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Tambe A, MacCarthy T, Pavri R. Interpretable deep learning reveals the role of an E-box motif in suppressing somatic hypermutation of AGCT motifs within human immunoglobulin variable regions. Front Immunol 2024; 15:1407470. [PMID: 38863710 PMCID: PMC11165027 DOI: 10.3389/fimmu.2024.1407470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 05/08/2024] [Indexed: 06/13/2024] Open
Abstract
Introduction Somatic hypermutation (SHM) of immunoglobulin variable (V) regions by activation induced deaminase (AID) is essential for robust, long-term humoral immunity against pathogen and vaccine antigens. AID mutates cytosines preferentially within WRCH motifs (where W=A or T, R=A or G and H=A, C or T). However, it has been consistently observed that the mutability of WRCH motifs varies substantially, with large variations in mutation frequency even between multiple occurrences of the same motif within a single V region. This has led to the notion that the immediate sequence context of WRCH motifs contributes to mutability. Recent studies have highlighted the potential role of local DNA sequence features in promoting mutagenesis of AGCT, a commonly mutated WRCH motif. Intriguingly, AGCT motifs closer to 5' ends of V regions, within the framework 1 (FW1) sub-region1, mutate less frequently, suggesting an SHM-suppressing sequence context. Methods Here, we systematically examined the basis of AGCT positional biases in human SHM datasets with DeepSHM, a machine-learning model designed to predict SHM patterns. This was combined with integrated gradients, an interpretability method, to interrogate the basis of DeepSHM predictions. Results DeepSHM predicted the observed positional differences in mutation frequencies at AGCT motifs with high accuracy. For the conserved, lowly mutating AGCT motifs in FW1, integrated gradients predicted a large negative contribution of 5'C and 3'G flanking residues, suggesting that a CAGCTG context in this location was suppressive for SHM. CAGCTG is the recognition motif for E-box transcription factors, including E2A, which has been implicated in SHM. Indeed, we found a strong, inverse relationship between E-box motif fidelity and mutation frequency. Moreover, E2A was found to associate with the V region locale in two human B cell lines. Finally, analysis of human SHM datasets revealed that naturally occurring mutations in the 3'G flanking residues, which effectively ablate the E-box motif, were associated with a significantly increased rate of AGCT mutation. Discussion Our results suggest an antagonistic relationship between mutation frequency and the binding of E-box factors like E2A at specific AGCT motif contexts and, therefore, highlight a new, suppressive mechanism regulating local SHM patterns in human V regions.
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Affiliation(s)
- Abhik Tambe
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, United States
| | - Thomas MacCarthy
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, United States
| | - Rushad Pavri
- Research Institute of Molecular Pathology (IMP), Vienna, Austria
- Peter Gorer Department of Immunobiology, School of Immunology & Microbial Sciences, King’s College London, London, United Kingdom
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2
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Weischedel J, Higgins L, Rogers S, Gramalla-Schmitz A, Wyrzykowska P, Borgoni S, MacCarthy T, Chahwan R. Modular cytosine base editing promotes epigenomic and genomic modifications. Nucleic Acids Res 2024; 52:e8. [PMID: 37994786 PMCID: PMC10810192 DOI: 10.1093/nar/gkad1118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 10/06/2023] [Accepted: 11/06/2023] [Indexed: 11/24/2023] Open
Abstract
Prokaryotic and eukaryotic adaptive immunity differ considerably. Yet, their fundamental mechanisms of gene editing via Cas9 and activation-induced deaminase (AID), respectively, can be conveniently complimentary. Cas9 is an RNA targeted dual nuclease expressed in several bacterial species. AID is a cytosine deaminase expressed in germinal centre B cells to mediate genomic antibody diversification. AID can also mediate epigenomic reprogramming via active DNA demethylation. It is known that sequence motifs, nucleic acid structures, and associated co-factors affect AID activity. But despite repeated attempts, deciphering AID's intrinsic catalytic activities and harnessing its targeted recruitment to DNA is still intractable. Even recent cytosine base editors are unable to fully recapitulate AID's genomic and epigenomic editing properties. Here, we describe the first instance of a modular AID-based editor that recapitulates the full spectrum of genomic and epigenomic editing activity. Our 'Swiss army knife' toolbox will help better understand AID biology per se as well as improve targeted genomic and epigenomic editing.
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Affiliation(s)
- Julian Weischedel
- Institute of Experimental Immunology, University of Zurich, Zurich 8057, Switzerland
| | - Laurence Higgins
- Living Systems Institute, University of Exeter, Exeter EX4 4QD, UK
| | - Sally Rogers
- Living Systems Institute, University of Exeter, Exeter EX4 4QD, UK
| | - Anna Gramalla-Schmitz
- Institute of Experimental Immunology, University of Zurich, Zurich 8057, Switzerland
| | - Paulina Wyrzykowska
- Institute of Experimental Immunology, University of Zurich, Zurich 8057, Switzerland
| | - Simone Borgoni
- Institute of Experimental Immunology, University of Zurich, Zurich 8057, Switzerland
| | - Thomas MacCarthy
- Department of Applied Mathematics & Statistics, Stony Brook University, NY 11794-3600, USA
| | - Richard Chahwan
- Institute of Experimental Immunology, University of Zurich, Zurich 8057, Switzerland
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3
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Bello A, Hirth G, Voigt S, Tepper S, Jungnickel B. Mechanism and regulation of secondary immunoglobulin diversification. Cell Cycle 2023; 22:2070-2087. [PMID: 37909747 PMCID: PMC10761156 DOI: 10.1080/15384101.2023.2275397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 10/20/2023] [Indexed: 11/03/2023] Open
Abstract
Secondary immunoglobulin diversification by somatic hypermutation and class switch recombination in B cells is instrumental for an adequate adaptive humoral immune response. These genetic events may, however, also introduce aberrations into other cellular genes and thereby cause B cell malignancies. While the basic mechanism of somatic hypermutation and class switch recombination is now well understood, their regulation and in particular the mechanism of their specific targeting to immunoglobulin genes is still rather mysterious. In this review, we summarize the current knowledge on the mechanism and regulation of secondary immunoglobulin diversification and discuss known mechanisms of physiological targeting to immunoglobulin genes and mistargeting to other cellular genes. We summarize open questions in the field and provide an outlook on future research.
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Affiliation(s)
- Amanda Bello
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Gianna Hirth
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Stefanie Voigt
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Sandra Tepper
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Berit Jungnickel
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
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4
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Del Pozo-Yauner L, Herrera GA, Perez Carreon JI, Turbat-Herrera EA, Rodriguez-Alvarez FJ, Ruiz Zamora RA. Role of the mechanisms for antibody repertoire diversification in monoclonal light chain deposition disorders: when a friend becomes foe. Front Immunol 2023; 14:1203425. [PMID: 37520549 PMCID: PMC10374031 DOI: 10.3389/fimmu.2023.1203425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 06/20/2023] [Indexed: 08/01/2023] Open
Abstract
The adaptive immune system of jawed vertebrates generates a highly diverse repertoire of antibodies to meet the antigenic challenges of a constantly evolving biological ecosystem. Most of the diversity is generated by two mechanisms: V(D)J gene recombination and somatic hypermutation (SHM). SHM introduces changes in the variable domain of antibodies, mostly in the regions that form the paratope, yielding antibodies with higher antigen binding affinity. However, antigen recognition is only possible if the antibody folds into a stable functional conformation. Therefore, a key force determining the survival of B cell clones undergoing somatic hypermutation is the ability of the mutated heavy and light chains to efficiently fold and assemble into a functional antibody. The antibody is the structural context where the selection of the somatic mutations occurs, and where both the heavy and light chains benefit from protective mechanisms that counteract the potentially deleterious impact of the changes. However, in patients with monoclonal gammopathies, the proliferating plasma cell clone may overproduce the light chain, which is then secreted into the bloodstream. This places the light chain out of the protective context provided by the quaternary structure of the antibody, increasing the risk of misfolding and aggregation due to destabilizing somatic mutations. Light chain-derived (AL) amyloidosis, light chain deposition disease (LCDD), Fanconi syndrome, and myeloma (cast) nephropathy are a diverse group of diseases derived from the pathologic aggregation of light chains, in which somatic mutations are recognized to play a role. In this review, we address the mechanisms by which somatic mutations promote the misfolding and pathological aggregation of the light chains, with an emphasis on AL amyloidosis. We also analyze the contribution of the variable domain (VL) gene segments and somatic mutations on light chain cytotoxicity, organ tropism, and structure of the AL fibrils. Finally, we analyze the most recent advances in the development of computational algorithms to predict the role of somatic mutations in the cardiotoxicity of amyloidogenic light chains and discuss the challenges and perspectives that this approach faces.
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Affiliation(s)
- Luis Del Pozo-Yauner
- Department of Pathology, University of South Alabama-College of Medicine, Mobile, AL, United States
| | - Guillermo A. Herrera
- Department of Pathology, University of South Alabama-College of Medicine, Mobile, AL, United States
| | | | - Elba A. Turbat-Herrera
- Department of Pathology, University of South Alabama-College of Medicine, Mobile, AL, United States
- Mitchell Cancer Institute, University of South Alabama-College of Medicine, Mobile, AL, United States
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5
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Russell ML, Simon N, Bradley P, Matsen FA. Statistical inference reveals the role of length, GC content, and local sequence in V(D)J nucleotide trimming. eLife 2023; 12:e85145. [PMID: 37227256 PMCID: PMC10212571 DOI: 10.7554/elife.85145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 04/11/2023] [Indexed: 05/26/2023] Open
Abstract
To appropriately defend against a wide array of pathogens, humans somatically generate highly diverse repertoires of B cell and T cell receptors (BCRs and TCRs) through a random process called V(D)J recombination. Receptor diversity is achieved during this process through both the combinatorial assembly of V(D)J-genes and the junctional deletion and insertion of nucleotides. While the Artemis protein is often regarded as the main nuclease involved in V(D)J recombination, the exact mechanism of nucleotide trimming is not understood. Using a previously published TCRβ repertoire sequencing data set, we have designed a flexible probabilistic model of nucleotide trimming that allows us to explore various mechanistically interpretable sequence-level features. We show that local sequence context, length, and GC nucleotide content in both directions of the wider sequence, together, can most accurately predict the trimming probabilities of a given V-gene sequence. Because GC nucleotide content is predictive of sequence-breathing, this model provides quantitative statistical evidence regarding the extent to which double-stranded DNA may need to be able to breathe for trimming to occur. We also see evidence of a sequence motif that appears to get preferentially trimmed, independent of GC-content-related effects. Further, we find that the inferred coefficients from this model provide accurate prediction for V- and J-gene sequences from other adaptive immune receptor loci. These results refine our understanding of how the Artemis nuclease may function to trim nucleotides during V(D)J recombination and provide another step toward understanding how V(D)J recombination generates diverse receptors and supports a powerful, unique immune response in healthy humans.
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Affiliation(s)
- Magdalena L Russell
- Computational Biology Program, Fred Hutchinson Cancer CenterSeattleUnited States
- Molecular and Cellular Biology Program, University of WashingtonSeattleUnited States
| | - Noah Simon
- Department of Biostatistics, University of WashingtonSeattleUnited States
| | - Philip Bradley
- Computational Biology Program, Fred Hutchinson Cancer CenterSeattleUnited States
- Institute for Protein Design, Department of Biochemistry, University of WashingtonSeattleUnited States
| | - Frederick A Matsen
- Computational Biology Program, Fred Hutchinson Cancer CenterSeattleUnited States
- Department of Genome Sciences, University of WashingtonSeattleUnited States
- Department of Statistics, University of WashingtonSeattleUnited States
- Howard Hughes Medical InstituteSeattleUnited States
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Mallaby J, Mwangi W, Ng J, Stewart A, Dorey-Robinson D, Kipling D, Hershberg U, Fraternali F, Nair V, Dunn-Walters D. Diversification of immunoglobulin genes by gene conversion in the domestic chicken ( Gallus gallus domesticus). DISCOVERY IMMUNOLOGY 2023; 2:kyad002. [PMID: 38567069 PMCID: PMC10917233 DOI: 10.1093/discim/kyad002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 12/29/2022] [Accepted: 01/18/2023] [Indexed: 04/04/2024]
Abstract
Sustainable modern poultry production depends on effective protection against infectious diseases and a diverse range of antibodies is key for an effective immune response. In the domestic chicken, somatic gene conversion is the dominant process in which the antibody immunoglobulin genes are diversified. Affinity maturation by somatic hypermutation (SHM) also occurs, but the relative contribution of gene conversion versus somatic hypermutation to immunoglobulin (Ig) gene diversity is poorly understood. In this study, we use high throughput long-read sequencing to study immunoglobulin diversity in multiple immune-associated tissues in Rhode Island Red chickens. To better understand the impact of genetic diversification in the chicken, a novel gene conversion identification software was developed (BrepConvert). In this study, BrepConvert enabled the identification of over 1 million gene conversion events. Mapping the occurrence of putative somatic gene conversion (SGC) events throughout the variable gene region revealed repetitive and highly restricted patterns of genetic insertions in both the antibody heavy and light chains. These patterns coincided with the locations of genetic variability in available pseudogenes and align with antigen binding sites, predominately the complementary determining regions (CDRs). We found biased usage of pseudogenes during gene conversion, as well as immunoglobulin heavy chain diversity gene (IGHD) preferences during V(D)J gene rearrangement, suggesting that antibody diversification in chickens is more focused than the genetic potential for diversity would suggest.
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Affiliation(s)
- Jessica Mallaby
- Department of Bioscience and Medicine, University of Surrey, Guildford, UK
- Pirbright Institute, Woking, UK
| | | | - Joseph Ng
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, UK
| | - Alexander Stewart
- Department of Bioscience and Medicine, University of Surrey, Guildford, UK
| | | | - David Kipling
- Department of Bioscience and Medicine, University of Surrey, Guildford, UK
| | - Uri Hershberg
- Department of Human Biology, University of Haifa, Haifa, Israel
| | - Franca Fraternali
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, UK
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Ghorbani A, Khataeipour SJ, Solbakken MH, Huebert DNG, Khoddami M, Eslamloo K, Collins C, Hori T, Jentoft S, Rise ML, Larijani M. Ancestral reconstruction reveals catalytic inactivation of activation-induced cytidine deaminase concomitant with cold water adaption in the Gadiformes bony fish. BMC Biol 2022; 20:293. [PMID: 36575514 PMCID: PMC9795746 DOI: 10.1186/s12915-022-01489-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 11/30/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Antibody affinity maturation in vertebrates requires the enzyme activation-induced cytidine deaminase (AID) which initiates secondary antibody diversification by mutating the immunoglobulin loci. AID-driven antibody diversification is conserved across jawed vertebrates since bony and cartilaginous fish. Two exceptions have recently been reported, the Pipefish and Anglerfish, in which the AID-encoding aicda gene has been lost. Both cases are associated with unusual reproductive behavior, including male pregnancy and sexual parasitism. Several cold water fish in the Atlantic cod (Gadinae) family carry an aicda gene that encodes for a full-length enzyme but lack affinity-matured antibodies and rely on antibodies of broad antigenic specificity. Hence, we examined the functionality of their AID. RESULTS By combining genomics, transcriptomics, immune responsiveness, and functional enzymology of AID from 36 extant species, we demonstrate that AID of that Atlantic cod and related fish have extremely lethargic or no catalytic activity. Through ancestral reconstruction and functional enzymology of 71 AID enzymes, we show that this enzymatic inactivation likely took place relatively recently at the emergence of the true cod family (Gadidae) from their ancestral Gadiformes order. We show that this AID inactivation is not only concordant with the previously shown loss of key adaptive immune genes and expansion of innate and cell-based immune genes in the Gadiformes but is further reflected in the genomes of these fish in the form of loss of AID-favored sequence motifs in their immunoglobulin variable region genes. CONCLUSIONS Recent demonstrations of the loss of the aicda gene in two fish species challenge the paradigm that AID-driven secondary antibody diversification is absolutely conserved in jawed vertebrates. These species have unusual reproductive behaviors forming an evolutionary pressure for a certain loss of immunity to avoid tissue rejection. We report here an instance of catalytic inactivation and functional loss of AID rather than gene loss in a conventionally reproducing vertebrate. Our data suggest that an expanded innate immunity, in addition to lower pathogenic pressures in a cold environment relieved the pressure to maintain robust secondary antibody diversification. We suggest that in this unique scenario, the AID-mediated collateral genome-wide damage would form an evolutionary pressure to lose AID function.
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Affiliation(s)
- Atefeh Ghorbani
- grid.61971.380000 0004 1936 7494Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada ,grid.25055.370000 0000 9130 6822Program in Immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada
| | - S. Javad Khataeipour
- grid.25055.370000 0000 9130 6822Department of Computer Science, Faculty of Science, Memorial University of Newfoundland, St. John’s, Canada
| | - Monica H. Solbakken
- grid.5510.10000 0004 1936 8921Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, Oslo, Norway
| | - David N. G. Huebert
- grid.61971.380000 0004 1936 7494Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada ,grid.25055.370000 0000 9130 6822Program in Immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada
| | - Minasadat Khoddami
- grid.61971.380000 0004 1936 7494Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Khalil Eslamloo
- grid.25055.370000 0000 9130 6822Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, Canada
| | - Cassandra Collins
- grid.61971.380000 0004 1936 7494Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
| | - Tiago Hori
- grid.25055.370000 0000 9130 6822Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, Canada
| | - Sissel Jentoft
- grid.5510.10000 0004 1936 8921Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Matthew L. Rise
- grid.25055.370000 0000 9130 6822Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, Canada
| | - Mani Larijani
- grid.61971.380000 0004 1936 7494Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada ,grid.25055.370000 0000 9130 6822Program in Immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada
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8
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Mallaby J, Ng J, Stewart A, Sinclair E, Dunn-Walters D, Hershberg U. Chickens, more than humans, focus the diversity of their immunoglobulin genes on the complementarity-determining region but utilise amino acids, indicative of a more cross-reactive antibody repertoire. Front Immunol 2022; 13:837246. [PMID: 36569888 PMCID: PMC9772431 DOI: 10.3389/fimmu.2022.837246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 11/21/2022] [Indexed: 12/12/2022] Open
Abstract
The mechanisms of B-cell diversification differ greatly between aves and mammals, but both produce B cells and antibodies capable of supporting an effective immune response. To see how differences in the generation of diversity might affect overall repertoire diversity, we have compared the diversity characteristics of immunoglobulin genes from domestic chickens to those from humans. Both use V(D)J gene rearrangement and somatic hypermutation, but only chickens use somatic gene conversion. A range of diversity analysis tools were used to investigate multiple aspects of amino acid diversity at both the germline and repertoire levels. The effect of differing amino acid usages on antibody characteristics was assessed. At both the germline and repertoire levels, chickens exhibited lower amino acid diversity in comparison to the human immunoglobulin genes, especially outside of the complementarity-determining region (CDR). Chickens were also found to possess much larger and more hydrophilic CDR3s with a higher predicted protein binding potential, suggesting that the antigen-binding site in chicken antibodies is more flexible and more polyreactive than that seen in human antibodies.
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Affiliation(s)
- Jessica Mallaby
- Department of Bioscience and Medicine, University of Surrey, Guildford, United Kingdom
| | - Joseph Ng
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Alex Stewart
- Department of Bioscience and Medicine, University of Surrey, Guildford, United Kingdom
| | - Emma Sinclair
- Department of Bioscience and Medicine, University of Surrey, Guildford, United Kingdom
| | - Deborah Dunn-Walters
- Department of Bioscience and Medicine, University of Surrey, Guildford, United Kingdom
| | - Uri Hershberg
- Department of Human Biology, University of Haifa, Haifa, Israel
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9
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Jeong SL, Zhang H, Yamaki S, Yang C, McKemy D, Lieber M, Pham P, Goodman M. Immunoglobulin somatic hypermutation in a defined biochemical system recapitulates affinity maturation and permits antibody optimization. Nucleic Acids Res 2022; 50:11738-11754. [PMID: 36321646 PMCID: PMC9723645 DOI: 10.1093/nar/gkac995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 10/10/2022] [Accepted: 10/18/2022] [Indexed: 11/05/2022] Open
Abstract
We describe a purified biochemical system to produce monoclonal antibodies (Abs) in vitro using activation-induced deoxycytidine deaminase (AID) and DNA polymerase η (Polη) to diversify immunoglobulin variable gene (IgV) libraries within a phage display format. AID and Polη function during B-cell affinity maturation by catalyzing somatic hypermutation (SHM) of immunoglobulin variable genes (IgV) to generate high-affinity Abs. The IgV mutational motif specificities observed in vivo are conserved in vitro. IgV mutations occurred in antibody complementary determining regions (CDRs) and less frequently in framework (FW) regions. A unique feature of our system is the use of AID and Polη to perform repetitive affinity maturation on libraries reconstructed from a preceding selection step. We have obtained scFv Abs against human glucagon-like peptide-1 receptor (GLP-1R), a target in the treatment of type 2 diabetes, and VHH nanobodies targeting Fatty Acid Amide Hydrolase (FAAH), involved in chronic pain, and artemin, a neurotropic factor that regulates cold pain. A round of in vitro affinity maturation typically resulted in a 2- to 4-fold enhancement in Ab-Ag binding, demonstrating the utility of the system. We tested one of the affinity matured nanobodies and found that it reduced injury-induced cold pain in a mouse model.
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Affiliation(s)
- Soo Lim Jeong
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Hongyu Zhang
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Shanni Yamaki
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Chenyu Yang
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - David D McKemy
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Michael R Lieber
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA,Departments of Pathology, Biochemistry & Molecular Biology, and Molecular Microbiology & Immunology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, CA 90033, USA
| | - Phuong Pham
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Myron F Goodman
- To whom correspondence should be addressed. Tel: +1 213 740 5190; Fax: +1 213 821 1138;
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10
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Tang C, Krantsevich A, MacCarthy T. Deep learning model of somatic hypermutation reveals importance of sequence context beyond hotspot targeting. iScience 2022; 25:103668. [PMID: 35036866 PMCID: PMC8749460 DOI: 10.1016/j.isci.2021.103668] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 11/08/2021] [Accepted: 12/16/2021] [Indexed: 11/23/2022] Open
Abstract
B cells undergo somatic hypermutation (SHM) of the Immunoglobulin (Ig) variable region to generate high-affinity antibodies. SHM relies on the activity of activation-induced deaminase (AID), which mutates C>U preferentially targeting WRC (W=A/T, R=A/G) hotspots. Downstream mutations at WA Polymerase η hotspots contribute further mutations. Computational models of SHM can describe the probability of mutations essential for vaccine responses. Previous studies using short subsequences (k-mers) failed to explain divergent mutability for the same k-mer. We developed the DeepSHM (Deep learning on SHM) model using k-mers of size 5-21, improving accuracy over previous models. Interpretation of DeepSHM identified an extended WWRCT motif with particularly high mutability. Increased mutability was further associated with lower surrounding G content. Our model also discovered a conserved AGYCTGGGGG (Y=C/T) motif within FW1 of IGHV3 family genes with unusually high T>G substitution rates. Thus, a wider sequence context increases predictive power and identifies features that drive mutational targeting.
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Affiliation(s)
- Catherine Tang
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, USA
| | - Artem Krantsevich
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, USA
| | - Thomas MacCarthy
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11794, USA
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, USA
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11
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Ye W, Liu X, He R, Gou L, Lu M, Yang G, Wen J, Wang X, Liu F, Ma S, Qian W, Jia S, Ding T, Sun L, Gao W. Improving antibody affinity through <i>in vitro</i> mutagenesis in complementarity determining regions. J Biomed Res 2022; 36:155-166. [PMID: 35545451 PMCID: PMC9179109 DOI: 10.7555/jbr.36.20220003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
High-affinity antibodies are widely used in diagnostics and for the treatment of human diseases. However, most antibodies are isolated from semi-synthetic libraries by phage display and do not possess in vivo affinity maturation, which is triggered by antigen immunization. It is therefore necessary to engineer the affinity of these antibodies by way of in vitro assaying. In this study, we optimized the affinity of two human monoclonal antibodies which were isolated by phage display in a previous related study. For the 42A1 antibody, which targets the liver cancer antigen glypican-3, the variant T57H in the second complementarity-determining region of the heavy chain (CDR-H2) exhibited a 2.6-fold improvement in affinity, as well as enhanced cell-binding activity. For the I4A3 antibody to severe acute respiratory syndrome coronavirus 2, beneficial single mutations in CDR-H2 and CDR-H3 were randomly combined to select the best synergistic mutations. Among these, the mutation S53P-S98T improved binding affinity (about 3.7 fold) and the neutralizing activity (about 12 fold) compared to the parent antibody. Taken together, single mutations of key residues in antibody CDRs were enough to increase binding affinity with improved antibody functions. The mutagenic combination of key residues in different CDRs creates additive enhancements. Therefore, this study provides a safe and effective in vitro strategy for optimizing antibody affinity.
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Affiliation(s)
- Wei Ye
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Xiaoyu Liu
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Ruiting He
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Liming Gou
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Ming Lu
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Gang Yang
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Jiaqi Wen
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Xufei Wang
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Fang Liu
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Sujuan Ma
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Weifeng Qian
- The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal Hospital, Gusu School, Nanjing Medical University, Suzhou, Jiangsu 215001, China
| | - Shaochang Jia
- Department of Biotherapy, Nanjing Jinling Hospital, Nanjing, Jiangsu 210002, China
| | - Tong Ding
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
| | - Luan Sun
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
- Wei Gao and Luan Sun, School of Basic Medical Sciences, Nanjing Medical University, 101 Longmian Road, Nanjing, Jiangsu 211166, China. Tel/Fax: +86-25-86869471/+86-25-86869471, E-mails:
and
| | - Wei Gao
- Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Personalized Cancer Medicine, Key Laboratory of Human Functional Genomics of Jiangsu Province, National Health Commission Key Laboratory of Antibody Techniques, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu 211166, China
- Wei Gao and Luan Sun, School of Basic Medical Sciences, Nanjing Medical University, 101 Longmian Road, Nanjing, Jiangsu 211166, China. Tel/Fax: +86-25-86869471/+86-25-86869471, E-mails:
and
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12
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Liu D, Lieber MR. The mechanisms of human lymphoid chromosomal translocations and their medical relevance. Crit Rev Biochem Mol Biol 2021; 57:227-243. [PMID: 34875186 DOI: 10.1080/10409238.2021.2004576] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The most common human lymphoid chromosomal translocations involve concurrent failures of the recombination activating gene (RAG) complex and Activation-Induced Deaminase (AID). These are two enzymes that are normally expressed for purposes of the two site-specific DNA recombination processes: V(D)J recombination and class switch recombination (CSR). First, though it is rare, a low level of expression of AID can introduce long-lived T:G mismatch lesions at 20-600 bp fragile zones. Second, the V(D)J recombination process can occasionally fail to rejoin coding ends, and this failure may permit an opportunity for Artemis:DNA-dependent kinase catalytic subunit (DNA-PKcs) to convert the T:G mismatch sites at the fragile zones into double-strand breaks. The 20-600 bp fragile zones must be, at least transiently, in a single-stranded DNA (ssDNA) state for the first step to occur, because AID only acts on ssDNA. Here we discuss the key DNA sequence features that lead to AID action at a fragile zone, which are (a) the proximity and density of strings of cytosine nucleotides (C-strings) that cause a B/A-intermediate DNA conformation; (b) overlapping AID hotspots that contain a methyl CpG (WRCG), which AID converts to a long-lived T:G mismatch; and (c) transcription, which, though not essential, favors increased ssDNA in the fragile zone. We also summarize chromosomal features of the focal fragile zones in lymphoid malignancies and discuss the clinical relevance of understanding the translocation mechanisms. Many of the key principles covered here are also relevant to chromosomal translocations in non-lymphoid somatic cells as well.
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Affiliation(s)
- Di Liu
- Department of Pathology & Laboratory Medicine, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology and Immunology, and Section of Computational Biology in the Department of Biological Sciences, USC Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Michael R Lieber
- Department of Pathology & Laboratory Medicine, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology and Immunology, and Section of Computational Biology in the Department of Biological Sciences, USC Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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13
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Yu G, Wu Y, Duan Z, Tang C, Xing H, Scharff MD, MacCarthy T. A Bayesian model based computational analysis of the relationship between bisulfite accessible single-stranded DNA in chromatin and somatic hypermutation of immunoglobulin genes. PLoS Comput Biol 2021; 17:e1009323. [PMID: 34491985 PMCID: PMC8462741 DOI: 10.1371/journal.pcbi.1009323] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 09/24/2021] [Accepted: 08/04/2021] [Indexed: 11/19/2022] Open
Abstract
The B cells in our body generate protective antibodies by introducing somatic hypermutations (SHM) into the variable region of immunoglobulin genes (IgVs). The mutations are generated by activation induced deaminase (AID) that converts cytosine to uracil in single stranded DNA (ssDNA) generated during transcription. Attempts have been made to correlate SHM with ssDNA using bisulfite to chemically convert cytosines that are accessible in the intact chromatin of mutating B cells. These studies have been complicated by using different definitions of "bisulfite accessible regions" (BARs). Recently, deep-sequencing has provided much larger datasets of such regions but computational methods are needed to enable this analysis. Here we leveraged the deep-sequencing approach with unique molecular identifiers and developed a novel Hidden Markov Model based Bayesian Segmentation algorithm to characterize the ssDNA regions in the IGHV4-34 gene of the human Ramos B cell line. Combining hierarchical clustering and our new Bayesian model, we identified recurrent BARs in certain subregions of both top and bottom strands of this gene. Using this new system, the average size of BARs is about 15 bp. We also identified potential G-quadruplex DNA structures in this gene and found that the BARs co-locate with G-quadruplex structures in the opposite strand. Using various correlation analyses, there is not a direct site-to-site relationship between the bisulfite accessible ssDNA and all sites of SHM but most of the highly AID mutated sites are within 15 bp of a BAR. In summary, we developed a novel platform to study single stranded DNA in chromatin at a base pair resolution that reveals potential relationships among BARs, SHM and G-quadruplexes. This platform could be applied to genome wide studies in the future.
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Affiliation(s)
- Guojun Yu
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Yingru Wu
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York, United States of America
| | - Zhi Duan
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Catherine Tang
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York, United States of America
| | - Haipeng Xing
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York, United States of America
| | - Matthew D. Scharff
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Thomas MacCarthy
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York, United States of America
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14
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Liu D, Loh YHE, Hsieh CL, Lieber MR. Mechanistic basis for chromosomal translocations at the E2A gene and its broader relevance to human B cell malignancies. Cell Rep 2021; 36:109387. [PMID: 34260910 PMCID: PMC8327686 DOI: 10.1016/j.celrep.2021.109387] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 03/31/2021] [Accepted: 06/21/2021] [Indexed: 11/22/2022] Open
Abstract
Analysis of translocation breakpoints in human B cell malignancies reveals that DNA double-strand breaks at oncogenes most frequently occur at CpG sites located within 20-600 bp fragile zones and depend on activation-induced deaminase (AID). AID requires single-stranded DNA (ssDNA) to act, but it has been unclear why or how this region transiently acquires a ssDNA state. Here, we demonstrate the ssDNA state in the 23 bp E2A fragile zone using several methods, including native bisulfite DNA structural analysis in live human pre-B cells. AID deamination within the E2A fragile zone does not require but is increased upon transcription. High C-string density, nascent RNA tails, and direct DNA sequence repeats prolong the ssDNA state of the E2A fragile zone and increase AID deamination at overlapping AID hotspots that contain the CpG sites at which breaks occur in patients. These features provide key insights into lymphoid fragile zones generally.
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Affiliation(s)
- Di Liu
- Departments of Pathology, Biochemistry & Molecular Biology, and Molecular Microbiology & Immunology, and Section of Molecular & Computational Biology (Department of Biological Sciences), USC Norris Comprehensive Cancer Center, University of Southern California and USC Keck School of Medicine, Los Angeles, CA, USA
| | - Yong-Hwee Eddie Loh
- USC Libraries Bioinformatics Services, University of Southern California and USC Keck School of Medicine, Los Angeles, CA, USA
| | - Chih-Lin Hsieh
- Department of Urology, USC Norris Comprehensive Cancer Center, University of Southern California and USC Keck School of Medicine, Los Angeles, CA, USA
| | - Michael R Lieber
- Departments of Pathology, Biochemistry & Molecular Biology, and Molecular Microbiology & Immunology, and Section of Molecular & Computational Biology (Department of Biological Sciences), USC Norris Comprehensive Cancer Center, University of Southern California and USC Keck School of Medicine, Los Angeles, CA, USA.
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15
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Role of Dot1L and H3K79 methylation in regulating somatic hypermutation of immunoglobulin genes. Proc Natl Acad Sci U S A 2021; 118:2104013118. [PMID: 34253616 DOI: 10.1073/pnas.2104013118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Somatic hypermutation (SHM) and class-switch recombination (CSR) of the immunoglobulin (Ig) genes allow B cells to make antibodies that protect us against a wide variety of pathogens. SHM is mediated by activation-induced deaminase (AID), occurs at a million times higher frequency than other mutations in the mammalian genome, and is largely restricted to the variable (V) and switch (S) regions of Ig genes. Using the Ramos human Burkitt's lymphoma cell line, we find that H3K79me2/3 and its methyltransferase Dot1L are more abundant on the V region than on the constant (C) region, which does not undergo mutation. In primary naïve mouse B cells examined ex vivo, the H3K79me2/3 modification appears constitutively in the donor Sμ and is inducible in the recipient Sγ1 upon CSR stimulation. Knockout and inhibition of Dot1L in Ramos cells significantly reduces V region mutation and the abundance of H3K79me2/3 on the V region and is associated with a decrease of polymerase II (Pol II) and its S2 phosphorylated form at the IgH locus. Knockout of Dot1L also decreases the abundance of BRD4 and CDK9 (a subunit of the P-TEFb complex) on the V region, and this is accompanied by decreased nascent transcripts throughout the IgH gene. Treatment with JQ1 (inhibitor of BRD4) or DRB (inhibitor of CDK9) decreases SHM and the abundance of Pol II S2P at the IgH locus. Since all these factors play a role in transcription elongation, our studies reinforce the idea that the chromatin context and dynamics of transcription are critical for SHM.
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16
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Wellner A, McMahon C, Gilman MSA, Clements JR, Clark S, Nguyen KM, Ho MH, Hu VJ, Shin JE, Feldman J, Hauser BM, Caradonna TM, Wingler LM, Schmidt AG, Marks DS, Abraham J, Kruse AC, Liu CC. Rapid generation of potent antibodies by autonomous hypermutation in yeast. Nat Chem Biol 2021; 17:1057-1064. [PMID: 34168368 DOI: 10.1038/s41589-021-00832-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 06/11/2021] [Indexed: 12/11/2022]
Abstract
The predominant approach for antibody generation remains animal immunization, which can yield exceptionally selective and potent antibody clones owing to the powerful evolutionary process of somatic hypermutation. However, animal immunization is inherently slow, not always accessible and poorly compatible with many antigens. Here, we describe 'autonomous hypermutation yeast surface display' (AHEAD), a synthetic recombinant antibody generation technology that imitates somatic hypermutation inside engineered yeast. By encoding antibody fragments on an error-prone orthogonal DNA replication system, surface-displayed antibody repertoires continuously mutate through simple cycles of yeast culturing and enrichment for antigen binding to produce high-affinity clones in as little as two weeks. We applied AHEAD to generate potent nanobodies against the SARS-CoV-2 S glycoprotein, a G-protein-coupled receptor and other targets, offering a template for streamlined antibody generation at large.
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Affiliation(s)
- Alon Wellner
- Department of Biomedical Engineering, University of California, Irvine, CA, USA
| | - Conor McMahon
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.,Vertex Pharmaceuticals, Boston, MA, USA
| | - Morgan S A Gilman
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Jonathan R Clements
- Department of Biomedical Engineering, University of California, Irvine, CA, USA
| | - Sarah Clark
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Kianna M Nguyen
- Department of Biomedical Engineering, University of California, Irvine, CA, USA
| | - Ming H Ho
- Department of Biomedical Engineering, University of California, Irvine, CA, USA
| | - Vincent J Hu
- Department of Biomedical Engineering, University of California, Irvine, CA, USA
| | - Jung-Eun Shin
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - Jared Feldman
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA
| | - Blake M Hauser
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA
| | | | - Laura M Wingler
- Department of Medicine, Duke University Medical Center, Durham, NC, USA.,Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC, USA.,Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA
| | - Aaron G Schmidt
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.,Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA
| | - Debora S Marks
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA.,Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Jonathan Abraham
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.,Broad Institute of Harvard and MIT, Cambridge, MA, USA.,Department of Medicine, Division of Infectious Diseases, Brigham and Women's Hospital, Boston, MA, USA
| | - Andrew C Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
| | - Chang C Liu
- Department of Biomedical Engineering, University of California, Irvine, CA, USA. .,Department of Chemistry, University of California, Irvine, CA, USA. .,Department of Molecular Biology & Biochemistry, University of California, Irvine, CA, USA.
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17
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Wang H, Yan K, Wang R, Yang Y, Shen Y, Yu C, Chen L. Antibody heavy chain CDR3 length-dependent usage of human IGHJ4 and IGHJ6 germline genes. Antib Ther 2021; 4:101-108. [PMID: 34195544 PMCID: PMC8237691 DOI: 10.1093/abt/tbab010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 06/07/2021] [Accepted: 06/10/2021] [Indexed: 12/26/2022] Open
Abstract
Therapeutic antibody discovery using synthetic diversity has been proved productive, especially for target proteins not suitable for traditional animal immunization-based antibody discovery approaches. Recently, many lines of evidences suggest that the quality of synthetic diversity design limits the development success of synthetic antibody hits. The aim of our study is to understand the quality limitation and to properly address the challenges with a better design. Using VH3–23 as a model framework, we observed and quantitatively mapped CDR-H3 loop length-dependent usage of human IGHJ4 and IGHJ6 germline genes in the natural human immune repertoire. Skewed usage of DH2-JH6 and DH3-JH6 rearrangements was quantitatively determined in a CDR-H3 length-dependent manner in natural human antibodies with long CDR-H3 loops. Structural modeling suggests choices of JH help to stabilize antibody CDR-H3 loop and JH only partially contributes to the paratope. Our observations shed light on the design of next-generation synthetic diversity with improved probability of success.
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Affiliation(s)
- Huimin Wang
- College of Life Science and Technology, Beijing University of Chemical Technology, #15 Beisanhuandong Rd, Chaoyang District, Beijing 100029, China
| | - Kai Yan
- Biotherapeutics, Biocytogen Pharmaceuticals (Beijing) Co. Ltd., #12 Baoshennan St, Daxing District, Beijing 102629, China
| | - Ruixue Wang
- Biotherapeutics, Biocytogen Pharmaceuticals (Beijing) Co. Ltd., #12 Baoshennan St, Daxing District, Beijing 102629, China
| | - Yi Yang
- Biotherapeutics, Biocytogen Pharmaceuticals (Beijing) Co. Ltd., #12 Baoshennan St, Daxing District, Beijing 102629, China
| | - Yuelei Shen
- Biotherapeutics, Biocytogen Pharmaceuticals (Beijing) Co. Ltd., #12 Baoshennan St, Daxing District, Beijing 102629, China
| | - Changyuan Yu
- College of Life Science and Technology, Beijing University of Chemical Technology, #15 Beisanhuandong Rd, Chaoyang District, Beijing 100029, China
| | - Lei Chen
- Biotherapeutics, Biocytogen Pharmaceuticals (Beijing) Co. Ltd., #12 Baoshennan St, Daxing District, Beijing 102629, China
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18
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Wang S. Meet Our Associate Editorial Board Member. Recent Pat Anticancer Drug Discov 2021. [DOI: 10.2174/157489281601210324142135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Shanzhi Wang
- University of Arkansas at Little Rock Arkansas, United States
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19
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Oppezzo P, Navarrete M, Chiorazzi N. AID in Chronic Lymphocytic Leukemia: Induction and Action During Disease Progression. Front Oncol 2021; 11:634383. [PMID: 34041018 PMCID: PMC8141630 DOI: 10.3389/fonc.2021.634383] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/23/2021] [Indexed: 12/12/2022] Open
Abstract
The enzyme activation-induced cytidine deaminase (AID) initiates somatic hypermutation (SHM) and class switch recombination (CSR) of immunoglobulin (Ig) genes, critical actions for an effective adaptive immune response. However, in addition to the benefits generated by its physiological roles, AID is an etiological factor for the development of human and murine leukemias and lymphomas. This review highlights the pathological role of AID and the consequences of its actions on the development, progression, and therapeutic refractoriness of chronic lymphocytic leukemia (CLL) as a model disease for mature lymphoid malignancies. First, we summarize pertinent aspects of the expression and function of AID in normal B lymphocytes. Then, we assess putative causes for AID expression in leukemic cells emphasizing the role of an activated microenvironment. Thirdly, we discuss the role of AID in lymphomagenesis, in light of recent data obtained by NGS analyses on the genomic landscape of leukemia and lymphomas, concentrating on the frequency of AID signatures in these cancers and correlating previously described tumor-gene drivers with the presence of AID off-target mutations. Finally, we discuss how these changes could affect tumor suppressor and proto-oncogene targets and how they could be associated with disease progression. Collectively, we hope that these sections will help to better understand the complex paradox between the physiological role of AID in adaptive immunity and its potential causative activity in B-cell malignancies.
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Affiliation(s)
- Pablo Oppezzo
- Research Laboratory on Chronic Lymphocytic Leukemia, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | | | - Nicholas Chiorazzi
- The Karches Center for Oncology Research, The Feinstein Institutes for Medical Research, New York, NY, United States
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20
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Tang C, MacCarthy T. Characterization of DNA G-Quadruplex Structures in Human Immunoglobulin Heavy Variable (IGHV) Genes. Front Immunol 2021; 12:671944. [PMID: 34040612 PMCID: PMC8141862 DOI: 10.3389/fimmu.2021.671944] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 04/12/2021] [Indexed: 11/21/2022] Open
Abstract
Activation-induced deaminase (AID) is a key enzyme involved in antibody diversification by initiating somatic hypermutation (SHM) and class-switch recombination (CSR) of the Immunoglobulin (Ig) loci. AID preferentially targets WRC (W=A/T, R=A/G) hotspot motifs and avoids SYC (S=C/G, Y=C/T) coldspots. G-quadruplex (G4) structures are four-stranded DNA secondary structures with key functions in transcription, translation and replication. In vitro studies have shown G4s to form and bind AID in Ig switch (S) regions. Alterations in the gene encoding AID can further disrupt AID-G4 binding and reduce CSR in vivo. However, it is still unclear whether G4s form in the variable (V) region, or how they may affect SHM. To assess the possibility of G4 formation in human V regions, we analyzed germline human Ig heavy chain V (IGHV) sequences, using a pre-trained deep learning model that predicts G4 potential. This revealed that many genes from the IGHV3 and IGHV4 families are predicted to have high G4 potential in the top and bottom strand, respectively. Different IGHV alleles also showed variability in G4 potential. Using a high-resolution (G4-seq) dataset of biochemically confirmed potential G4s in IGHV genes, we validated our computational predictions. G4-seq also revealed variation between S and V regions in the distribution of potential G4s, with the V region having overall reduced G4 abundance compared to the S region. The density of AGCT motifs, where two AGC hotspots overlap on both strands, was roughly 2.6-fold greater in the V region than the Constant (C) region, which does not mutate despite having predicted G4s at similar levels. However, AGCT motifs in both V and C regions were less abundant than in S regions. In silico mutagenesis experiments showed that G4 potentials were generally robust to mutation, although large deviations from germline states were found, mostly in framework regions. G4 potential is also associated with higher mutability of certain WRC hotspots on the same strand. In addition, CCC coldspots opposite a predicted G4 were shown to be targeted significantly more for mutation. Our overall assessment reveals plausible evidence of functional G4s forming in the Ig V region.
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Affiliation(s)
- Catherine Tang
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, United States
| | - Thomas MacCarthy
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, United States.,Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY, United States
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21
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Krantsevich A, Tang C, MacCarthy T. Correlations in Somatic Hypermutation Between Sites in IGHV Genes Can Be Explained by Interactions Between AID and/or Polη Hotspots. Front Immunol 2021; 11:618409. [PMID: 33603748 PMCID: PMC7884765 DOI: 10.3389/fimmu.2020.618409] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 12/18/2020] [Indexed: 12/27/2022] Open
Abstract
The somatic hypermutation (SHM) of Immunoglobulin (Ig) genes is a key process during antibody affinity maturation in B cells. The mutagenic enzyme activation induced deaminase (AID) is required for SHM and has a preference for WRC hotspots in DNA. Error-prone repair mechanisms acting downstream of AID introduce further mutations, including DNA polymerase eta (Polη), part of the non-canonical mismatch repair pathway (ncMMR), which preferentially generates mutations at WA hotspots. Previously proposed mechanistic models lead to a variety of predictions concerning interactions between hotspots, for example, how mutations in one hotspot will affect another hotspot. Using a large, high-quality, Ig repertoire sequencing dataset, we evaluated pairwise correlations between mutations site-by-site using an unbiased measure similar to mutual information which we termed “mutational association” (MA). Interactions are dominated by relatively strong correlations between nearby sites (short-range MAs), which can be almost entirely explained by interactions between overlapping hotspots for AID and/or Polη. We also found relatively weak dependencies between almost all sites throughout each gene (longer-range MAs), although these arise mostly as a statistical consequence of high pairwise mutation frequencies. The dominant short-range interactions are also highest within the most highly mutating IGHV sub-regions, such as the complementarity determining regions (CDRs), where there is a high hotspot density. Our results suggest that the hotspot preferences for AID and Polη have themselves evolved to allow for greater interactions between AID and/or Polη induced mutations.
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Affiliation(s)
- Artem Krantsevich
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, United States
| | - Catherine Tang
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, United States
| | - Thomas MacCarthy
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, United States.,Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY, United States
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22
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The Role of APOBECs in Viral Replication. Microorganisms 2020; 8:microorganisms8121899. [PMID: 33266042 PMCID: PMC7760323 DOI: 10.3390/microorganisms8121899] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/25/2020] [Accepted: 11/26/2020] [Indexed: 12/14/2022] Open
Abstract
Apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like (APOBEC) proteins are a diverse and evolutionarily conserved family of cytidine deaminases that provide a variety of functions from tissue-specific gene expression and immunoglobulin diversity to control of viruses and retrotransposons. APOBEC family expansion has been documented among mammalian species, suggesting a powerful selection for their activity. Enzymes with a duplicated zinc-binding domain often have catalytically active and inactive domains, yet both have antiviral function. Although APOBEC antiviral function was discovered through hypermutation of HIV-1 genomes lacking an active Vif protein, much evidence indicates that APOBECs also inhibit virus replication through mechanisms other than mutagenesis. Multiple steps of the viral replication cycle may be affected, although nucleic acid replication is a primary target. Packaging of APOBECs into virions was first noted with HIV-1, yet is not a prerequisite for viral inhibition. APOBEC antagonism may occur in viral producer and recipient cells. Signatures of APOBEC activity include G-to-A and C-to-T mutations in a particular sequence context. The importance of APOBEC activity for viral inhibition is reflected in the identification of numerous viral factors, including HIV-1 Vif, which are dedicated to antagonism of these deaminases. Such viral antagonists often are only partially successful, leading to APOBEC selection for viral variants that enhance replication or avoid immune elimination.
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23
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Ott JA, Harrison J, Flajnik MF, Criscitiello MF. Nurse shark T-cell receptors employ somatic hypermutation preferentially to alter alpha/delta variable segments associated with alpha constant region. Eur J Immunol 2020; 50:1307-1320. [PMID: 32346855 DOI: 10.1002/eji.201948495] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/02/2020] [Accepted: 04/24/2020] [Indexed: 12/25/2022]
Abstract
In addition to canonical TCR and BCR, cartilaginous fish assemble noncanonical TCR that employ various B-cell components. For example, shark T cells associate alpha (TCR-α) or delta (TCR-δ) constant (C) regions with Ig heavy chain (H) variable (V) segments or TCR-associated Ig-like V (TAILV) segments to form chimeric IgV-TCR, and combine TCRδC with both Ig-like and TCR-like V segments to form the doubly rearranging NAR-TCR. Activation-induced (cytidine) deaminase-catalyzed somatic hypermutation (SHM), typically used for B-cell affinity maturation, also is used by TCR-α during selection in the shark thymus presumably to salvage failing receptors. Here, we found that the use of SHM by nurse shark TCR varies depending on the particular V segment or C region used. First, SHM significantly alters alpha/delta V (TCRαδV) segments using TCR αC but not δC. Second, mutation to IgHV segments associated with TCR δC was reduced compared to mutation to TCR αδV associated with TCR αC. Mutation was present but limited in V segments of all other TCR chains including NAR-TCR. Unexpectedly, we found preferential rearrangement of the noncanonical IgHV-TCRδC over canonical TCR αδV-TCRδC receptors. The differential use of SHM may reveal how activation-induced (cytidine) deaminase targets V regions.
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Affiliation(s)
- Jeannine A Ott
- Comparative Immunogenetics Laboratory, Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
| | - Jenna Harrison
- Comparative Immunogenetics Laboratory, Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
| | - Martin F Flajnik
- Department of Microbiology and Immunology, School of Medicine, University of Maryland at Baltimore, Baltimore, MD, USA
| | - Michael F Criscitiello
- Comparative Immunogenetics Laboratory, Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA.,Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, Texas A&M University, College Station, TX, USA
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24
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Pham P, Malik S, Mak C, Calabrese PC, Roeder RG, Goodman MF. AID-RNA polymerase II transcription-dependent deamination of IgV DNA. Nucleic Acids Res 2020; 47:10815-10829. [PMID: 31566237 PMCID: PMC6846656 DOI: 10.1093/nar/gkz821] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 09/09/2019] [Accepted: 09/13/2019] [Indexed: 12/16/2022] Open
Abstract
Activation-induced deoxycytidine deaminase (AID) initiates somatic hypermutation (SHM) in immunoglobulin variable (IgV) genes to produce high-affinity antibodies. SHM requires IgV transcription by RNA polymerase II (Pol II). A eukaryotic transcription system including AID has not been reported previously. Here, we reconstitute AID-catalyzed deamination during Pol II transcription elongation in conjunction with DSIF transcription factor. C→T mutations occur at similar frequencies on non-transcribed strand (NTS) and transcribed strand (TS) DNA. In contrast, bacteriophage T7 Pol generates NTS mutations predominantly. AID-Pol II mutations are strongly favored in WRC and WGCW overlapping hot motifs (W = A or T, R = A or G) on both DNA strands. Single mutations occur on 70% of transcribed DNA clones. Mutations are correlated over a 15 nt distance in multiply mutated clones, suggesting that deaminations are catalyzed processively within a stalled or backtracked transcription bubble. Site-by-site comparisons for biochemical and human memory B-cell mutational spectra in an IGHV3-23*01 target show strongly favored deaminations occurring in the antigen-binding complementarity determining regions (CDR) compared to the framework regions (FW). By exhibiting consistency with B-cell SHM, our in vitro data suggest that biochemically defined reconstituted Pol II transcription systems can be used to investigate how, when and where AID is targeted.
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Affiliation(s)
- Phuong Pham
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Sohail Malik
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, NY 10065, USA
| | - Chiho Mak
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
| | - Peter C Calabrese
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Robert G Roeder
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, NY 10065, USA
| | - Myron F Goodman
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA.,Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
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25
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Tang C, Bagnara D, Chiorazzi N, Scharff MD, MacCarthy T. AID Overlapping and Polη Hotspots Are Key Features of Evolutionary Variation Within the Human Antibody Heavy Chain (IGHV) Genes. Front Immunol 2020; 11:788. [PMID: 32425948 PMCID: PMC7204545 DOI: 10.3389/fimmu.2020.00788] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 04/07/2020] [Indexed: 01/09/2023] Open
Abstract
Somatic hypermutation (SHM) of the immunoglobulin variable (IgV) loci is a key process in antibody affinity maturation. The enzyme activation-induced deaminase (AID), initiates SHM by creating C → U mismatches on single-stranded DNA (ssDNA). AID has preferential hotspot motif targets in the context of WRC/GYW (W = A/T, R = A/G, Y = C/T) and particularly at WGCW overlapping hotspots where hotspots appear opposite each other on both strands. Subsequent recruitment of the low-fidelity DNA repair enzyme, Polymerase eta (Polη), during mismatch repair, creates additional mutations at WA/TW sites. Although there are more than 50 functional immunoglobulin heavy chain variable (IGHV) segments in humans, the fundamental differences between these genes and their ability to respond to all possible foreign antigens is still poorly understood. To better understand this, we generated profiles of WGCW hotspots in each of the human IGHV genes and found the expected high frequency in complementarity determining regions (CDRs) that encode the antigen binding sites but also an unexpectedly high frequency of WGCW in certain framework (FW) sub-regions. Principal Components Analysis (PCA) of these overlapping AID hotspot profiles revealed that one major difference between IGHV families is the presence or absence of WGCW in a sub-region of FW3 sometimes referred to as “CDR4.” Further differences between members of each family (e.g., IGHV1) are primarily determined by their WGCW densities in CDR1. We previously suggested that the co-localization of AID overlapping and Polη hotspots was associated with high mutability of certain IGHV sub-regions, such as the CDRs. To evaluate the importance of this feature, we extended the WGCW profiles, combining them with local densities of Polη (WA) hotspots, thus describing the co-localization of both types of hotspots across all IGHV genes. We also verified that co-localization is associated with higher mutability. PCA of the co-localization profiles showed CDR1 and CDR2 as being the main contributors to variance among IGHV genes, consistent with the importance of these sub-regions in antigen binding. Our results suggest that AID overlapping (WGCW) hotspots alone or in conjunction with Polη (WA/TW) hotspots are key features of evolutionary variation between IGHV genes.
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Affiliation(s)
- Catherine Tang
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, United States
| | - Davide Bagnara
- Karches Center for Oncology Research, The Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY, United States.,Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Nicholas Chiorazzi
- Karches Center for Oncology Research, The Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY, United States
| | - Matthew D Scharff
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Thomas MacCarthy
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, United States
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26
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Li X, Van Deventer JA, Hassoun S. ASAP-SML: An antibody sequence analysis pipeline using statistical testing and machine learning. PLoS Comput Biol 2020; 16:e1007779. [PMID: 32339164 PMCID: PMC7205315 DOI: 10.1371/journal.pcbi.1007779] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 05/07/2020] [Accepted: 03/08/2020] [Indexed: 11/18/2022] Open
Abstract
Antibodies are capable of potently and specifically binding individual antigens and, in some cases, disrupting their functions. The key challenge in generating antibody-based inhibitors is the lack of fundamental information relating sequences of antibodies to their unique properties as inhibitors. We develop a pipeline, Antibody Sequence Analysis Pipeline using Statistical testing and Machine Learning (ASAP-SML), to identify features that distinguish one set of antibody sequences from antibody sequences in a reference set. The pipeline extracts feature fingerprints from sequences. The fingerprints represent germline, CDR canonical structure, isoelectric point and frequent positional motifs. Machine learning and statistical significance testing techniques are applied to antibody sequences and extracted feature fingerprints to identify distinguishing feature values and combinations thereof. To demonstrate how it works, we applied the pipeline on sets of antibody sequences known to bind or inhibit the activities of matrix metalloproteinases (MMPs), a family of zinc-dependent enzymes that promote cancer progression and undesired inflammation under pathological conditions, against reference datasets that do not bind or inhibit MMPs. ASAP-SML identifies features and combinations of feature values found in the MMP-targeting sets that are distinct from those in the reference sets.
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Affiliation(s)
- Xinmeng Li
- Department of Computer Science, Tufts University, Massachusetts, United States of America
| | - James A. Van Deventer
- Department of Chemical and Biological Engineering, Tufts University, Massachusetts, United States of America
- Department of Biomedical Engineering, Tufts University, Massachusetts, United States of America
| | - Soha Hassoun
- Department of Computer Science, Tufts University, Massachusetts, United States of America
- Department of Chemical and Biological Engineering, Tufts University, Massachusetts, United States of America
- * E-mail:
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27
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Singh GB, Byun H, Ali AF, Medina F, Wylie D, Shivram H, Nash AK, Lozano MM, Dudley JP. A Protein Antagonist of Activation-Induced Cytidine Deaminase Encoded by a Complex Mouse Retrovirus. mBio 2019; 10:e01678-19. [PMID: 31409681 PMCID: PMC6692512 DOI: 10.1128/mbio.01678-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 07/08/2019] [Indexed: 01/27/2023] Open
Abstract
Complex human-pathogenic retroviruses cause high morbidity and mortality worldwide, but resist antiviral drugs and vaccine development due to evasion of the immune response. A complex retrovirus, mouse mammary tumor virus (MMTV), requires replication in B and T lymphocytes for mammary gland transmission and is antagonized by the innate immune restriction factor murine Apobec3 (mA3). To determine whether the regulatory/accessory protein Rem affects innate responses to MMTV, a splice-donor mutant (MMTV-SD) lacking Rem expression was injected into BALB/c mice. Mammary tumors induced by MMTV-SD had a lower proviral load, lower incidence, and longer latency than mammary tumors induced by wild-type MMTV (MMTV-WT). MMTV-SD proviruses had many G-to-A mutations on the proviral plus strand, but also C-to-T transitions within WRC motifs. Similarly, a lymphomagenic MMTV variant lacking Rem expression showed decreased proviral loads and increased WRC motif mutations relative to those in wild-type-virus-induced tumors, consistent with activation-induced cytidine deaminase (AID) mutagenesis in lymphoid cells. These mutations are typical of the Apobec family member AID, a B-cell-specific mutagenic protein involved in antibody variable region hypermutation. In contrast, mutations in WRC motifs and proviral loads were similar in MMTV-WT and MMTV-SD proviruses from tumors in AID-insufficient mice. AID was not packaged in MMTV virions. Rem coexpression in transfection experiments led to AID proteasomal degradation. Our data suggest that rem specifies a human-pathogenic immunodeficiency virus type 1 (HIV-1) Vif-like protein that inhibits AID and antagonizes innate immunity during MMTV replication in lymphocytes.IMPORTANCE Complex retroviruses, such as human-pathogenic immunodeficiency virus type 1 (HIV-1), cause many human deaths. These retroviruses produce lifelong infections through viral proteins that interfere with host immunity. The complex retrovirus mouse mammary tumor virus (MMTV) allows for studies of host-pathogen interactions not possible in humans. A mutation preventing expression of the MMTV Rem protein in two different MMTV strains decreased proviral loads in tumors and increased viral genome mutations typical of an evolutionarily ancient enzyme, AID. Although the presence of AID generally improves antibody-based immunity, it may contribute to human cancer progression. We observed that coexpression of MMTV Rem and AID led to AID destruction. Our results suggest that Rem is the first known protein inhibitor of AID and that further experiments could lead to new disease treatments.
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Affiliation(s)
- Gurvani B Singh
- Dept. of Molecular Biosciences, LaMontagne Center for Infectious Disease, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Hyewon Byun
- Dept. of Molecular Biosciences, LaMontagne Center for Infectious Disease, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Almas F Ali
- Dept. of Molecular Biosciences, LaMontagne Center for Infectious Disease, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Frank Medina
- Dept. of Molecular Biosciences, LaMontagne Center for Infectious Disease, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Dennis Wylie
- Computational Biology and Bioinformatics and Center for Biomedical Research Support, The University of Texas at Austin, Austin, Texas, USA
| | - Haridha Shivram
- Dept. of Molecular Biosciences, LaMontagne Center for Infectious Disease, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Andrea K Nash
- Dept. of Molecular Biosciences, LaMontagne Center for Infectious Disease, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Mary M Lozano
- Dept. of Molecular Biosciences, LaMontagne Center for Infectious Disease, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Jaquelin P Dudley
- Dept. of Molecular Biosciences, LaMontagne Center for Infectious Disease, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
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28
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Lim CC, Choong YS, Lim TS. Cognizance of Molecular Methods for the Generation of Mutagenic Phage Display Antibody Libraries for Affinity Maturation. Int J Mol Sci 2019; 20:E1861. [PMID: 30991723 PMCID: PMC6515083 DOI: 10.3390/ijms20081861] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 04/10/2019] [Accepted: 04/12/2019] [Indexed: 12/25/2022] Open
Abstract
Antibodies leverage on their unique architecture to bind with an array of antigens. The strength of interaction has a direct relation to the affinity of the antibodies towards the antigen. In vivo affinity maturation is performed through multiple rounds of somatic hypermutation and selection in the germinal centre. This unique process involves intricate sequence rearrangements at the gene level via molecular mechanisms. The emergence of in vitro display technologies, mainly phage display and recombinant DNA technology, has helped revolutionize the way antibody improvements are being carried out in the laboratory. The adaptation of molecular approaches in vitro to replicate the in vivo processes has allowed for improvements in the way recombinant antibodies are designed and tuned. Combinatorial libraries, consisting of a myriad of possible antibodies, are capable of replicating the diversity of the natural human antibody repertoire. The isolation of target-specific antibodies with specific affinity characteristics can also be accomplished through modification of stringent protocols. Despite the ability to screen and select for high-affinity binders, some 'fine tuning' may be required to enhance antibody binding in terms of its affinity. This review will provide a brief account of phage display technology used for antibody generation followed by a summary of different combinatorial library characteristics. The review will focus on available strategies, which include molecular approaches, next generation sequencing, and in silico approaches used for antibody affinity maturation in both therapeutic and diagnostic applications.
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Affiliation(s)
- Chia Chiu Lim
- Institute for Research in Molecular Medicine, Universiti Sains Malaysia, Penang 11800, Malaysia.
| | - Yee Siew Choong
- Institute for Research in Molecular Medicine, Universiti Sains Malaysia, Penang 11800, Malaysia.
| | - Theam Soon Lim
- Institute for Research in Molecular Medicine, Universiti Sains Malaysia, Penang 11800, Malaysia.
- Analytical Biochemistry Research Centre, Universiti Sains Malaysia, Penang 11800, Malaysia.
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29
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Vieira MC, Zinder D, Cobey S. Selection and Neutral Mutations Drive Pervasive Mutability Losses in Long-Lived Anti-HIV B-Cell Lineages. Mol Biol Evol 2019; 35:1135-1146. [PMID: 29688540 PMCID: PMC5913683 DOI: 10.1093/molbev/msy024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
High-affinity antibodies arise within weeks of infection from the evolution of B-cell receptors under selection to improve antigen recognition. This rapid adaptation is enabled by the distribution of highly mutable "hotspot" motifs in B-cell receptor genes. High mutability in antigen-binding regions (complementarity determining regions [CDRs]) creates variation in binding affinity, whereas low mutability in structurally important regions (framework regions [FRs]) may reduce the frequency of destabilizing mutations. During the response, loss of mutational hotspots and changes in their distribution across CDRs and FRs are predicted to compromise the adaptability of B-cell receptors, yet the contributions of different mechanisms to gains and losses of hotspots remain unclear. We reconstructed changes in anti-HIV B-cell receptor sequences and show that mutability losses were ∼56% more frequent than gains in both CDRs and FRs, with the higher relative mutability of CDRs maintained throughout the response. At least 21% of the total mutability loss was caused by synonymous mutations. However, nonsynonymous substitutions caused most (79%) of the mutability loss in CDRs. Because CDRs also show strong positive selection, this result suggests that selection for mutations that increase binding affinity contributed to loss of mutability in antigen-binding regions. Although recurrent adaptation to evolving viruses could indirectly select for high mutation rates, we found no evidence of indirect selection to increase or retain hotspots. Our results suggest mutability losses are intrinsic to both the neutral and adaptive evolution of B-cell populations and might constrain their adaptation to rapidly evolving pathogens such as HIV and influenza.
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Affiliation(s)
- Marcos C Vieira
- Department of Ecology and Evolution, University of Chicago, Chicago, IL
| | - Daniel Zinder
- Department of Ecology and Evolution, University of Chicago, Chicago, IL
| | - Sarah Cobey
- Department of Ecology and Evolution, University of Chicago, Chicago, IL
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30
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Koers J, Derksen NIL, Ooijevaar-de Heer P, Nota B, van de Bovenkamp FS, Vidarsson G, Rispens T. Biased N-Glycosylation Site Distribution and Acquisition across the Antibody V Region during B Cell Maturation. THE JOURNAL OF IMMUNOLOGY 2019; 202:2220-2228. [PMID: 30850477 DOI: 10.4049/jimmunol.1801622] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 02/01/2019] [Indexed: 12/28/2022]
Abstract
Abs can acquire N-linked glycans in their V regions during Ag-specific B cell responses. Among others, these N-linked glycans can affect Ag binding and Ab stability. Elevated N-linked glycosylation has furthermore been associated with several B cell-associated pathologies. Basic knowledge about patterns of V region glycosylation at different stages of B cell development is scarce. The aim of the current study is to establish patterns of N-glycosylation sites in Ab V regions of naive and memory B cell subsets. We analyzed the distribution and acquisition of N-glycosylation sites within Ab V regions of peripheral blood and bone marrow B cells of 12 healthy individuals, eight myasthenia gravis patients, and six systemic lupus erythematosus patients, obtained by next-generation sequencing. N-glycosylation sites are clustered around CDRs and the DE loop for both H and L chains, with similar frequencies for healthy donors and patients. No evidence was found for an overall selection bias against acquiring an N-glycosylation site, except for the CDR3 of the H chain. Interestingly, both IgE and IgG4 subsets have a 2-fold higher propensity to acquire Fab glycans compared with IgG1 or IgA. When expressed as rmAb, 35 out of 38 (92%) nongermline N-glycosylation sites became occupied. These results point toward a differential selection pressure of N-glycosylation site acquisition during affinity maturation of B cells, which depends on the location within the V region and is isotype and subclass dependent. Elevated Fab glycosylation represents an additional hallmark of TH2-like IgG4/IgE responses.
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Affiliation(s)
- Jana Koers
- Department of Immunopathology, Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center, University of Amsterdam, 1066 CX Amsterdam, the Netherlands;
| | - Ninotska I L Derksen
- Department of Immunopathology, Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center, University of Amsterdam, 1066 CX Amsterdam, the Netherlands
| | - Pleuni Ooijevaar-de Heer
- Department of Immunopathology, Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center, University of Amsterdam, 1066 CX Amsterdam, the Netherlands
| | - Benjamin Nota
- Department of Research Facilities, Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center, University of Amsterdam, 1066 CX Amsterdam, the Netherlands
| | - Fleur S van de Bovenkamp
- Department of Immunopathology, Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center, University of Amsterdam, 1066 CX Amsterdam, the Netherlands.,Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, 2333 ZA Leiden, the Netherlands; and
| | - Gestur Vidarsson
- Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center, University of Amsterdam, 1066 CX Amsterdam, the Netherlands
| | - Theo Rispens
- Department of Immunopathology, Sanquin Research and Landsteiner Laboratory, Amsterdam University Medical Center, University of Amsterdam, 1066 CX Amsterdam, the Netherlands
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31
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Yeap LS, Meng FL. Cis- and trans-factors affecting AID targeting and mutagenic outcomes in antibody diversification. Adv Immunol 2019; 141:51-103. [PMID: 30904133 DOI: 10.1016/bs.ai.2019.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Antigen receptor diversification is a hallmark of adaptive immunity which allows specificity of the receptor to particular antigen. B cell receptor (BCR) or its secreted form, antibody, is diversified through antigen-independent and antigen-dependent mechanisms. During B cell development in bone marrow, BCR is diversified via V(D)J recombination mediated by RAG endonuclease. Upon stimulation by antigen, B cell undergo somatic hypermutation (SHM) to allow affinity maturation and class switch recombination (CSR) to change the effector function of the antibody. Both SHM and CSR are initiated by activation-induced cytidine deaminase (AID). Repair of AID-initiated lesions through different DNA repair pathways results in diverse mutagenic outcomes. Here, we focus on discussing cis- and trans-factors that target AID to its substrates and factors that affect different outcomes of AID-initiated lesions. The knowledge of mechanisms that govern AID targeting and outcomes could be harnessed to elicit rare functional antibodies and develop ex vivo antibody diversification approaches with diversifying base editors.
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Affiliation(s)
- Leng-Siew Yeap
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Fei-Long Meng
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China.
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32
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Schramm CA, Douek DC. Beyond Hot Spots: Biases in Antibody Somatic Hypermutation and Implications for Vaccine Design. Front Immunol 2018; 9:1876. [PMID: 30154794 PMCID: PMC6102386 DOI: 10.3389/fimmu.2018.01876] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 07/30/2018] [Indexed: 11/15/2022] Open
Abstract
The evolution of antibodies in an individual during an immune response by somatic hypermutation (SHM) is essential for the ability of the immune system to recognize and remove the diverse spectrum of antigens that may be encountered. These mutations are not produced at random; nucleotide motifs that result in increased or decreased rates of mutation were first reported in 1992. Newer models that estimate the propensity for mutation for every possible 5- or 7-nucleotide motif have emphasized the complexity of SHM targeting and suggested possible new hot spot motifs. Even with these fine-grained approaches, however, non-local context matters, and the mutations observed at a specific nucleotide motif varies between species and even by locus, gene segment, and position along the gene segment within a single species. An alternative method has been provided to further abstract away the molecular mechanisms underpinning SHM, prompted by evidence that certain stereotypical amino acid substitutions are favored at each position of a particular V gene. These "substitution profiles," whether obtained from a single B cell lineage or an entire repertoire, offer a simplified approach to predict which substitutions will be well-tolerated and which will be disfavored, without the need to consider path-dependent effects from neighboring positions. However, this comes at the cost of merging the effects of two distinct biological processes, the generation of mutations, and the selection acting on those mutations. Since selection is contingent on the particular antigens an individual has been exposed to, this suggests that SHM may have evolved to prefer mutations that are most likely to be useful against pathogens that have co-evolved with us. Alternatively, the ability to select favorable mutations may be strongly limited by the biases of SHM targeting. In either scenario, the sequence space explored by SHM is significantly limited and this consequently has profound implications for the rational design of vaccine strategies.
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Affiliation(s)
- Chaim A. Schramm
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, United States
| | - Daniel C. Douek
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, United States
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33
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Caldwell RB, Braselmann H, Heuer S, Schötz U, Zitzelsberger H. Gain-of-function analysis of cis-acting diversification elements in DT40 cells. Immunol Cell Biol 2018; 96:948-957. [PMID: 29665088 DOI: 10.1111/imcb.12158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 04/09/2018] [Accepted: 04/09/2018] [Indexed: 02/02/2023]
Abstract
Activation-induced cytidine deaminase (AID) is required for the immunoglobulin diversification processes of somatic hypermutation, gene conversion and class-switch recombination. The targeting of AID's deamination activity is thought to be a combination of cis- and trans-acting elements, but has not been fully elucidated. Deletion analysis of putative proximal cis-regulatory motifs, while helpful, fails to identify additive versus cumulative effects, redundancy, and may create new motifs where none previously existed. In contrast, gain-of-function analysis can be more insightful with fewer of the same drawbacks and the output is a positive result. Here, we show five defined DNA regions of the avian Igλ locus that are sufficient to confer events of hypermutation to a target gene. In our analysis, the essential cis-targeting elements fully reconstituted diversification of a transgene under heterologous promotion in the avian B-cell line DT40. Furthermore, to the best of our knowledge two of the five regions we report on here have not previously been described as individually having an influence on somatic hypermutation.
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Affiliation(s)
- Randolph B Caldwell
- Department of Radiation Sciences - Research Unit Radiation Cytogenetics, Helmholtz Center Munich - German Research Center for Environmental Health (GmbH), Neuherberg, 85764, Germany
| | - Herbert Braselmann
- Department of Radiation Sciences - Research Unit Radiation Cytogenetics, Helmholtz Center Munich - German Research Center for Environmental Health (GmbH), Neuherberg, 85764, Germany
| | - Steffen Heuer
- Department of Radiation Sciences - Research Unit Radiation Cytogenetics, Helmholtz Center Munich - German Research Center for Environmental Health (GmbH), Neuherberg, 85764, Germany
| | - Ulrike Schötz
- Department of Radiotherapy and Radiooncology, Philipps-University Marburg, University Hospital Gießen and Marburg, Marburg, 35043, Germany
| | - Horst Zitzelsberger
- Department of Radiation Sciences - Research Unit Radiation Cytogenetics, Helmholtz Center Munich - German Research Center for Environmental Health (GmbH), Neuherberg, 85764, Germany.,Helmholtz Center Munich, Clinical Cooperation Group 'Personalized Radiotherapy of Head and Neck Cancer', Neuherberg, 85764, Germany.,Department of Radiotherapy and Radiation Oncology, Ludwig-Maximilians-Universitaet, University Hospital Munich, Munich, 81377, Germany
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Abstract
Long-term survivors of human immunodeficiency virus (HIV) infection have been shown to have a greatly increased incidence of B cell lymphomas. This increased lymphomagenesis suggests some link between HIV infection and the destabilization of the host B cell genome, a phenomenon also suggested by the extraordinary high frequency of mutation, insertion, and deletion in the broadly neutralizing HIV antibodies. Since HIV does not infect B cells, the molecular mechanisms of this genomic instability remain to be fully defined. Here, we demonstrate that the cell membrane-permeable HIV Tat proteins enhance activation-induced deaminase (AID)-mediated somatic hypermutation (SHM) of antibody V regions through their modulation of the endogenous polymerase II (Pol II) transcriptional process. Extremely small amounts of Tat that could come from bystander HIV-infected cells were sufficient to promote SHM. Our data suggest HIV Tat is one missing link between HIV infection and the overall B cell genomic instability in AIDS patients. Although the introduction of antiretroviral therapy (ART) has successfully controlled primary effects of human immunodeficiency virus (HIV) infection, such as HIV proliferation and HIV-induced immune deficiency, it did not eliminate the increased susceptibility of HIV-infected patients to B cell lymphomas. We find that a secreted HIV protein, Tat, enhances the intrinsic antibody diversification mechanism by increasing the AID-induced somatic mutations at the heavy-chain variable (VH) regions in human B cells. This could contribute to the high rate of mutation in the variable regions of broadly neutralizing anti-HIV antibodies and the genomewide mutations leading to B cell malignancies in HIV carriers.
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Ott JA, Castro CD, Deiss TC, Ohta Y, Flajnik MF, Criscitiello MF. Somatic hypermutation of T cell receptor α chain contributes to selection in nurse shark thymus. eLife 2018; 7:28477. [PMID: 29664399 PMCID: PMC5931798 DOI: 10.7554/elife.28477] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 04/16/2018] [Indexed: 12/17/2022] Open
Abstract
Since the discovery of the T cell receptor (TcR), immunologists have assigned somatic hypermutation (SHM) as a mechanism employed solely by B cells to diversify their antigen receptors. Remarkably, we found SHM acting in the thymus on α chain locus of shark TcR. SHM in developing shark T cells likely is catalyzed by activation-induced cytidine deaminase (AID) and results in both point and tandem mutations that accumulate non-conservative amino acid replacements within complementarity-determining regions (CDRs). Mutation frequency at TcRα was as high as that seen at B cell receptor loci (BcR) in sharks and mammals, and the mechanism of SHM shares unique characteristics first detected at shark BcR loci. Additionally, fluorescence in situ hybridization showed the strongest AID expression in thymic corticomedullary junction and medulla. We suggest that TcRα utilizes SHM to broaden diversification of the primary αβ T cell repertoire in sharks, the first reported use in vertebrates.
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Affiliation(s)
- Jeannine A Ott
- Comparative Immunogenetics Laboratory, Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, Texas, United States
| | - Caitlin D Castro
- Department of Microbiology and Immunology, University of Maryland at Baltimore, Baltimore, United States
| | - Thaddeus C Deiss
- Comparative Immunogenetics Laboratory, Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, Texas, United States
| | - Yuko Ohta
- Department of Microbiology and Immunology, University of Maryland at Baltimore, Baltimore, United States
| | - Martin F Flajnik
- Department of Microbiology and Immunology, University of Maryland at Baltimore, Baltimore, United States
| | - Michael F Criscitiello
- Comparative Immunogenetics Laboratory, Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, Texas, United States.,Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, Texas A&M University, Texas, United States
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36
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Castiblanco DP, Norton DD, Maul RW, Gearhart PJ. J H6 downstream intronic sequence is dispensable for RNA polymerase II accumulation and somatic hypermutation of the variable gene in Ramos cells. Mol Immunol 2018; 97:101-108. [PMID: 29625296 DOI: 10.1016/j.molimm.2018.03.031] [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: 01/04/2018] [Revised: 03/09/2018] [Accepted: 03/30/2018] [Indexed: 02/03/2023]
Abstract
Activation-induced deaminase (AID) introduces nucleotide substitutions within the variable region of immunoglobulin genes to promote antibody diversity. This activity, which is limited to 1.5 kb downstream of the variable gene promoter, mutates both the coding exon and downstream intronic sequences. We recently reported that RNA polymerase II accumulates in these regions during transcription in mice. This build-up directly correlates with the area that is accessible to AID, and manipulation of RNA polymerase II levels alters the mutation frequency. To address whether the intronic DNA sequence by itself can regulate RNA polymerase II accumulation and promote mutagenesis, we deleted 613 bp of DNA downstream of the JH6 intron in the human Ramos B cell line. The loss of this sequence did not alter polymerase abundance or mutagenesis in the variable gene, suggesting that most of the intronic sequence is dispensable for somatic hypermutation.
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Affiliation(s)
- Diana P Castiblanco
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Darrell D Norton
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
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Abstract
Somatic assembly of T cell receptor and B cell receptor (BCR) genes produces a vast diversity of lymphocyte antigen recognition capacity. The advent of efficient high-throughput sequencing of lymphocyte antigen receptor genes has recently generated unprecedented opportunities for exploration of adaptive immune responses. With these opportunities have come significant challenges in understanding the analysis techniques that most accurately reflect underlying biological phenomena. In this regard, sample preparation and sequence analysis techniques, which have largely been borrowed and adapted from other fields, continue to evolve. Here, we review current methods and challenges of library preparation, sequencing and statistical analysis of lymphocyte receptor repertoire studies. We discuss the general steps in the process of immune repertoire generation including sample preparation, platforms available for sequencing, processing of sequencing data, measurable features of the immune repertoire, and the statistical tools that can be used for analysis and interpretation of the data. Because BCR analysis harbors additional complexities, such as immunoglobulin (Ig) (i.e., antibody) gene somatic hypermutation and class switch recombination, the emphasis of this review is on Ig/BCR sequence analysis.
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Affiliation(s)
- Neha Chaudhary
- Division of Rheumatology, Department of Medicine, Immunology and Allergy, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
| | - Duane R. Wesemann
- Division of Rheumatology, Department of Medicine, Immunology and Allergy, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
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38
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Álvarez-Prado ÁF, Pérez-Durán P, Pérez-García A, Benguria A, Torroja C, de Yébenes VG, Ramiro AR. A broad atlas of somatic hypermutation allows prediction of activation-induced deaminase targets. J Exp Med 2018; 215:761-771. [PMID: 29374026 PMCID: PMC5839764 DOI: 10.1084/jem.20171738] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 11/22/2017] [Accepted: 12/21/2017] [Indexed: 12/18/2022] Open
Abstract
Activation-induced deaminase (AID) initiates antibody diversification in germinal center (GC) B cells through the deamination of cytosines on immunoglobulin genes. AID can also target other regions in the genome, triggering mutations or chromosome translocations, with major implications for oncogenic transformation. However, understanding the specificity of AID has proved extremely challenging. We have sequenced at very high depth >1,500 genomic regions from GC B cells and identified 275 genes targeted by AID, including 30 of the previously known 35 AID targets. We have also identified the most highly mutated hotspot for AID activity described to date. Furthermore, integrative analysis of the molecular features of mutated genes coupled to machine learning has produced a powerful predictive tool for AID targets. We also have found that base excision repair and mismatch repair back up each other to faithfully repair AID-induced lesions. Finally, our data establish a novel link between AID mutagenic activity and lymphomagenesis.
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Affiliation(s)
- Ángel F Álvarez-Prado
- B Cell Biology Lab, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Pablo Pérez-Durán
- B Cell Biology Lab, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Arantxa Pérez-García
- B Cell Biology Lab, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Alberto Benguria
- Genomics Unit, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Carlos Torroja
- Bioinformatics Unit, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Virginia G de Yébenes
- B Cell Biology Lab, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Almudena R Ramiro
- B Cell Biology Lab, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
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39
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Chen L, Duan Y, Benatuil L, Stine WB. Analysis of 5518 unique, productively rearranged human VH3-23*01 gene sequences reveals CDR-H3 length-dependent usage of the IGHD2 gene family. Protein Eng Des Sel 2017; 30:603-609. [PMID: 28472386 DOI: 10.1093/protein/gzx027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 04/18/2017] [Indexed: 01/16/2023] Open
Abstract
Clear and accurate understanding of diversity in antibody complementarity-determining regions (CDRs) is critical for antibody discovery and engineering. Previous observations of antibody CDR-H3 diversity were based on analyzing available antibody sequences in the public databases. The results may not accurately reflect that of natural antibody repertoire due to erroneous species annotation and the presence of man-made CDR loop diversity in public antibody sequence databases. In this study, in a precisely controlled germline context, we explored the relationship between amino acid composition and CDR-H3 length using 5518 unique productively rearranged human VH3-23*01 gene sequences. CDR-H3 length-dependent usage of the Cys-Xn-Cys motif is reported here.
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Affiliation(s)
- Lei Chen
- Abbvie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, USA
| | - Yuanyuan Duan
- Data and Statistical Sciences, 100 Research Drive, Worcester, MA 01605, USA
| | - Lorenzo Benatuil
- Abbvie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, USA
| | - William B Stine
- Abbvie Bioresearch Center, 100 Research Drive, Worcester, MA 01605, USA
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40
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Thientosapol ES, Sharbeen G, Lau KKE, Bosnjak D, Durack T, Stevanovski I, Weninger W, Jolly CJ. Proximity to AGCT sequences dictates MMR-independent versus MMR-dependent mechanisms for AID-induced mutation via UNG2. Nucleic Acids Res 2017; 45:3146-3157. [PMID: 28039326 PMCID: PMC5389528 DOI: 10.1093/nar/gkw1300] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 12/16/2016] [Indexed: 11/30/2022] Open
Abstract
AID deaminates C to U in either strand of Ig genes, exclusively producing C:G/G:C to T:A/A:T transition mutations if U is left unrepaired. Error-prone processing by UNG2 or mismatch repair diversifies mutation, predominantly at C:G or A:T base pairs, respectively. Here, we show that transversions at C:G base pairs occur by two distinct processing pathways that are dictated by sequence context. Within and near AGCT mutation hotspots, transversion mutation at C:G was driven by UNG2 without requirement for mismatch repair. Deaminations in AGCT were refractive both to processing by UNG2 and to high-fidelity base excision repair (BER) downstream of UNG2, regardless of mismatch repair activity. We propose that AGCT sequences resist faithful BER because they bind BER-inhibitory protein(s) and/or because hemi-deaminated AGCT motifs innately form a BER-resistant DNA structure. Distal to AGCT sequences, transversions at G were largely co-dependent on UNG2 and mismatch repair. We propose that AGCT-distal transversions are produced when apyrimidinic sites are exposed in mismatch excision patches, because completion of mismatch repair would require bypass of these sites.
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Affiliation(s)
- Eddy Sanchai Thientosapol
- Centenary Institute, Royal Prince Alfred Hospital, Camperdown NSW 2050, and Sydney Medical School, The University of Sydney, Sydney NSW 2006, Australia
| | - George Sharbeen
- Centenary Institute, Royal Prince Alfred Hospital, Camperdown NSW 2050, and Sydney Medical School, The University of Sydney, Sydney NSW 2006, Australia
| | - K K Edwin Lau
- Centenary Institute, Royal Prince Alfred Hospital, Camperdown NSW 2050, and Sydney Medical School, The University of Sydney, Sydney NSW 2006, Australia
| | - Daniel Bosnjak
- Centenary Institute, Royal Prince Alfred Hospital, Camperdown NSW 2050, and Sydney Medical School, The University of Sydney, Sydney NSW 2006, Australia
| | - Timothy Durack
- Centenary Institute, Royal Prince Alfred Hospital, Camperdown NSW 2050, and Sydney Medical School, The University of Sydney, Sydney NSW 2006, Australia
| | - Igor Stevanovski
- Centenary Institute, Royal Prince Alfred Hospital, Camperdown NSW 2050, and Sydney Medical School, The University of Sydney, Sydney NSW 2006, Australia
| | - Wolfgang Weninger
- Centenary Institute, Royal Prince Alfred Hospital, Camperdown NSW 2050, and Sydney Medical School, The University of Sydney, Sydney NSW 2006, Australia
| | - Christopher J Jolly
- Centenary Institute, Royal Prince Alfred Hospital, Camperdown NSW 2050, and Sydney Medical School, The University of Sydney, Sydney NSW 2006, Australia
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41
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Sequence intrinsic somatic mutation mechanisms contribute to affinity maturation of VRC01-class HIV-1 broadly neutralizing antibodies. Proc Natl Acad Sci U S A 2017; 114:8614-8619. [PMID: 28747530 DOI: 10.1073/pnas.1709203114] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Variable regions of Ig chains provide the antigen recognition portion of B-cell receptors and derivative antibodies. Ig heavy-chain variable region exons are assembled developmentally from V, D, J gene segments. Each variable region contains three antigen-contacting complementarity-determining regions (CDRs), with CDR1 and CDR2 encoded by the V segment and CDR3 encoded by the V(D)J junction region. Antigen-stimulated germinal center (GC) B cells undergo somatic hypermutation (SHM) of V(D)J exons followed by selection for SHMs that increase antigen-binding affinity. Some HIV-1-infected human subjects develop broadly neutralizing antibodies (bnAbs), such as the potent VRC01-class bnAbs, that neutralize diverse HIV-1 strains. Mature VRC01-class bnAbs, including VRC-PG04, accumulate very high SHM levels, a property that hinders development of vaccine strategies to elicit them. Because many VRC01-class bnAb SHMs are not required for broad neutralization, high overall SHM may be required to achieve certain functional SHMs. To elucidate such requirements, we used a V(D)J passenger allele system to assay, in mouse GC B cells, sequence-intrinsic SHM-targeting rates of nucleotides across substrates representing maturation stages of human VRC-PG04. We identify rate-limiting SHM positions for VRC-PG04 maturation, as well as SHM hotspots and intrinsically frequent deletions associated with SHM. We find that mature VRC-PG04 has low SHM capability due to hotspot saturation but also demonstrate that generation of new SHM hotspots and saturation of existing hotspot regions (e.g., CDR3) does not majorly influence intrinsic SHM in unmutated portions of VRC-PG04 progenitor sequences. We discuss implications of our findings for bnAb affinity maturation mechanisms.
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42
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Yuan C, Chu CC, Yan XJ, Bagnara D, Chiorazzi N, MacCarthy T. The Number of Overlapping AID Hotspots in Germline IGHV Genes Is Inversely Correlated with Mutation Frequency in Chronic Lymphocytic Leukemia. PLoS One 2017; 12:e0167602. [PMID: 28125682 PMCID: PMC5268644 DOI: 10.1371/journal.pone.0167602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/16/2016] [Indexed: 02/07/2023] Open
Abstract
The targeting of mutations by Activation-Induced Deaminase (AID) is a key step in generating antibody diversity at the Immunoglobulin (Ig) loci but is also implicated in B-cell malignancies such as chronic lymphocytic leukemia (CLL). AID has previously been shown to preferentially deaminate WRC (W = A/T, R = A/G) hotspots. WGCW sites, which contain an overlapping WRC hotspot on both DNA strands, mutate at much higher frequency than single hotspots. Human Ig heavy chain (IGHV) genes differ in terms of WGCW numbers, ranging from 4 for IGHV3-48*03 to as many as 12 in IGHV1-69*01. An absence of V-region mutations in CLL patients ("IGHV unmutated", or U-CLL) is associated with a poorer prognosis compared to "IGHV mutated" (M-CLL) patients. The reasons for this difference are still unclear, but it has been noted that particular IGHV genes associate with U-CLL vs M-CLL. For example, patients with IGHV1-69 clones tend to be U-CLL with a poor prognosis, whereas patients with IGHV3-30 tend to be M-CLL and have a better prognosis. Another distinctive feature of CLL is that ~30% of (mostly poor prognosis) patients can be classified into "stereotyped" subsets, each defined by HCDR3 similarity, suggesting selection, possibly for a self-antigen. We analyzed >1000 IGHV genes from CLL patients and found a highly significant statistical relationship between the number of WGCW hotspots in the germline V-region and the observed mutation frequency in patients. However, paradoxically, this correlation was inverse, with V-regions with more WGCW hotspots being less likely to be mutated, i.e., more likely to be U-CLL. The number of WGCW hotspots in particular, are more strongly correlated with mutation frequency than either non-overlapping (WRC) hotspots or more general models of mutability derived from somatic hypermutation data. Furthermore, this correlation is not observed in sequences from the B cell repertoires of normal individuals and those with autoimmune diseases.
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Affiliation(s)
- Chaohui Yuan
- Department of Applied Mathematics and Statistics, Stony Brook University, NY, United States of America
| | - Charles C Chu
- The Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY, United States of America.,Departments of Medicine and Molecular Medicine, Hofstra Northwell School of Medicine, Hempstead, NY, United States of America
| | - Xiao-Jie Yan
- The Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY, United States of America
| | - Davide Bagnara
- The Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY, United States of America
| | - Nicholas Chiorazzi
- The Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY, United States of America.,Departments of Medicine and Molecular Medicine, Hofstra Northwell School of Medicine, Hempstead, NY, United States of America
| | - Thomas MacCarthy
- Department of Applied Mathematics and Statistics, Stony Brook University, NY, United States of America
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43
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Methot S, Di Noia J. Molecular Mechanisms of Somatic Hypermutation and Class Switch Recombination. Adv Immunol 2017; 133:37-87. [DOI: 10.1016/bs.ai.2016.11.002] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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44
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Kwong PD, Chuang G, DeKosky BJ, Gindin T, Georgiev IS, Lemmin T, Schramm CA, Sheng Z, Soto C, Yang A, Mascola JR, Shapiro L. Antibodyomics: bioinformatics technologies for understanding B-cell immunity to HIV-1. Immunol Rev 2017; 275:108-128. [PMID: 28133812 PMCID: PMC5516196 DOI: 10.1111/imr.12480] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Numerous antibodies have been identified from HIV-1-infected donors that neutralize diverse strains of HIV-1. These antibodies may provide the basis for a B cell-mediated HIV-1 vaccine. However, it has been unclear how to elicit similar antibodies by vaccination. To address this issue, we have undertaken an informatics-based approach to understand the genetic and immunologic processes controlling the development of HIV-1-neutralizing antibodies. As DNA sequencing comprises the fastest growing database of biological information, we focused on incorporating next-generation sequencing of B-cell transcripts to determine the origin, maturation pathway, and prevalence of broadly neutralizing antibody lineages (Antibodyomics1, 2, 4, and 6). We also incorporated large-scale robotic analyses of serum neutralization to identify and quantify neutralizing antibodies in donor cohorts (Antibodyomics3). Statistical analyses furnish another layer of insight (Antibodyomics5), with physical characteristics of antibodies and their targets through molecular dynamics simulations (Antibodyomics7) and free energy perturbation analyses (Antibodyomics8) providing information-rich output. Functional interrogation of individual antibodies (Antibodyomics9) and synthetic antibody libraries (Antibodyomics10) also yields multi-dimensional data by which to understand and improve antibodies. Antibodyomics, described here, thus comprise resolution-enhancing tools, which collectively embody an information-driven discovery engine aimed toward the development of effective B cell-based vaccines.
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Affiliation(s)
- Peter D. Kwong
- Vaccine Research CenterNational Institute of Allergy and Infectious DiseasesNational Institutes of HealthBethesdaMDUSA
- Department of Biochemistry & Molecular BiophysicsColumbia UniversityNew YorkNYUSA
| | - Gwo‐Yu Chuang
- Vaccine Research CenterNational Institute of Allergy and Infectious DiseasesNational Institutes of HealthBethesdaMDUSA
| | - Brandon J. DeKosky
- Vaccine Research CenterNational Institute of Allergy and Infectious DiseasesNational Institutes of HealthBethesdaMDUSA
| | - Tatyana Gindin
- Department of Biochemistry & Molecular BiophysicsColumbia UniversityNew YorkNYUSA
| | - Ivelin S. Georgiev
- Vanderbilt Vaccine Center and Department of Pathology, Microbiology, and ImmunologyVanderbilt University Medical CenterNashvilleTNUSA
| | - Thomas Lemmin
- Department of Pharmaceutical ChemistryUniversity of California San FranciscoSan FranciscoCAUSA
| | - Chaim A. Schramm
- Vaccine Research CenterNational Institute of Allergy and Infectious DiseasesNational Institutes of HealthBethesdaMDUSA
- Department of Biochemistry & Molecular BiophysicsColumbia UniversityNew YorkNYUSA
- Department of Systems BiologyColumbia UniversityNew YorkNYUSA
| | - Zizhang Sheng
- Department of Biochemistry & Molecular BiophysicsColumbia UniversityNew YorkNYUSA
- Department of Systems BiologyColumbia UniversityNew YorkNYUSA
| | - Cinque Soto
- Vaccine Research CenterNational Institute of Allergy and Infectious DiseasesNational Institutes of HealthBethesdaMDUSA
| | - An‐Suei Yang
- Genomics Research CenterAcademia SinicaTaipeiTaiwan
| | - John R. Mascola
- Vaccine Research CenterNational Institute of Allergy and Infectious DiseasesNational Institutes of HealthBethesdaMDUSA
| | - Lawrence Shapiro
- Vaccine Research CenterNational Institute of Allergy and Infectious DiseasesNational Institutes of HealthBethesdaMDUSA
- Department of Biochemistry & Molecular BiophysicsColumbia UniversityNew YorkNYUSA
- Department of Systems BiologyColumbia UniversityNew YorkNYUSA
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45
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Detanico T, Phillips M, Wysocki LJ. Functional Versatility of AGY Serine Codons in Immunoglobulin Variable Region Genes. Front Immunol 2016; 7:525. [PMID: 27920779 PMCID: PMC5118421 DOI: 10.3389/fimmu.2016.00525] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 11/10/2016] [Indexed: 11/13/2022] Open
Abstract
In systemic autoimmunity, autoantibodies directed against nuclear antigens (Ags) often arise by somatic hypermutation (SHM) that converts AGT and AGC (AGY) Ser codons into Arg codons. This can occur by three different single-base changes. Curiously, AGY Ser codons are far more abundant in complementarity-determining regions (CDRs) of IgV-region genes than expected for random codon use or from species-specific codon frequency data. CDR AGY codons are also more abundant than TCN Ser codons. We show that these trends hold even in cartilaginous fishes. Because AGC is a preferred target for SHM by activation-induced cytidine deaminase, we asked whether the AGY abundance was solely due to a selection pressure to conserve high mutability in CDRs regardless of codon context but found that this was not the case. Instead, AGY triplets were selectively enriched in the Ser codon reading frame. Motivated by reports implicating a functional role for poly/autoreactive specificities in antiviral antibodies, we also analyzed mutations at AGY in antibodies directed against a number of different viruses and found that mutations producing Arg codons in antiviral antibodies were indeed frequent. Unexpectedly, however, we also found that AGY codons mutated often to encode nearly all of the amino acids that are reported to provide the most frequent contacts with Ag. In many cases, mutations producing codons for these alternative amino acids in antiviral antibodies were more frequent than those producing Arg codons. Mutations producing each of these key amino acids required only single-base changes in AGY. AGY is the only codon group in which two-thirds of random mutations generate codons for these key residues. Finally, by directly analyzing X-ray structures of immune complexes from the RCSB protein database, we found that Ag-contact residues generated via SHM occurred more often at AGY than at any other codon group. Thus, preservation of AGY codons in antibody genes appears to have been driven by their exceptional functional versatility, despite potential autoreactive consequences.
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Affiliation(s)
- Thiago Detanico
- Department of Biomedical Research, National Jewish Health , Denver, CO , USA
| | - Matthew Phillips
- Department of Biomedical Research, National Jewish Health , Denver, CO , USA
| | - Lawrence J Wysocki
- Department of Biomedical Research, National Jewish Health, Denver, CO, USA; Department of Immunology University of Colorado School of Medicine, Denver, CO, USA
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Sheng Z, Schramm CA, Connors M, Morris L, Mascola JR, Kwong PD, Shapiro L. Effects of Darwinian Selection and Mutability on Rate of Broadly Neutralizing Antibody Evolution during HIV-1 Infection. PLoS Comput Biol 2016; 12:e1004940. [PMID: 27191167 PMCID: PMC4871536 DOI: 10.1371/journal.pcbi.1004940] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 04/24/2016] [Indexed: 01/09/2023] Open
Abstract
Accumulation of somatic mutations in antibody variable regions is critical for antibody affinity maturation, with HIV-1 broadly neutralizing antibodies (bnAbs) generally requiring years to develop. We recently found that the rate at which mutations accumulate decreases over time, but the mechanism governing this slowing is unclear. In this study, we investigated whether natural selection and/or mutability of the antibody variable region contributed significantly to observed decrease in rate. We used longitudinally sampled sequences of immunoglobulin transcripts of single lineages from each of 3 donors, as determined by next generation sequencing. We estimated the evolutionary rates of the complementarity determining regions (CDRs), which are most significant for functional selection, and found they evolved about 1.5- to 2- fold faster than the framework regions. We also analyzed the presence of AID hotspots and coldspots at different points in lineage development and observed an average decrease in mutability of less than 10 percent over time. Altogether, the correlation between Darwinian selection strength and evolutionary rate trended toward significance, especially for CDRs, but cannot fully explain the observed changes in evolutionary rate. The mutability modulated by AID hotspots and coldspots changes correlated only weakly with evolutionary rates. The combined effects of Darwinian selection and mutability contribute substantially to, but do not fully explain, evolutionary rate change for HIV-1-targeting bnAb lineages. In an infected individual, the HIV-1 Env gene evolves at a rate of about 0.015 substitutions per site per year. Changes in viral epitopes in turn stimulate the co-evolution of recognizing antibody lineages. We previously showed that young antibody lineages can evolve at a rate ~10-fold faster than observed for HIV-1 and the rate of antibody evolution decreases over time. Here we investigate two factors, Darwinian selection and genetic mutability, which have been shown to influence evolutionary rates in other settings. We quantified both of these factors for three broadly HIV-1-neutralizing antibody lineages, and analyzed the association of these factors with changes in evolutionary rate. We found that Darwinian selection is a major factor in the slowing of evolutionary rate, while genetic mutability modulates antibody evolutionary rate weakly. Moreover, the combined effects of the two factors are unlikely to fully account for the slowing of antibody evolutionary rate.
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Affiliation(s)
- Zizhang Sheng
- Department of Biochemistry and Molecular Biophysics and Department of Systems Biology, Columbia University, New York, New York, United States of America
| | - Chaim A. Schramm
- Department of Biochemistry and Molecular Biophysics and Department of Systems Biology, Columbia University, New York, New York, United States of America
| | - Mark Connors
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lynn Morris
- Center for HIV and STIs, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Center for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Congella, South Africa
| | - John R. Mascola
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Peter D. Kwong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lawrence Shapiro
- Department of Biochemistry and Molecular Biophysics and Department of Systems Biology, Columbia University, New York, New York, United States of America
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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Chen Z, Eder MD, Elos MT, Viboolsittiseri SS, Chen X, Wang JH. Interplay between Target Sequences and Repair Pathways Determines Distinct Outcomes of AID-Initiated Lesions. THE JOURNAL OF IMMUNOLOGY 2016; 196:2335-47. [PMID: 26810227 DOI: 10.4049/jimmunol.1502184] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 12/22/2015] [Indexed: 11/19/2022]
Abstract
Activation-induced deaminase (AID) functions by deaminating cytosines and causing U:G mismatches, a rate-limiting step of Ab gene diversification. However, precise mechanisms regulating AID deamination frequency remain incompletely understood. Moreover, it is not known whether different sequence contexts influence the preferential access of mismatch repair or uracil glycosylase (UNG) to AID-initiated U:G mismatches. In this study, we employed two knock-in models to directly compare the mutability of core Sμ and VDJ exon sequences and their ability to regulate AID deamination and subsequent repair process. We find that the switch (S) region is a much more efficient AID deamination target than the V region. Igh locus AID-initiated lesions are processed by error-free and error-prone repair. S region U:G mismatches are preferentially accessed by UNG, leading to more UNG-dependent deletions, enhanced by mismatch repair deficiency. V region mutation hotspots are largely determined by AID deamination. Recurrent and conserved S region motifs potentially function as spacers between AID deamination hotspots. We conclude that the pattern of mutation hotspots and DNA break generation is influenced by sequence-intrinsic properties, which regulate AID deamination and affect the preferential access of downstream repair. Our studies reveal an evolutionarily conserved role for substrate sequences in regulating Ab gene diversity and AID targeting specificity.
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Affiliation(s)
- Zhangguo Chen
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045; and Department of Biomedical Research, National Jewish Health, Denver, CO 80206
| | - Maxwell D Eder
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045; and
| | - Mihret T Elos
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045; and
| | - Sawanee S Viboolsittiseri
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045; and
| | - Xiaomi Chen
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045; and
| | - Jing H Wang
- Department of Immunology and Microbiology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045; and Department of Biomedical Research, National Jewish Health, Denver, CO 80206
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Yeap LS, Hwang JK, Du Z, Meyers RM, Meng FL, Jakubauskaitė A, Liu M, Mani V, Neuberg D, Kepler TB, Wang JH, Alt FW. Sequence-Intrinsic Mechanisms that Target AID Mutational Outcomes on Antibody Genes. Cell 2015; 163:1124-1137. [PMID: 26582132 DOI: 10.1016/j.cell.2015.10.042] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 09/01/2015] [Accepted: 10/13/2015] [Indexed: 12/27/2022]
Abstract
In activated B lymphocytes, AID initiates antibody variable (V) exon somatic hypermutation (SHM) for affinity maturation in germinal centers (GCs) and IgH switch (S) region DNA breaks (DSBs) for class-switch recombination (CSR). To resolve long-standing questions, we have developed an in vivo assay to study AID targeting of passenger sequences replacing a V exon. First, we find AID targets SHM hotspots within V exon and S region passengers at similar frequencies and that the normal SHM process frequently generates deletions, indicating that SHM and CSR employ the same mechanism. Second, AID mutates targets in diverse non-Ig passengers in GC B cells at levels similar to those of V exons, definitively establishing the V exon location as "privileged" for SHM. Finally, Peyer's patch GC B cells generate a reservoir of V exons that are highly mutated before selection for affinity maturation. We discuss the implications of these findings for harnessing antibody diversification mechanisms.
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Affiliation(s)
- Leng-Siew Yeap
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine at Boston Children's Hospital, and Department of Genetics, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Joyce K Hwang
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine at Boston Children's Hospital, and Department of Genetics, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Zhou Du
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine at Boston Children's Hospital, and Department of Genetics, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Robin M Meyers
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine at Boston Children's Hospital, and Department of Genetics, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Fei-Long Meng
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine at Boston Children's Hospital, and Department of Genetics, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Agnė Jakubauskaitė
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine at Boston Children's Hospital, and Department of Genetics, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Mengyuan Liu
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine at Boston Children's Hospital, and Department of Genetics, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Vinidhra Mani
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine at Boston Children's Hospital, and Department of Genetics, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Donna Neuberg
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Thomas B Kepler
- Department of Microbiology, Boston University School of Medicine, Boston, MA 02215, USA
| | - Jing H Wang
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine at Boston Children's Hospital, and Department of Genetics, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Frederick W Alt
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine at Boston Children's Hospital, and Department of Genetics, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
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49
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Cobey S, Wilson P, Matsen FA. The evolution within us. Philos Trans R Soc Lond B Biol Sci 2015; 370:20140235. [PMID: 26194749 PMCID: PMC4528412 DOI: 10.1098/rstb.2014.0235] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2015] [Indexed: 01/05/2023] Open
Abstract
The B-cell immune response is a remarkable evolutionary system found in jawed vertebrates. B-cell receptors, the membrane-bound form of antibodies, are capable of evolving high affinity to almost any foreign protein. High germline diversity and rapid evolution upon encounter with antigen explain the general adaptability of B-cell populations, but the dynamics of repertoires are less well understood. These dynamics are scientifically and clinically important. After highlighting the remarkable characteristics of naive and experienced B-cell repertoires, especially biased usage of genes encoding the B-cell receptors, we contrast methods of sequence analysis and their attempts to explain patterns of B-cell evolution. These phylogenetic approaches are currently unlinked to explicit models of B-cell competition, which analyse repertoire evolution at the level of phenotype, the affinities and specificities to particular antigenic sites. The models, in turn, suggest how chance, infection history and other factors contribute to different patterns of immunodominance and protection between people. Challenges in rational vaccine design, specifically vaccines to induce broadly neutralizing antibodies to HIV, underscore critical gaps in our understanding of B cells' evolutionary and ecological dynamics.
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Affiliation(s)
- Sarah Cobey
- Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA
| | - Patrick Wilson
- Department of Medicine, University of Chicago, Chicago, IL 60637, USA Committee on Immunology, University of Chicago, Chicago, IL 60637, USA Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL 60637, USA
| | - Frederick A Matsen
- Computational Biology Program, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
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