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Phongbunchoo Y, Braikia FZ, Pessoa-Rodrigues C, Ramamoorthy S, Ramachandran H, Grosschedl A, Ma F, Cauchy P, Akhtar A, Sen R, Mittler G, Grosschedl R. YY1-mediated enhancer-promoter communication in the immunoglobulin μ locus is regulated by MSL/MOF recruitment. Cell Rep 2024; 43:114456. [PMID: 38990722 DOI: 10.1016/j.celrep.2024.114456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 05/02/2024] [Accepted: 06/21/2024] [Indexed: 07/13/2024] Open
Abstract
The rearrangement and expression of the immunoglobulin μ heavy chain (Igh) gene require communication of the intragenic Eμ and 3' regulatory region (RR) enhancers with the variable (VH) gene promoter. Eμ binding of the transcription factor YY1 has been implicated in enhancer-promoter communication, but the YY1 protein network remains obscure. By analyzing the comprehensive proteome of the 1-kb Eμ wild-type enhancer and that of Eμ lacking the YY1 binding site, we identified the male-specific lethal (MSL)/MOF complex as a component of the YY1 protein network. We found that MSL2 recruitment depends on YY1 and that gene knockout of Msl2 in primary pre-B cells reduces μ gene expression and chromatin looping of Eμ to the 3' RR enhancer and VH promoter. Moreover, Mof heterozygosity in mice impaired μ expression and early B cell differentiation. Together, these data suggest that the MSL/MOF complex regulates Igh gene expression by augmenting YY1-mediated enhancer-promoter communication.
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Affiliation(s)
- Yutthaphong Phongbunchoo
- Laboratory of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Fatima-Zohra Braikia
- Laboratory of Molecular Biology & Immunology, National Institute on Aging, NIH, Baltimore, MD, USA
| | - Cecilia Pessoa-Rodrigues
- Department of Chromatin Regulation, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Senthilkumar Ramamoorthy
- Laboratory of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany; Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany; Institute of Medical Bioinformatics and Systems Medicine, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Haribaskar Ramachandran
- Laboratory of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Anna Grosschedl
- Laboratory of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Fei Ma
- Laboratory of Molecular Biology & Immunology, National Institute on Aging, NIH, Baltimore, MD, USA
| | - Pierre Cauchy
- Laboratory of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Asifa Akhtar
- Department of Chromatin Regulation, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany.
| | - Ranjan Sen
- Laboratory of Molecular Biology & Immunology, National Institute on Aging, NIH, Baltimore, MD, USA.
| | - Gerhard Mittler
- Proteomics Facility, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany.
| | - Rudolf Grosschedl
- Laboratory of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany.
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2
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Al Jamal I, Parquet M, Guiyedi K, Aoufouchi S, Le Guillou M, Rizzo D, Pollet J, Dupont M, Boulin M, Faumont N, Boutouil H, Jardin F, Ruminy P, El Hamel C, Lerat J, Al Hamaoui S, Makdissy N, Feuillard J, Gachard N, Peron S. IGH 3'RR recombination uncovers a non-germinal center imprint and c-MYC-dependent IGH rearrangement in unmutated chronic lymphocytic leukemia. Haematologica 2024; 109:466-478. [PMID: 37496419 PMCID: PMC10828775 DOI: 10.3324/haematol.2023.282897] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 07/20/2023] [Indexed: 07/28/2023] Open
Abstract
Chronic lymphocytic leukemia (CLL) is an incurable indolent non-Hodgkin lymphoma characterized by tumor B cells that weakly express a B-cell receptor. The mutational status of the variable region (IGHV) within the immunoglobulin heavy chain (IGH) locus is an important prognosis indicator and raises the question of the CLL cell of origin. Mutated IGHV gene CLL are genetically imprinted by activation-induced cytidine deaminase (AID). AID is also required for IGH rearrangements: class switch recombination and recombination between switch Mu (Sμ) and the 3' regulatory region (3'RR) (Sμ-3'RRrec). The great majority of CLL B cells being unswitched led us to examine IGH rearrangement blockade in CLL. Our results separated CLL into two groups on the basis of Sμ-3'RRrec counts per sample: Sμ-3'RRrecHigh cases (mostly unmutated CLL) and Sμ-3'RRrecLow cases (mostly mutated CLL), but not based on the class switch recombination junction counts. Sμ-3'RRrec appeared to be ongoing in Sμ-3'RRrecHigh CLL cells and comparison of Sμ-3'RRrec junction structural features pointed to different B-cell origins for both groups. In accordance with IGHV mutational status and PIM1 mutation rate, Sμ-3'RRrecHigh CLL harbor a non-germinal center experienced B-cell imprint while Sμ-3'RRrecLow CLL are from AID-experienced B cells from a secondary lymphoid organ. In addition to the proposals already made concerning the CLL cell of origin, our study highlights that analysis of IGH recombinatory activity can identify CLL cases from different origins. Finally, on-going Sμ-3'RRrec in Sμ-3'RRrecHigh cells appeared to presumably be the consequence of high c-MYC expression, as c-MYC overexpression potentiated IGH rearrangements and Sμ-3'RRrec, even in the absence of AID for the latter.
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Affiliation(s)
- Israa Al Jamal
- Centre National de la Recherche Scientifique (CNRS) Unite Mixte de Recherche (UMR) 7276/INSERM U1262, Universite de Limoges, Limoges, France; Faculty of Sciences, GSBT Genomic Surveillance and Biotherapy Team, Mont Michel Campus, Lebanese University, Tripoli
| | - Milene Parquet
- Centre National de la Recherche Scientifique (CNRS) Unite Mixte de Recherche (UMR) 7276/INSERM U1262, Universite de Limoges, Limoges
| | - Kenza Guiyedi
- Centre National de la Recherche Scientifique (CNRS) Unite Mixte de Recherche (UMR) 7276/INSERM U1262, Universite de Limoges, Limoges
| | - Said Aoufouchi
- CNRS UMR9019, Gustave Roussy, B-cell and Genome Plasticity Team, Villejuif, France and Universite Paris-Saclay, Orsay
| | - Morwenna Le Guillou
- CNRS UMR9019, Gustave Roussy, B-cell and Genome Plasticity Team, Villejuif, France and Universite Paris-Saclay, Orsay
| | - David Rizzo
- Centre National de la Recherche Scientifique (CNRS) Unite Mixte de Recherche (UMR) 7276/INSERM U1262, Universite de Limoges, Limoges, France; Laboratoire d'Hematologie Biologique, Centre Hospitalier Universitaire de Limoges, Limoges
| | - Justine Pollet
- Centre National de la Recherche Scientifique (CNRS) Unite Mixte de Recherche (UMR) 7276/INSERM U1262, Universite de Limoges, Limoges
| | - Marine Dupont
- Centre National de la Recherche Scientifique (CNRS) Unite Mixte de Recherche (UMR) 7276/INSERM U1262, Universite de Limoges, Limoges, France; Laboratoire d'Hematologie Biologique, Centre Hospitalier Universitaire de Limoges, Limoges
| | - Melanie Boulin
- Centre National de la Recherche Scientifique (CNRS) Unite Mixte de Recherche (UMR) 7276/INSERM U1262, Universite de Limoges, Limoges, France; Laboratoire d'Hematologie Biologique, Centre Hospitalier Universitaire de Limoges, Limoges
| | - Nathalie Faumont
- Centre National de la Recherche Scientifique (CNRS) Unite Mixte de Recherche (UMR) 7276/INSERM U1262, Universite de Limoges, Limoges
| | - Hend Boutouil
- Centre National de la Recherche Scientifique (CNRS) Unite Mixte de Recherche (UMR) 7276/INSERM U1262, Universite de Limoges, Limoges
| | - Fabrice Jardin
- Inserm U1245 and Department of Henri-Becquerel Hematology Center and Normandie Univ UNIROUEN, Rouen
| | - Philippe Ruminy
- Inserm U1245 and Department of Henri-Becquerel Hematology Center and Normandie Univ UNIROUEN, Rouen
| | - Chahrazed El Hamel
- Collection Biologique Hopital de la Mere et de l'Enfant (CB-HME), Department of Pediatrics, Limoges University Hospital, Limoges
| | - Justine Lerat
- Department of Otorinolaryngology, Limoges University Hospital, Limoges
| | - Samar Al Hamaoui
- Faculty of Sciences, GSBT Genomic Surveillance and Biotherapy Team, Mont Michel Campus, Lebanese University, Tripoli
| | - Nehman Makdissy
- Faculty of Sciences, GSBT Genomic Surveillance and Biotherapy Team, Mont Michel Campus, Lebanese University, Tripoli
| | - Jean Feuillard
- Centre National de la Recherche Scientifique (CNRS) Unite Mixte de Recherche (UMR) 7276/INSERM U1262, Universite de Limoges, Limoges, France; Laboratoire d'Hematologie Biologique, Centre Hospitalier Universitaire de Limoges, Limoges
| | - Nathalie Gachard
- Centre National de la Recherche Scientifique (CNRS) Unite Mixte de Recherche (UMR) 7276/INSERM U1262, Universite de Limoges, Limoges, France; Laboratoire d'Hematologie Biologique, Centre Hospitalier Universitaire de Limoges, Limoges
| | - Sophie Peron
- Centre National de la Recherche Scientifique (CNRS) Unite Mixte de Recherche (UMR) 7276/INSERM U1262, Universite de Limoges, Limoges.
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Mielczarek O, Rogers CH, Zhan Y, Matheson LS, Stubbington MJT, Schoenfelder S, Bolland DJ, Javierre BM, Wingett SW, Várnai C, Segonds-Pichon A, Conn SJ, Krueger F, Andrews S, Fraser P, Giorgetti L, Corcoran AE. Intra- and interchromosomal contact mapping reveals the Igh locus has extensive conformational heterogeneity and interacts with B-lineage genes. Cell Rep 2023; 42:113074. [PMID: 37676766 PMCID: PMC10548092 DOI: 10.1016/j.celrep.2023.113074] [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: 02/27/2023] [Revised: 06/28/2023] [Accepted: 08/18/2023] [Indexed: 09/09/2023] Open
Abstract
To produce a diverse antibody repertoire, immunoglobulin heavy-chain (Igh) loci undergo large-scale alterations in structure to facilitate juxtaposition and recombination of spatially separated variable (VH), diversity (DH), and joining (JH) genes. These chromosomal alterations are poorly understood. Uncovering their patterns shows how chromosome dynamics underpins antibody diversity. Using tiled Capture Hi-C, we produce a comprehensive map of chromatin interactions throughout the 2.8-Mb Igh locus in progenitor B cells. We find that the Igh locus folds into semi-rigid subdomains and undergoes flexible looping of the VH genes to its 3' end, reconciling two views of locus organization. Deconvolution of single Igh locus conformations using polymer simulations identifies thousands of different structures. This heterogeneity may underpin the diversity of V(D)J recombination events. All three immunoglobulin loci also participate in a highly specific, developmentally regulated network of interchromosomal interactions with genes encoding B cell-lineage factors. This suggests a model of interchromosomal coordination of B cell development.
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Affiliation(s)
- Olga Mielczarek
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Carolyn H Rogers
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; Immunology Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Yinxiu Zhan
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Louise S Matheson
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; Immunology Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Michael J T Stubbington
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Stefan Schoenfelder
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Daniel J Bolland
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; Immunology Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Biola M Javierre
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Steven W Wingett
- Bioinformatics Group, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Csilla Várnai
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Anne Segonds-Pichon
- Bioinformatics Group, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Simon J Conn
- Flinders Health and Medical Research Institute, College of Medicine and Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Felix Krueger
- Bioinformatics Group, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Simon Andrews
- Bioinformatics Group, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Peter Fraser
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Luca Giorgetti
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Anne E Corcoran
- Nuclear Dynamics Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK; Immunology Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.
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4
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A de novo transcription-dependent TAD boundary underpins critical multiway interactions during antibody class switch recombination. Mol Cell 2023; 83:681-697.e7. [PMID: 36736317 DOI: 10.1016/j.molcel.2023.01.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 11/04/2022] [Accepted: 01/09/2023] [Indexed: 02/05/2023]
Abstract
Interactions between transcription and cohesin-mediated loop extrusion can influence 3D chromatin architecture. However, their relevance in biology is unclear. Here, we report a direct role for such interactions in the mechanism of antibody class switch recombination (CSR) at the murine immunoglobulin heavy chain locus (Igh). Using Tri-C to measure higher-order multiway interactions on single alleles, we find that the juxtaposition (synapsis) of transcriptionally active donor and acceptor Igh switch (S) sequences, an essential step in CSR, occurs via the interaction of loop extrusion complexes with a de novo topologically associating domain (TAD) boundary formed via transcriptional activity across S regions. Surprisingly, synapsis occurs predominantly in proximity to the 3' CTCF-binding element (3'CBE) rather than the Igh super-enhancer, suggesting a two-step mechanism whereby transcription of S regions is not topologically coupled to synapsis, as has been previously proposed. Altogether, these insights advance our understanding of how 3D chromatin architecture regulates CSR.
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5
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Martin OA, Thomas M, Marquet M, Bruzeau C, Garot A, Brousse M, Bender S, Carrion C, Choi JE, Vuong BQ, Gearhart PJ, Maul RW, Le Noir S, Pinaud E. The IgH Eµ-MAR regions promote UNG-dependent error-prone repair to optimize somatic hypermutation. Front Immunol 2023; 14:1030813. [PMID: 36865553 PMCID: PMC9971809 DOI: 10.3389/fimmu.2023.1030813] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 01/13/2023] [Indexed: 02/16/2023] Open
Abstract
Intoduction Two scaffold/matrix attachment regions (5'- and 3'-MARsEµ ) flank the intronic core enhancer (cEµ) within the immunoglobulin heavy chain locus (IgH). Besides their conservation in mice and humans, the physiological role of MARsEµ is still unclear and their involvement in somatic hypermutation (SHM) has never been deeply evaluated. Methods Our study analyzed SHM and its transcriptional control in a mouse model devoid of MARsEµ , further combined to relevant models deficient for base excision repair and mismatch repair. Results We observed an inverted substitution pattern in of MARsEµ -deficient animals: SHM being decreased upstream from cEµ and increased downstream of it. Strikingly, the SHM defect induced by MARsEµ -deletion was accompanied by an increase of sense transcription of the IgH V region, excluding a direct transcription-coupled effect. Interestingly, by breeding to DNA repair-deficient backgrounds, we showed that the SHM defect, observed upstream from cEµ in this model, was not due to a decrease in AID deamination but rather the consequence of a defect in base excision repair-associated unfaithful repair process. Discussion Our study pointed out an unexpected "fence" function of MARsEµ regions in limiting the error-prone repair machinery to the variable region of Ig gene loci.
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Affiliation(s)
- Ophélie A Martin
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Morgane Thomas
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Marie Marquet
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Charlotte Bruzeau
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Armand Garot
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Mylène Brousse
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Sébastien Bender
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France.,Centre Hospitalier Universitaire Dupuytren, Service d'Immunopathologie, Limoges, France
| | - Claire Carrion
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Jee Eun Choi
- The Graduate Center, The City University of New York, New York, NY, United States
| | - Bao Q Vuong
- The Graduate Center, The City University of New York, New York, NY, United States
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Sandrine Le Noir
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Eric Pinaud
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
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6
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The role of chromatin loop extrusion in antibody diversification. Nat Rev Immunol 2022; 22:550-566. [PMID: 35169260 PMCID: PMC9376198 DOI: 10.1038/s41577-022-00679-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2022] [Indexed: 12/15/2022]
Abstract
Cohesin mediates chromatin loop formation across the genome by extruding chromatin between convergently oriented CTCF-binding elements. Recent studies indicate that cohesin-mediated loop extrusion in developing B cells presents immunoglobulin heavy chain (Igh) variable (V), diversity (D) and joining (J) gene segments to RAG endonuclease through a process referred to as RAG chromatin scanning. RAG initiates V(D)J recombinational joining of these gene segments to generate the large number of different Igh variable region exons that are required for immune responses to diverse pathogens. Antigen-activated mature B cells also use chromatin loop extrusion to mediate the synapsis, breakage and end joining of switch regions flanking Igh constant region exons during class-switch recombination, which allows for the expression of different antibody constant region isotypes that optimize the functions of antigen-specific antibodies to eliminate pathogens. Here, we review recent advances in our understanding of chromatin loop extrusion during V(D)J recombination and class-switch recombination at the Igh locus.
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7
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Bruzeau C, Cook-Moreau J, Pinaud E, Le Noir S. Contribution of Immunoglobulin Enhancers to B Cell Nuclear Organization. Front Immunol 2022; 13:877930. [PMID: 35812441 PMCID: PMC9263370 DOI: 10.3389/fimmu.2022.877930] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 05/26/2022] [Indexed: 11/19/2022] Open
Abstract
B cells undergo genetic rearrangements at immunoglobulin gene (Ig) loci during B cell maturation. First V(D)J recombination occurs during early B cell stages followed by class switch recombination (CSR) and somatic hypermutation (SHM) which occur during mature B cell stages. Given that RAG1/2 induces DNA double strand breaks (DSBs) during V(D)J recombination and AID (Activation-Induced Deaminase) leads to DNA modifications (mutations during SHM or DNA DSBs during CSR), it is mandatory that IgH rearrangements be tightly regulated to avoid any mutations or translocations within oncogenes. Ig loci contain various cis-regulatory elements that are involved in germline transcription, chromatin modifications or RAG/AID recruitment. Ig cis-regulatory elements are increasingly recognized as being involved in nuclear positioning, heterochromatin addressing and chromosome loop regulation. In this review, we examined multiple data showing the critical interest of studying Ig gene regulation at the whole nucleus scale. In this context, we highlighted the essential function of Ig gene regulatory elements that now have to be considered as nuclear organizers in B lymphocytes.
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8
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Aksenova AY, Zhuk AS, Lada AG, Zotova IV, Stepchenkova EI, Kostroma II, Gritsaev SV, Pavlov YI. Genome Instability in Multiple Myeloma: Facts and Factors. Cancers (Basel) 2021; 13:5949. [PMID: 34885058 PMCID: PMC8656811 DOI: 10.3390/cancers13235949] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/20/2021] [Accepted: 11/22/2021] [Indexed: 02/06/2023] Open
Abstract
Multiple myeloma (MM) is a malignant neoplasm of terminally differentiated immunoglobulin-producing B lymphocytes called plasma cells. MM is the second most common hematologic malignancy, and it poses a heavy economic and social burden because it remains incurable and confers a profound disability to patients. Despite current progress in MM treatment, the disease invariably recurs, even after the transplantation of autologous hematopoietic stem cells (ASCT). Biological processes leading to a pathological myeloma clone and the mechanisms of further evolution of the disease are far from complete understanding. Genetically, MM is a complex disease that demonstrates a high level of heterogeneity. Myeloma genomes carry numerous genetic changes, including structural genome variations and chromosomal gains and losses, and these changes occur in combinations with point mutations affecting various cellular pathways, including genome maintenance. MM genome instability in its extreme is manifested in mutation kataegis and complex genomic rearrangements: chromothripsis, templated insertions, and chromoplexy. Chemotherapeutic agents used to treat MM add another level of complexity because many of them exacerbate genome instability. Genome abnormalities are driver events and deciphering their mechanisms will help understand the causes of MM and play a pivotal role in developing new therapies.
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Affiliation(s)
- Anna Y. Aksenova
- Laboratory of Amyloid Biology, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Anna S. Zhuk
- International Laboratory “Computer Technologies”, ITMO University, 197101 St. Petersburg, Russia;
| | - Artem G. Lada
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA;
| | - Irina V. Zotova
- Department of Genetics and Biotechnology, St. Petersburg State University, 199034 St. Petersburg, Russia; (I.V.Z.); (E.I.S.)
- Vavilov Institute of General Genetics, St. Petersburg Branch, Russian Academy of Sciences, 199034 St. Petersburg, Russia
| | - Elena I. Stepchenkova
- Department of Genetics and Biotechnology, St. Petersburg State University, 199034 St. Petersburg, Russia; (I.V.Z.); (E.I.S.)
- Vavilov Institute of General Genetics, St. Petersburg Branch, Russian Academy of Sciences, 199034 St. Petersburg, Russia
| | - Ivan I. Kostroma
- Russian Research Institute of Hematology and Transfusiology, 191024 St. Petersburg, Russia; (I.I.K.); (S.V.G.)
| | - Sergey V. Gritsaev
- Russian Research Institute of Hematology and Transfusiology, 191024 St. Petersburg, Russia; (I.I.K.); (S.V.G.)
| | - Youri I. Pavlov
- Eppley Institute for Research in Cancer, Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Departments of Biochemistry and Molecular Biology, Microbiology and Pathology, Genetics Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
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9
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Ferrad M, Ghazzaui N, Issaoui H, Marchiol T, Cook-Moreau J, Denizot Y. Deletion of the 3'RR cis-enhancer IgH element affects DNA repair junctions during B-cell class switch recombination. Immunol Lett 2021; 240:12-14. [PMID: 34599945 DOI: 10.1016/j.imlet.2021.09.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 09/23/2021] [Indexed: 01/18/2023]
Affiliation(s)
- Melissa Ferrad
- UMR CNRS 7276, INSERM U1262, Equipe Labellisée LIGUE 2018, Université de Limoges, CBRS, rue Pr. Descottes, 87025 Limoges, France
| | - Nour Ghazzaui
- UMR CNRS 7276, INSERM U1262, Equipe Labellisée LIGUE 2018, Université de Limoges, CBRS, rue Pr. Descottes, 87025 Limoges, France
| | - Hussein Issaoui
- UMR CNRS 7276, INSERM U1262, Equipe Labellisée LIGUE 2018, Université de Limoges, CBRS, rue Pr. Descottes, 87025 Limoges, France
| | - Tiffany Marchiol
- UMR CNRS 7276, INSERM U1262, Equipe Labellisée LIGUE 2018, Université de Limoges, CBRS, rue Pr. Descottes, 87025 Limoges, France
| | - Jeanne Cook-Moreau
- UMR CNRS 7276, INSERM U1262, Equipe Labellisée LIGUE 2018, Université de Limoges, CBRS, rue Pr. Descottes, 87025 Limoges, France
| | - Yves Denizot
- UMR CNRS 7276, INSERM U1262, Equipe Labellisée LIGUE 2018, Université de Limoges, CBRS, rue Pr. Descottes, 87025 Limoges, France.
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10
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Dauba A, Khamlichi AA. Long-Range Control of Class Switch Recombination by Transcriptional Regulatory Elements. Front Immunol 2021; 12:738216. [PMID: 34594340 PMCID: PMC8477019 DOI: 10.3389/fimmu.2021.738216] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 08/17/2021] [Indexed: 01/18/2023] Open
Abstract
Immunoglobulin class switch recombination (CSR) plays a crucial role in adaptive immune responses through a change of the effector functions of antibodies and is triggered by T-cell-dependent as well as T-cell-independent antigens. Signals generated following encounter with each type of antigen direct CSR to different isotypes. At the genomic level, CSR occurs between highly repetitive switch sequences located upstream of the constant gene exons of the immunoglobulin heavy chain locus. Transcription of switch sequences is mandatory for CSR and is induced in a stimulation-dependent manner. Switch transcription takes place within dynamic chromatin domains and is regulated by long-range regulatory elements which promote alignment of partner switch regions in CSR centers. Here, we review recent work and models that account for the function of long-range transcriptional regulatory elements and the chromatin-based mechanisms involved in the control of CSR.
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Affiliation(s)
- Audrey Dauba
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, Université Paul Sabatier, Toulouse, France
| | - Ahmed Amine Khamlichi
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, Université Paul Sabatier, Toulouse, France
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11
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Kasprzyk ME, Sura W, Dzikiewicz-Krawczyk A. Enhancing B-Cell Malignancies-On Repurposing Enhancer Activity towards Cancer. Cancers (Basel) 2021; 13:3270. [PMID: 34210001 PMCID: PMC8269369 DOI: 10.3390/cancers13133270] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/24/2021] [Accepted: 06/28/2021] [Indexed: 01/19/2023] Open
Abstract
B-cell lymphomas and leukemias derive from B cells at various stages of maturation and are the 6th most common cancer-related cause of death. While the role of several oncogenes and tumor suppressors in the pathogenesis of B-cell neoplasms was established, recent research indicated the involvement of non-coding, regulatory sequences. Enhancers are DNA elements controlling gene expression in a cell type- and developmental stage-specific manner. They ensure proper differentiation and maturation of B cells, resulting in production of high affinity antibodies. However, the activity of enhancers can be redirected, setting B cells on the path towards cancer. In this review we discuss different mechanisms through which enhancers are exploited in malignant B cells, from the well-studied translocations juxtaposing oncogenes to immunoglobulin loci, through enhancer dysregulation by sequence variants and mutations, to enhancer hijacking by viruses. We also highlight the potential of therapeutic targeting of enhancers as a direction for future investigation.
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12
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Abstract
B lymphocytes change antibody heavy chain (IgH) isotypes by a recombination/deletion process called IgH class switch recombination (CSR). CSR involves introduction of DNA breaks into a donor switch (S) region and also into one of six downstream S regions, with joining of the breaks changing antibody isotype. A chromatin super-anchor, of unknown function, is located just downstream of the IgH locus. We show that complete deletion of this super-anchor variably decreases CSR to most S regions and creates an ectopic S region downstream of IgH locus that undergoes aberrant CSR-driven chromosomal rearrangements. Based on these and other findings, we conclude that the super-anchor downstream of IgH is a critical insulator for focusing potentially dangerous CSR rearrangements to the IgH locus. IgH class switch recombination (CSR) replaces Cμ constant region (CH) exons with one of six downstream CHs by joining transcription-targeted double-strand breaks (DSBs) in the Cμ switch (S) region to DSBs in a downstream S region. Chromatin loop extrusion underlies fundamental CSR mechanisms including 3′IgH regulatory region (3′IgHRR)-mediated S region transcription, CSR center formation, and deletional CSR joining. There are 10 consecutive CTCF-binding elements (CBEs) downstream of the 3′IgHRR, termed the “3′IgH CBEs.” Prior studies showed that deletion of eight 3′IgH CBEs did not detectably affect CSR. Here, we report that deletion of all 3′IgH CBEs impacts, to varying degrees, germline transcription and CSR of upstream S regions, except that of Sγ1. Moreover, deletion of all 3′IgH CBEs rendered the 6-kb region just downstream highly transcribed and caused sequences within to be aligned with Sμ, broken, and joined to form aberrant CSR rearrangements. These findings implicate the 3′IgH CBEs as critical insulators for focusing loop extrusion-mediated 3′IgHRR transcriptional and CSR activities on upstream CH locus targets.
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13
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Rogers CH, Mielczarek O, Corcoran AE. Dynamic 3D Locus Organization and Its Drivers Underpin Immunoglobulin Recombination. Front Immunol 2021; 11:633705. [PMID: 33679727 PMCID: PMC7930373 DOI: 10.3389/fimmu.2020.633705] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 12/30/2020] [Indexed: 01/10/2023] Open
Abstract
A functional adaptive immune system must generate enormously diverse antigen receptor (AgR) repertoires from a limited number of AgR genes, using a common mechanism, V(D)J recombination. The AgR loci are among the largest in the genome, and individual genes must overcome huge spatial and temporal challenges to co-localize with optimum variability. Our understanding of the complex mechanisms involved has increased enormously, due in part to new technologies for high resolution mapping of AgR structure and dynamic movement, underpinning mechanisms, and resulting repertoires. This review will examine these advances using the paradigm of the mouse immunoglobulin heavy chain (Igh) locus. We will discuss the key regulatory elements implicated in Igh locus structure. Recent next generation repertoire sequencing methods have shown that local chromatin state at V genes contribute to recombination efficiency. Next on the multidimensional scale, we will describe imaging studies that provided the first picture of the large-scale dynamic looping and contraction the Igh locus undergoes during recombination. We will discuss chromosome conformation capture (3C)-based technologies that have provided higher resolution pictures of Igh locus structure, including the different models that have evolved. We will consider the key transcription factors (PAX5, YY1, E2A, Ikaros), and architectural factors, CTCF and cohesin, that regulate these processes. Lastly, we will discuss a plethora of recent exciting mechanistic findings. These include Rag recombinase scanning for convergent RSS sequences within DNA loops; identification of Igh loop extrusion, and its putative role in Rag scanning; the roles of CTCF, cohesin and cohesin loading factor, WAPL therein; a new phase separation model for Igh locus compartmentalization. We will draw these together and conclude with some horizon-scanning and unresolved questions.
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Affiliation(s)
- Carolyn H Rogers
- Lymphocyte Signalling and Development Programme, Babraham Institute, Cambridge, United Kingdom
| | - Olga Mielczarek
- Nuclear Dynamics Programme, Babraham Institute, Cambridge, United Kingdom
| | - Anne E Corcoran
- Lymphocyte Signalling and Development Programme, Babraham Institute, Cambridge, United Kingdom
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14
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Qiu X, Ma F, Zhao M, Cao Y, Shipp L, Liu A, Dutta A, Singh A, Braikia FZ, De S, Wood WH, Becker KG, Zhou W, Ji H, Zhao K, Atchison ML, Sen R. Altered 3D chromatin structure permits inversional recombination at the IgH locus. SCIENCE ADVANCES 2020; 6:eaaz8850. [PMID: 32851160 PMCID: PMC7428332 DOI: 10.1126/sciadv.aaz8850] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 07/01/2020] [Indexed: 05/05/2023]
Abstract
Immunoglobulin heavy chain (IgH) genes are assembled by two sequential DNA rearrangement events that are initiated by recombination activating gene products (RAG) 1 and 2. Diversity (DH) gene segments rearrange first, followed by variable (VH) gene rearrangements. Here, we provide evidence that each rearrangement step is guided by different rules of engagement between rearranging gene segments. DH gene segments, which recombine by deletion of intervening DNA, must be located within a RAG1/2 scanning domain for efficient recombination. In the absence of intergenic control region 1, a regulatory sequence that delineates the RAG scanning domain on wild-type IgH alleles, VH and DH gene segments can recombine with each other by both deletion and inversion of intervening DNA. We propose that VH gene segments find their targets by distinct mechanisms from those that apply to DH gene segments. These distinctions may underlie differential allelic choice associated with each step of IgH gene assembly.
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Affiliation(s)
- Xiang Qiu
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Fei Ma
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Mingming Zhao
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Yaqiang Cao
- Laboratory of Epigenome Biology, Systems Biology Center, National Heart Lung and Blood Institute, Bethesda, MD 20892, USA
| | - Lillian Shipp
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Angela Liu
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Arun Dutta
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Amit Singh
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Fatima Zohra Braikia
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Supriyo De
- Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, MD 21224, USA
| | - William H. Wood
- Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, MD 21224, USA
| | - Kevin G. Becker
- Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, MD 21224, USA
| | - Weiqiang Zhou
- Department of Biostatistics, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, 21205, USA
| | - Hongkai Ji
- Department of Biostatistics, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, 21205, USA
| | - Keji Zhao
- Laboratory of Epigenome Biology, Systems Biology Center, National Heart Lung and Blood Institute, Bethesda, MD 20892, USA
| | - Michael L. Atchison
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Ranjan Sen
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
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15
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Oudinet C, Braikia FZ, Dauba A, Khamlichi AA. Mechanism and regulation of class switch recombination by IgH transcriptional control elements. Adv Immunol 2020; 147:89-137. [PMID: 32981636 DOI: 10.1016/bs.ai.2020.06.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Class switch recombination (CSR) plays an important role in humoral immunity by generating antibodies with different effector functions. CSR to a particular antibody isotype is induced by external stimuli, and occurs between highly repetitive switch (S) sequences. CSR requires transcription across S regions, which generates long non-coding RNAs and secondary structures that promote accessibility of S sequences to activation-induced cytidine deaminase (AID). AID initiates DNA double-strand breaks (DSBs) intermediates that are repaired by general DNA repair pathways. Switch transcription is controlled by various regulatory elements, including enhancers and insulators. The current paradigm posits that transcriptional control of CSR involves long-range chromatin interactions between regulatory elements and chromatin loops-stabilizing factors, which promote alignment of partner S regions in a CSR centre (CSRC) and initiation of CSR. In this review, we focus on the role of IgH transcriptional control elements in CSR and the chromatin-based mechanisms underlying this control.
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Affiliation(s)
- Chloé Oudinet
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, Toulouse, France; Institut de Pharmacologie et de Biologie Structurale, CNRS, Université Paul Sabatier, Toulouse, France
| | - Fatima-Zohra Braikia
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, Toulouse, France; Institut de Pharmacologie et de Biologie Structurale, CNRS, Université Paul Sabatier, Toulouse, France
| | - Audrey Dauba
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, Toulouse, France; Institut de Pharmacologie et de Biologie Structurale, CNRS, Université Paul Sabatier, Toulouse, France
| | - Ahmed Amine Khamlichi
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, Toulouse, France; Institut de Pharmacologie et de Biologie Structurale, CNRS, Université Paul Sabatier, Toulouse, France.
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16
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Ferrad M, Ghazzaui N, Issaoui H, Cook-Moreau J, Denizot Y. Mouse Models of c-myc Deregulation Driven by IgH Locus Enhancers as Models of B-Cell Lymphomagenesis. Front Immunol 2020; 11:1564. [PMID: 32793219 PMCID: PMC7390917 DOI: 10.3389/fimmu.2020.01564] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/15/2020] [Indexed: 01/18/2023] Open
Abstract
Chromosomal translocations linking various oncogenes to transcriptional enhancers of the immunoglobulin heavy chain (IgH) locus are often implicated as the cause of B-cell malignancies. Two major IgH transcriptional enhancers have been reported so far. The Eμ enhancer located upstream of the Cμ gene controls early events in B-cell maturation such as VDJ recombination. The 3' regulatory region (3'RR) located downstream from the Cα gene controls late events in B-cell maturation such as IgH transcription, somatic hypermutation, and class switch recombination. Convincing demonstrations of the essential contributions of both Eμ and 3'RR in B-cell lymphomagenesis have been provided by transgenic and knock-in animal models which bring the oncogene c-myc under Eμ/3'RR transcriptional control. This short review summarizes the different mouse models so far available and their interests/limitations for progress in our understanding of human c-myc-induced B-cell lymphomagenesis.
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Affiliation(s)
- Melissa Ferrad
- Inserm U1262, UMR CNRS 7276, Equipe Labellisée LIGUE 2018, Université de Limoges, Limoges, France
| | - Nour Ghazzaui
- Inserm U1262, UMR CNRS 7276, Equipe Labellisée LIGUE 2018, Université de Limoges, Limoges, France
| | - Hussein Issaoui
- Inserm U1262, UMR CNRS 7276, Equipe Labellisée LIGUE 2018, Université de Limoges, Limoges, France
| | - Jeanne Cook-Moreau
- Inserm U1262, UMR CNRS 7276, Equipe Labellisée LIGUE 2018, Université de Limoges, Limoges, France
| | - Yves Denizot
- Inserm U1262, UMR CNRS 7276, Equipe Labellisée LIGUE 2018, Université de Limoges, Limoges, France
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17
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Vecchio E, Fiume G, Correnti S, Romano S, Iaccino E, Mimmi S, Maisano D, Nisticò N, Quinto I. Insights about MYC and Apoptosis in B-Lymphomagenesis: An Update from Murine Models. Int J Mol Sci 2020; 21:E4265. [PMID: 32549409 PMCID: PMC7352788 DOI: 10.3390/ijms21124265] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 06/10/2020] [Accepted: 06/11/2020] [Indexed: 01/18/2023] Open
Abstract
The balance between cell survival and cell death represents an essential part of human tissue homeostasis, while altered apoptosis contributes to several pathologies and can affect the treatment efficacy. Impaired apoptosis is one of the main cancer hallmarks and some types of lymphomas harbor mutations that directly affect key regulators of cell death (such as BCL-2 family members). The development of novel techniques in the field of immunology and new animal models has greatly accelerated our understanding of oncogenic mechanisms in MYC-associated lymphomas. Mouse models are a powerful tool to reveal multiple genes implicated in the genesis of lymphoma and are extensively used to clarify the molecular mechanism of lymphoma, validating the gene function. Key features of MYC-induced apoptosis will be discussed here along with more recent studies on MYC direct and indirect interactors, including their cooperative action in lymphomagenesis. We review our current knowledge about the role of MYC-induced apoptosis in B-cell malignancies, discussing the transcriptional regulation network of MYC and regulatory feedback action of miRs during MYC-driven lymphomagenesis. More importantly, the finding of new modulators of apoptosis now enabling researchers to translate the discoveries that have been made in the laboratory into clinical practice to positively impact human health.
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Affiliation(s)
- Eleonora Vecchio
- Department of Experimental and Clinical Medicine, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy; (G.F.); (S.C.); (S.R.); (E.I.); (S.M.); (D.M.); (N.N.)
| | | | | | | | | | | | | | | | - Ileana Quinto
- Department of Experimental and Clinical Medicine, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy; (G.F.); (S.C.); (S.R.); (E.I.); (S.M.); (D.M.); (N.N.)
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18
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Rao TN, Kumar S, Pulikkottil AJ, Oliveri F, Hendriks RW, Beckel F, Fehling HJ. Novel, Non-Gene-Destructive Knock-In Reporter Mice Refute the Concept of Monoallelic Gata3 Expression. THE JOURNAL OF IMMUNOLOGY 2020; 204:2600-2611. [PMID: 32213568 DOI: 10.4049/jimmunol.2000025] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 02/26/2020] [Indexed: 02/04/2023]
Abstract
Accurately tuned expression levels of the transcription factor GATA-3 are crucial at several stages of T cell and innate lymphoid cell development and differentiation. Moreover, several lines of evidence suggest that Gata3 expression might provide a reliable molecular marker for the identification of elusive progenitor cell subsets at the earliest stages of T lineage commitment. To be able to faithfully monitor Gata3 expression noninvasively at the single-cell level, we have generated a novel strain of knock-in reporter mice, termed GATIR, by inserting an expression cassette encoding a bright fluorescent marker into the 3'-untranslated region of the endogenous Gata3 locus. Importantly, in contrast to three previously published strains of Gata3 reporter mice, GATIR mice preserve physiological Gata3 expression on the targeted allele. In this study, we show that GATIR mice faithfully reflect endogenous Gata3 expression without disturbing the development of GATA-3-dependent lymphoid cell populations. We further show that GATIR mice provide an ideal tool for noninvasive monitoring of Th2 polarization and straightforward identification of innate lymphoid cell 2 progenitor populations. Finally, as our reporter is non-gene-destructive, GATIR mice can be bred to homozygosity, not feasible with previously published strains of Gata3 reporter mice harboring disrupted alleles. The availability of hetero- and homozygous Gata3 reporter mice with an exceptionally bright fluorescent marker, allowed us to visualize allelic Gata3 expression in individual cells simply by flow cytometry. The unambiguous results obtained provide compelling evidence against previously postulated monoallelic Gata3 expression in early T lineage and hematopoietic stem cell subsets.
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Affiliation(s)
| | - Suresh Kumar
- Institute of Immunology, University Hospital, D-89081 Ulm, Germany; and
| | | | - Franziska Oliveri
- Institute of Immunology, University Hospital, D-89081 Ulm, Germany; and
| | - Rudi W Hendriks
- Department of Pulmonary Medicine, Erasmus Medical Center, NL-3000 CA Rotterdam, the Netherlands
| | - Franziska Beckel
- Institute of Immunology, University Hospital, D-89081 Ulm, Germany; and
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19
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Oudinet C, Braikia FZ, Dauba A, Khamlichi AA. Recombination may occur in the absence of transcription in the immunoglobulin heavy chain recombination centre. Nucleic Acids Res 2020; 48:3553-3566. [PMID: 32086526 PMCID: PMC7144927 DOI: 10.1093/nar/gkaa108] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 02/06/2020] [Accepted: 02/19/2020] [Indexed: 12/18/2022] Open
Abstract
Developing B cells undergo V(D)J recombination to generate a vast repertoire of Ig molecules. V(D)J recombination is initiated by the RAG1/RAG2 complex in recombination centres (RCs), where gene segments become accessible to the complex. Whether transcription is the causal factor of accessibility or whether it is a side product of other processes that generate accessibility remains a controversial issue. At the IgH locus, V(D)J recombination is controlled by Eμ enhancer, which directs the transcriptional, epigenetic and recombinational events in the IgH RC. Deletion of Eμ enhancer affects both transcription and recombination, making it difficult to conclude if Eμ controls the two processes through the same or different mechanisms. By using a mouse line carrying a CpG-rich sequence upstream of Eμ enhancer and analyzing transcription and recombination at the single-cell level, we found that recombination could occur in the RC in the absence of detectable transcription, suggesting that Eμ controls transcription and recombination through distinct mechanisms. Moreover, while the normally Eμ-dependent transcription and demethylating activities were impaired, recruitment of chromatin remodeling complexes was unaffected. RAG1 was efficiently recruited, thus compensating for the defective transcription-associated recruitment of RAG2, and providing a mechanistic basis for RAG1/RAG2 assembly to initiate V(D)J recombination.
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Affiliation(s)
- Chloé Oudinet
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, Université Paul Sabatier, 31077 Toulouse, France
| | - Fatima-Zohra Braikia
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, Université Paul Sabatier, 31077 Toulouse, France
| | - Audrey Dauba
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, Université Paul Sabatier, 31077 Toulouse, France
| | - Ahmed Amine Khamlichi
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, Université Paul Sabatier, 31077 Toulouse, France
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20
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Jones BG, Sealy RE, Penkert RR, Surman SL, Maul RW, Neale G, Xu B, Gearhart PJ, Hurwitz JL. Complex sex-biased antibody responses: estrogen receptors bind estrogen response elements centered within immunoglobulin heavy chain gene enhancers. Int Immunol 2020; 31:141-156. [PMID: 30407507 DOI: 10.1093/intimm/dxy074] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 11/02/2018] [Indexed: 01/10/2023] Open
Abstract
Nuclear hormone receptors including the estrogen receptor (ERα) and the retinoic acid receptor regulate a plethora of biological functions including reproduction, circulation and immunity. To understand how estrogen and other nuclear hormones influence antibody production, we characterized total serum antibody isotypes in female and male mice of C57BL/6J, BALB/cJ and C3H/HeJ mouse strains. Antibody levels were higher in females compared to males in all strains and there was a female preference for IgG2b production. Sex-biased patterns were influenced by vitamin levels, and by antigen specificity toward influenza virus or pneumococcus antigens. To help explain sex biases, we examined the direct effects of estrogen on immunoglobulin heavy chain sterile transcript production among purified, lipopolysaccharide-stimulated B cells. Supplemental estrogen in B-cell cultures significantly increased immunoglobulin heavy chain sterile transcripts. Chromatin immunoprecipitation analyses of activated B cells identified significant ERα binding to estrogen response elements (EREs) centered within enhancer elements of the immunoglobulin heavy chain locus, including the Eµ enhancer and hypersensitive site 1,2 (HS1,2) in the 3' regulatory region. The ERE in HS1,2 was conserved across animal species, and in humans marked a site of polymorphism associated with the estrogen-augmented autoimmune disease, lupus. Taken together, the results highlight: (i) the important targets of ERα in regulatory regions of the immunoglobulin heavy chain locus that influence antibody production, and (ii) the complexity of mechanisms by which estrogen instructs sex-biased antibody production profiles.
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Affiliation(s)
- Bart G Jones
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Danny Thomas Place, Memphis, USA
| | - Robert E Sealy
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Danny Thomas Place, Memphis, USA
| | - Rhiannon R Penkert
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Danny Thomas Place, Memphis, USA
| | - Sherri L Surman
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Danny Thomas Place, Memphis, USA
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Geoff Neale
- Hartwell Center for Bioinformatics & Biotechnology, St. Jude Children's Research Hospital, Memphis, USA
| | - Beisi Xu
- Computational Biology, St. Jude Children's Research Hospital, Memphis, USA
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Julia L Hurwitz
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Danny Thomas Place, Memphis, USA.,Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, USA
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21
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Ghazzaui N, Issaoui H, Ferrad M, Carrion C, Cook-Moreau J, Denizot Y, Boyer F. Eμ and 3'RR transcriptional enhancers of the IgH locus cooperate to promote c-myc-induced mature B-cell lymphomas. Blood Adv 2020; 4:28-39. [PMID: 31899800 PMCID: PMC6960469 DOI: 10.1182/bloodadvances.2019000845] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/12/2019] [Indexed: 01/18/2023] Open
Abstract
Numerous B-cell lymphomas feature translocations linking oncogenes to different locations in the immunoglobulin heavy chain (IgH) locus. During Burkitt lymphoma (BL), IgH breakpoints for c-myc translocation stand either close to JH segments or within switch regions. Transcription, accessibility, and remodeling of the IgH locus are under the control of the 2 potent cis-acting enhancer elements: Eμ and the 3' regulatory region (3'RR). To ensure their respective contributions to oncogene deregulation in the context of the endogenous IgH locus, we studied transgenic mice harboring a knock-in of c-myc in various positions of the IgH locus (3' to JH segments, 5' to Cμ with Eμ deletion and Cα). The observed spectrum of tumors, kinetics of emergence, and transcriptome analysis provide strong evidence that both Eμ and 3'RR deregulate c-myc and cooperate together to promote B-cell lymphomagenesis. Transgenics mimicking endemic BL (with c-myc placed 3' to JH segments) exhibited the highest rate of B-cell lymphoma emergence, the highest Ki67 index of proliferation, and the highest transcriptomic similarities to human BL. The 3'RR enhancer alone deregulated c-myc and initiated the development of BL-like lymphomas, suggesting that its targeting would be of therapeutic interest to reduce c-myc oncogenicity in vivo.
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Affiliation(s)
- Nour Ghazzaui
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 7276, Institut National de la Santé et de la Recherche Médicale U1262, Equipe Labellisée Ligue 2018, Université de Limoges, Limoges, France
| | - Hussein Issaoui
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 7276, Institut National de la Santé et de la Recherche Médicale U1262, Equipe Labellisée Ligue 2018, Université de Limoges, Limoges, France
| | - Mélissa Ferrad
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 7276, Institut National de la Santé et de la Recherche Médicale U1262, Equipe Labellisée Ligue 2018, Université de Limoges, Limoges, France
| | - Claire Carrion
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 7276, Institut National de la Santé et de la Recherche Médicale U1262, Equipe Labellisée Ligue 2018, Université de Limoges, Limoges, France
| | - Jeanne Cook-Moreau
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 7276, Institut National de la Santé et de la Recherche Médicale U1262, Equipe Labellisée Ligue 2018, Université de Limoges, Limoges, France
| | - Yves Denizot
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 7276, Institut National de la Santé et de la Recherche Médicale U1262, Equipe Labellisée Ligue 2018, Université de Limoges, Limoges, France
| | - François Boyer
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 7276, Institut National de la Santé et de la Recherche Médicale U1262, Equipe Labellisée Ligue 2018, Université de Limoges, Limoges, France
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22
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Kappa-on-Heavy (KoH) bodies are a distinct class of fully-human antibody-like therapeutic agents with antigen-binding properties. Proc Natl Acad Sci U S A 2019; 117:292-299. [PMID: 31879340 DOI: 10.1073/pnas.1901734117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We describe a Kappa-on-Heavy (KoH) mouse that produces a class of highly diverse, fully human, antibody-like agents. This mouse was made by replacing the germline variable sequences of both the Ig heavy-chain (IgH) and Ig kappa (IgK) loci with the human IgK germline variable sequences, producing antibody-like molecules with an antigen binding site made up of 2 kappa variable domains. These molecules, named KoH bodies, structurally mimic naturally existing Bence-Jones light-chain dimers in their variable domains and remain wild-type in their antibody constant domains. Unlike artificially diversified, nonimmunoglobulin alternative scaffolds (e.g., DARPins), KoH bodies consist of a configuration of normal Ig scaffolds that undergo natural diversification in B cells. Monoclonal KoH bodies have properties similar to those of conventional antibodies but exhibit an enhanced ability to bind small molecules such as the endogenous cardiotonic steroid marinobufagenin (MBG) and nicotine. A comparison of crystal structures of MBG bound to a KoH Fab versus a conventional Fab showed that the KoH body has a much deeper binding pocket, allowing MBG to be held 4 Å further down into the combining site between the 2 variable domains.
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23
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Dinesh RK, Barnhill B, Ilanges A, Wu L, Michelson DA, Senigl F, Alinikula J, Shabanowitz J, Hunt DF, Schatz DG. Transcription factor binding at Ig enhancers is linked to somatic hypermutation targeting. Eur J Immunol 2019; 50:380-395. [PMID: 31821534 DOI: 10.1002/eji.201948357] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 10/05/2019] [Accepted: 12/02/2019] [Indexed: 01/15/2023]
Abstract
Secondary diversification of the Ig repertoire occurs through somatic hypermutation (SHM), gene conversion (GCV), and class switch recombination (CSR)-three processes that are initiated by activation-induced cytidine deaminase (AID). AID targets Ig genes at orders of magnitude higher than the rest of the genome, but the basis for this specificity is poorly understood. We have previously demonstrated that enhancers and enhancer-like sequences from Ig genes are capable of stimulating SHM of neighboring genes in a capacity distinct from their roles in increasing transcription. Here, we use an in vitro proteomics approach to identify E-box, MEF2, Ets, and Ikaros transcription factor family members as potential binders of these enhancers. ChIP assays in the hypermutating Ramos B cell line confirmed that many of these factors bound the endogenous Igλ enhancer and/or the IgH intronic enhancer (Eμ) in vivo. Further investigation using SHM reporter assays identified binding sites for E2A and MEF2B in Eμ and demonstrated an association between loss of factor binding and decreases in the SHM stimulating activity of Eμ mutants. Our results provide novel insights into trans-acting factors that dictate SHM targeting and link their activity to specific DNA binding sites within Ig enhancers.
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Affiliation(s)
- Ravi K Dinesh
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA
| | - Benjamin Barnhill
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Anoj Ilanges
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA
| | - Lizhen Wu
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA
| | - Daniel A Michelson
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA
| | - Filip Senigl
- Institute of Molecular Genetics, Czech Academy of Sciences, Videnska 1083, CZ-14220, Prague 4, Czech Republic
| | - Jukka Alinikula
- Institute of Biomedicine, University of Turku, Turku, Finland
| | | | - Donald F Hunt
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA.,Department of Pathology, University of Virginia, Charlottesville, VA, USA
| | - David G Schatz
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA
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24
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Heltzel JMH, Gearhart PJ. What Targets Somatic Hypermutation to the Immunoglobulin Loci? Viral Immunol 2019; 33:277-281. [PMID: 31770070 DOI: 10.1089/vim.2019.0149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
One of the most profound enigmas in B cell biology is how activation-induced deaminase (AID) is targeted to a very small region of DNA in the immunoglobulin loci. Two specific regions are singled out: the variable region of 2 kb that contains rearranged genes on the heavy, κ light, and λ light chain loci, and the switch region of ∼4 kb that contains an extensive stretch of G:C rich DNA on the heavy chain locus. Transcription is required for AID recruitment; however, many genes are also highly transcribed and do not undergo the catastrophic mutagenesis that occurs in variable and switch regions. The DNA sequences of these regions cause RNA polymerase II to accumulate for an extended distance of 2-4 kb. The stalled polymerases then recruit the transcription cofactor Spt5, and AID, which deaminates cytosines to uracils in exposed transcription bubbles. Thus, the immunoglobulin loci are unique in that a favorable combination of DNA sequences and 3' transcription enhancers make them the perfect storm for AID-induced somatic hypermutation.
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Affiliation(s)
- Justin M H Heltzel
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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25
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Issaoui H, Ghazzaui N, Ferrad M, Boyer F, Denizot Y. Class switch recombination junctions are not affected by the absence of the immunoglobulin heavy chain E μ enhancer. Cell Mol Immunol 2019; 16:671-673. [PMID: 30967637 DOI: 10.1038/s41423-019-0229-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 03/16/2019] [Indexed: 01/18/2023] Open
Affiliation(s)
- Hussein Issaoui
- UMR CNRS 7276, INSERM U1262, Equipe Labellisée LIGUE 2018, University of Limoges, CBRS, rue Pr. Descottes, 87025, Limoges, France
| | - Nour Ghazzaui
- UMR CNRS 7276, INSERM U1262, Equipe Labellisée LIGUE 2018, University of Limoges, CBRS, rue Pr. Descottes, 87025, Limoges, France
| | - Mélissa Ferrad
- UMR CNRS 7276, INSERM U1262, Equipe Labellisée LIGUE 2018, University of Limoges, CBRS, rue Pr. Descottes, 87025, Limoges, France
| | - François Boyer
- UMR CNRS 7276, INSERM U1262, Equipe Labellisée LIGUE 2018, University of Limoges, CBRS, rue Pr. Descottes, 87025, Limoges, France
| | - Yves Denizot
- UMR CNRS 7276, INSERM U1262, Equipe Labellisée LIGUE 2018, University of Limoges, CBRS, rue Pr. Descottes, 87025, Limoges, France.
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26
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Yeap LS, Meng FL. Cis- and trans-factors affecting AID targeting and mutagenic outcomes in antibody diversification. Adv Immunol 2019; 141:51-103. [PMID: 30904133 DOI: 10.1016/bs.ai.2019.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Antigen receptor diversification is a hallmark of adaptive immunity which allows specificity of the receptor to particular antigen. B cell receptor (BCR) or its secreted form, antibody, is diversified through antigen-independent and antigen-dependent mechanisms. During B cell development in bone marrow, BCR is diversified via V(D)J recombination mediated by RAG endonuclease. Upon stimulation by antigen, B cell undergo somatic hypermutation (SHM) to allow affinity maturation and class switch recombination (CSR) to change the effector function of the antibody. Both SHM and CSR are initiated by activation-induced cytidine deaminase (AID). Repair of AID-initiated lesions through different DNA repair pathways results in diverse mutagenic outcomes. Here, we focus on discussing cis- and trans-factors that target AID to its substrates and factors that affect different outcomes of AID-initiated lesions. The knowledge of mechanisms that govern AID targeting and outcomes could be harnessed to elicit rare functional antibodies and develop ex vivo antibody diversification approaches with diversifying base editors.
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Affiliation(s)
- Leng-Siew Yeap
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Fei-Long Meng
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China.
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27
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Kuri-Magaña H, Collado-Torres L, Jaffe AE, Valdovinos-Torres H, Ovilla-Muñoz M, Téllez-Sosa J, Bonifaz LC, Martínez-Barnetche J. Non-coding Class Switch Recombination-Related Transcription in Human Normal and Pathological Immune Responses. Front Immunol 2018; 9:2679. [PMID: 30519242 PMCID: PMC6260145 DOI: 10.3389/fimmu.2018.02679] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Accepted: 10/30/2018] [Indexed: 12/22/2022] Open
Abstract
Antibody class switch recombination (CSR) to IgG, IgA, or IgE is a hallmark of adaptive immunity, allowing antibody function diversification beyond IgM. CSR involves a deletion of the IgM/IgD constant region genes placing a new acceptor Constant gene, downstream of the VDJH exon. CSR depends on non-coding (CSRnc) transcription of donor Iμ and acceptor IH exons, located 5′ upstream of each CH coding gene. Although, our knowledge of the role of CSRnc transcription has advanced greatly, its extension and importance in healthy and diseased humans is scarce. We analyzed CSRnc transcription in 70,603 publicly available RNA-seq samples, including GTEx, TCGA, and the Sequence Read Archive using recount2, an online resource consisting of normalized RNA-seq gene and exon counts, as well as, coverage BigWig files that can be programmatically accessed through R. CSRnc transcription was validated with a qRT-PCR assay for Iμ, Iγ3, and Iγ1 in humans in response to vaccination. We mapped IH transcription for the human IGH locus, including the less understood IGHD gene. CSRnc transcription was restricted to B cells and is widely distributed in normal adult tissues, but predominant in blood, spleen, MALT-containing tissues, visceral adipose tissue and some so-called “immune privileged” tissues. However, significant Iγ4 expression was found even in non-lymphoid fetal tissues. CSRnc expression in cancer tissues mimicked the expression of their normal counterparts, with notable pattern changes in some common cancer subsets. CSRnc transcription in tumors appears to result from tumor infiltration by B cells, since CSRnc transcription was not detected in corresponding tumor-derived immortal cell lines. Additionally, significantly increased Iδ transcription in ileal mucosa in Crohn's disease with ulceration was found. In conclusion, CSRnc transcription occurs in multiple anatomical locations beyond classical secondary lymphoid organs, representing a potentially useful marker of effector B cell responses in normal and pathological immune responses. The pattern of IH exon expression may reveal clues of the local immune response (i.e., cytokine milieu) in health and disease. This is a great example of how the public recount2 data can be used to further our understanding of transcription, including regions outside the known transcriptome.
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Affiliation(s)
- Helena Kuri-Magaña
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Mexico.,Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Leonardo Collado-Torres
- Lieber Institute for Brain Development, Baltimore, MD, United States.,Center for Computational Biology, Johns Hopkins University, Baltimore, MD, United States
| | - Andrew E Jaffe
- Lieber Institute for Brain Development, Baltimore, MD, United States.,Center for Computational Biology, Johns Hopkins University, Baltimore, MD, United States.,Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Humberto Valdovinos-Torres
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Mexico
| | - Marbella Ovilla-Muñoz
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Mexico
| | - Juan Téllez-Sosa
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Mexico
| | - Laura C Bonifaz
- Unidad de Investigación Medica en Inmunoquímica, Hospital de Especialidades, Centro Medico Nacional Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), Mexico City, Mexico
| | - Jesús Martínez-Barnetche
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Mexico
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28
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Kumari G, Gerasimova T, Du H, De S, Wood WH, Becker KG, Sen R. Misregulation of the IgH Locus in Thymocytes. Front Immunol 2018; 9:2426. [PMID: 30483245 PMCID: PMC6244664 DOI: 10.3389/fimmu.2018.02426] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 10/02/2018] [Indexed: 12/27/2022] Open
Abstract
Functional antigen receptor genes are assembled by somatic rearrangements that are largely lymphocyte lineage specific. The immunoglobulin heavy chain (IgH) gene locus is unique amongst the seven antigen receptor loci in undergoing partial gene rearrangements in the wrong lineage. Here we demonstrate that breakdown of lineage-specificity is associated with inappropriate activation of the Eμ enhancer during T cell development by a different constellation of transcription factors than those used in developing B cells. This is reflected in reduced enhancer-induced epigenetic changes, eRNAs, formation of the RAG1/2-rich recombination center, attenuated chromatin looping and markedly different utilization of DH gene segments in CD4+CD8+ (DP) thymocytes. Additionally, CTCF-dependent VH locus compaction is disrupted in DP cells despite comparable transcription factor binding in both lineages. These observations identify multiple mechanisms that contribute to lineage-specific antigen receptor gene assembly.
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Affiliation(s)
- Gita Kumari
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD, United States
| | - Tatiana Gerasimova
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD, United States
| | - Hansen Du
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD, United States
| | - Supriyo De
- Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, MD, United States
| | - William H Wood
- Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, MD, United States
| | - Kevin G Becker
- Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, MD, United States
| | - Ranjan Sen
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD, United States
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29
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Delgado-Benito V, Rosen DB, Wang Q, Gazumyan A, Pai JA, Oliveira TY, Sundaravinayagam D, Zhang W, Andreani M, Keller L, Kieffer-Kwon KR, Pękowska A, Jung S, Driesner M, Subbotin RI, Casellas R, Chait BT, Nussenzweig MC, Di Virgilio M. The Chromatin Reader ZMYND8 Regulates Igh Enhancers to Promote Immunoglobulin Class Switch Recombination. Mol Cell 2018; 72:636-649.e8. [PMID: 30293785 PMCID: PMC6242708 DOI: 10.1016/j.molcel.2018.08.042] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 07/01/2018] [Accepted: 08/25/2018] [Indexed: 01/18/2023]
Abstract
Class switch recombination (CSR) is a DNA recombination reaction that diversifies the effector component of antibody responses. CSR is initiated by activation-induced cytidine deaminase (AID), which targets transcriptionally active immunoglobulin heavy chain (Igh) switch donor and acceptor DNA. The 3′ Igh super-enhancer, 3′ regulatory region (3′RR), is essential for acceptor region transcription, but how this function is regulated is unknown. Here, we identify the chromatin reader ZMYND8 as an essential regulator of the 3′RR. In B cells, ZMYND8 binds promoters and super-enhancers, including the Igh enhancers. ZMYND8 controls the 3′RR activity by modulating the enhancer transcriptional status. In its absence, there is increased 3′RR polymerase loading and decreased acceptor region transcription and CSR. In addition to CSR, ZMYND8 deficiency impairs somatic hypermutation (SHM) of Igh, which is also dependent on the 3′RR. Thus, ZMYND8 controls Igh diversification in mature B lymphocytes by regulating the activity of the 3′ Igh super-enhancer. ZMYND8 is required for GLT of acceptor S regions and Class Switch Recombination ZMYND8 supports efficient somatic hypermutation of the Igh variable regions ZMYND8 binds B cell super-enhancers, including the 3′ Igh enhancer ZMYND8 modulates the transcriptional status and activity of the 3′ Igh enhancer
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Affiliation(s)
- Verónica Delgado-Benito
- Laboratory of DNA Repair and Maintenance of Genome Stability, The Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany
| | - Daniel B Rosen
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Qiao Wang
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Anna Gazumyan
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Joy A Pai
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Thiago Y Oliveira
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Devakumar Sundaravinayagam
- Laboratory of DNA Repair and Maintenance of Genome Stability, The Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany
| | - Wenzhu Zhang
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY 10065, USA
| | - Matteo Andreani
- Laboratory of DNA Repair and Maintenance of Genome Stability, The Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany
| | - Lisa Keller
- Laboratory of DNA Repair and Maintenance of Genome Stability, The Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany
| | | | | | - Seolkyoung Jung
- Lymphocyte Nuclear Biology, NIAMS, NCI, NIH, Bethesda, MD 20892, USA
| | - Madlen Driesner
- Laboratory of DNA Repair and Maintenance of Genome Stability, The Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany
| | - Roman I Subbotin
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY 10065, USA
| | - Rafael Casellas
- Lymphocyte Nuclear Biology, NIAMS, NCI, NIH, Bethesda, MD 20892, USA
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY 10065, USA
| | - Michel C Nussenzweig
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA; Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Michela Di Virgilio
- Laboratory of DNA Repair and Maintenance of Genome Stability, The Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany.
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30
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Lin SG, Ba Z, Alt FW, Zhang Y. RAG Chromatin Scanning During V(D)J Recombination and Chromatin Loop Extrusion are Related Processes. Adv Immunol 2018; 139:93-135. [PMID: 30249335 DOI: 10.1016/bs.ai.2018.07.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
An effective adaptive immune system depends on the ability of developing B and T cells to generate diverse immunoglobulin (Ig) and T cell receptor repertoires, respectively. Such diversity is achieved through a programmed somatic recombination process whereby germline V, D, and J segments of antigen receptor loci are assembled to form the variable region V(D)J exons of Ig and TCRs. Studies of this process, termed V(D)J recombination, have provided key insights into our understanding of a variety of general gene regulatory and DNA repair processes over the last several decades. V(D)J recombination is initiated by the RAG endonuclease which generates DNA double-stranded breaks at the borders of V, D, and J segments. In this review, we cover recent work that has elucidated RAG structure and work that revealed that RAG has a novel chromatin scanning activity, likely mediated by chromatin loop extrusion, that contributes to its ability to locate V, D, J gene segment substrates within large chromosomal loop domains bounded by CTCF-binding elements (CBEs). This latter function, coupled with the role CBE-based chromatin loop domains and subdomains within them play in focusing V(D)J recombination activity within antigen receptor loci, provide mechanistic explanations for long-standing questions regarding V(D)J segment usage diversification and in limiting potentially deleterious off-target RAG-initiated recombination events genome-wide. This review will focus mainly on studies of the mouse Ig heavy chain locus, but the principles described also apply to other Ig loci and to TCR loci in mice and humans.
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Affiliation(s)
- Sherry G Lin
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, United States
| | - Zhaoqing Ba
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, United States
| | - Frederick W Alt
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, United States.
| | - Yu Zhang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, and Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, United States
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31
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Castiblanco DP, Norton DD, Maul RW, Gearhart PJ. J H6 downstream intronic sequence is dispensable for RNA polymerase II accumulation and somatic hypermutation of the variable gene in Ramos cells. Mol Immunol 2018; 97:101-108. [PMID: 29625296 DOI: 10.1016/j.molimm.2018.03.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/09/2018] [Accepted: 03/30/2018] [Indexed: 02/03/2023]
Abstract
Activation-induced deaminase (AID) introduces nucleotide substitutions within the variable region of immunoglobulin genes to promote antibody diversity. This activity, which is limited to 1.5 kb downstream of the variable gene promoter, mutates both the coding exon and downstream intronic sequences. We recently reported that RNA polymerase II accumulates in these regions during transcription in mice. This build-up directly correlates with the area that is accessible to AID, and manipulation of RNA polymerase II levels alters the mutation frequency. To address whether the intronic DNA sequence by itself can regulate RNA polymerase II accumulation and promote mutagenesis, we deleted 613 bp of DNA downstream of the JH6 intron in the human Ramos B cell line. The loss of this sequence did not alter polymerase abundance or mutagenesis in the variable gene, suggesting that most of the intronic sequence is dispensable for somatic hypermutation.
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Affiliation(s)
- Diana P Castiblanco
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Darrell D Norton
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
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32
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Qiu X, Kumari G, Gerasimova T, Du H, Labaran L, Singh A, De S, Wood WH, Becker KG, Zhou W, Ji H, Sen R. Sequential Enhancer Sequestration Dysregulates Recombination Center Formation at the IgH Locus. Mol Cell 2018; 70:21-33.e6. [PMID: 29576529 DOI: 10.1016/j.molcel.2018.02.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 12/19/2017] [Accepted: 02/13/2018] [Indexed: 12/22/2022]
Abstract
Immunoglobulin heavy-chain (IgH) genes are assembled by DNA rearrangements that juxtapose a variable (VH), a diversity (DH), and a joining (JH) gene segment. Here, we report that in the absence of intergenic control region 1 (IGCR1), the intronic enhancer (Eμ) associates with the next available CTCF binding site located close to VH81X via putative heterotypic interactions involving YY1 and CTCF. The alternate Eμ/VH81X loop leads to formation of a distorted recombination center and altered DH rearrangements and disrupts chromosome conformation that favors distal VH recombination. Cumulatively, these features drive highly skewed, Eμ-dependent recombination of VH81X. Sequential deletion of CTCF binding regions on IGCR1-deleted alleles suggests that they influence recombination of single proximal VH gene segments. Our observations demonstrate that Eμ interacts differently with IGCR1- or VH-associated CTCF binding sites and thereby identify distinct roles for insulator-like elements in directing enhancer activity.
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Affiliation(s)
- Xiang Qiu
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Gita Kumari
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Tatiana Gerasimova
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Hansen Du
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Lawal Labaran
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Amit Singh
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Supriyo De
- Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, MD 21224, USA
| | - William H Wood
- Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, MD 21224, USA
| | - Kevin G Becker
- Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, MD 21224, USA
| | - Weiqiang Zhou
- Department of Biostatistics, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Hongkai Ji
- Department of Biostatistics, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Ranjan Sen
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA.
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33
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Saintamand A, Ghazzaui N, Issaoui H, Denizot Y. [The IgH 3'RR: Doctor Jekyll and Mister Hyde of B-cell maturation and lymphomagenesis]. Med Sci (Paris) 2017; 33:963-970. [PMID: 29200394 DOI: 10.1051/medsci/20173311013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The four transcriptional enhancers located in the 3' regulatory region (3'RR) of the IgH locus control the late phases of B-cell maturation, namely IgH locus transcription, somatic hypermutation and class switch recombination. Doctor Jekyll by nature, the 3'RR acts as Mister Hyde in case of oncogenic translocation at the IgH locus taking under its transcriptional control the translocated oncogene. The aim of this review is to show this duality on the basis of the latest scientific advances in the structure and function of the 3'RR and to hIghlight the targeting of the 3'RR as a potential therapeutic approach in mature B-cell lymphomas.
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Affiliation(s)
- Alexis Saintamand
- UMR CNRS 7276, Université de Limoges, rue Pr Descottes, 87025 Limoges, France
| | - Nour Ghazzaui
- UMR CNRS 7276, Université de Limoges, rue Pr Descottes, 87025 Limoges, France
| | - Hussein Issaoui
- UMR CNRS 7276, Université de Limoges, rue Pr Descottes, 87025 Limoges, France
| | - Yves Denizot
- UMR CNRS 7276, Université de Limoges, rue Pr Descottes, 87025 Limoges, France
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34
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Saintamand A, Vincent-Fabert C, Marquet M, Ghazzaui N, Magnone V, Pinaud E, Cogné M, Denizot Y. E μ and 3'RR IgH enhancers show hierarchic unilateral dependence in mature B-cells. Sci Rep 2017; 7:442. [PMID: 28348365 PMCID: PMC5428668 DOI: 10.1038/s41598-017-00575-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/03/2017] [Indexed: 01/18/2023] Open
Abstract
Enhancer and super-enhancers are master regulators of cell fate. While they act at long-distances on adjacent genes, it is unclear whether they also act on one another. The immunoglobulin heavy chain (IgH) locus is unique in carrying two super-enhancers at both ends of the constant gene cluster: the 5'Eμ super-enhancer promotes VDJ recombination during the earliest steps of B-cell ontogeny while the 3' regulatory region (3'RR) is essential for late differentiation. Since they carry functional synergies in mature B-cells and physically interact during IgH locus DNA looping, we investigated if they were independent engines of locus remodelling or if their function was more intimately intermingled, their optimal activation then requiring physical contact with each other. Analysis of chromatin marks, enhancer RNA transcription and accessibility in Eμ- and 3'RR-deficient mice show, in mature activated B-cells, an unilateral dependence of this pair of enhancers: while the 3'RR acts in autonomy, Eμ in contrast likely falls under control of the 3'RR.
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Affiliation(s)
- A Saintamand
- CNRS UMR 7276, CRIBL, Université de Limoges, Limoges, France. .,INSERM U1236, Université Rennes 1, Rennes, France.
| | | | - M Marquet
- CNRS UMR 7276, CRIBL, Université de Limoges, Limoges, France
| | - N Ghazzaui
- CNRS UMR 7276, CRIBL, Université de Limoges, Limoges, France
| | - V Magnone
- CNRS et Université de Nice Sophia Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 6097, Sophia, Antipolis, France
| | - E Pinaud
- CNRS UMR 7276, CRIBL, Université de Limoges, Limoges, France
| | - M Cogné
- CNRS UMR 7276, CRIBL, Université de Limoges, Limoges, France
| | - Y Denizot
- CNRS UMR 7276, CRIBL, Université de Limoges, Limoges, France.
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35
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Laffleur B, Basu U, Lim J. RNA Exosome and Non-coding RNA-Coupled Mechanisms in AID-Mediated Genomic Alterations. J Mol Biol 2017; 429:3230-3241. [PMID: 28069372 DOI: 10.1016/j.jmb.2016.12.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/21/2016] [Accepted: 12/27/2016] [Indexed: 12/31/2022]
Abstract
The eukaryotic RNA exosome is a well-conserved protein complex with ribonuclease activity implicated in RNA metabolism. Various families of non-coding RNAs have been identified as substrates of the complex, underscoring its role as a non-coding RNA processing/degradation unit. However, the role of RNA exosome and its RNA processing activity on DNA mutagenesis/alteration events have not been investigated until recently. B lymphocytes use two DNA alteration mechanisms, class switch recombination (CSR) and somatic hypermutation (SHM), to re-engineer their antibody gene expressing loci until a tailored antibody gene for a specific antigen is satisfactorily generated. CSR and SHM require the essential activity of the DNA activation-induced cytidine deaminase (AID). Causing collateral damage to the B-cell genome during CSR and SHM, AID induces unwanted (and sometimes oncogenic) mutations at numerous non-immunoglobulin gene sequences. Recent studies have revealed that AID's DNA mutator activity is regulated by the RNA exosome complex, thus providing an example of a mechanism that relates DNA mutagenesis to RNA processing. Here, we review the emergent functions of RNA exosome during CSR, SHM, and other chromosomal alterations in B cells, and discuss implications relevant to mechanisms that maintain B-cell genomic integrity.
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Affiliation(s)
- Brice Laffleur
- Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Uttiya Basu
- Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
| | - Junghyun Lim
- Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
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36
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YY1 controls Eμ-3'RR DNA loop formation and immunoglobulin heavy chain class switch recombination. Blood Adv 2016; 1:15-20. [PMID: 29167838 DOI: 10.1182/bloodadvances.2016000372] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Key Points
Transcription factor YY1 regulates the IgH Eμ-3′RR long-distance DNA loop without the YY1 transcriptional activation domain. YY1 constructs that rescue the Eμ-3′RR DNA loop also restore CSR strongly arguing for the necessity of this long-distance DNA loop for CSR.
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37
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Somatic hypermutation in immunity and cancer: Critical analysis of strand-biased and codon-context mutation signatures. DNA Repair (Amst) 2016; 45:1-24. [DOI: 10.1016/j.dnarep.2016.07.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 07/01/2016] [Indexed: 01/01/2023]
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38
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Related Mechanisms of Antibody Somatic Hypermutation and Class Switch Recombination. Microbiol Spectr 2016; 3:MDNA3-0037-2014. [PMID: 26104555 DOI: 10.1128/microbiolspec.mdna3-0037-2014] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The primary antibody repertoire is generated by mechanisms involving the assembly of the exons that encode the antigen-binding variable regions of immunoglobulin heavy (IgH) and light (IgL) chains during the early development of B lymphocytes. After antigen-dependent activation, mature B lymphocytes can further alter their IgH and IgL variable region exons by the process of somatic hypermutation (SHM), which allows the selection of B cells in which SHMs resulted in the production of antibodies with increased antigen affinity. In addition, during antigen-dependent activation, B cells can also change the constant region of their IgH chain through a DNA double-strand-break (DSB) dependent process referred to as IgH class switch recombination (CSR), which generates B cell progeny that produce antibodies with different IgH constant region effector functions that are best suited for a elimination of a particular pathogen or in a particular setting. Both the mutations that underlie SHM and the DSBs that underlie CSR are initiated in target genes by activation-induced cytidine deaminase (AID). This review describes in depth the processes of SHM and CSR with a focus on mechanisms that direct AID cytidine deamination in activated B cells and mechanisms that promote the differential outcomes of such cytidine deamination.
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39
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Saintamand A, Rouaud P, Garot A, Saad F, Carrion C, Oblet C, Cogné M, Pinaud E, Denizot Y. The IgH 3' regulatory region governs μ chain transcription in mature B lymphocytes and the B cell fate. Oncotarget 2016; 6:4845-52. [PMID: 25742787 PMCID: PMC4467119 DOI: 10.18632/oncotarget.3010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 12/21/2014] [Indexed: 12/11/2022] Open
Abstract
We report that the IgH 3' regulatory region (3'RR) has no role on μ chain transcription and pre-BCR expression in B cell progenitors. In contrast, analysis of heterozygous IgH aΔ3'RR/bwt mice indicated that the 3'RR controls μ chain transcripts in mature splenocytes and impacts membrane IgM density without obvious effect on BCR signals (colocalisation with lipid rafts and phosphorylation of Erk and Akt after BCR crosslinking). Deletion of the 3'RR modulates the B cell fate to less marginal zone B cells. In conclusion, the 3'RR is dispensable for pre-BCR expression and necessary for optimal commitments toward the marginal zone B cell fate. These results reinforce the concept of a dual regulation of the IgH locus transcription and accessibility by 5' elements at immature B cell stages, and by the 3'RR as early as the resting mature B cell stage and then along further activation and differentiation.
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Affiliation(s)
| | | | | | | | | | | | - Michel Cogné
- CNRS, CRIBL, UMR 7276, Limoges, France.,Université de Limoges, CRIBL, UMR 7276, Limoges, France.,Institut Universitaire de France, Paris, France
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40
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Saintamand A, Vincent-Fabert C, Garot A, Rouaud P, Oruc Z, Magnone V, Cogné M, Denizot Y. Deciphering the importance of the palindromic architecture of the immunoglobulin heavy-chain 3' regulatory region. Nat Commun 2016; 7:10730. [PMID: 26883548 PMCID: PMC4757795 DOI: 10.1038/ncomms10730] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 01/15/2016] [Indexed: 01/16/2023] Open
Abstract
The IgH 3' regulatory region (3'RR) controls class switch recombination (CSR) and somatic hypermutation (SHM) in B cells. The mouse 3'RR contains four enhancer elements with hs1,2 flanked by inverted repeated sequences and the centre of a 25-kb palindrome bounded by two hs3 enhancer inverted copies (hs3a and hs3b). hs4 lies downstream of the palindrome. In mammals, evolution maintained this unique palindromic arrangement, suggesting that it is functionally significant. Here we report that deconstructing the palindromic IgH 3'RR strongly affects its function even when enhancers are preserved. CSR and IgH transcription appear to be poorly dependent on the 3'RR architecture and it is more or less preserved, provided 3'RR enhancers are present. By contrast, a ‘palindromic effect' significantly lowers VH germline transcription, AID recruitment and SHM. In conclusion, this work indicates that the IgH 3'RR does not simply pile up enhancer units but also optimally exposes them into a functional architecture of crucial importance. The IgH 3' regulatory region contains an evolutionarily conserved palindromic sequence flanking important enhancer elements. Here the authors show that the palindrome is required for generating antibody diversity.
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Affiliation(s)
| | | | - Armand Garot
- Université de Limoges, CRIBL, UMR CNRS 7276, Limoges 87025, France
| | - Pauline Rouaud
- Université de Limoges, CRIBL, UMR CNRS 7276, Limoges 87025, France
| | - Zeliha Oruc
- Université de Limoges, CRIBL, UMR CNRS 7276, Limoges 87025, France
| | - Virginie Magnone
- CNRS et Université de Nice Sophia Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire, UMR 6097, Sophia Antipolis 06560, France
| | - Michel Cogné
- Université de Limoges, CRIBL, UMR CNRS 7276, Limoges 87025, France.,Institut Universitaire de France, Paris 75231, France
| | - Yves Denizot
- Université de Limoges, CRIBL, UMR CNRS 7276, Limoges 87025, France
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41
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Sequential activation and distinct functions for distal and proximal modules within the IgH 3' regulatory region. Proc Natl Acad Sci U S A 2016; 113:1618-23. [PMID: 26831080 DOI: 10.1073/pnas.1514090113] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
As a master regulator of functional Ig heavy chain (IgH) expression, the IgH 3' regulatory region (3'RR) controls multiple transcription events at various stages of B-cell ontogeny, from newly formed B cells until the ultimate plasma cell stage. The IgH 3'RR plays a pivotal role in early B-cell receptor expression, germ-line transcription preceding class switch recombination, interactions between targeted switch (S) regions, variable region transcription before somatic hypermutation, and antibody heavy chain production, but the functional ranking of its different elements is still inaccurate, especially that of its evolutionarily conserved quasi-palindromic structure. By comparing relevant previous knockout (KO) mouse models (3'RR KO and hs3b-4 KO) to a novel mutant devoid of the 3'RR quasi-palindromic region (3'PAL KO), we pinpointed common features and differences that specify two distinct regulatory entities acting sequentially during B-cell ontogeny. Independently of exogenous antigens, the 3'RR distal part, including hs4, fine-tuned B-cell receptor expression in newly formed and naïve B-cell subsets. At mature stages, the 3'RR portion including the quasi-palindrome dictated antigen-dependent locus remodeling (global somatic hypermutation and class switch recombination to major isotypes) in activated B cells and antibody production in plasma cells.
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42
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Montefiori L, Wuerffel R, Roqueiro D, Lajoie B, Guo C, Gerasimova T, De S, Wood W, Becker KG, Dekker J, Liang J, Sen R, Kenter AL. Extremely Long-Range Chromatin Loops Link Topological Domains to Facilitate a Diverse Antibody Repertoire. Cell Rep 2016; 14:896-906. [PMID: 26804913 DOI: 10.1016/j.celrep.2015.12.083] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/29/2015] [Accepted: 12/16/2015] [Indexed: 12/19/2022] Open
Abstract
Early B cell development is characterized by large-scale Igh locus contraction prior to V(D)J recombination to facilitate a highly diverse Ig repertoire. However, an understanding of the molecular architecture that mediates locus contraction remains unclear. We have combined high-resolution chromosome conformation capture (3C) techniques with 3D DNA FISH to identify three conserved topological subdomains. Each of these topological folds encompasses a major VH gene family that become juxtaposed in pro-B cells via megabase-scale chromatin looping. The transcription factor Pax5 organizes the subdomain that spans the VHJ558 gene family. In its absence, the J558 VH genes fail to associate with the proximal VH genes, thereby providing a plausible explanation for reduced VHJ558 gene rearrangements in Pax5-deficient pro-B cells. We propose that Igh locus contraction is the cumulative effect of several independently controlled chromatin subdomains that provide the structural infrastructure to coordinate optimal antigen receptor assembly.
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Affiliation(s)
- Lindsey Montefiori
- Gene Regulation Section, Laboratory of Molecular Biology and Immunology, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
| | - Robert Wuerffel
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Damian Roqueiro
- Department of Bioengineering, University of Illinois College of Engineering and College of Medicine, Chicago, IL 60612-7344, USA
| | - Bryan Lajoie
- Howard Hughes Medical Institute and Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605-0103, USA
| | - Changying Guo
- Gene Regulation Section, Laboratory of Molecular Biology and Immunology, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
| | - Tatiana Gerasimova
- Gene Regulation Section, Laboratory of Molecular Biology and Immunology, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
| | - Supriyo De
- Gene Expression and Genomics Unit, Laboratory of Genetics, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
| | - William Wood
- Gene Expression and Genomics Unit, Laboratory of Genetics, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
| | - Kevin G Becker
- Gene Expression and Genomics Unit, Laboratory of Genetics, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
| | - Job Dekker
- Howard Hughes Medical Institute and Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605-0103, USA
| | - Jie Liang
- Department of Bioengineering, University of Illinois College of Engineering and College of Medicine, Chicago, IL 60612-7344, USA
| | - Ranjan Sen
- Gene Regulation Section, Laboratory of Molecular Biology and Immunology, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA.
| | - Amy L Kenter
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA.
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43
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Rother MB, Palstra RJ, Jhunjhunwala S, van Kester KAM, van IJcken WFJ, Hendriks RW, van Dongen JJM, Murre C, van Zelm MC. Nuclear positioning rather than contraction controls ordered rearrangements of immunoglobulin loci. Nucleic Acids Res 2016; 44:175-86. [PMID: 26384565 PMCID: PMC4705691 DOI: 10.1093/nar/gkv928] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 09/05/2015] [Accepted: 09/07/2015] [Indexed: 12/31/2022] Open
Abstract
Progenitor-B cells recombine their immunoglobulin (Ig) loci to create unique antigen receptors. Despite a common recombination machinery, the Ig heavy and Ig light chain loci rearrange in a stepwise manner. We studied pre-pro-B cells and Rag(-/-) progenitor-B cells to determine whether Ig locus contraction or nuclear positioning is decisive for stepwise rearrangements. We found that both Ig loci were contracted in pro-B and pre-B cells. Igh relocated from the nuclear lamina to central domains only at the pro-B cell stage, whereas, Igκ remained sequestered at the lamina, and only at the pre-B cell stage located to central nuclear domains. Finally, in vitro induced re-positioning of Ig alleles away from the nuclear periphery increased germline transcription of Ig loci in pre-pro-B cells. Thus, Ig locus contraction juxtaposes genomically distant elements to mediate efficient recombination, however, sequential positioning of Ig loci away from the nuclear periphery determines stage-specific accessibility of Ig loci.
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Affiliation(s)
- Magdalena B Rother
- Department of Immunology, Erasmus MC, University Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Robert-Jan Palstra
- Department of Biochemistry, Erasmus MC, University Medical Center, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Suchit Jhunjhunwala
- Department of Molecular Biology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0377, USA
| | - Kevin A M van Kester
- Department of Immunology, Erasmus MC, University Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Wilfred F J van IJcken
- Center for Biomics, Erasmus MC, University Medical Center, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Rudi W Hendriks
- Department of Pulmonary Medicine, Erasmus MC, University Medical Center, PO Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Jacques J M van Dongen
- Department of Immunology, Erasmus MC, University Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Cornelis Murre
- Department of Molecular Biology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0377, USA
| | - Menno C van Zelm
- Department of Immunology, Erasmus MC, University Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
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44
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Abstract
Gerasimova et al. describe a three-step pathway that establishes the structure of the 2.8-Mb immunoglobulin heavy chain gene (IgH) locus in pro-B cells. Each step uses a different transcription factor and leads to increasing levels of structural organization. Conformation of antigen receptor gene loci spatially juxtaposes rearranging gene segments in the appropriate cell lineage and developmental stage. We describe a three-step pathway that establishes the structure of the 2.8-Mb immunoglobulin heavy chain gene (IgH) locus in pro-B cells. Each step uses a different transcription factor and leads to increasing levels of structural organization. CTCF mediates one level of compaction that folds the locus into several 250- to 400-kb subdomains, and Pax5 further compacts the 2-Mb region that encodes variable (VH) gene segments. The 5′ and 3′ domains are brought together by the transcription factor YY1 to establish the configuration within which gene recombination initiates. Such stepwise mechanisms may apply more generally to establish regulatory fine structure within megabase-sized topologically associated domains.
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45
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Proudhon C, Hao B, Raviram R, Chaumeil J, Skok JA. Long-Range Regulation of V(D)J Recombination. Adv Immunol 2015; 128:123-82. [PMID: 26477367 DOI: 10.1016/bs.ai.2015.07.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Given their essential role in adaptive immunity, antigen receptor loci have been the focus of analysis for many years and are among a handful of the most well-studied genes in the genome. Their investigation led initially to a detailed knowledge of linear structure and characterization of regulatory elements that confer control of their rearrangement and expression. However, advances in DNA FISH and imaging combined with new molecular approaches that interrogate chromosome conformation have led to a growing appreciation that linear structure is only one aspect of gene regulation and in more recent years, the focus has switched to analyzing the impact of locus conformation and nuclear organization on control of recombination. Despite decades of work and intense effort from numerous labs, we are still left with an incomplete picture of how the assembly of antigen receptor loci is regulated. This chapter summarizes our advances to date and points to areas that need further investigation.
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Affiliation(s)
- Charlotte Proudhon
- Department of Pathology, New York University School of Medicine, New York, USA
| | - Bingtao Hao
- Department of Pathology, New York University School of Medicine, New York, USA
| | - Ramya Raviram
- Department of Pathology, New York University School of Medicine, New York, USA
| | - Julie Chaumeil
- Institut Curie, CNRS UMR3215, INSERM U934, Paris, France
| | - Jane A Skok
- Department of Pathology, New York University School of Medicine, New York, USA.
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46
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Ebert A, Hill L, Busslinger M. Spatial Regulation of V-(D)J Recombination at Antigen Receptor Loci. Adv Immunol 2015; 128:93-121. [PMID: 26477366 DOI: 10.1016/bs.ai.2015.07.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Lymphocytes express a diverse repertoire of antigen receptors, which are able to recognize a large variety of foreign pathogens. Functional antigen receptor genes are assembled by V(D)J recombination in immature B cells (Igh and Igk) and T cells (Tcr b and Tcra/d). V(D)J recombination takes place in the 3' proximal domain containing the D, J, and C gene segments, whereas 31 (Tcrb) to 200 (Igh) V genes are spread over a large region of 0.67 (Tcrb) to 3 (Igk) megabase pairs. The spatial regulation of V(D)J recombination has been best studied for the Igh locus, which undergoes reversible contraction by long-range looping in pro-B cells. This large-scale contraction brings distantly located VH genes into close proximity of the DJH-rearranged gene segment, which facilitates VH-DJH recombination. The B-cell-specific Pax5, ubiquitous YY1, and architectural CTCF/cohesin proteins regulate Igh locus contraction in pro-B cells by binding to multiple sites in the VH gene cluster. These regulators also control the pro-B-cell-specific activity of the distally located PAIR elements, which may be involved in the regulation of VH-DJH recombination by promoting locus contraction. Moreover, the large VH gene cluster of the Igh locus undergoes flexible long-range looping, which guarantees similar participation of all VH genes in VH-DJH recombination to generate a diverse antibody repertoire. Importantly, long-range looping is a more general regulatory principle, as other antigen receptor loci also undergo reversible contraction at the developmental stage, where they engage in V-(D)J recombination.
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Affiliation(s)
- Anja Ebert
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Louisa Hill
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria
| | - Meinrad Busslinger
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria.
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47
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Developmental Switch in the Transcriptional Activity of a Long-Range Regulatory Element. Mol Cell Biol 2015. [PMID: 26195822 DOI: 10.1128/mcb.00509-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Eukaryotic gene expression is often controlled by distant regulatory elements. In developing B lymphocytes, transcription is associated with V(D)J recombination at immunoglobulin loci. This process is regulated by remote cis-acting elements. At the immunoglobulin heavy chain (IgH) locus, the 3' regulatory region (3'RR) promotes transcription in mature B cells. This led to the notion that the 3'RR orchestrates the IgH locus activity at late stages of B cell maturation only. However, long-range interactions involving the 3'RR were detected in early B cells, but the functional consequences of these interactions were unknown. Here we show that not only does the 3'RR affect transcription at distant sites within the IgH variable region but also it conveys a transcriptional silencing activity on both sense and antisense transcription. The 3'RR-mediated silencing activity is switched off upon completion of VH-DJH recombination. Our findings reveal a developmentally controlled, stage-dependent shift in the transcriptional activity of a master regulatory element.
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48
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Bonaud A, Lechouane F, Le Noir S, Monestier O, Cogné M, Sirac C. Efficient AID targeting of switch regions is not sufficient for optimal class switch recombination. Nat Commun 2015; 6:7613. [PMID: 26146363 DOI: 10.1038/ncomms8613] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 05/26/2015] [Indexed: 02/07/2023] Open
Abstract
Antibody affinity maturation relies on activation-induced cytidine deaminase (AID)-dependent somatic hypermutation (SHM) of immunoglobulin (Ig) loci. Class switch recombination (CSR) can in parallel occur between AID-targeted, transcribed, spliced and repetitive switch (S) regions. AID thus initiates not only mutations but also double-strand breaks (DSBs). What governs the choice between those two outcomes remains uncertain. Here we explore whether insertion of transcribed intronic S regions in a locus (Igκ) strongly recruiting AID is sufficient for efficient CSR. Although strongly targeted by AID and carrying internal deletions, the knocked-in S regions only undergo rare CSR-like events. This model confirms S regions as exquisite SHM targets, extending AID activity far from transcription initiation sites, and shows that such spliced and repetitive AID targets are not sufficient by themselves for CSR. Beyond transcription and AID recruitment, additional IgH elements are thus needed for CSR, restricting this hazardous gene remodelling to IgH loci.
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Affiliation(s)
- Amélie Bonaud
- Immunology, CNRS UMR 7276, Centre Nationale de la Recherche Scientifique, Université de Limoges, Limoges 87025, France
| | - Fabien Lechouane
- Immunology, CNRS UMR 7276, Centre Nationale de la Recherche Scientifique, Université de Limoges, Limoges 87025, France
| | - Sandrine Le Noir
- Immunology, CNRS UMR 7276, Centre Nationale de la Recherche Scientifique, Université de Limoges, Limoges 87025, France
| | - Olivier Monestier
- Immunology, CNRS UMR 7276, Centre Nationale de la Recherche Scientifique, Université de Limoges, Limoges 87025, France
| | - Michel Cogné
- 1] Immunology, CNRS UMR 7276, Centre Nationale de la Recherche Scientifique, Université de Limoges, Limoges 87025, France. [2] Institut Universitaire de France, Paris 75000, France
| | - Christophe Sirac
- Immunology, CNRS UMR 7276, Centre Nationale de la Recherche Scientifique, Université de Limoges, Limoges 87025, France
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Saintamand A, Rouaud P, Saad F, Rios G, Cogné M, Denizot Y. Elucidation of IgH 3′ region regulatory role during class switch recombination via germline deletion. Nat Commun 2015; 6:7084. [DOI: 10.1038/ncomms8084] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 04/01/2015] [Indexed: 02/06/2023] Open
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Complete cis Exclusion upon Duplication of the Eμ Enhancer at the Immunoglobulin Heavy Chain Locus. Mol Cell Biol 2015; 35:2231-41. [PMID: 25896912 DOI: 10.1128/mcb.00294-15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Developing lymphocytes somatically diversify their antigen-receptor loci through V(D)J recombination. The process is associated with allelic exclusion, which results in monoallelic expression of an antigen receptor locus. Various cis-regulatory elements control V(D)J recombination in a developmentally regulated manner, but their role in allelic exclusion is still unclear. At the immunoglobulin heavy chain locus (IgH), the Eμ enhancer plays a critical role in V(D)J recombination. We generated a mouse line with a replacement mutation in the constant region of the locus that duplicates the Eμ enhancer and allows premature expression of the γ3 heavy chain. Strikingly, IgM expression was completely and specifically excluded in cis from the mutant allele. This cis exclusion recapitulated the main features of allelic exclusion, including differential exclusion of variable genes. Notably, sense and antisense transcription within the distal variable domain and distal V(H)-DJ(H) recombination were inhibited. cis exclusion was established and stably maintained despite an active endogenous Eμ enhancer. The data reveal the importance of the dynamic, developmental stage-dependent interplay between IgH locus enhancers and signaling in the induction and maintenance of allelic exclusion.
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