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Class switch recombination

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https://www.readbyqxmd.com/read/28933967/aid-biology-a-pathological-and-clinical-perspective
#1
Meenal Choudhary, Anubhav Tamrakar, Amit Kumar Singh, Monika Jain, Ankit Jaiswal, Prashant Kodgire
Activation-induced cytidine deaminase (AID), primarily expressed in activated mature B lymphocytes in germinal centers, is the key factor in adaptive immune response against foreign antigens. AID is responsible for producing high-affinity and high-specificity antibodies against an infectious agent, through the physiological DNA alteration processes of antibody genes by somatic hypermutation (SHM) and class-switch recombination (CSR) and functions by deaminating deoxycytidines (dC) to deoxyuridines (dU), thereby introducing point mutations and double-stranded chromosomal breaks (DSBs)...
September 21, 2017: International Reviews of Immunology
https://www.readbyqxmd.com/read/28928744/ccctc-binding-factor-locks-premature-igh-germline-transcription-and-restrains-class-switch-recombination
#2
Ester Marina-Zárate, Arantxa Pérez-García, Almudena R Ramiro
In response to antigenic stimulation B cells undergo class switch recombination (CSR) at the immunoglobulin heavy chain (IgH) to replace the primary IgM/IgD isotypes by IgG, IgE, or IgA. CSR is initiated by activation-induced cytidine deaminase (AID) through the deamination of cytosine residues at the switch (S) regions of IgH. B cell stimulation promotes germline transcription (GLT) of specific S regions, a necessary event prior to CSR because it facilitates AID access to S regions. Here, we show that CCCTC-binding factor (CTCF)-deficient mice are severely impaired in the generation of germinal center B cells and plasma cells after immunization in vivo, most likely due to impaired cell survival...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28867784/the-complex-interplay-between-dna-injury-and-repair-in-enzymatically-induced-mutagenesis-and-dna-damage-in-b-lymphocytes
#3
REVIEW
Mahnoush Bahjat, Jeroen E J Guikema
Lymphocytes are endowed with unique and specialized enzymatic mutagenic properties that allow them to diversify their antigen receptors, which are crucial sensors for pathogens and mediators of adaptive immunity. During lymphocyte development, the antigen receptors expressed by B and T lymphocytes are assembled in an antigen-independent fashion by ordered variable gene segment recombinations (V(D)J recombination), which is a highly ordered and regulated process that requires the recombination activating gene products 1 & 2 (RAG1, RAG2)...
August 30, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28790320/activation-induced-cytidine-deaminase-targets-suv4-20-mediated-histone-h4k20-trimethylation-to-class-switch-recombination-sites
#4
Virginia C Rodríguez-Cortez, Paloma Martínez-Redondo, Francesc Català-Moll, Javier Rodríguez-Ubreva, Antonio Garcia-Gomez, Ganesh Poorani-Subramani, Laura Ciudad, Henar Hernando, Arantxa Pérez-García, Carlos Company, José M Urquiza, Almudena R Ramiro, Javier M Di Noia, Alejandro Vaquero, Esteban Ballestar
Activation-induced cytidine deaminase (AID) triggers antibody diversification in B cells by catalysing deamination and subsequently mutating immunoglobulin (Ig) genes. Association of AID with RNA Pol II and occurrence of epigenetic changes during Ig gene diversification suggest participation of AID in epigenetic regulation. AID is mutated in hyper-IgM type 2 (HIGM2) syndrome. Here, we investigated the potential role of AID in the acquisition of epigenetic changes. We discovered that AID binding to the IgH locus promotes an increase in H4K20me3...
August 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28783691/characterization-of-t-and-b-cell-repertoire-diversity-in-patients-with-rag-deficiency
#5
Yu Nee Lee, Francesco Frugoni, Kerry Dobbs, Irit Tirosh, Likun Du, Francesca A Ververs, Heng Ru, Lisa Ott de Bruin, Mehdi Adeli, Jacob H Bleesing, David Buchbinder, Manish J Butte, Caterina Cancrini, Karin Chen, Sharon Choo, Reem A Elfeky, Andrea Finocchi, Ramsay L Fuleihan, Andrew R Gennery, Dalia H El-Ghoneimy, Lauren A Henderson, Waleed Al-Herz, Elham Hossny, Robert P Nelson, Sung-Yun Pai, Niraj C Patel, Shereen M Reda, Pere Soler-Palacin, Raz Somech, Paolo Palma, Hao Wu, Silvia Giliani, Jolan E Walter, Luigi D Notarangelo
Recombination-activating genes 1 and 2 (RAG1 and RAG2) play a critical role in T and B cell development by initiating the recombination process that controls the expression of T cell receptor (TCR) and immunoglobulin genes. Mutations in the RAG1 and RAG2 genes in humans cause a broad spectrum of phenotypes, including severe combined immunodeficiency (SCID) with lack of T and B cells, Omenn syndrome, leaky SCID, and combined immunodeficiency with granulomas or autoimmunity (CID-G/AI). Using next-generation sequencing, we analyzed the TCR and B cell receptor (BCR) repertoire in 12 patients with RAG mutations presenting with Omenn syndrome (n = 5), leaky SCID (n = 3), or CID-G/AI (n = 4)...
December 16, 2016: Science Immunology
https://www.readbyqxmd.com/read/28780374/maternal-t-and-b-cell-engraftment-in-two-cases-of-x-linked-severe-combined-immunodeficiency-with-igg1-gammopathy
#6
Tsubasa Okano, Takuro Nishikawa, Eri Watanabe, Takashi Watanabe, Takehiro Takashima, Tzu-Wen Yeh, Motoi Yamashita, Mari Tanaka-Kubota, Satoshi Miyamoto, Noriko Mitsuiki, Masatoshi Takagi, Yoshifumi Kawano, Yoshiki Mochizuki, Kohsuke Imai, Hirokazu Kanegane, Tomohiro Morio
X-linked severe combined immunodeficiency (X-SCID), caused by defects in the common gamma chain, is typically characterized by T and NK cell defects with the presence of B cells. T cell dysfunction and impaired class-switch recombination of B cells mean that patients typically have defects in class-switched immunoglobulins (IgG, IgA, and IgE) with detectable IgM. Here, we describe two patients with X-SCID with IgG1 gammopathy, in whom we identified maternal T and B cell engraftment. Exclusively, maternal B cells were found among the IgD(-)CD27(+) class-switched memory B cells, whereas the patients' B cells remained naïve...
August 3, 2017: Clinical Immunology: the Official Journal of the Clinical Immunology Society
https://www.readbyqxmd.com/read/28757211/aid-recognizes-structured-dna-for-class-switch-recombination
#7
Qi Qiao, Li Wang, Fei-Long Meng, Joyce K Hwang, Frederick W Alt, Hao Wu
Activation-induced cytidine deaminase (AID) initiates both class switch recombination (CSR) and somatic hypermutation (SHM) in antibody diversification. Mechanisms of AID targeting and catalysis remain elusive despite its critical immunological roles and off-target effects in tumorigenesis. Here, we produced active human AID and revealed its preferred recognition and deamination of structured substrates. G-quadruplex (G4)-containing substrates mimicking the mammalian immunoglobulin switch regions are particularly good AID substrates in vitro...
August 3, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28724724/brct-domain-protein-brit1-influences-class-switch-recombination
#8
Wei-Feng Yen, Ashutosh Chaudhry, Bharat Vaidyanathan, William T Yewdell, Joseph N Pucella, Rahul Sharma, Yulong Liang, Kaiyi Li, Alexander Y Rudensky, Jayanta Chaudhuri
DNA double-strand breaks (DSBs) serve as obligatory intermediates for Ig heavy chain (Igh) class switch recombination (CSR). The mechanisms by which DSBs are resolved to promote long-range DNA end-joining while suppressing genomic instability inherently associated with DSBs are yet to be fully elucidated. Here, we use a targeted short-hairpin RNA screen in a B-cell lymphoma line to identify the BRCT-domain protein BRIT1 as an effector of CSR. We show that conditional genetic deletion of BRIT1 in mice leads to a marked increase in unrepaired Igh breaks and a significant reduction in CSR in ex vivo activated splenic B cells...
July 19, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28716949/biochemical-regulatory-features-of-aid-remain-conserved-from-lamprey-to-humans
#9
Emma M Quinlan, Justin J King, Chris T Amemiya, Ellen Hsu, Mani Larijani
Activation induced cytidine deaminase (AID) is a genome-mutating enzyme that initiates class switch recombination and somatic hypermutation of antibodies in jawed vertebrates. We previously described the biochemical properties of human AID and found that it is an unusual enzyme in that it exhibits binding affinities for its substrate DNA and catalytic rates several orders of magnitude higher and lower, respectively, than a typical enzyme. Recently, we solved the functional structure of AID and demonstrated that these properties are due to non-specific DNA binding on its surface, along with a catalytic pocket that predominantly assumes a closed conformation...
July 17, 2017: Molecular and Cellular Biology
https://www.readbyqxmd.com/read/28676801/cd25-b-1a-cells-express-aicda
#10
Hiroaki Kaku, Nichol E Holodick, Joseph R Tumang, Thomas L Rothstein
B-1a cells are innate-like B-lymphocytes producing natural antibodies. Activation-induced cytidine deaminase (AID), a product of the Aicda gene, plays a central role in class-switch recombination and somatic hypermutation in B cells. Although a role for Aicda in B-1a cells has been suggested on the basis of experiments with knock out (KO) mice, whether B-1a cells express Aicda, and if so, which B-1a cell subpopulation expresses Aicda, remains unknown. Here, we demonstrate that B-1 cells express Aicda, but at a level below that expressed by germinal center (GC) B cells...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28610800/human-igg-repertoire-of-malaria-antigen-immunized-human-immune-system-his-mice
#11
Raquel Tayar Nogueira, Vincent Sahi, Jing Huang, Moriya Tsuji
Humanized mouse models present an important tool for preclinical evaluation of new vaccines and therapeutics. Here we show the human variable repertoire of antibody sequences cloned from a previously described human immune system (HIS) mouse model that possesses functional human CD4+ T cells and B cells, namely HIS-CD4/B mice. We sequenced variable IgG genes from single memory B-cell and plasma-cell sorted from splenocytes or whole blood lymphocytes of HIS-CD4/B mice that were vaccinated with a human plasmodial antigen, a recombinant Plasmodium falciparum circumsporozoite protein (rPfCSP)...
August 2017: Immunology Letters
https://www.readbyqxmd.com/read/28607112/cutting-edge-active-tgf-%C3%AE-1-released-from-garp-tgf-%C3%AE-1-complexes-on-the-surface-of-stimulated-human-b-lymphocytes-increases-class-switch-recombination-and-production-of-iga
#12
Olivier Dedobbeleer, Julie Stockis, Bas van der Woning, Pierre G Coulie, Sophie Lucas
Production of active TGF-β is regulated at a posttranslational level and implies release of the mature cytokine dimer from the inactive, latent TGF-β precursor. There are several cell-type specific mechanisms of TGF-β activation. We identified a new mechanism operating on the surface of human regulatory T cells and involving membrane protein GARP, which binds latent TGF-β1. The paracrine activity of regulatory T cell-derived TGF-β1 contributes to immunosuppression and can be inhibited with anti-GARP Abs...
July 15, 2017: Journal of Immunology: Official Journal of the American Association of Immunologists
https://www.readbyqxmd.com/read/28574479/r-loops-in-the-regulation-of-antibody-gene-diversification
#13
REVIEW
Rushad Pavri
For nearly three decades, R loops have been closely linked with class switch recombination (CSR), the process that generates antibody isotypes and that occurs via a complex cascade initiated by transcription-coupled mutagenesis in switch recombination sequences. R loops form during transcription of switch recombination sequences in vitro and in vivo, and there is solid evidence that R loops are required for efficient class switching. The classical model of R loops posits that they boost mutation rates by generating stable and long tracts of single-stranded DNA that serve as the substrate for activation induced deaminase (AID), the enzyme that initiates the CSR reaction cascade by co-transcriptionally mutating ssDNA in switch recombination sequences...
June 2, 2017: Genes
https://www.readbyqxmd.com/read/28570559/analysis-of-dna-polymerase-%C3%AE-function-in-meiotic-recombination-immunoglobulin-class-switching-and-dna-damage-tolerance
#14
Kei-Ichi Takata, Shelley Reh, Matthew J Yousefzadeh, Maciej J Zelazowski, Sarita Bhetawal, David Trono, Megan G Lowery, Maria Sandoval, Yoko Takata, Yue Lu, Kevin Lin, Jianjun Shen, Donna F Kusewitt, Kevin M McBride, Francesca Cole, Richard D Wood
DNA polymerase ν (pol ν), encoded by the POLN gene, is an A-family DNA polymerase in vertebrates and some other animal lineages. Here we report an in-depth analysis of pol ν-defective mice and human cells. POLN is very weakly expressed in most tissues, with the highest relative expression in testis. We constructed multiple mouse models for Poln disruption and detected no anatomic abnormalities, alterations in lifespan, or changed causes of mortality. Mice with inactive Poln are fertile and have normal testis morphology...
June 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28550350/recent-advances-in-the-study-of-immunodeficiency-and-dna-damage-response
#15
REVIEW
Tomohiro Morio
DNA breaks can be induced by exogenous stimuli or by endogenous stress, but are also generated during recombination of V, D, and J genes (V(D)J recombination), immunoglobulin class switch recombination (CSR). Among various DNA breaks generated, DNA double strand break (DSB) is the most deleterious one. DNA damage response (DDR) is initiated when DSBs are detected, leading to DNA break repair by non-homologous end joining (NHEJ). The process is critically important for the generation of diversity for foreign antigens; and failure to exert DNA repair leads to immunodeficiency such as severe combined immunodeficiency and hyper-IgM syndrome...
May 26, 2017: International Journal of Hematology
https://www.readbyqxmd.com/read/28544931/role-for-rif1-interacting-partner-ddx1-in-blm-recruitment-to-dna-double-strand-breaks
#16
Lei Li, Ho-Yin Poon, Matthew R Hildebrandt, Elizabeth A Monckton, Devon R Germain, Richard P Fahlman, Roseline Godbout
Human Rap1-interacting factor 1 (RIF1) is an important player in the repair of DNA double strand breaks (DSBs). RIF1 acts downstream of 53BP1, with well-documented roles in class switch recombination in B-cells and inhibition of end resection initiation in BRCA1-defective cells. Here, we report that DEAD Box 1 (DDX1), a RNA helicase also implicated in DSB repair, interacts with RIF1, with co-localization of DDX1 and RIF1 observed throughout interphase. Recruitment of DDX1 to DSBs is dependent on RIF1, with RIF1 depletion abolishing DDX1-mediated facilitation of homologous recombination at DSBs...
July 2017: DNA Repair
https://www.readbyqxmd.com/read/28535205/a-transcriptional-serenaid-the-role-of-noncoding-rnas-in-class-switch-recombination
#17
William T Yewdell, Jayanta Chaudhuri
During an immune response, activated B cells may undergo class switch recombination (CSR), a molecular rearrangement that allows B cells to switch from expressing IgM and IgD to a secondary antibody heavy chain isotype such as IgG, IgA or IgE. Secondary antibody isotypes provide the adaptive immune system with distinct effector functions to optimally combat various pathogens. CSR occurs between repetitive DNA elements within the immunoglobulin heavy chain (Igh) locus, termed switch (S) regions and requires the DNA-modifying enzyme activation-induced cytidine deaminase (AID)...
April 1, 2017: International Immunology
https://www.readbyqxmd.com/read/28533409/inducible-ctcf-insulator-delays-the-igh-3-regulatory-region-mediated-activation-of-germline-promoters-and-alters-class-switching
#18
Fatima-Zohra Braikia, Chloé Oudinet, Dania Haddad, Zeliha Oruc, Domenico Orlando, Audrey Dauba, Marc Le Bert, Ahmed Amine Khamlichi
Class switch recombination (CSR) plays an important role in adaptive immune response by enabling mature B cells to switch from IgM expression to the expression of downstream isotypes. CSR is preceded by inducible germline (GL) transcription of the constant genes and is controlled by the 3' regulatory region (3'RR) in a stimulus-dependent manner. Why the 3'RR-mediated up-regulation of GL transcription is delayed to the mature B-cell stage is presently unknown. Here we show that mice devoid of an inducible CTCF binding element, located in the α constant gene, display a marked isotype-specific increase of GL transcription in developing and resting splenic B cells and altered CSR in activated B cells...
June 6, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28515723/different-somatic-hypermutation-levels-among-antibody-subclasses-disclosed-by-a-new-next-generation-sequencing-based-antibody-repertoire-analysis
#19
Kazutaka Kitaura, Hiroshi Yamashita, Hitomi Ayabe, Tadasu Shini, Takaji Matsutani, Ryuji Suzuki
A diverse antibody repertoire is primarily generated by the rearrangement of V, D, and J genes and subsequent somatic hypermutation (SHM). Class-switch recombination (CSR) produces various isotypes and subclasses with different functional properties. Although antibody isotypes and subclasses are considered to be produced by both direct and sequential CSR, it is still not fully understood how SHMs accumulate during the process in which antibody subclasses are generated. Here, we developed a new next-generation sequencing (NGS)-based antibody repertoire analysis capable of identifying all antibody isotype and subclass genes and used it to examine the peripheral blood mononuclear cells of 12 healthy individuals...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28499720/t-follicular-helper-and-th2-cells-in-allergic-responses
#20
REVIEW
Masato Kubo
IL-4 is a cytokine commonly secreted by TH2 and follicular helper T (TFH) cells after antigenic sensitization. TH2 cells have been thought to be the major contributor of B cell help as a source of IL-4 responsible for class switch recombination to Immunoglobulin G1 (IgG1) and Immunoglobulin E (IgE). Importantly, there are some differences in transcriptional regulation between these two T cell subsets. The IL-4 production by TH2 and TFH cells is distinctively regulated by two pathways, GATA-3-mediated Il4-HS2 enhancer and Notch mediated Il4-CNS-2 enhancer...
July 2017: Allergology International: Official Journal of the Japanese Society of Allergology
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