree (named P43) segregated a susceptible trait with a fully penetrant phenotype. Genetic mapping and whole exome sequencing led to the identification of the causative nonsense mutation L3X in the Receptor-type tyrosine-protein phosphatase C gene (Ptprc(L3X)), which encodes for the tyrosine phosphatase CD45. Expression of MCP1, IL-6, MMP3, MMP8, and the ICP4 viral gene were significantly increased in the brain stems of infected Ptprc(L3X) mice accounting for hyper-inflammation and pathological damages caused by viral replication. Ptprc(L3X) mutation drastically affects the early stages of thymocytes development but also the final stage of B cell maturation. Transfer of total splenocytes from heterozygous littermates into Ptprc(L3X) mice resulted in a complete HSV-1 protective effect. Furthermore, T cells were the only cell population to fully restore resistance to HSV-1 in the mutants, an effect that required both the CD4⁺ and CD8⁺ T cells and could be attributed to function of CD4⁺ T helper 1 (Th1) cells in CD8⁺ T cell recruitment to the site of infection. Altogether, these results revealed the CD45-mediated T cell function as potentially critical for infection and viral spread to the brain, and also for subsequent HSE development.
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Affiliation(s)
- Grégory Caignard
- Departments of Human Genetics and Medicine, McGill University, Montréal, Quebec, Canada
| | | | - Michael Leney-Greene
- Departments of Human Genetics and Medicine, McGill University, Montréal, Quebec, Canada
| | - Benoit Charbonneau
- Departments of Human Genetics and Medicine, McGill University, Montréal, Quebec, Canada
| | - Anne Dumaine
- Departments of Human Genetics and Medicine, McGill University, Montréal, Quebec, Canada
| | - Nassima Fodil-Cornu
- Departments of Human Genetics and Medicine, McGill University, Montréal, Quebec, Canada
| | - Michal Pyzik
- Departments of Human Genetics and Medicine, McGill University, Montréal, Quebec, Canada
| | - Pablo Cingolani
- School of Computer Science and McGill Centre for Bioinformatics, McGill University, Montréal, Quebec, Canada
| | | | | | - Huaijian Guo
- Laboratory of Molecular Oncology, Clinical Research Institute of Montréal, Montréal, Quebec, Canada
| | - Maya Saleh
- Departments of Biochemistry and Medicine, McGill University, Montréal, Quebec, Canada
| | - André Veillette
- Laboratory of Molecular Oncology, Clinical Research Institute of Montréal, Montréal, Quebec, Canada
| | - Marc Lathrop
- McGill University and Genome Québec Innovation Centre, Montréal, Quebec, Canada
| | - Mathieu Blanchette
- School of Computer Science and McGill Centre for Bioinformatics, McGill University, Montréal, Quebec, Canada
| | - Jacek Majewski
- McGill University and Genome Québec Innovation Centre, Montréal, Quebec, Canada
| | - Angela Pearson
- INRS-Institut Armand-Frappier, Université du Québec, Laval, Quebec, Canada
| | - Silvia M. Vidal
- Departments of Human Genetics and Medicine, McGill University, Montréal, Quebec, Canada
- * E-mail:
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Litvinova LS, Mazunin IO, Gutsol AA, Sokhonevich NA, Khaziakhmatova OG, Kofanova KA. Dose-response effect of steroid hormones on Gfi1 and U2af1l4 gene expression in T lymphocytes at different stages of differentiation. Mol Biol 2013. [DOI: 10.1134/s0026893313040092] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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20
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Martinez NM, Lynch KW. Control of alternative splicing in immune responses: many regulators, many predictions, much still to learn. Immunol Rev 2013; 253:216-36. [PMID: 23550649 PMCID: PMC3621013 DOI: 10.1111/imr.12047] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Most mammalian pre-mRNAs are alternatively spliced in a manner that alters the resulting open reading frame. Consequently, alternative pre-mRNA splicing provides an important RNA-based layer of protein regulation and cellular function. The ubiquitous nature of alternative splicing coupled with the advent of technologies that allow global interrogation of the transcriptome have led to an increasing awareness of the possibility that widespread changes in splicing patterns contribute to lymphocyte function during an immune response. Indeed, a few notable examples of alternative splicing have clearly been demonstrated to regulate T-cell responses to antigen. Moreover, several proteins key to the regulation of splicing in T cells have recently been identified. However, much remains to be done to truly identify the spectrum of genes that are regulated at the level of splicing in immune cells and to determine how many of these are controlled by currently known factors and pathways versus unknown mechanisms. Here, we describe the proteins, pathways, and mechanisms that have been shown to regulate alternative splicing in human T cells and discuss what is and is not known about the genes regulated by such factors. Finally, we highlight unifying themes with regards to the mechanisms and consequences of alternative splicing in the adaptive immune system and give our view of important directions for future studies.
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Affiliation(s)
- Nicole M Martinez
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6059, USA
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Heterogeneous nuclear ribonucleoprotein L-like (hnRNPLL) and elongation factor, RNA polymerase II, 2 (ELL2) are regulators of mRNA processing in plasma cells. Proc Natl Acad Sci U S A 2012; 109:16252-7. [PMID: 22991471 DOI: 10.1073/pnas.1214414109] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
B cells and plasma cells possess distinct RNA processing environments that respectively promote the expression of membrane-associated Ig by B cells versus the secretion of Ig by plasma cells. Through a combination of transcriptional profiling and screening using a lentiviral short-hairpin RNA interference library, we show that both the splicing factor hnRNPLL and the transcription elongation factor ELL2 modulate the ratio of secreted versus membrane-encoding Ighg2b transcripts in MPC11 plasmacytoma cell lines. hnRNPLL and ELL2 are both highly expressed in primary plasma cells relative to B cells, but hnRNPLL binds Ighg2b mRNA transcripts and promotes an increase in levels of the membrane-encoding Ighg2b isoform at the expense of the secreted Ighg2b isoform, whereas ELL2 counteracts this effect and drives Ig secretion by increasing the frequency of the secreted Ighg2b isoform. As in T cells, hnRNPLL also alters the splicing pattern of mRNA encoding the adhesion receptor CD44, promoting exon inclusion, and decreasing the overall level of CD44 expression. Further characterization of ELL2-dependent transcription by RNA-Seq revealed that ∼12% of transcripts expressed by plasma cells were differentially processed because of the activities of ELL2, including B-cell maturation antigen BCMA, a receptor with a defined role in plasma cell survival. Taken together, our data identify hnRNPLL and ELL2 as regulators of pre-mRNA processing in plasma cells.
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22
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Yabas M, Godfrey DI, Goodnow CC, Hoyne GF. Differential requirement for the CD45 splicing regulator hnRNPLL for accumulation of NKT and conventional T cells. PLoS One 2011; 6:e26440. [PMID: 22073166 PMCID: PMC3208548 DOI: 10.1371/journal.pone.0026440] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 09/27/2011] [Indexed: 11/30/2022] Open
Abstract
Natural killer T (NKT) cells represent an important regulatory T cell subset that develops in the thymus and contains immature (NK1.1lo) and mature (NK1.1hi) cell subsets. Here we show in mice that an inherited mutation in heterogeneous ribonucleoprotein L-like protein (hnRNPLLthunder), that shortens the survival of conventional T cells, has no discernible effect on NKT cell development, homeostasis or effector function. Thus, Hnrpll deficiency effectively increases the NKT∶T cell ratio in the periphery. However, Hnrpll mutation disrupts CD45RA, RB and RC exon silencing of the Ptprc mRNA in both NKT and conventional T cells, and leads to a comparably dramatic shift to high molecular weight CD45 isoforms. In addition, Hnrpll mutation has a cell intrinsic effect on the expression of the developmentally regulated cell surface marker NK1.1 on NKT cells in the thymus and periphery but does not affect cell numbers. Therefore our results highlight both overlapping and divergent roles for hnRNPLL between conventional T cells and NKT cells. In both cell subsets it is required as a trans-acting factor to regulate alternative splicing of the Ptprc mRNA, but it is only required for survival of conventional T cells.
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Affiliation(s)
- Mehmet Yabas
- Department of Immunology, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Dale I. Godfrey
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Australia
| | - Christopher C. Goodnow
- Department of Immunology, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
- * E-mail: (CG); (GH)
| | - Gerard F. Hoyne
- Department of Immunology, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
- * E-mail: (CG); (GH)
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Hoyne GF, Chapman G, Sontani Y, Pursglove SE, Dunwoodie SL. A cell autonomous role for the Notch ligand Delta-like 3 in αβ T-cell development. Immunol Cell Biol 2010; 89:696-705. [PMID: 21151194 DOI: 10.1038/icb.2010.154] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Notch signalling is critical to help direct T-cell lineage commitment in early T-cell progenitors and in the development of αβ T-cells. Epithelial and stromal cell populations in the thymus express the Notch DSL (Delta, Serrate and Lag2)ligands Delta-like 1 (Dll1), Delta-like 4 (Dll4), Jagged 1 and Jagged 2, and induce Notch signalling in thymocytes that express the Notch receptor. At present there is nothing known about the role of the Delta-like 3 (Dll3) ligand in the immune system. Here we describe a novel cell autonomous role for Dll3 in αβ T-cell development. We show that Dll3 cannot activate Notch when expressed in trans but like other Notch ligands it can inhibit Notch signalling when expressed in cis with the receptor. The loss of Dll3 leads to an increase in Hes5 expression in double positive thymocytes and their increased production of mature CD4(+) and CD8(+) T cells. Studies using competitive irradiation chimeras proved that Dll3 acts in a cell autonomous manner to regulate positive selection but not negative selection of autoreactive T cells. Our results indicate that Dll3 has a unique function during T-cell development that is distinct from the role played by the other DSL ligands of Notch and is in keeping with other recent studies indicating that Dll1 and Dll3 ligands have non-overlapping roles during embryonic development.
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Affiliation(s)
- Gerard F Hoyne
- The Laboratory of T Cell Development and Regulation, John Curtin School of Medical Research, Australian National University Canberra, Canberra, Australian Capital Territory, Australia.
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