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Tirosh I, Yamazaki Y, Frugoni F, Ververs FA, Allenspach EJ, Zhang Y, Burns S, Al-Herz W, Noroski L, Walter JE, Gennery AR, van der Burg M, Notarangelo LD, Lee YN. Recombination activity of human recombination-activating gene 2 (RAG2) mutations and correlation with clinical phenotype. J Allergy Clin Immunol 2018; 143:726-735. [PMID: 29772310 DOI: 10.1016/j.jaci.2018.04.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 04/22/2018] [Accepted: 04/27/2018] [Indexed: 12/22/2022]
Abstract
BACKGROUND Mutations in recombination-activating gene (RAG) 1 and RAG2 are associated with a broad range of clinical and immunologic phenotypes in human subjects. OBJECTIVE Using a flow cytometry-based assay, we aimed to measure the recombinase activity of naturally occurring RAG2 mutant proteins and to correlate our results with the severity of the clinical and immunologic phenotype. METHODS Abelson virus-transformed Rag2-/- pro-B cells engineered to contain an inverted green fluorescent protein (GFP) cassette flanked by recombination signal sequences were transduced with retroviruses encoding either wild-type or 41 naturally occurring RAG2 variants. Bicistronic vectors were used to introduce compound heterozygous RAG2 variants. The percentage of GFP-expressing cells was evaluated by using flow cytometry, and high-throughput sequencing was used to analyze rearrangements at the endogenous immunoglobulin heavy chain (Igh) locus. RESULTS The RAG2 variants showed a wide range of recombination activity. Mutations associated with severe combined immunodeficiency and Omenn syndrome had significantly lower activity than those detected in patients with less severe clinical presentations. Four variants (P253R, F386L, N474S, and M502V) previously thought to be pathogenic were found to have wild-type levels of activity. Use of bicistronic vectors permitted us to assess more carefully the effect of compound heterozygous mutations, with good correlation between GFP expression and the number and diversity of Igh rearrangements. CONCLUSIONS Our data support genotype-phenotype correlation in the setting of RAG2 deficiency. The assay described can be used to define the possible disease-causing role of novel RAG2 variants and might help predict the severity of the clinical phenotype.
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Affiliation(s)
- Irit Tirosh
- Division of Immunology, Boston Children's Hospital, Harvard Medical School, Boston, Mass
| | - Yasuhiro Yamazaki
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Md
| | - Francesco Frugoni
- Division of Immunology, Boston Children's Hospital, Harvard Medical School, Boston, Mass
| | - Francesca A Ververs
- Division of Immunology, Boston Children's Hospital, Harvard Medical School, Boston, Mass
| | - Eric J Allenspach
- Department of Pediatrics, University of Washington School of Medicine, Seattle, Wash; Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, Wash
| | - Yu Zhang
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Md
| | - Siobhan Burns
- Institute for Immunity and Transplantation, University College London, London, United Kingdom; Department of Immunology, Royal Free London NHS Foundation Trust, London, United Kingdom
| | - Waleed Al-Herz
- Department of Pediatrics, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait
| | - Lenora Noroski
- Division of Allergy and Immunology, Baylor College of Medicine, Texas Children's Hospital, Houston, Tex
| | - Jolan E Walter
- Division of Pediatric Allergy/Immunology, University of South Florida and Johns Hopkins All Children's Hospital, St Petersburg, Fla
| | - Andrew R Gennery
- Department of Pediatric Immunology, Newcastle Upon Tyne Hospital, NHS Foundation Trust, United Kingdom and Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Mirjam van der Burg
- Department of Immunology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Luigi D Notarangelo
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Md.
| | - Yu Nee Lee
- Pediatric Department A and the Immunology Service, "Edmond and Lily Safra" Children's Hospital, Jeffrey Modell Foundation Center, Sheba Medical Center, Tel Hashomer, Ramat-Gan and Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
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Xu K, Liu H, Shi Z, Song G, Zhu X, Jiang Y, Zhou Z, Liu X. Disruption of the RAG2 zinc finger motif impairs protein stability and causes immunodeficiency. Eur J Immunol 2015; 46:1011-9. [PMID: 26692406 DOI: 10.1002/eji.201545896] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Revised: 11/18/2015] [Accepted: 12/15/2015] [Indexed: 12/28/2022]
Abstract
Although the RAG2 core domain is the minimal region required for V(D)J recombination, the noncore region also plays important roles in the regulation of recombination, and mutations in this region are often related to severe combined immunodeficiency. A complete understanding of the functions of the RAG2 noncore region and the potential contributions of its individual residues has not yet been achieved. Here, we show that the zinc finger motif within the noncore region of RAG2 is indispensable for maintaining the stability of the RAG2 protein. The zinc finger motif in the noncore region of RAG2 is highly conserved from zebrafish to humans. Knock-in mice carrying a zinc finger mutation (C478Y) exhibit decreased V(D)J recombination efficiency and serious impairment in T/B-cell development due to RAG2 instability. Further studies also reveal the importance of the zinc finger motif for RAG2 stability. Moreover, mice harboring a RAG2 noncore region mutation (N474S), which is located near C478 but is not zinc-binding, exhibit no impairment in either RAG2 stability or T/B-cell development. Taken together, our findings contribute to defining critical functions of the RAG2 zinc finger motif and provide insights into the relationships between the mutations within this motif and immunodeficiency diseases.
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Affiliation(s)
- Ke Xu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Haifeng Liu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Zhubing Shi
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Guangrong Song
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xiaoyan Zhu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yuzhang Jiang
- Department of Medical Laboratory, Huaian First People's Hospital, Nanjing Medical University, Huaian, Jiangsu, China
| | - Zhaocai Zhou
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xiaolong Liu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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Couëdel C, Roman C, Jones A, Vezzoni P, Villa A, Cortes P. Analysis of mutations from SCID and Omenn syndrome patients reveals the central role of the Rag2 PHD domain in regulating V(D)J recombination. J Clin Invest 2010; 120:1337-44. [PMID: 20234091 DOI: 10.1172/jci41305] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 01/20/2010] [Indexed: 01/22/2023] Open
Abstract
Rag2 plays an essential role in the generation of antigen receptors. Mutations that impair Rag2 function can lead to severe combined immunodeficiency (SCID), a condition characterized by complete absence of T and B cells, or Omenn syndrome (OS), a form of SCID characterized by the virtual absence of B cells and the presence of oligoclonal autoreactive T cells. Here, we present a comparative study of a panel of mutations that were identified in the noncanonical plant homeodomain (PHD) of Rag2 in patients with SCID or OS. We show that PHD mutant mouse Rag2 proteins that correspond to those found in these patients greatly impaired endogenous recombination of Ig gene segments in a Rag2-deficient pro-B cell line and that this correlated with decreased protein stability, impaired nuclear localization, and/or loss of the interaction between Rag2 and core histones. Our results demonstrate that point mutations in the PHD of Rag2 compromise the functionality of the entire protein, thus explaining why the phenotype of cells expressing PHD point mutants differs from those expressing core Rag2 protein that lacks the entire C-terminal region and is therefore devoid of the regulation imposed by the PHD. Together, our findings reveal the various deleterious effects of PHD Rag2 mutations and demonstrate the crucial role of this domain in regulating antigen receptor gene assembly. We believe these results reveal new mechanisms of immunodeficiency in SCID and OS.
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Affiliation(s)
- Chrystelle Couëdel
- Immunology Institute, Department of Medicine, Mount Sinai School of Medicine, New York, New York 10029, USA
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