1
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An Igh distal enhancer modulates antigen receptor diversity by determining locus conformation. Nat Commun 2023; 14:1225. [PMID: 36869028 PMCID: PMC9984487 DOI: 10.1038/s41467-023-36414-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 01/31/2023] [Indexed: 03/05/2023] Open
Abstract
The mouse Igh locus is organized into a developmentally regulated topologically associated domain (TAD) that is divided into subTADs. Here we identify a series of distal VH enhancers (EVHs) that collaborate to configure the locus. EVHs engage in a network of long-range interactions that interconnect the subTADs and the recombination center at the DHJH gene cluster. Deletion of EVH1 reduces V gene rearrangement in its vicinity and alters discrete chromatin loops and higher order locus conformation. Reduction in the rearrangement of the VH11 gene used in anti-PtC responses is a likely cause of the observed reduced splenic B1 B cell compartment. EVH1 appears to block long-range loop extrusion that in turn contributes to locus contraction and determines the proximity of distant VH genes to the recombination center. EVH1 is a critical architectural and regulatory element that coordinates chromatin conformational states that favor V(D)J rearrangement.
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2
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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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3
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Peycheva M, Neumann T, Malzl D, Nazarova M, Schoeberl UE, Pavri R. DNA replication timing directly regulates the frequency of oncogenic chromosomal translocations. Science 2022; 377:eabj5502. [DOI: 10.1126/science.abj5502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Chromosomal translocations result from the joining of DNA double-strand breaks (DSBs) and frequently cause cancer. However, the steps linking DSB formation to DSB ligation remain undeciphered. We report that DNA replication timing (RT) directly regulates lymphomagenic
Myc
translocations during antibody maturation in B cells downstream of DSBs and independently of DSB frequency. Depletion of minichromosome maintenance complexes alters replication origin activity, decreases translocations, and deregulates global RT. Ablating a single origin at
Myc
causes an early-to-late RT switch, loss of translocations, and reduced proximity with the immunoglobulin heavy chain (
Igh
) gene, its major translocation partner. These phenotypes were reversed by restoring early RT. Disruption of early RT also reduced tumorigenic translocations in human leukemic cells. Thus, RT constitutes a general mechanism in translocation biogenesis linking DSB formation to DSB ligation.
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Affiliation(s)
- Mihaela Peycheva
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030 Vienna, Austria
| | - Tobias Neumann
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030 Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna Biocenter, 1030 Vienna, Austria
| | - Daniel Malzl
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030 Vienna, Austria
| | - Mariia Nazarova
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030 Vienna, Austria
| | - Ursula E. Schoeberl
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030 Vienna, Austria
| | - Rushad Pavri
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030 Vienna, Austria
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4
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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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5
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Shen HM, Wuerffel R, Cantillo JF, Priyadarshi S, Lei X, Liang J, Wu YL, Kenter AL. Loop extrusion promotes an alternate pathway for isotype switching. Cell Rep 2021; 37:110059. [PMID: 34818547 PMCID: PMC8979556 DOI: 10.1016/j.celrep.2021.110059] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 07/22/2021] [Accepted: 11/03/2021] [Indexed: 01/02/2023] Open
Abstract
Class-switch recombination (CSR) involves replacement of the Cμ
constant region with another downstream CH region. CSR is initiated
by activation-induced cytidine deaminase (AID)-mediated DNA breaks that are
targeted to transcriptionally active switch (S) regions. S region promoters
(Prs) direct synapsis by associating with the Eμ and 3′Eα
enhancers that jointly anchor a chromatin loop. We report that asymmetric loop
extrusion allows 3′Eα to track along the locus and form Pr-Pr-E
interactions that mediate CSR between downstream S regions, followed by
switching to donor Sμ. This alternative pathway bypasses sequential
switching and creates immunoglobulin (Ig)E+ B cells in the absence of
IgG1 expression. Based on the analysis of diagnostic CSR products in B cell
subsets, we identify a BCR-negative cell intermediate that is pivotal to
efficient CSR. Shen et al. report that 3′Eα tracks along the Igh locus via
unidirectional loop extrusion to form germline transcript promoter (Pr)-Pr-E
interactions that mediate an alternative CSR pathway. B cell intermediates of
CSR are identified, which are AID-dependent, surface BCR-negative, and in the
G1 phase of the cell cycle.
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Affiliation(s)
- Hong Ming Shen
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Robert Wuerffel
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Jose F Cantillo
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Saurabh Priyadarshi
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Xue Lei
- Department of Bioengineering, University of Illinois Colleges of Engineering and Medicine, Chicago, IL 60612-7344, USA
| | - Jie Liang
- Department of Bioengineering, University of Illinois Colleges of Engineering and Medicine, Chicago, IL 60612-7344, USA
| | - Yee Ling Wu
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL 60153, USA
| | - Amy L Kenter
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA.
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6
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Three-dimensional genome rewiring during the development of antibody-secreting cells. Biochem Soc Trans 2021; 48:1109-1119. [PMID: 32453419 PMCID: PMC7329350 DOI: 10.1042/bst20191104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/26/2020] [Accepted: 04/28/2020] [Indexed: 01/08/2023]
Abstract
The development of B lymphocytes into antibody-secreting plasma cells is central to the adaptive immune system in that it confers protective and specific antibody response against invading pathogen. This developmental process involves extensive morphological and functional alterations that begin early after antigenic stimulation. These include chromatin restructuring that is critical in regulating gene expression, DNA rearrangement and other cellular processes. Here we outline the recent understanding of the three-dimensional architecture of the genome, specifically focused on its contribution to the process of B cell activation and terminal differentiation into antibody-secreting cells.
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7
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Fitz J, Neumann T, Steininger M, Wiedemann EM, Garcia AC, Athanasiadis A, Schoeberl UE, Pavri R. Spt5-mediated enhancer transcription directly couples enhancer activation with physical promoter interaction. Nat Genet 2020; 52:505-515. [PMID: 32251373 DOI: 10.1038/s41588-020-0605-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Accepted: 02/28/2020] [Indexed: 12/19/2022]
Abstract
Active enhancers are frequently transcribed, yet the regulatory role of enhancer transcription remains debated. Here, we depleted the RNA polymerase II pausing and elongation factor Spt5 in activated mouse B cells and found that approximately 50% of enhancer-gene pairs showed co-regulated transcription, consistent with a potential functional requirement for enhancer transcription. In particular, Spt5 depletion led to loss of super-enhancer-promoter physical interaction and gene expression at the immunoglobulin heavy-chain locus (Igh), abrogating antibody class switch recombination. This defect correlated strictly with loss of enhancer transcription but did not affect acetylation of histone H3 at lysine 27, chromatin accessibility and occupancy of Mediator and cohesin at the enhancer. Strikingly, CRISPRa-mediated rescue of enhancer transcription in Spt5-depleted cells restored Igh gene expression. Our work suggests that Spt5-mediated enhancer transcription underlies the physical and functional interaction between a subset of active enhancers and their target promoters.
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Affiliation(s)
- Johanna Fitz
- Research Institute of Molecular Pathology (IMP), Vienna, Austria
| | - Tobias Neumann
- Research Institute of Molecular Pathology (IMP), Vienna, Austria
| | | | | | | | | | | | - Rushad Pavri
- Research Institute of Molecular Pathology (IMP), Vienna, Austria.
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8
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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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9
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Jones BG, Penkert RR, Surman SL, Sealy RE, Pelletier S, Xu B, Neale G, Maul RW, Gearhart PJ, Hurwitz JL. Matters of life and death: How estrogen and estrogen receptor binding to the immunoglobulin heavy chain locus may influence outcomes of infection, allergy, and autoimmune disease. Cell Immunol 2019; 346:103996. [PMID: 31703914 DOI: 10.1016/j.cellimm.2019.103996] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/20/2019] [Accepted: 10/24/2019] [Indexed: 12/21/2022]
Abstract
Sex hormones are best known for their influences on reproduction, but they also have profound influences on the immune response. Examples of sex-specific differences include: (i) the relatively poor control of influenza virus infections in males compared to females, (ii) allergic asthma, an IgE-associated hypersensitivity reaction that is exacerbated in adolescent females compared to males, and (iii) systemic lupus erythematosus, a life-threatening autoimmune disease with a 9:1 female:male bias. Here we consider how estrogen and estrogen receptor α (ERα) may influence the immune response by modifying class switch recombination (CSR) and immunoglobulin expression patterns. We focus on ERα binding to enhancers (Eμ and the 3' regulatory region) and switch sites (Sµ and Sε) in the immunoglobulin heavy chain locus. Our preliminary data from ChIP-seq analyses of purified, activated B cells show estrogen-mediated changes in the positioning of ERα binding within and near Sµ and Sε. In the presence of estrogen, ERα is bound not only to estrogen response elements (ERE), but also to adenosine-cytidine (AC)-repeats and poly adenosine (poly A) sequences, in some cases within constant region gene introns. We propose that by binding these sites, estrogen and ERα directly participate in the DNA loop formation required for CSR. We further suggest that estrogen regulates immunoglobulin expression patterns and can thereby influence life-and-death outcomes of infection, hypersensitivity, and autoimmune disease.
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Affiliation(s)
- Bart G Jones
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Rhiannon R Penkert
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Sherri L Surman
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Robert E Sealy
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Stephane Pelletier
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Beisi Xu
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Geoff Neale
- Hartwell Center for Bioinformatics & Biotechnology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Robert W Maul
- National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Patricia J Gearhart
- National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - J L Hurwitz
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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10
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Abstract
Vast repertoires of unique antigen receptors are created in developing lymphocytes. The antigen receptor loci contain many variable (V), diversity (D), and joining (J) gene segments that are arrayed across very large genomic expanses and are joined to form variable-region exons. This process creates the potential for an organism to respond to large numbers of different pathogens. Here, we consider the underlying molecular mechanisms that favor some V genes for recombination prior to selection of the final antigen receptor repertoire. We discuss chromatin structures that form in antigen receptor loci to permit spatial proximity among the V, D, and J gene segments and how these relate to the generation of antigen receptor diversity.
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Affiliation(s)
- Amy L Kenter
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL, 60612-7344, USA
| | - Ann J Feeney
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, 92037, USA
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11
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Woolaver RA, Wang X, Dollin Y, Xie P, Wang JH, Chen Z. TRAF2 Deficiency in B Cells Impairs CD40-Induced Isotype Switching That Can Be Rescued by Restoring NF-κB1 Activation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2018; 201:3421-3430. [PMID: 30341187 PMCID: PMC6246814 DOI: 10.4049/jimmunol.1800337] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 09/20/2018] [Indexed: 12/22/2022]
Abstract
Effective humoral immunity requires class switch recombination (CSR) catalyzed by activation-induced cytidine deaminase (AID). In response to T cell-dependent (TD) Ags, CSR can be induced by CD40 signaling in B cells. TNFR-associated factors 2 and 3 (TRAF2/TRAF3) function as adaptors of the CD40 signaling pathway. B cell-intrinsic TRAF2 or TRAF3 (B-TRAF2 or B-TRAF3) knockout mice were previously reported to have indistinguishable phenotypes in gene expression, B cell survival and development, and enlarged peripheral lymphoid organs. However, it remains unknown whether deficiency of B-TRAF2 or B-TRAF3 differentially affects TD humoral immune responses and CD40-induced CSR. In this article, we show that B-TRAF2 is essential for optimal isotype switching induced by in vivo TD Ag immunization or by engaging CD40 in vitro. Our data clarify the controversial role of B-TRAF3 and confirm its dispensability in CD40-induced CSR. Mechanistically, CD40-induced AID expression was markedly impaired by B-TRAF2, but not B-TRAF3, deficiency. Moreover, B-TRAF2 deficiency causes defective activation of the NF-κB1 complex in a CD40-autonomous manner, and restoring CD40-induced NF-κB1 activation in TRAF2-deficient B cells rescues AID expression and CSR. We conclude that TRAF2 is essential but TRAF3 is dispensable for TD humoral immunity and CD40-induced CSR. Our studies provide significant biological bases for optimizing treatment of B cell-associated immune disorders by targeting CD40 signaling.
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Affiliation(s)
- Rachel A Woolaver
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
| | - Xiaoguang Wang
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
| | - Yonatan Dollin
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
| | - Ping Xie
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854; and
- Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08901
| | - Jing H Wang
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045;
| | - Zhangguo Chen
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045;
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12
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Song P, Zheng N, Liu Y, Tian C, Wu X, Ma X, Chen D, Zou X, Wang G, Wang H, Zhang Y, Lu S, Wu C, Wu Z. Deficient humoral responses and disrupted B-cell immunity are associated with fatal SFTSV infection. Nat Commun 2018; 9:3328. [PMID: 30127439 PMCID: PMC6102208 DOI: 10.1038/s41467-018-05746-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 07/24/2018] [Indexed: 02/06/2023] Open
Abstract
Severe Fever with Thrombocytopenia Syndrome (SFTS), an emerging infectious disease caused by a novel phlebovirus, is associated with high fatality. Therapeutic interventions are lacking and disease pathogenesis is yet to be fully elucidated. The anti-viral immune response has been reported, but humoral involvement in viral pathogenesis is poorly understood. Here we show defective serological responses to SFTSV is associated with disease fatality and a combination of B-cell and T-cell impairment contribute to disruption of anti-viral immunity. The serological profile in deceased patients is characterized by absence of specific IgG to viral nucleocapsid and glycoprotein due to failure of B-cell class switching. Expansion and impairment of antibody secretion is a signature of fatal SFTSV infection. Apoptosis of monocytes in the early stage of infection diminishes antigen-presentation by dendritic cells, impedes differentiation and function of T follicular helper cells, and contributes to failure of the virus-specific humoral response. SFTSV is a novel phlebovirus associated with high fatality, but understanding of pathogenesis is lacking. Here the authors show defective cellular immunity, deficient antibody production and defunct humoral immunity is associated with fatal infection in human cases of infection.
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Affiliation(s)
- Peixin Song
- Department of Infectious Diseases, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, People's Republic of China
| | - Nan Zheng
- Center for Public Health Research, Nanjing University Medical School, Nanjing, People's Republic of China.,State Key Lab of Analytical Chemistry for Life Science, Nanjing University, Nanjing, People's Republic of China.,Jiangsu Laboratory for Molecular Medicines, Nanjing University Medical School, Nanjing, People's Republic of China
| | - Yong Liu
- Department of Experimental Medicine, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, People's Republic of China
| | - Chen Tian
- Department of Infectious Diseases, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, People's Republic of China
| | - Xilin Wu
- Center for Public Health Research, Nanjing University Medical School, Nanjing, People's Republic of China.,Jiangsu Laboratory for Molecular Medicines, Nanjing University Medical School, Nanjing, People's Republic of China
| | - Xiaohua Ma
- Y-Clone BioMedical, Ltd., Suzhou Hi-Tech Innovation Park, Suzhou, People's Republic of China
| | - Deyan Chen
- Center for Public Health Research, Nanjing University Medical School, Nanjing, People's Republic of China.,State Key Lab of Analytical Chemistry for Life Science, Nanjing University, Nanjing, People's Republic of China
| | - Xue Zou
- Center for Public Health Research, Nanjing University Medical School, Nanjing, People's Republic of China.,State Key Lab of Analytical Chemistry for Life Science, Nanjing University, Nanjing, People's Republic of China
| | - Guiyang Wang
- Department of Infectious Diseases, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, People's Republic of China
| | - Huanru Wang
- Center for Public Health Research, Nanjing University Medical School, Nanjing, People's Republic of China.,State Key Lab of Analytical Chemistry for Life Science, Nanjing University, Nanjing, People's Republic of China
| | - Yongyang Zhang
- Department of Infectious Diseases, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, People's Republic of China
| | - Sufang Lu
- Department of Infectious Diseases, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, People's Republic of China
| | - Chao Wu
- Department of Infectious Diseases, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, People's Republic of China
| | - Zhiwei Wu
- Center for Public Health Research, Nanjing University Medical School, Nanjing, People's Republic of China. .,State Key Lab of Analytical Chemistry for Life Science, Nanjing University, Nanjing, People's Republic of China. .,Jiangsu Laboratory for Molecular Medicines, Nanjing University Medical School, Nanjing, People's Republic of China.
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13
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Boller S, Li R, Grosschedl R. Defining B Cell Chromatin: Lessons from EBF1. Trends Genet 2018; 34:257-269. [PMID: 29336845 DOI: 10.1016/j.tig.2017.12.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 12/14/2017] [Accepted: 12/19/2017] [Indexed: 12/11/2022]
Abstract
Hematopoiesis is regulated by signals from the microenvironment, transcription factor networks, and changes of the epigenetic landscape. Transcription factors interact with and shape chromatin to allow for lineage- and cell type-specific changes in gene expression. During B lymphopoiesis, epigenetic regulation is observed in multilineage progenitors in which a specific chromatin context is established, at the onset of the B cell differentiation when early B cell factor 1 (EBF1) induces lineage-specific changes in chromatin, during V(D)J recombination and after antigen-driven activation of B cells and terminal differentiation. In this review, we discuss the epigenetic changes underlying B cell differentiation, focusing on the role of transcription factor EBF1 in B cell lineage priming.
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Affiliation(s)
- Sören Boller
- Department of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Rui Li
- Department of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Rudolf Grosschedl
- Department of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany.
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14
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DNA Replication Origins in Immunoglobulin Switch Regions Regulate Class Switch Recombination in an R-Loop-Dependent Manner. Cell Rep 2017; 17:2927-2942. [PMID: 27974207 DOI: 10.1016/j.celrep.2016.11.041] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 09/07/2016] [Accepted: 11/11/2016] [Indexed: 11/22/2022] Open
Abstract
Class switch recombination (CSR) at the immunoglobulin heavy chain (IgH) locus generates antibody isotypes. CSR depends on double-strand breaks (DSBs) induced by activation-induced cytidine deaminase (AID). Although DSB formation and repair machineries are active in G1 phase, efficient CSR is dependent on cell proliferation and S phase entry; however, the underlying mechanisms are obscure. Here, we show that efficient CSR requires the replicative helicase, the Mcm complex. Mcm proteins are enriched at IgH switch regions during CSR, leading to assembly of facultative replication origins that require Mcm helicase function for productive CSR. Assembly of CSR-associated origins is facilitated by R loops and promotes the physical proximity (synapsis) of recombining switch regions, which is reduced by R loop inhibition or Mcm complex depletion. Thus, R loops contribute to replication origin specification that promotes DSB resolution in CSR. This suggests a mechanism for the dependence of CSR on S phase and cell division.
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15
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Gerasimčik N, He M, Dahlberg CIM, Kuznetsov NV, Severinson E, Westerberg LS. The Small Rho GTPases Rac1 and Rac2 Are Important for T-Cell Independent Antigen Responses and for Suppressing Switching to IgG2b in Mice. Front Immunol 2017; 8:1264. [PMID: 29056938 PMCID: PMC5635268 DOI: 10.3389/fimmu.2017.01264] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 09/22/2017] [Indexed: 01/18/2023] Open
Abstract
The Rho GTPases Cdc42, Rac1, and Rac2 coordinate receptor signaling to cell adhesion, migration, and proliferation. Deletion of Rac1 and Rac2 early during B cell development leads to failure in B cell entry into the splenic white pulp. Here, we sought to understand the role of Rac1 and Rac2 in B cell functionality and during the humoral antibody response. To circumvent the migratory deficiency of B cells lacking both Rac1 and Rac2, we took the approach to inducibly delete Rac1 in Rac2−/− B cells in the spleen (Rac1BRac2−/− B cells). Rac1BRac2−/− mice had normal differentiation of splenic B cell populations, except for a reduction in marginal zone B cells. Rac1BRac2−/− B cells showed normal spreading response on antibody-coated layers, while both Rac2−/− and Rac1BRac2−/− B cells had reduced homotypic adhesion and decreased proliferative response when compared to wild-type B cells. Upon challenge with the T-cell-independent antigen TNP-conjugated lipopolysaccharide, Rac1BRac2−/− mice showed reduced antibody response. In contrast, in response to the T-cell-dependent antigen sheep red blood cells, Rac1BRac2−/− mice had increased serum titers of IgG1 and IgG2b. During in vitro Ig class switching, Rac1BRac2−/− B cells had elevated germline γ2b transcripts leading to increased Ig class switching to IgG2b. Our data suggest that Rac1 and Rac2 serve an important role in regulation of the B cell humoral immune response and in suppressing Ig class switching to IgG2b.
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Affiliation(s)
- Natalija Gerasimčik
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.,Department of Rheumatology and Inflammation Research, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Minghui He
- Department of Microbiology Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Carin I M Dahlberg
- Department of Microbiology Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.,Department of Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden
| | - Nikolai V Kuznetsov
- Department of Microbiology Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Eva Severinson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Lisa S Westerberg
- Department of Microbiology Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
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16
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Feldman S, Wuerffel R, Achour I, Wang L, Carpenter PB, Kenter AL. 53BP1 Contributes to Igh Locus Chromatin Topology during Class Switch Recombination. THE JOURNAL OF IMMUNOLOGY 2017; 198:2434-2444. [PMID: 28159901 DOI: 10.4049/jimmunol.1601947] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 01/05/2017] [Indexed: 01/01/2023]
Abstract
In B lymphocytes, Ig class switch recombination (CSR) is induced by activation-induced cytidine deaminase, which initiates a cascade of events leading to DNA double-strand break formation in switch (S) regions. Resolution of DNA double-strand breaks proceeds through formation of S-S synaptic complexes. S-S synapsis is mediated by a chromatin loop that spans the C region domain of the Igh locus. S-S junctions are joined via a nonhomologous end joining DNA repair process. CSR occurs via an intrachromosomal looping out and deletion mechanism that is 53BP1 dependent. However, the mechanism by which 53BP1 facilitates deletional CSR and inhibits inversional switching events remains unknown. We report a novel architectural role for 53BP1 in Igh chromatin looping in mouse B cells. Long-range interactions between the Eμ and 3'Eα enhancers are significantly diminished in the absence of 53BP1. In contrast, germline transcript promoter:3'Eα looping interactions are unaffected by 53BP1 deficiency. Furthermore, 53BP1 chromatin occupancy at sites in the Igh locus is B cell specific, is correlated with histone H4 lysine 20 marks, and is subject to chromatin spreading. Thus, 53BP1 is required for three-dimensional organization of the Igh locus and provides a plausible explanation for the link with 53BP1 enforcement of deletional CSR.
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Affiliation(s)
- Scott Feldman
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344; and
| | - Robert Wuerffel
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344; and
| | - Ikbel Achour
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344; and
| | - Lili Wang
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344; and
| | - Phillip B Carpenter
- Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX 77030
| | - Amy L Kenter
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344; and
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17
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MBD4 Facilitates Immunoglobulin Class Switch Recombination. Mol Cell Biol 2017; 37:MCB.00316-16. [PMID: 27777312 DOI: 10.1128/mcb.00316-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 09/30/2016] [Indexed: 01/02/2023] Open
Abstract
Immunoglobulin heavy chain class switch recombination (CSR) requires targeted formation of DNA double-strand breaks (DSBs) in repetitive switch region elements followed by ligation between distal breaks. The introduction of DSBs is initiated by activation-induced cytidine deaminase (AID) and requires base excision repair (BER) and mismatch repair (MMR). The BER enzyme methyl-CpG binding domain protein 4 (MBD4) has been linked to the MMR pathway through its interaction with MutL homologue 1 (MLH1). We find that when Mbd4 exons 6 to 8 are deleted in a switching B cell line, DSB formation is severely reduced and CSR frequency is impaired. Impaired CSR can be rescued by ectopic expression of Mbd4 Mbd4 deficiency yields a deficit in DNA end processing similar to that found in MutS homologue 2 (Msh2)- and Mlh1-deficient B cells. We demonstrate that microhomology-rich S-S junctions are enriched in cells in which Mbd4 is deleted. Our studies suggest that Mbd4 is a component of MMR-directed DNA end processing.
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18
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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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19
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Rocha PP, Raviram R, Fu Y, Kim J, Luo VM, Aljoufi A, Swanzey E, Pasquarella A, Balestrini A, Miraldi ER, Bonneau R, Petrini J, Schotta G, Skok JA. A Damage-Independent Role for 53BP1 that Impacts Break Order and Igh Architecture during Class Switch Recombination. Cell Rep 2016; 16:48-55. [PMID: 27320916 PMCID: PMC4927351 DOI: 10.1016/j.celrep.2016.05.073] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 04/27/2016] [Accepted: 05/17/2016] [Indexed: 01/03/2023] Open
Abstract
During class switch recombination (CSR), B cells replace the Igh Cμ or δ exons with another down-stream constant region exon (CH), altering the anti-body isotype. CSR occurs through the introduction of AID-mediated double-strand breaks (DSBs) in switch regions and subsequent ligation of broken ends. Here, we developed an assay to investigate the dynamics of DSB formation in individual cells. We demonstrate that the upstream switch region Sμ is first targeted during recombination and that the mechanism underlying this control relies on 53BP1. Surprisingly, regulation of break order occurs through residual binding of 53BP1 to chromatin before the introduction of damage and independent of its established role in DNA repair. Using chromosome conformation capture, we show that 53BP1 mediates changes in chromatin architecture that affect break order. Finally, our results explain how changes in Igh architecture in the absence of 53BP1 could promote inversional rearrangements that compromise CSR.
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Affiliation(s)
- Pedro P Rocha
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
| | - Ramya Raviram
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA; Department of Biology, New York University, New York, NY 10003, USA
| | - Yi Fu
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - JungHyun Kim
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Vincent M Luo
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Arafat Aljoufi
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Emily Swanzey
- Department of Developmental Genetics, New York University School of Medicine, New York, NY 10016, USA
| | - Alessandra Pasquarella
- Ludwig Maximilians University and Munich Center for Integrated Protein Science (CiPSM), Biomedical Center, Planegg-Martinsried 80336, Germany
| | - Alessia Balestrini
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | | | - Richard Bonneau
- Department of Biology, New York University, New York, NY 10003, USA; Department of Computer Science, Courant Institute of Mathematical Sciences, New York, NY 10012, USA; Simons Center for Data Analysis, New York, NY 10010, USA
| | - John Petrini
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Gunnar Schotta
- Ludwig Maximilians University and Munich Center for Integrated Protein Science (CiPSM), Biomedical Center, Planegg-Martinsried 80336, Germany
| | - Jane A Skok
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
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20
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Thomas-Claudepierre AS, Robert I, Rocha PP, Raviram R, Schiavo E, Heyer V, Bonneau R, Luo VM, Reddy JK, Borggrefe T, Skok JA, Reina-San-Martin B. Mediator facilitates transcriptional activation and dynamic long-range contacts at the IgH locus during class switch recombination. J Exp Med 2016; 213:303-12. [PMID: 26903242 PMCID: PMC4813673 DOI: 10.1084/jem.20141967] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 01/15/2016] [Indexed: 12/21/2022] Open
Abstract
Thomas-Claudepierre et al. report that mediator facilitates the long-range contacts between acceptor switch regions and the IgH locus enhancers during class switch recombination and their transcriptional activation. Immunoglobulin (Ig) class switch recombination (CSR) is initiated by the transcription-coupled recruitment of activation-induced cytidine deaminase (AID) to Ig switch regions (S regions). During CSR, the IgH locus undergoes dynamic three-dimensional structural changes in which promoters, enhancers, and S regions are brought to close proximity. Nevertheless, little is known about the underlying mechanisms. In this study, we show that Med1 and Med12, two subunits of the mediator complex implicated in transcription initiation and long-range enhancer/promoter loop formation, are dynamically recruited to the IgH locus enhancers and the acceptor regions during CSR and that their knockdown in CH12 cells results in impaired CSR. Furthermore, we show that conditional inactivation of Med1 in B cells results in defective CSR and reduced acceptor S region transcription. Finally, we show that in B cells undergoing CSR, the dynamic long-range contacts between the IgH enhancers and the acceptor regions correlate with Med1 and Med12 binding and that they happen at a reduced frequency in Med1-deficient B cells. Our results implicate the mediator complex in the mechanism of CSR and are consistent with a model in which mediator facilitates the long-range contacts between S regions and the IgH locus enhancers during CSR and their transcriptional activation.
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Affiliation(s)
- Anne-Sophie Thomas-Claudepierre
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France Institut National de la Santé et de la Recherche Médicale, Unité 964, 67404 Illkirch, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, 67404 Illkirch, France Université de Strasbourg, 67400 Illkirch, France
| | - Isabelle Robert
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France Institut National de la Santé et de la Recherche Médicale, Unité 964, 67404 Illkirch, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, 67404 Illkirch, France Université de Strasbourg, 67400 Illkirch, France
| | - Pedro P Rocha
- Department of Pathology, School of Medicine, New York University, New York, NY 10003
| | - Ramya Raviram
- Department of Pathology, School of Medicine, New York University, New York, NY 10003 Department of Biology, New York University, New York, NY 10003
| | - Ebe Schiavo
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France Institut National de la Santé et de la Recherche Médicale, Unité 964, 67404 Illkirch, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, 67404 Illkirch, France Université de Strasbourg, 67400 Illkirch, France
| | - Vincent Heyer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France Institut National de la Santé et de la Recherche Médicale, Unité 964, 67404 Illkirch, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, 67404 Illkirch, France Université de Strasbourg, 67400 Illkirch, France
| | - Richard Bonneau
- Department of Biology, New York University, New York, NY 10003 Department of Computer Science, Courant Institute of Mathematical Sciences, New York, NY 10003 Simons Center for Data Analysis, New York, NY 10010
| | - Vincent M Luo
- Department of Pathology, School of Medicine, New York University, New York, NY 10003 Department of Biology, New York University, New York, NY 10003
| | - Janardan K Reddy
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60208
| | | | - Jane A Skok
- Department of Pathology, School of Medicine, New York University, New York, NY 10003 New York University Cancer Institute, New York University, New York, NY 10003
| | - Bernardo Reina-San-Martin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France Institut National de la Santé et de la Recherche Médicale, Unité 964, 67404 Illkirch, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, 67404 Illkirch, France Université de Strasbourg, 67400 Illkirch, France
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21
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AID hits the jackpot when missing the target. Curr Opin Immunol 2016; 39:96-102. [PMID: 26845615 DOI: 10.1016/j.coi.2016.01.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 01/12/2016] [Accepted: 01/14/2016] [Indexed: 01/07/2023]
Abstract
Activation induced deaminase is the single B cell specific factor mediating class switch recombination and somatic hypermutation. Numerous studies have shown that AID preferentially targets Ig substrates and also attacks non-Ig substrates to create DNA damage that contributes to lymphomagenesis. AID targeting to Ig loci is linked to transcription but the mechanism governing this process has been obscure. Here we discuss research that illustrates the connection between AID targeting to DNA substrates and transcription processes to reveal rules governing the specificity of AID attack. These observations are woven together to provide a integrated view of AID function and a surprising linkage with global regulation of gene expression.
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