1
|
Dong Y, Wu C, Zhao X, Zhang P, Zhang H, Zheng M, Li S, Jiao J, Yu X, Lv Z, Ji Y. Epigenetic modifications of the V H region after DJ H recombination in Pro-B cells. Immunology 2017; 152:218-231. [PMID: 28502113 DOI: 10.1111/imm.12758] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 04/27/2017] [Accepted: 05/08/2017] [Indexed: 12/19/2022] Open
Abstract
The variable region of murine immunoglobulin heavy chain (Igh) is assembled by sequential DH -JH and VH -DJH recombination. The accessibility of the Igh locus determines the order of rearrangement. Because of the large number of VH genes and the lack of a suitable model, the epigenetic modifications of VH genes after DJH recombination have not previously been characterized. Here, we employed two v-Abl pro-B cell lines, in which the Igh locus is in germline and DJH -recombined configurations, respectively. The DJH junction displays the characteristics of a recombination centre, such as high levels of activation-associated histone modifications and recombination-activating gene protein (RAG) binding in DJH -rearranged pro-B cells, which extend the recombination centre model proposed for the germline Igh locus. The different domains of the VH region have distinct epigenetic characteristics after DJH recombination. Distal VH genes have higher levels of active histone modifications, germline transcription and Pax5 binding, and good quality recombination signal sequences. Proximal VH genes are relatively close to the DJH recombination centre, which partially compensates for the low levels of the above active epigenetic modifications. DJH recombination centre might serve as a cis-acting element to regulate the accessibility of the VH region. Furthermore, we demonstrate that RAG weakly binds to functional VH genes, which is the first detailed assessment of RAG dynamic binding to VH genes. We provide a way for VH -DJH recombination in which the VH gene is brought into close proximity with the DJH recombination centre for RAG binding by a Pax5-dependent chromosomal compaction event, and held in this position for subsequent cleavage and VH -DJH joining.
Collapse
Affiliation(s)
- Yanying Dong
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Caijun Wu
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Xiaohui Zhao
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Ping Zhang
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Hua Zhang
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Mingzhe Zheng
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Shichang Li
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Junna Jiao
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Xiaozhuo Yu
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Zhuangwei Lv
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Yanhong Ji
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| |
Collapse
|
2
|
Abstract
Single-molecule FRET (smFRET) and single-molecule colocalization (smCL) assays have allowed us to observe the recombination-activating gene (RAG) complex reaction mechanism in real time. Our smFRET data have revealed distinct bending modes at recombination signal sequence (RSS)-conserved regions before nicking and synapsis. We show that high mobility group box 1 (HMGB1) acts as a cofactor in stabilizing conformational changes at the 12RSS heptamer and increasing RAG1/2 binding affinity for 23RSS. Using smCL analysis, we have quantitatively measured RAG1/2 dwell time on 12RSS, 23RSS, and non-RSS DNA, confirming a strict RSS molecular specificity that was enhanced in the presence of a partner RSS in solution. Our studies also provide single-molecule determination of rate constants that were previously only possible by indirect methods, allowing us to conclude that RAG binding, bending, and synapsis precede catalysis. Our real-time analysis offers insight into the requirements for RSS-RSS pairing, architecture of the synaptic complex, and dynamics of the paired RSS substrates. We show that the synaptic complex is extremely stable and that heptamer regions of the 12RSS and 23RSS substrates in the synaptic complex are closely associated in a stable conformational state, whereas nonamer regions are perpendicular. Our data provide an enhanced and comprehensive mechanistic description of the structural dynamics and associated enzyme kinetics of variable, diversity, and joining [V(D)J] recombination.
Collapse
|
3
|
Maman Y, Teng G, Seth R, Kleinstein SH, Schatz DG. RAG1 targeting in the genome is dominated by chromatin interactions mediated by the non-core regions of RAG1 and RAG2. Nucleic Acids Res 2016; 44:9624-9637. [PMID: 27436288 PMCID: PMC5175335 DOI: 10.1093/nar/gkw633] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 06/16/2016] [Accepted: 07/02/2016] [Indexed: 02/01/2023] Open
Abstract
The RAG1/RAG2 endonuclease initiates V(D)J recombination at antigen receptor loci but also binds to thousands of places outside of these loci. RAG2 localizes directly to lysine 4 trimethylated histone 3 (H3K4me3) through a plant homeodomain (PHD) finger. The relative contribution of RAG2-dependent and RAG1-intrinsic mechanisms in determining RAG1 binding patterns is not known. Through analysis of deep RAG1 ChIP-seq data, we provide a quantitative description of the forces underlying genome-wide targeting of RAG1. Surprisingly, sequence-specific DNA binding contributes minimally to RAG1 targeting outside of antigen receptor loci. Instead, RAG1 binding is driven by two distinct modes of interaction with chromatin: the first is driven by H3K4me3, promoter-focused and dependent on the RAG2 PHD, and the second is defined by H3K27Ac, enhancer-focused and dependent on ‘non-core’ portions of RAG1. Based on this and additional chromatin and genomic features, we formulated a predictive model of RAG1 targeting to the genome. RAG1 binding sites predicted by our model correlate well with observed patterns of RAG1-mediated breaks in human pro-B acute lymphoblastic leukemia. Overall, this study provides an integrative model for RAG1 genome-wide binding and off-target activity and reveals a novel role for the RAG1 non-core region in RAG1 targeting.
Collapse
Affiliation(s)
- Yaakov Maman
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011, USA
| | - Grace Teng
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011, USA
| | - Rashu Seth
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011, USA
| | - Steven H Kleinstein
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011, USA.,Interdepartmental Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT 06511, USA.,Department of Pathology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - David G Schatz
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011, USA .,Howard Hughes Medical Institute, 295 Congress Avenue, New Haven, CT 06511, USA
| |
Collapse
|
4
|
Abstract
Analysis of chromosomal translocation sequence locations in human lymphomas has provided valuable clues about the mechanism of the translocations and when they occur. Biochemical analyses on the mechanisms of DNA breakage and rejoining permit formulation of detailed models of the human chromosomal translocation process in lymphoid neoplasms. Most human lymphomas are derived from B cells in which a DNA break at an oncogene is initiated by activation-induced deaminase (AID). The partner locus in many cases is located at one of the antigen receptor loci, and this break is generated by the recombination activating gene (RAG) complex or by AID. After breakage, the joining process typically occurs by non-homologous DNA end-joining (NHEJ). Some of the insights into this mechanism also apply to translocations that occur in non-lymphoid neoplasms.
Collapse
Affiliation(s)
- Michael R Lieber
- USC Norris Comprehensive Cancer Center, Room 5428, University of Southern California Keck School of Medicine, 1441 Eastlake Avenue, MC9176, Los Angeles, California 90089-9176, USA
| |
Collapse
|
5
|
Recruitment of RAG1 and RAG2 to Chromatinized DNA during V(D)J Recombination. Mol Cell Biol 2015; 35:3701-13. [PMID: 26303526 DOI: 10.1128/mcb.00219-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/09/2015] [Indexed: 11/20/2022] Open
Abstract
V(D)J recombination is initiated by the binding of the RAG1 and RAG2 proteins to recombination signal sequences (RSSs) that consist of conserved heptamer and nonamer sequences separated by a spacer of either 12 or 23 bp. Here, we used RAG-inducible pro-B v-Abl cell lines in conjunction with chromatin immunoprecipitation to better understand the protein and RSS requirements for RAG recruitment to chromatin. Using a catalytic mutant form of RAG1 to prevent recombination, we did not observe cooperation between RAG1 and RAG2 in their recruitment to endogenous Jκ gene segments over a 48-h time course. Using retroviral recombination substrates, we found that RAG1 was recruited inefficiently to substrates lacking an RSS or containing a single RSS, better to substrates with two 12-bp RSSs (12RSSs) or two 23-bp RSSs (23RSSs), and more efficiently to a substrate with a 12/23RSS pair. RSS mutagenesis demonstrated a major role for the nonamer element in RAG1 binding, and correspondingly, a cryptic RSS consisting of a repeat of CA dinucleotides, which poorly re-creates the nonamer, was ineffective in recruiting RAG1. Our findings suggest that 12RSS-23RSS cooperation (the "12/23 rule") is important not only for regulating RAG-mediated DNA cleavage but also for the efficiency of RAG recruitment to chromatin.
Collapse
|
6
|
Teng G, Maman Y, Resch W, Kim M, Yamane A, Qian J, Kieffer-Kwon KR, Mandal M, Ji Y, Meffre E, Clark MR, Cowell LG, Casellas R, Schatz DG. RAG Represents a Widespread Threat to the Lymphocyte Genome. Cell 2015; 162:751-65. [PMID: 26234156 PMCID: PMC4537821 DOI: 10.1016/j.cell.2015.07.009] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 04/14/2015] [Accepted: 06/02/2015] [Indexed: 11/26/2022]
Abstract
The RAG1 endonuclease, together with its cofactor RAG2, is essential for V(D)J recombination but is a potent threat to genome stability. The sources of RAG1 mis-targeting and the mechanisms that have evolved to suppress it are poorly understood. Here, we report that RAG1 associates with chromatin at thousands of active promoters and enhancers in the genome of developing lymphocytes. The mouse and human genomes appear to have responded by reducing the abundance of "cryptic" recombination signals near RAG1 binding sites. This depletion operates specifically on the RSS heptamer, whereas nonamers are enriched at RAG1 binding sites. Reversing this RAG-driven depletion of cleavage sites by insertion of strong recombination signals creates an ectopic hub of RAG-mediated V(D)J recombination and chromosomal translocations. Our findings delineate rules governing RAG binding in the genome, identify areas at risk of RAG-mediated damage, and highlight the evolutionary struggle to accommodate programmed DNA damage in developing lymphocytes.
Collapse
Affiliation(s)
- Grace Teng
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011, USA
| | - Yaakov Maman
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011, USA
| | - Wolfgang Resch
- Genomics and Immunity, NIAMS, Center of Cancer Research, NCI, National Institutes of Health, Bethesda, MD 20892, USA
| | - Min Kim
- Division of Biomedical Informatics, Department of Clinical Sciences, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Box 9066, Dallas, TX 75390-9066, USA
| | - Arito Yamane
- Genomics and Immunity, NIAMS, Center of Cancer Research, NCI, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jason Qian
- Genomics and Immunity, NIAMS, Center of Cancer Research, NCI, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kyong-Rim Kieffer-Kwon
- Genomics and Immunity, NIAMS, Center of Cancer Research, NCI, National Institutes of Health, Bethesda, MD 20892, USA
| | - Malay Mandal
- Department of Medicine, Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL 60637, USA
| | - Yanhong Ji
- Department of Immunology and Microbiology, College of Medicine, Xi'an Jiao Tong University, 76 Yan Ta West Road, Box 37, Xian, Shaanxi 710061, PRC
| | - Eric Meffre
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011, USA
| | - Marcus R Clark
- Department of Medicine, Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL 60637, USA
| | - Lindsay G Cowell
- Division of Biomedical Informatics, Department of Clinical Sciences, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Box 9066, Dallas, TX 75390-9066, USA
| | - Rafael Casellas
- Genomics and Immunity, NIAMS, Center of Cancer Research, NCI, National Institutes of Health, Bethesda, MD 20892, USA.
| | - David G Schatz
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011, USA; Howard Hughes Medical Institute, 295 Congress Avenue, New Haven, CT 06511, USA.
| |
Collapse
|
7
|
Abstract
The recombination-activating gene products, RAG1 and RAG2, initiate V(D)J recombination during lymphocyte development by cleaving DNA adjacent to conserved recombination signal sequences (RSSs). The reaction involves DNA binding, synapsis, and cleavage at two RSSs located on the same DNA molecule and results in the assembly of antigen receptor genes. We have developed single-molecule assays to examine RSS binding by RAG1/2 and their cofactor high-mobility group-box protein 1 (HMGB1) as they proceed through the steps of this reaction. These assays allowed us to observe in real time the individual molecular events of RAG-mediated cleavage. As a result, we are able to measure the binding statistics (dwell times) and binding energies of the initial RAG binding events and characterize synapse formation at the single-molecule level, yielding insights into the distribution of dwell times in the paired complex and the propensity for cleavage on forming the synapse. Interestingly, we find that the synaptic complex has a mean lifetime of roughly 400 s and that its formation is readily reversible, with only ∼40% of observed synapses resulting in cleavage at consensus RSS binding sites.
Collapse
|
8
|
Shimazaki N, Lieber MR. Histone methylation and V(D)J recombination. Int J Hematol 2014; 100:230-7. [PMID: 25060705 DOI: 10.1007/s12185-014-1637-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 07/08/2014] [Accepted: 07/08/2014] [Indexed: 01/27/2023]
Abstract
V(D)J recombination is the process by which the diversity of antigen receptor genes is generated and is also indispensable for lymphocyte development. This recombination event occurs in a cell lineage- and stage-specific manner, and is carefully controlled by chromatin structure and ordered histone modifications. The recombinationally active V(D)J loci are associated with hypermethylation at lysine4 of histone H3 and hyperacetylation of histones H3/H4. The recombination activating gene 1 (RAG1) and RAG2 complex initiates recombination by introducing double-strand DNA breaks at recombination signal sequences (RSS) adjacent to each coding sequence. To be recognized by the RAG complex, RSS sites must be within an open chromatin context. In addition, the RAG complex specifically recognizes hypermethylated H3K4 through its plant homeodomain (PHD) finger in the RAG2 C terminus, which stimulates RAG catalytic activity via that interaction. In this review, we describe how histone methylation controls V(D)J recombination and discuss its potential role in lymphoid malignancy by mistargeting the RAG complex.
Collapse
Affiliation(s)
- Noriko Shimazaki
- Section of Molecular and Computational Biology, Departments of Pathology, Biochemistry and Molecular Biology, Molecular Microbiology and Immunology, USC Norris Comprehensive Cancer Ctr., Rm. 5428, 1441 Eastlake Ave., MC 9176, Los Angeles, CA, 90089-9176, USA,
| | | |
Collapse
|