1
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Meffre E. The establishment of early B cell tolerance in humans: lessons from primary immunodeficiency diseases. Ann N Y Acad Sci 2012; 1246:1-10. [PMID: 22236425 DOI: 10.1111/j.1749-6632.2011.06347.x] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Patients with primary immunodeficiency (PID) provide rare opportunities to study the impact of specific gene mutations on the regulation of human B cell tolerance. Alterations in B cell receptor and Toll-like receptor signaling pathways result in a defective central checkpoint and a failure to counterselect developing autoreactive B cells in the bone marrow. In contrast, CD40L- and MHC class II-deficient patients only displayed peripheral B cell tolerance defects, suggesting that decreased numbers of regulatory T cells and increased concentration of B cell activating factor (BAFF) may interfere with the peripheral removal of autoreactive B cells. The pathways regulating B cell tolerance identified in PID patients are likely to be affected in patients with rheumatoid arthritis, systemic lupus erythematosus, and type 1 diabetes who display defective central and peripheral B cell tolerance checkpoints. Indeed, risk alleles encoding variants altering BCR signaling, such as PTPN22 alleles associated with the development of these diseases, interfere with the removal of developing autoreactive B cells. Hence, insights into B cell selection from PID patients are highly relevant to the understanding of the etiology of autoimmune conditions.
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Affiliation(s)
- Eric Meffre
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut 06511, USA.
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2
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Activation-induced cytidine deaminase (AID) is required for B-cell tolerance in humans. Proc Natl Acad Sci U S A 2011; 108:11554-9. [PMID: 21700883 DOI: 10.1073/pnas.1102600108] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Impaired immune functions leading to primary immunodeficiencies often correlate with paradoxical autoimmune complications; patients with hyper-IgM syndromes who are deficient in activation-induced cytidine deaminase (AID), which is required for class-switch recombination and somatic hypermutation, are prone to develop autoimmune diseases. To investigate the impact of AID-deficiency on early B-cell tolerance checkpoints in humans, we tested by ELISA the reactivity of recombinant antibodies isolated from single B cells from AID-deficient patients. New emigrant/transitional and mature naive B cells from AID-deficient patients express an abnormal Ig repertoire and high frequencies of autoreactive antibodies, demonstrating that AID is required for the establishment of both central and peripheral B-cell tolerance. In addition, B-cell tolerance was further breached in AID-deficient patients as illustrated by the detection of anti-nuclear IgM antibodies in the serum of all patients. Thus, we identified a major and previously unsuspected role for AID in the removal of developing autoreactive B cells in humans.
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3
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Mazari L, Ouarzane M, Zouali M. Subversion of B lymphocyte tolerance by hydralazine, a potential mechanism for drug-induced lupus. Proc Natl Acad Sci U S A 2007; 104:6317-22. [PMID: 17404230 PMCID: PMC1851062 DOI: 10.1073/pnas.0610434104] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Accumulating evidence indicates that epigenetic alterations contribute to exacerbated activation or deregulation of the mechanisms that maintain tolerance to self-antigens in patients with lupus, a systemic autoimmune disease that can be triggered by medications taken to treat a variety of conditions. Here, we tested the effect of hydralazine, an antihypertensive drug that triggers lupus, on receptor editing, a chief mechanism of B lymphocyte tolerance to self-antigens. Using mice expressing transgenic human Igs, we found that hydralazine impairs up-regulation of RAG-2 gene expression and reduces secondary Ig gene rearrangements. Receptor editing was also partially abolished in a dose-dependent manner by a specific inhibitor of MEK1/2. Adoptive transfer of bone marrow B cells pretreated with hydralazine or with a MEK inhibitor to naïve syngeneic mice resulted in autoantibody production. We conclude that, by disrupting receptor editing, hydralazine subverts B lymphocyte tolerance to self and contributes to generation of pathogenic autoreactivity. We also postulate that inhibition of the Erk signaling pathway contributes to the pathogenesis of hydralazine-induced lupus and idiopathic human lupus.
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Affiliation(s)
- Lynda Mazari
- Institut National de la Santé et de la Recherche Médicale, U430, University of Paris 6, F-75674 Paris, France
| | - Meryem Ouarzane
- Institut National de la Santé et de la Recherche Médicale, U430, University of Paris 6, F-75674 Paris, France
| | - Moncef Zouali
- Institut National de la Santé et de la Recherche Médicale, U430, University of Paris 6, F-75674 Paris, France
- *To whom correspondence should be addressed at:
Institut National de la Santé et de la Recherche Médicale U606, Centre Viggo Petersen, Hôpital Lariboisière, 2, Rue Ambroise Paré, 75475 Paris Cedex 10, France. E-mail:
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4
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Espinoza CR, Feeney AJ. Chromatin accessibility and epigenetic modifications differ between frequently and infrequently rearranging VH genes. Mol Immunol 2007; 44:2675-85. [PMID: 17218014 PMCID: PMC2570232 DOI: 10.1016/j.molimm.2006.12.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 11/16/2006] [Accepted: 12/06/2006] [Indexed: 11/30/2022]
Abstract
The molecular mechanisms that control the temporal and lineage-specific accessibility, as well as the rearrangement frequency of V(H) genes for V(H)-to-DJ(H) recombination, are not fully understood. We previously found a positive correlation between the extent of histone acetylation and the differential rearrangement frequency of individual V(H) genes. Here, we demonstrated that poorly rearranging V(H) genes are more highly associated with histone H3 dimethylated at lysine 9, a marker of repressive chromatin, than frequently rearranging V(H) genes. We also observed a positive relationship between the differential binding of Pax5 to individual V(H)S107 genes and rearrangement frequency. Furthermore, we showed that accessibility of the regions flanking the Pax5 binding site and the recombination signal sequence (RSS) to restriction enzyme cleavage correspond with the differential rearrangement frequency of the V(H)S107 family members. In addition, we found that the CpG sites located in the coding regions of V(H) genes are methylated in general, while the extent of DNA methylation drops dramatically near the RSS. For the V(H)S107 family, one CpG site located 101bp upstream of the RSS showed variable methylation that correlates with rearrangement frequency, and the methylation status of a CpG site located 34bp downstream of the RSS could also favor the rearrangement of V1 over V11. These findings suggest that the extent of histone modifications, chromatin accessibility, DNA methylation, as well as the differential binding of Pax5 to V(H) coding regions, could all influence the rearrangement frequency of individual V(H) genes, although some of these mechanisms are not strictly B cell specific.
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Affiliation(s)
- Celia R Espinoza
- The Scripps Research Institute, Department of Immunology IMM-22, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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5
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Franklin A. Hypothesis: a biological role for germline transcription in the mechanism of V(D)J recombination--implications for initiation of allelic exclusion. Immunol Cell Biol 2006; 84:396-403. [PMID: 16594898 DOI: 10.1111/j.1440-1711.2006.01437.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The sequences that encode the antigen-binding sites of IgH and IgL chains - variable (V), diversity (D, H chain loci only) and joining (J) sequences - are configured as separate DNA segments at the germline level. Expression of an Ig molecule requires V(D)J assembly. Productive V(D)J recombination is monoallelic. How rearrangement is initiated differentially at maternal and paternal alleles is unclear. The products of recombination activating gene (RAG)1 and RAG2 mediate rearrangement by cleaving the DNA between an unrearranged gene segment and adjacent recombination signal sequences (RSS). It is proposed that supercoiling generated during germline transcription at Ig loci (which occurs concomitantly with rearrangement) is required at RSS for RAG1/2 recognition. Rearrangement might hence initiate sequentially at maternal and paternal alleles where deregulated germline transcription causes RAG1/2 recognition of RSS to become stochastic.
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Affiliation(s)
- Andrew Franklin
- Biocontrol Group, School of Botany and Zoology, Australian National University, Canberra, Australian Capital Territory, Australia.
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6
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Espinoza CR, Feeney AJ. The extent of histone acetylation correlates with the differential rearrangement frequency of individual VH genes in pro-B cells. THE JOURNAL OF IMMUNOLOGY 2006; 175:6668-75. [PMID: 16272322 DOI: 10.4049/jimmunol.175.10.6668] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
During B lymphocyte development, Ig heavy and L chain genes are assembled by V(D)J recombination. Individual V, D, and J genes rearrange at very different frequencies in vivo, and the natural variation in recombination signal sequence does not account for all of these differences. Because a permissive chromatin structure is necessary for the accessibility of VH genes for VH to DJH recombination, we hypothesized that gene rearrangement frequency might be influenced by the extent of histone modifications. Indeed, we found in freshly isolated pro-B cells from muMT mice a positive correlation between the level of enrichment of VHS107 genes in the acetylated histone fractions as assayed by chromatin immunoprecipitation, and their relative rearrangement frequency in vivo. In the VH7183 family, the very frequently rearranging VH81X gene showed the highest association with acetylated histones, especially in the newborn. Together, our data show that the extent of histone modifications in pro-B cells should be considered as a mechanism by which accessibility and the rearrangement level of individual VH genes is regulated.
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Affiliation(s)
- Celia R Espinoza
- Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA
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7
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Feo F, De Miglio MR, Simile MM, Muroni MR, Calvisi DF, Frau M, Pascale RM. Hepatocellular carcinoma as a complex polygenic disease. Interpretive analysis of recent developments on genetic predisposition. Biochim Biophys Acta Rev Cancer 2005; 1765:126-47. [PMID: 16216419 DOI: 10.1016/j.bbcan.2005.08.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Revised: 08/25/2005] [Accepted: 08/26/2005] [Indexed: 01/11/2023]
Abstract
The different frequency of hepatocellular carcinoma (HCC) in humans at risk suggests a polygenic predisposition. However, detection of genetic variants is difficult in genetically heterogeneous human population. Studies on mouse and rat models identified 7 hepatocarcinogenesis susceptibility (Hcs) and 2 resistance (Hcr) loci in mice, and 7 Hcs and 9 Hcr loci in rats, controlling multiplicity and size of neoplastic liver lesions. Six liver neoplastic nodule remodeling (Lnnr) loci control number and volume of re-differentiating lesions in rat. A Hcs locus, with high phenotypic effects, and various epistatic gene-gene interactions were identified in rats, suggesting a genetic model of predisposition to hepatocarcinogenesis with different subset of low-penetrance genes, at play in different subsets of population, and a major locus. This model is in keeping with human HCC epidemiology. Several putative modifier genes in rodents, deregulated in HCC, are located in chromosomal segments syntenic to sites of chromosomal aberrations in humans, suggesting possible location of predisposing loci. Resistance to HCC is associated with lower genomic instability and downregulation of cell cycle key genes in preneoplastic and neoplastic lesions. p16(INK4A) upregulation occurs in susceptible and resistant rat lesions. p16(INK4A)-induced growth restraint was circumvented by Hsp90/Cdc37 chaperons and E2f4 nuclear export by Crm1 in susceptible, but not in resistant rats and human HCCs with better prognosis. Thus, protective mechanisms seem to be modulated by HCC modifiers, and differences in their efficiency influence the susceptibility to hepatocarcinogenesis and probably the prognosis of human HCC.
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Affiliation(s)
- F Feo
- Department of Biomedical Sciences, Division of Experimental Pathology and Oncology, University of Sassari, Via P. Manzella 4, 07100 Sasssari, Italy.
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8
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Liu GB, Yan H, Jiang YF, Chen R, Pettigrew JD, Zhao KN. The properties of CpG islands in the putative promoter regions of human immunoglobulin (Ig) genes. Gene 2005; 358:127-38. [PMID: 16112518 DOI: 10.1016/j.gene.2005.06.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2005] [Revised: 05/25/2005] [Accepted: 06/09/2005] [Indexed: 12/27/2022]
Abstract
CpG island is a GC-rich motif occurred in gene promoter region, which can play important roles in gene silencing and imprinting. Here, we present a set of discriminant functions that can recognize the structural and compositional features of CpG islands in the putative promoter regions (PPRs) of human and mouse immunoglobulin (Ig) genes. We showed that the PPRs of both human and mouse Ig genes irrespective of gene chromosomal localization are apparently CpG island poor, with a low percentage of the CpG islands overlapped with the transcription start site (TSS). The human Ig genes that have CpG islands in the PPRs show a very narrow range of CpG densities. 47% of the Ig genes fall in the range of 3.5-4 CpGs/100 bp. In contrast, the non-Ig genes examined have a wide range of the density of CpG island, with 10.5% having the density of 8.1-15 CpGs/100 bp. Meantime, five patterns of the CpG distributions within the CpG islands have been classified: Pat A, B, C, D, and E. 21.6% and 10.8% of the Ig genes fall into the Pat B and Pat D groups, respectively, which were significantly higher than the non-Ig genes examined (8.2% and 3.8%). Moreover, the length of CpG islands is shorter in human Ig genes than in non-Ig genes but is much longer than in mouse orthologues. These findings provide a clear picture of non-neutral and nonrandom occurrence of the CpG islands in the PPRs of human and mouse Ig genes, which facilitate rational recommendations regarding their nomenclature.
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Affiliation(s)
- Guang B Liu
- Vision, Touch and Hearing Research Centre, Faculty of Biomedical Sciences, The University of Queensland, Brisbane, Qld 4072, Australia.
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9
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Abstract
Coregulation of lymphoid-specific gene sets is achieved by a series of epigenetic mechanisms. Association with higher-order chromosomal structures (nuclear subcompartments repressing or favouring gene expression) and locus control regions affects recombination and transcription of clonotypic antigen receptors and expression of a series of other lymphoid-specific genes. Locus control regions can regulate DNA methylation patterns in their vicinity. They may induce tissue- and site-specific DNA demethylation and affect, thereby, accessibility to recombination-activating proteins, transcription factors, and enzymes involved in histone modifications. Both DNA methylation and the Polycomb group of proteins (PcG) function as alternative systems of epigenetic memory in lymphoid cells. Complexes of PcG proteins mark their target genes by covalent histone tail modifications and influence lymphoid development and rearrangement of IgH genes. Ectopic expression of protein noncoding microRNAs may affect the generation of B-lineage cells, too, by guiding effector complexes to sites of heterochromatin assembly. Coregulation of lymphoid and viral promoters is also possible. EBNA 2, a nuclear protein encoded by episomal Epstein-Barr virus genomes, binds to the cellular protein CBF1 (C promoter binding factor 1) and operates, thereby, a regulatory network to activate latent viral promoters and cellular promoters associated with CBF1 binding sites.Key words : lymphoid cells, coregulation of gene batteries, epigenetic regulation, nuclear subcompartment switch, locus control region, DNA methylation, Polycomb group of proteins, histone modifications, microRNA, Epstein-Barr virus, EBNA 2, regulatory network.
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Affiliation(s)
- Ildikó Györy
- Microbiological Research Group, National Center for Epidemiology, Budapest, Hungary
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10
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Abstract
A functional immune system is one of the prerequisites for the survival of a species. Humans have one of the most complicated immune systems, with the ability to learn from and adapt to pathogens. At first, a primary repertoire of antibodies is generated, which, upon antigen encounter, will diversify and adapt to produce a highly specific and potent secondary response, part of which is kept in memory to fight off future infections. In this review, the mechanism as well as the specificities of the key protein in the secondary immune response, activation-induced cytidine deaminase (AID), are highlighted, as well as its role in the DNA deamination model of immunoglobulin diversification. The review also highlights aspects of AID's regulation on both the transcriptional as well as post-translational level and its potential molecular mechanism and specificity. Furthermore, it expands outside the involvement of AID in somatic hypermutation, class switching, and gene conversion to discuss the implications of DNA deamination in epigenetic modifications of DNA (as a potential demethylase), the induction of mutations during oncogenesis, and includes an evolutionary comparison to the DNA deaminase family member APOBEC3G, a key protein in human immunodeficiency virus pathogenesis.
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Affiliation(s)
- Svend Petersen-Mahrt
- DNA Editing Laboratory, Cancer Research UK, Clare Hall Laboratories, South Mimms Hert, UK.
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11
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Blanco-Betancourt CE, Moncla A, Milili M, Jiang YL, Viegas-Péquignot EM, Roquelaure B, Thuret I, Schiff C. Defective B-cell-negative selection and terminal differentiation in the ICF syndrome. Blood 2004; 103:2683-90. [PMID: 14645008 DOI: 10.1182/blood-2003-08-2632] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Immunodeficiency, centromeric region instability, and facial anomalies (ICF) syndrome is a rare autosomal recessive disease. Mutations in the DNA methyltransferase 3B (DNMT3B) gene are responsible for most ICF cases reported. We investigated the B-cell defects associated with agammaglobulinemia in this syndrome by analyzing primary B cells from 4 ICF patients. ICF peripheral blood (PB) contains only naive B cells; memory and gut plasma cells are absent. Naive ICF B cells bear potentially autoreactive long heavy chain variable regions complementarity determining region 3's (V(H)CDR3's) enriched with positively charged residues, in contrast to normal PB transitional and mature B cells, indicating that negative selection is impaired in patients. Like anergic B cells in transgenic models, newly generated and immature B cells accumulate in PB. Moreover, these cells secrete immunoglobulins and exhibit increased apoptosis following in vitro activation. However, they are able to up-regulate CD86, indicating that mechanisms other than anergy participate in silencing of ICF B cells. One patient without DNMT3B mutations shows differences in immunoglobulin E (IgE) switch induction, suggesting that immunodeficiency could vary with the genetic origin of the syndrome. In this study, we determined that negative selection breakdown and peripheral B-cell maturation blockage contribute to agammaglobulinemia in the ICF syndrome.
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12
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Goudeau B, Huetz F, Samson S, Di Santo JP, Cumano A, Beg A, Israël A, Mémet S. IkappaBalpha/IkappaBepsilon deficiency reveals that a critical NF-kappaB dosage is required for lymphocyte survival. Proc Natl Acad Sci U S A 2003; 100:15800-5. [PMID: 14665694 PMCID: PMC307648 DOI: 10.1073/pnas.2535880100] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2003] [Accepted: 10/23/2003] [Indexed: 01/24/2023] Open
Abstract
In most cells, the NF-kappaB transcription factor is sequestered in the cytoplasm by interaction with inhibitory proteins, the IkappaBs. Here, we show that combined IkappaBalpha/IkappaBepsilon deficiency in mice leads to neonatal death, elevated kappaB binding activity, overexpression of NF-kappaB target genes, and disruption of lymphocyte production. In IkappaBalpha/IkappaBepsilon-deficient fetuses, B220+IgM+ B cells and single-positive T cells die by apoptosis. In adults, IkappaBalpha-/-IkappaBepsilon-/- reconstituted chimeras exhibit a nearly complete absence of T and B cells that is not rescued by cotransfer with wild-type bone marrow. These findings demonstrate that IkappaBs tightly control NF-kappaB activity in vivo and that increased NF-kappaB activity intrinsically impairs lymphocyte survival. Because reduction or rise of NF-kappaB activity leads to similar dysfunction, they also reveal that only a narrow window of NF-kappaB activity is tolerated by lymphocytes.
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Affiliation(s)
- Bertrand Goudeau
- Unité de Biologie Moléculaire de l'Expression Génique, Unité de Recherche Associée, Centre National de la Recherche Scientifique 2582, Unité de Biologie Moléculaire du Gène, Paris Cedex 15, France
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13
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Abstract
In the mammalian immune system, V(D)J rearrangement of immunoglobulin (Ig) and T-cell receptor (TCR) genes is regulated in a lineage- and stage-specific fashion. Because each of the seven loci capable of rearrangement utilizes the same recombination machinery, it is thought that V(D)J recombination of each antigen receptor locus is regulated through the differential accessibility of each locus to the V(D)J recombination machinery. Accumulating evidence indicates that chromatin remodeling mediated by DNA methylation and demethylation plays important roles in regulating V(D)J recombination and germline transcription through the Ig and TCR loci. DNA demethylation within the antigen receptor loci appears to be regulated by cis-elements also required for coordinated V(D)J recombination and germline transcription. In this paper, we critically examine the relationship between demethylation and V(D)J recombination as well as the mechanism to regulate DNA demethylation within the antigen receptor loci.
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Affiliation(s)
- Matthew Inlay
- Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0322, USA
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14
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Düber S, Engel H, Rolink A, Kretschmer K, Weiss S. Germline transcripts of immunoglobulin light chain variable regions are structurally diverse and differentially expressed. Mol Immunol 2003; 40:509-16. [PMID: 14563370 DOI: 10.1016/s0161-5890(03)00226-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The murine pre-B cell line R2-bfl, which can be induced to differentiate in vitro, was used to study germline transcription of variable regions of the light chain loci. RNA from these cells was subjected to a 3'-RACE and germline transcripts from 17 individual Vkappa gene segments belonging to 12 Vkappa families were characterized. Germline transcripts of all three Vlambda regions were similarly analyzed. The synchronous differentiation of R2-bfl cells was then used to investigate the order of appearance of germline transcripts of the V and JC clusters of both light chain loci. This was taken as indicator for accessibility of a particular locus to rearrangement. Germline transcripts of the JCkappa cluster and the Vkappa family most proximal to JCkappa was detectable already at day 0, while transcripts of the most distal Vkappa family became apparent after initiation of differentiation at day 1. Transcripts of the JClambda cluster could be found at day 2, whereas transcripts of the Vlambda region were already present at day 1. Thus, the lambda locus becomes accessible to rearrangement later during development than kappa, confirming and extending our previous findings. The V and JC clusters open at the same stage of development although slight asynchronicities were found for the Vlambda and the distal Vkappa gene segments.
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Affiliation(s)
- Sandra Düber
- Molecular Immunology, GBF, German Research Centre for Biotechnology, Mascheroder Weg 1, D-38124 Braunschweig, Germany.
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15
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Maier H, Colbert J, Fitzsimmons D, Clark DR, Hagman J. Activation of the early B-cell-specific mb-1 (Ig-alpha) gene by Pax-5 is dependent on an unmethylated Ets binding site. Mol Cell Biol 2003; 23:1946-60. [PMID: 12612069 PMCID: PMC149480 DOI: 10.1128/mcb.23.6.1946-1960.2003] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methylation of cytosine in CpG dinucleotides promotes transcriptional repression in mammals by blocking transcription factor binding and recruiting methyl-binding proteins that initiate chromatin remodeling. Here, we use a novel cell-based system to show that retrovirally expressed Pax-5 protein activates endogenous early B-cell-specific mb-1 genes in plasmacytoma cells, but only when the promoter is hypomethylated. CpG methylation does not directly affect binding of the promoter by Pax-5. Instead, methylation of an adjacent CpG interferes with assembly of ternary complexes comprising Pax-5 and Ets proteins. In electrophoretic mobility shift assays, recruitment of Ets-1 is blocked by methylation of the Ets site (5'CCGGAG) on the antisense strand. In transfection assays, selective methylation of a single CpG within the Pax-5-dependent Ets site greatly reduces mb-1 promoter activity. Prior demethylation of the endogenous mb-1 promoter is required for its activation by Pax-5 in transduced cells. Although B-lineage cells have only unmethylated mb-1 genes and do not modulate methylation of the mb-1 promoter during development, other tissues feature high percentages of methylated alleles. Together, these studies demonstrate a novel DNA methylation-dependent mechanism for regulating transcriptional activity through the inhibition of DNA-dependent protein-protein interactions.
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MESH Headings
- Animals
- Antigens, CD/genetics
- B-Lymphocytes/metabolism
- Binding Sites
- Bone Marrow Cells/metabolism
- CD79 Antigens
- Cell Lineage
- CpG Islands
- DNA Methylation
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Gene Expression Regulation, Neoplastic
- Humans
- Macromolecular Substances
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- PAX5 Transcription Factor
- Plasma Cells/metabolism
- Plasmacytoma/pathology
- Promoter Regions, Genetic/genetics
- Proto-Oncogene Protein c-ets-1
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-ets
- Receptors, Antigen, B-Cell/genetics
- Recombinant Fusion Proteins/physiology
- Specific Pathogen-Free Organisms
- Transcription Factors/deficiency
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transcription Factors/physiology
- Transcription, Genetic/genetics
- Transfection
- Tumor Cells, Cultured
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Affiliation(s)
- Holly Maier
- Integrated Department of Immunology, National Jewish Medical and Research Center, 1400 Jackson Street, K516B, Denver, CO 80206, USA
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16
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Affiliation(s)
- D G Hesslein
- Department of Cell Biology and Section of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520-8011, USA.
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17
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Maës J, O'Neill LP, Cavelier P, Turner BM, Rougeon F, Goodhardt M. Chromatin remodeling at the Ig loci prior to V(D)J recombination. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:866-74. [PMID: 11441093 DOI: 10.4049/jimmunol.167.2.866] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Rearrangement of Ig H and L chain genes is highly regulated and takes place sequentially during B cell development. Several lines of evidence indicate that chromatin may modulate accessibility of the Ig loci for V(D)J recombination. In this study, we show that remodeling of V and J segment chromatin occurs before V(D)J recombination at the endogenous H and kappa L chain loci. In recombination-activating gene-deficient pro-B cells, there is a reorganization of nucleosomal structure over the H chain J(H) cluster and increased DNase I sensitivity of V(H) and J(H) segments. The pro-B/pre-B cell transition is marked by a decrease in the DNase I sensitivity of V(H) segments and a reciprocal increase in the nuclease sensitivity of Vkappa and Jkappa segments. In contrast, J(H) segments remain DNase I sensitive, and their nucleosomal organization is maintained in mu(+) recombination-activating gene-deficient pre-B cells. These results indicate that initiation of rearrangement is associated with changes in the chromatin structure of both V and J segments, whereas stopping recombination involves changes in only V segment chromatin. We further find an increase in histone H4 acetylation at both the H and kappa L chain loci at the pro-B cell stage. Although histone H4 acetylation appears to be an early change associated with B cell commitment, acetylation alone is not sufficient to promote subsequent modifications in Ig chromatin.
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Affiliation(s)
- J Maës
- Unité de Génétique et Biochimie du Développement, Unité de Recherche Associée Centre National de la Recherche Scientifique 1960, Département d'Immunologie, Institut Pasteur, Paris, France
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18
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Mostoslavsky R, Kirillov A, Ji YH, Goldmit M, Holzmann M, Wirth T, Cedar H, Bergman Y. Demethylation and the establishment of kappa allelic exclusion. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2001; 64:197-206. [PMID: 11232285 DOI: 10.1101/sqb.1999.64.197] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- R Mostoslavsky
- Hubert H. Humphrey Center for Experimental Medicine and Cancer Research, Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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19
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Cherry SR, Beard C, Jaenisch R, Baltimore D. V(D)J recombination is not activated by demethylation of the kappa locus. Proc Natl Acad Sci U S A 2000; 97:8467-72. [PMID: 10880575 PMCID: PMC26971 DOI: 10.1073/pnas.150218497] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2000] [Indexed: 11/18/2022] Open
Abstract
V(D)J recombination is thought to be regulated by changes in the accessibility of target sites, such as modulation of methylation. To test whether demethylation of the kappa locus can activate recombination, we generated two recombinationally active B cell lines in which the gene for maintenance of genomic DNA methylation, Dnmt1, was flanked with loxP sites. Transduction with a retrovirus expressing both the cre recombinase and green fluorescent protein allowed us to purify recombinationally active cells devoid of methylation. Loss of methylation of the kappa locus was not sufficient to activate recombination, although transcription was activated in one line. It appears that demethylation of the kappa locus is not the rate-limiting step for altering accessibility and thus regulated demethylation does not generate specificity of recombination.
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Affiliation(s)
- S R Cherry
- The Whitehead Institute, 9 Cambridge Center, Cambridge, MA 02142, USA
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20
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Bentolila LA, Olson S, Marshall A, Rougeon F, Paige CJ, Doyen N, Wu GE. Extensive Junctional Diversity in Ig Light Chain Genes from Early B Cell Progenitors of μMT Mice. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.4.2123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Nontemplated (N) nucleotide additions contribute significantly to the junctional diversity of all Ag receptor chains in adult mice except Ig light (L) chains, primarily because terminal deoxynucleotidyl transferase (TdT) expression is turned off at the time of their rearrangement in pre-B cells. However, because some Ig L chain gene rearrangements are detectable earlier during B cell ontogeny when TdT expression is thought to be maximal, we have examined the junctional processing of κ- and λ-chain genes of CD45(B220)+CD43+ pro-B cells from μMT mice. We found that both κ and λ coding junctions formed in these B cell precursors were extensively diversified with N-region additions. Together, these findings demonstrate that Ig L chain genes are equally accessible to TdT in pro-B cells as Ig heavy chain genes. Surprisingly, however, the two L chain isotypes differed in the pattern of N addition, which was more prevalent at the λ-chain locus. We observed the same diversity pattern in pre-B cells from TdT-transgenic mice. These results suggest that some aspects of TdT processing could be influenced by factors intrinsic to the sequence of Ig genes and/or the process of V(D)J recombination itself.
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Affiliation(s)
- Laurent A. Bentolila
- *Unité de Génétique et Biochimie du Développement, Unité de Recherche Associée, Centre National de la Recherche Scientifique 1960, Département d’Immunologie, Institut Pasteur, Paris, France; and
| | - Stacy Olson
- †Department of Immunology, University of Toronto, and Ontario Cancer Institute, Toronto, Canada
| | - Aaron Marshall
- †Department of Immunology, University of Toronto, and Ontario Cancer Institute, Toronto, Canada
| | - François Rougeon
- *Unité de Génétique et Biochimie du Développement, Unité de Recherche Associée, Centre National de la Recherche Scientifique 1960, Département d’Immunologie, Institut Pasteur, Paris, France; and
| | - Christopher J. Paige
- †Department of Immunology, University of Toronto, and Ontario Cancer Institute, Toronto, Canada
| | - Noëlle Doyen
- *Unité de Génétique et Biochimie du Développement, Unité de Recherche Associée, Centre National de la Recherche Scientifique 1960, Département d’Immunologie, Institut Pasteur, Paris, France; and
| | - Gillian E. Wu
- †Department of Immunology, University of Toronto, and Ontario Cancer Institute, Toronto, Canada
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21
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Fitzsimmons SP, Rotz BT, Shapiro MA. Asymmetric Contribution to Ig Repertoire Diversity by Vκ Exons: Differences in the Utilization of Vκ10 Exons. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.161.5.2290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The mouse has approximately 140 germline Vκ genes, and functional Vκ exons are expressed at roughly equivalent levels in the preimmune repertoire. We have examined the expression of individual members of the Vκ10 family. Vκ10A and Vκ10B genes have been utilized in numerous hybridomas and myelomas, while Vκ10C has not. In this study, we have cloned the Vκ10C gene and shown that it is structurally functional, has the expected promoter elements and recombination signal sequences, and that it is capable of recombination. Vκ10C mRNA, however, is present at levels at least 1000-fold lower than Vκ10A and Vκ10B in adult spleens. While there are no sequence differences in the octamer or TATA box between Vκ10C and Vκ10A, there are three nucleotide changes in the promoter region. These promoters equally drive the expression of a reporter gene in B cells or plasma cells, but the Vκ10A promoter is able to drive expression in pre-B cell lines significantly better than the Vκ10C promoter (p < 0.05). Vκ10C rearrangements can be detected in bone marrow and splenic DNA. Therefore, the lack of Vκ10C expression may reflect the inability of Vκ10C-rearranged cells to undergo positive or negative selection. Our results suggest that the available Ab repertoire is shaped not only by the number of structurally functional genes, but also by the ability of assembled genes to be expressed at critical points during B cell maturation.
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Affiliation(s)
- Sean P. Fitzsimmons
- Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, MD 20892
| | - Benjamin T. Rotz
- Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, MD 20892
| | - Marjorie A. Shapiro
- Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, MD 20892
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22
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Hempel WM, Leduc I, Mathieu N, Tripathi RK, Ferrier P. Accessibility control of V(D)J recombination: lessons from gene targeting. Adv Immunol 1998; 69:309-52. [PMID: 9646847 DOI: 10.1016/s0065-2776(08)60610-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- W M Hempel
- Centre d'Immunologie INSERM-CNRS de Marseille-Luminy, France
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23
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Hale MA, Garrard WT. A targeted kappa immunoglobulin gene containing a deletion of the nuclear matrix association region exhibits spontaneous hyper-recombination in pre-B cells. Mol Immunol 1998; 35:609-20. [PMID: 9823759 DOI: 10.1016/s0161-5890(98)00060-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previous studies employing ectopic integration of reporter genes have shown that the nuclear matrix association region (MAR) adjacent to the intronic enhancer of the mouse kappa immunoglobulin (Ig) gene is required for high level transcription of rearranged genes, demethylation, reduction of position effects and maximal somatic hypermutation in B cells. To test for the function of this MAR in its natural chromosomal environment, we pursued the 'HIT-and-RUN' procedure with the mouse pre-B cell line 103 to create a targeted MAR deletion. We observed a 'HIT' targeting frequency of 1/684 but 0/2100 'RUN' clones maintained the MAR-deleted germline locus because of an unexpected hyper-recombination for Vkappa-Jkappa joining, specifically to the MAR-deleted allele, and primarily at Jkappa4 and Jkappa5. This hyper-recombination was correlated with undermethylation of the Jkappa-Ckappa region but not with the level of local transcription. These results are consistent with the possibility that the MAR and/or DNA methylation negatively regulate(s) Vkappa-Jkappa joining during the pre-B cell stage of development.
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Affiliation(s)
- M A Hale
- Department of Molecular Biology and Oncology, University of Texas Southwestern Medical Center, Dallas 75235-9140, USA
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24
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Mostoslavsky R, Singh N, Kirillov A, Pelanda R, Cedar H, Chess A, Bergman Y. Kappa chain monoallelic demethylation and the establishment of allelic exclusion. Genes Dev 1998; 12:1801-11. [PMID: 9637682 PMCID: PMC316908 DOI: 10.1101/gad.12.12.1801] [Citation(s) in RCA: 170] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Allelic exclusion in kappa light-chain synthesis is thought to result from a feedback mechanism by which the expression of a functional kappa light chain on the surface of the B cell leads to an intracellular signal that down-regulates the V(D)J recombinase, thus precluding rearrangement of the other allele. Whereas such a feedback mechanism clearly plays a role in the maintenance of allelic exclusion, here we provide evidence suggesting that the initial establishment of allelic exclusion involves differential availability of the two kappa alleles for rearrangement. Analysis of kappa+ B-cell populations and of individual kappa+ B cells that have rearranged only one allele demonstrates that in these cells, critical sites on the rearranged allele are unmethylated, whereas the nonrearranged allele remains methylated. This pattern is apparently generated by demethylation that is initiated at the small pre-B cell stage, on a single allele, in a process that occurs prior to rearrangement and requires the presence in cis of both the intronic and 3' kappa enhancers. Taken together with data demonstrating that undermethylation is required for rearrangement, these results indicate that demethylation may actually underly the process of allelic exclusion by directing the initial choice of a single kappa allele for rearrangement.
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Affiliation(s)
- R Mostoslavsky
- The Hubert H. Humphrey Center for Experimental Medicine and Cancer Research, The Hebrew University Hadassah Medical School, Jerusalem 91120, Israel
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25
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Wiese M, Pajeva IK. Molecular modeling study of the multidrug resistance modifiers cis- and trans-flupentixol. DIE PHARMAZIE 1997; 52:679-85. [PMID: 9347570 DOI: 10.1002/eji.1830270706] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Recent drug-membrane interaction and quantitative structure-activity relationship studies of thioxanthenes and related compounds acting as multidrug resistance (MDR) modifiers pointed to the importance of the stereoisomery for their MDR reversing activity. Therefore a molecular modeling study of trans-(T) and cis-flupentixol (C) was performed in order to elucidate the observed discrepancy between equal binding potency to P-glycoprotein and different MDR reversing activity of the two stereoisomers. The results show that the 2 to 3-fold difference in MDR reversing activity of T compared to C might be related to a different orientation of the molecules in the membrane lipid environment. From the conformations generated by the SYBYL systematic search procedure those comprising local energy minima were selected and further optimized with semiempirical quantum chemistry methods. From the optimized conformations those that corresponded to 1H NMR results on drug conformations in lipid environment were selected for further molecular modeling studies. The electrostatic and lipophilic fields of T and C were compared in order to identify molecular properties related to the activity difference. The results show that the electrostatic fields of the drugs when similar in shape are dissimilar and that the lipophilic and hydrophilic regions are clearer separated in T in comparison with C. This imposes a better fitting of T compared to C to membrane lipid environment in accordance with the observed higher interaction strength of T with phospholipids.
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Affiliation(s)
- M Wiese
- Institut für Pharmazeutische Chemie, Martin-Luther-Universität Halle-Wittenberg, Germany
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26
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Mostoslavsky R, Bergman Y. DNA methylation: regulation of gene expression and role in the immune system. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1333:F29-50. [PMID: 9294017 DOI: 10.1016/s0304-419x(97)00010-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- R Mostoslavsky
- The Hubert H. Humphrey Center for Experimental Medicine and Cancer Research, The Hebrew University Hadassah Medical School, Jerusalem, Israel
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27
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O'Brien DP, Oltz EM, Van Ness BG. Coordinate transcription and V(D)J recombination of the kappa immunoglobulin light-chain locus: NF-kappaB-dependent and -independent pathways of activation. Mol Cell Biol 1997; 17:3477-87. [PMID: 9199283 PMCID: PMC232201 DOI: 10.1128/mcb.17.7.3477] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
To further elucidate the potential role of mitogens and cytokines in regulation of the kappa immunoglobulin light-chain locus, we have characterized the activation of transcription factor binding, kappa germ line transcription, DNase I hypersensitivity, and Vkappa-to-Jkappa recombination upon induction of model pre-B-cell lines. We find that both lipopolysaccharide (LPS) and gamma interferon (IFN-gamma) are capable of activating germ line transcription, DNase I hypersensitivity, and recombination of the kappa locus. We also find that transforming growth factor beta is capable of completely inhibiting LPS activation of transcription and recombination but has no apparent effect on activation of transcription factor binding, including activation of NF-kappaB. To address the functional role of NF-kappaB in LPS and IFN-gamma induction of these events, we blocked the nuclear translocation of NF-kappaB by overexpression of a dominant negative mutant of IkappaB-alpha (IkappaB deltaN). Overexpression of the IkappaB deltaN protein results in an inhibition of LPS but not IFN-gamma activation of germ line transcription, DNase I hypersensitivity, and Vkappa-to-Jkappa recombination. Our results demonstrate that activation of NF-kappaB is necessary but not sufficient for LPS activation of transcription and recombination at kappa. These results also suggest that NF-kappaB is not required for IFN-gamma activation of transcription or recombination. These results are important in establishing that there are multiple independent pathways of activation of both transcription and recombination.
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Affiliation(s)
- D P O'Brien
- Department of Biochemistry and Institute of Human Genetics, University of Minnesota, Minneapolis 55455, USA
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28
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Villey I, Quartier P, Selz F, de Villartay JP. Germ-line transcription and methylation status of the TCR-J alpha locus in its accessible configuration. Eur J Immunol 1997; 27:1619-25. [PMID: 9247569 DOI: 10.1002/eji.1830270705] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have generated two in vivo mouse models to study the regulation of DNA accessibility to the V(D)J recombinase machinery in the T cell receptor (TCR)-J alpha locus. In recombination activating gene (RAG)-deficient mice, both injection of a TCR-beta chain transgene (RTB mice) or anti-CD3-epsilon treatment in vivo (RT3 mice) lead to the same phenotype with homogeneous thymocyte populations blocked at the CD4+ CD8+ double positive (DP) stage. At this developmental stage, the TCR-alpha rearrangements are about to start, and the TCR-J alpha locus is frozen in an accessible but yet unrearranged configuration in these mice. We show high level of TCR-alpha germ-line transcription in thymocytes from RTB and RT3 mice. Transcripts are skewed towards the 5' end of the TCR-J alpha locus, and the T early alpha (TEA) sterile transcript is predominant and therefore provides a useful marker for the TCR-J alpha locus opening. Analysis of the DNA methylation status reveals a global surmethylation of the TCR-J alpha locus in the thymus in comparison with non-lymphoid cells in these mice. We propose that hypermethylation of the locus could precede a progressive demethylation, providing a specific protective and regulatory role in the rearrangement events.
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MESH Headings
- Animals
- Antibodies, Monoclonal/pharmacology
- CD3 Complex/immunology
- DNA Methylation
- Gene Rearrangement, T-Lymphocyte/immunology
- Germ Cells/immunology
- Germ Cells/metabolism
- Mice
- Mice, Knockout
- Mice, Transgenic
- Models, Biological
- Promoter Regions, Genetic/immunology
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Sequence Deletion
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- Thymus Gland/immunology
- Thymus Gland/metabolism
- Transcription, Genetic/immunology
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Affiliation(s)
- I Villey
- INSERM U429, Hôpital Necker-enfants malades, Paris, France
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29
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Kirillov A, Kistler B, Mostoslavsky R, Cedar H, Wirth T, Bergman Y. A role for nuclear NF-kappaB in B-cell-specific demethylation of the Igkappa locus. Nat Genet 1996; 13:435-41. [PMID: 8696338 DOI: 10.1038/ng0895-435] [Citation(s) in RCA: 187] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The immunoglobulin kappa gene is specifically demethylated during B-cell maturation in a process which utilizes discrete cis-acting modules such as the intronic kappa enhancer element and the matrix attachment region (MAR). While any MAR sequence is sufficient for this reaction, mutation analysis indicates that tissue specificity is mediated by kappaB binding sequences within the kappa intronic enhancer. The plasmacytoma cell line S107 lacks kappaB binding activity and fails to demethylate the kappa locus. However, B-cell specific demethylation is restored by the introduction of an active kappaB binding protein gene relB. This represents the first demonstration of a trans-acting factor involved in cell-type-specific demethylation, and suggests that the same protein-DNA recognition system used for transcription may also contribute to the earlier developmental events that bring about activation of the kappa locus.
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Affiliation(s)
- A Kirillov
- The Hubert H. Humphrey Center for Experimental Medicine and Cancer Research, Hebrew University, Hadassah Medical School, Jerusalem, Israel
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30
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Abstract
Evidence for recombination suppression has been identified in linkage studies of several unstable DNA diseases. Also sex-specific changes in recombination frequency have been detected at the loci of Huntington's disease and myotonic dystrophy. It can be hypothesized that meiotic recombination is regulated by genome-wide genomic imprinting and that changes in meiotic recombination imply the presence of the genomic imprinting defect. If aberrant recombination at the locus of trinucleotide repeat expansion is verified, new theoretical and experimental opportunities will arise in studies on the role of genomic imprinting in the unstable DNA disease.
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Affiliation(s)
- A Petronis
- Neurogenetics Section, Clarke Institute of Psychiatry, Toronto, Ontario, Canada.
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31
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Sleckman BP, Gorman JR, Alt FW. Accessibility control of antigen-receptor variable-region gene assembly: role of cis-acting elements. Annu Rev Immunol 1996; 14:459-81. [PMID: 8717521 DOI: 10.1146/annurev.immunol.14.1.459] [Citation(s) in RCA: 238] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Antigen receptor variable region genes are assembled from germline variable (V), diversity (D), and joining (J) gene segments. This process requires expression of V(D)J recombinase activity, and "accessibility" of variable gene segments to this recombinase. The exact mechanism by which variable gene segments become accessible during development is not known. However, several studies have shown that cis-acting elements that regulate transcription may also function to regulate accessibility. Here we review the evidence that transcriptional promoters, enhancers, and silencers are involved in regulation of accessibility. The manner in which these elements may combine to regulate accessibility is addressed. In addition, current and potential strategies for identifying and analyzing cis-acting elements that mediate locus accessibility are discussed.
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Affiliation(s)
- B P Sleckman
- Howard Hughes Medical Institute, Children's Hospital, Boston, Massachusetts 02115, USA
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32
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Stiernholm BJ, Berinstein NL. Mutations in immunoglobulin V gene promoters may cause reduced germline transcription and diminished recombination frequencies. Ann N Y Acad Sci 1995; 764:116-20. [PMID: 7486509 DOI: 10.1111/j.1749-6632.1995.tb55813.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- B J Stiernholm
- Department of Immunology, University of Toronto, Ontario, Canada
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33
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Fernex C, Capone M, Ferrier P. The V(D)J recombinational and transcriptional activities of the immunoglobulin heavy-chain intronic enhancer can be mediated through distinct protein-binding sites in a transgenic substrate. Mol Cell Biol 1995; 15:3217-26. [PMID: 7760817 PMCID: PMC230554 DOI: 10.1128/mcb.15.6.3217] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Immunoglobulin and T-cell receptor gene transcriptional enhancers encompass sequences which stimulate V(D)J recombination of associated variable gene segments. To address the question of whether enhancer-mediated transcriptional activation and recombinational activation depend on the same cis-regulatory sequences, we have produced transgenic mice by using recombination substrates containing various mutations in the immunoglobulin heavy-chain intronic enhancer (E mu). Analysis of substrate rearrangements indicated that specific compound elements including E-box transcriptional motifs are crucial for the recombinational activity of E mu in the developing B and T lymphocytes. In most cases, a faithful correlation between the levels of substrate germ line transcription and recombination was observed. However, some of the E mu mutants which were able to activate transcription of the unrearranged substrate were inefficient in stimulating transgene recombination, implying that the latter function depends on molecular events other than the mere activation of transcription and that both activities can be mediated through distinct regulatory sequences. Together, these results support a model in which lymphoid gene enhancers, in addition to providing docking sites for factors that dictate transcriptional accessibility, must have some specific function(s) for activating V(D)J recombination.
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Affiliation(s)
- C Fernex
- Centre d'Immunologie INSERM-CNRS de Marseille-Luminy, France
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34
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Rossignol JL, Faugeron G. MIP: an epigenetic gene silencing process in Ascobolus immersus. Curr Top Microbiol Immunol 1995; 197:179-91. [PMID: 7493492 DOI: 10.1007/978-3-642-79145-1_12] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- J L Rossignol
- Institut de Génétique et Microbiologie, Université Paris-Sud, Orsay, France
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35
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Okada A, Mendelsohn M, Alt F. Differential activation of transcription versus recombination of transgenic T cell receptor beta variable region gene segments in B and T lineage cells. J Exp Med 1994; 180:261-72. [PMID: 8006587 PMCID: PMC2191553 DOI: 10.1084/jem.180.1.261] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
We have tested the ability of the T cell receptor beta (TCR-beta) transcriptional enhancer (E beta) to confer transcriptional activation and tissue-specific V(D)J recombination of TCR-beta V, D, and J segments in a transgenic minilocus recombination substrate. We find that the minimal E beta element, as previously shown for a DNA segment that contained the E mu element, promotes a high level of substrate D to J beta rearrangement in both B and T cells, but only promotes V beta to DJ beta rearrangement in T cells. Thus, both the E mu and E beta elements similarly direct V(D)J recombination of this substrate in vivo, supporting a general role for transcriptional enhancers in the normal regulation of this rearrangement process. Surprisingly, however, we found that both the V beta and DJ beta portion of the constructs were transcribed in an enhancer-dependent fashion (conferred by either E mu or E beta) in both B and T lineage cells, including normal precursor B cells propagated in culture. These findings indicate that, at least in some contexts, transcriptional activation, per se, is not sufficient to confer V(D)J recombinational accessibility to a substrate V gene segment.
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MESH Headings
- Animals
- Base Sequence
- Cells, Cultured
- Enhancer Elements, Genetic
- Gene Rearrangement, beta-Chain T-Cell Antigen Receptor
- Lymphocytes/immunology
- Mice
- Mice, Inbred CBA
- Mice, Transgenic
- Molecular Sequence Data
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Recombination, Genetic
- Transcription, Genetic
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Affiliation(s)
- A Okada
- Howard Hughes Medical Institute, Children's Hospital, Boston, Massachusetts 02115
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36
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Lewis SM. The mechanism of V(D)J joining: lessons from molecular, immunological, and comparative analyses. Adv Immunol 1994; 56:27-150. [PMID: 8073949 DOI: 10.1016/s0065-2776(08)60450-2] [Citation(s) in RCA: 482] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- S M Lewis
- Division of Biology, California Institute of Technology, Pasadena 91125
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