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Dhakal S, Park HS, Seddu K, Lee JS, Creisher PS, Seibert B, Davis KM, Hernandez IR, Maul RW, Klein SL. Estradiol mediates greater germinal center responses to influenza vaccination in female than male mice. mBio 2024; 15:e0032624. [PMID: 38441028 PMCID: PMC11005424 DOI: 10.1128/mbio.00326-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 02/09/2024] [Indexed: 03/06/2024] Open
Abstract
Adult females of reproductive age develop greater antibody responses to inactivated influenza vaccines (IIV) than males. How sex, age, and sex steroid concentrations impact B cells and durability of IIV-induced immunity and protection over 4 months post-vaccination (mpv) was analyzed. Vaccinated adult females had greater germinal center B cell and plasmablast frequencies in lymphoid tissues, higher neutralizing antibody responses 1-4 mpv, and better protection against live H1N1 challenge than adult males. Aged mice, regardless of sex, had reduced B cell frequencies, less durable antibody responses, and inferior protection after challenge than adult mice, which correlated with diminished estradiol among aged females. To confirm that greater IIV-induced immunity was caused by sex hormones, four core genotype (FCG) mice were used, in which the testes-determining gene, Sry, was deleted from chromosome Y (ChrY) and transferred to Chr3 to separate gonadal sex (i.e., ovaries or testes) from sex chromosome complement (i.e., XX or XY complement). Vaccinated, gonadal female FCG mice (XXF and XYF) had greater numbers of B cells, higher antiviral antibody titers, and reduced pulmonary virus titers following live H1N1 challenge than gonadal FCG males (XYM and XXM). To establish that lower estradiol concentrations cause diminished immunity, adult and aged females received either a placebo or estradiol replacement therapy prior to IIV. Estradiol replacement significantly increased IIV-induced antibody responses and reduced morbidity after the H1N1 challenge among aged females. These data highlight that estradiol is a targetable mechanism mediating greater humoral immunity following vaccination among adult females.IMPORTANCEFemales of reproductive ages develop greater antibody responses to influenza vaccines than males. We hypothesized that female-biased immunity and protection against influenza were mediated by estradiol signaling in B cells. Using diverse mouse models ranging from advanced-age mice to transgenic mice that separate sex steroids from sex chromosome complement, those mice with greater concentrations of estradiol consistently had greater numbers of antibody-producing B cells in lymphoid tissue, higher antiviral antibody titers, and greater protection against live influenza virus challenge. Treatment of aged female mice with estradiol enhanced vaccine-induced immunity and protection against disease, suggesting that estradiol signaling in B cells is critical for improved vaccine outcomes in females.
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Affiliation(s)
- Santosh Dhakal
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Han-Sol Park
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Kumba Seddu
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - John S. Lee
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Patrick S. Creisher
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Brittany Seibert
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Kimberly M. Davis
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Isabella R. Hernandez
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Robert W. Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Sabra L. Klein
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
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Dhakal S, Park HS, Seddu K, Lee J, Creisher PS, Davis KM, Hernandez IR, Maul RW, Klein SL. Estradiol Mediates Greater Germinal Center Responses to Influenza Vaccination in Female than Male Mice. bioRxiv 2023:2023.11.27.568847. [PMID: 38077071 PMCID: PMC10705292 DOI: 10.1101/2023.11.27.568847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2023]
Abstract
Adult females of reproductive ages develop greater antibody responses to inactivated influenza vaccine (IIV) than males. How sex, age, and sex steroid changes impact B cells and durability of IIV-induced immunity and protection over 4-months post-vaccination (mpv) was analyzed. Vaccinated adult females had greater germinal center (GC) B cell and plasmablast frequencies in lymphoid tissues, higher neutralizing antibody responses 1-4 mpv, and better protection against live H1N1 challenge than adult males. Aged mice, regardless of sex, had reduced B cell frequencies, less durable antibody responses, and inferior protection after challenge than adult mice, which correlated with diminished estradiol among aged females. To confirm that greater IIV-induced immunity was caused by sex hormones, four core genotype (FCG) mice were used, in which the testes determining gene, Sry, was deleted from ChrY and transferred to Chr3, to separate gonadal sex (i.e., ovaries or testes) from sex chromosome complement (i.e., XX or XY complement). Vaccinated, gonadal female FCG mice (XXF and XYF) had greater numbers of B cells, higher antiviral antibody titers, and reduced pulmonary virus titers following live H1N1 challenge than gonadal FCG males (XYM and XXM). To establish that lower estradiol concentrations cause diminished immunity, adult and aged females received either a placebo or estradiol replacement therapy prior to IIV. Estradiol replacement significantly increased IIV-induced antibody responses and reduced morbidity after the H1N1 challenge among aged females. These data highlight that estradiol is a targetable mechanism mediating greater humoral immunity following vaccination among adult females.
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Affiliation(s)
- Santosh Dhakal
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Han-Sol Park
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Kumba Seddu
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - John Lee
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Patrick S. Creisher
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Kimberly M. Davis
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Isabella R. Hernandez
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Robert W. Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Sabra L. Klein
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
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Herman AB, Tsitsipatis D, Anerillas C, Mazan-Mamczarz K, Carr AE, Gregg JM, Wang M, Zhang J, Michel M, Henry-Smith C, Harris SC, Munk R, Martindale JL, Piao Y, Fan J, Mattison JA, De S, Abdelmohsen K, Maul RW, Tanaka T, Moore AZ, DeMouth ME, Sidoli S, Ferrucci L, Liu Y, de Cabo R, Lakatta EG, Gorospe M. DPP4 inhibition impairs senohemostasis to improve plaque stability in atherosclerotic mice. J Clin Invest 2023:165933. [PMID: 37097759 DOI: 10.1172/jci165933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023] Open
Abstract
Senescent vascular smooth muscle cells (VSMCs) accumulate in the vasculature with age and tissue damage, and secrete factors that promote atherosclerotic plaque vulnerability and disease. Here, we report increased levels and activity of dipeptidyl peptidase 4 (DPP4), a serine protease, in senescent VSMCs. Analysis of the conditioned media from senescent VSMCs revealed a unique senescence-associated secretory phenotype (SASP) signature comprising many complement and coagulation factors; silencing or inhibiting DPP4 reduced these factors and increased cell death. Serum samples from persons with high risk for cardiovascular disease contained high levels of DPP4-regulated complement and coagulation factors. Importantly, DPP4 inhibition reduced senescent cell burden and coagulation and improved plaque stability, while single-cell resolution of senescent VSMCs reflected the senomorphic and senolytic effects of DPP4 inhibition in murine atherosclerosis. We propose that DPP4-regulated factors could be exploited therapeutically to reduce senescent cell function, reverse senohemostasis, and improve vascular disease.
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Affiliation(s)
- Allison B Herman
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Dimitrios Tsitsipatis
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Carlos Anerillas
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Krystyna Mazan-Mamczarz
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Angelica E Carr
- Laboratory of Genetics and Genomic, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Jordan M Gregg
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Mingyi Wang
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Jing Zhang
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Marc Michel
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Charnae' Henry-Smith
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Sophia C Harris
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Rachel Munk
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Jennifer L Martindale
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Yulan Piao
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Jinshui Fan
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Julie A Mattison
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Supriyo De
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Kotb Abdelmohsen
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Toshiko Tanaka
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Ann Z Moore
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Megan E DeMouth
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, United States of America
| | - Simone Sidoli
- Department of Biochemistry, Albert Einstein College of Medcine, Bronx, United States of America
| | - Luigi Ferrucci
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Yie Liu
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Rafael de Cabo
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
| | - Myriam Gorospe
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, United States of America
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Martin OA, Thomas M, Marquet M, Bruzeau C, Garot A, Brousse M, Bender S, Carrion C, Choi JE, Vuong BQ, Gearhart PJ, Maul RW, Le Noir S, Pinaud E. The IgH Eµ-MAR regions promote UNG-dependent error-prone repair to optimize somatic hypermutation. Front Immunol 2023; 14:1030813. [PMID: 36865553 PMCID: PMC9971809 DOI: 10.3389/fimmu.2023.1030813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 01/13/2023] [Indexed: 02/16/2023] Open
Abstract
Intoduction Two scaffold/matrix attachment regions (5'- and 3'-MARsEµ ) flank the intronic core enhancer (cEµ) within the immunoglobulin heavy chain locus (IgH). Besides their conservation in mice and humans, the physiological role of MARsEµ is still unclear and their involvement in somatic hypermutation (SHM) has never been deeply evaluated. Methods Our study analyzed SHM and its transcriptional control in a mouse model devoid of MARsEµ , further combined to relevant models deficient for base excision repair and mismatch repair. Results We observed an inverted substitution pattern in of MARsEµ -deficient animals: SHM being decreased upstream from cEµ and increased downstream of it. Strikingly, the SHM defect induced by MARsEµ -deletion was accompanied by an increase of sense transcription of the IgH V region, excluding a direct transcription-coupled effect. Interestingly, by breeding to DNA repair-deficient backgrounds, we showed that the SHM defect, observed upstream from cEµ in this model, was not due to a decrease in AID deamination but rather the consequence of a defect in base excision repair-associated unfaithful repair process. Discussion Our study pointed out an unexpected "fence" function of MARsEµ regions in limiting the error-prone repair machinery to the variable region of Ig gene loci.
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Affiliation(s)
- Ophélie A Martin
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Morgane Thomas
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Marie Marquet
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Charlotte Bruzeau
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Armand Garot
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Mylène Brousse
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Sébastien Bender
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France.,Centre Hospitalier Universitaire Dupuytren, Service d'Immunopathologie, Limoges, France
| | - Claire Carrion
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Jee Eun Choi
- The Graduate Center, The City University of New York, New York, NY, United States
| | - Bao Q Vuong
- The Graduate Center, The City University of New York, New York, NY, United States
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Sandrine Le Noir
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
| | - Eric Pinaud
- Laboratoire Contrôle de la Réponse Immune B et des Lymphoproliférations (CRIBL), Université de Limoges, CNRS Unité Mixte de Recherche 7276, Inserm Unité 1262, Limoges, France
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Taylor JA, Hutchinson MA, Gearhart PJ, Maul RW. Antibodies in action: the role of humoral immunity in the fight against atherosclerosis. Immun Ageing 2022; 19:59. [PMID: 36461105 PMCID: PMC9717479 DOI: 10.1186/s12979-022-00316-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 11/21/2022] [Indexed: 12/03/2022]
Abstract
The sequestering of oxidation-modified low-density lipoprotein by macrophages results in the accumulation of fatty deposits within the walls of arteries. Necrosis of these cells causes a release of intercellular epitopes and the activation of the adaptive immune system, which we predict leads to robust autoantibody production. T cells produce cytokines that act in the plaque environment and further stimulate B cell antibody production. B cells in atherosclerosis meanwhile have a mixed role based on subclass. The current model is that B-1 cells produce protective IgM antibodies in response to oxidation-specific epitopes that work to control plaque formation, while follicular B-2 cells produce class-switched antibodies (IgG, IgA, and IgE) which exacerbate the disease. Over the course of this review, we discuss further the validation of these protective antibodies while evaluating the current dogma regarding class-switched antibodies in atherosclerosis. There are several contradictory findings regarding the involvement of class-switched antibodies in the disease. We hypothesize that this is due to antigen-specificity, and not simply isotype, being important, and that a closer evaluation of these antibodies' targets should be conducted. We propose that specific antibodies may have therapeutical potential in preventing and controlling plaque development within a clinical setting.
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Affiliation(s)
- Joshua A. Taylor
- grid.419475.a0000 0000 9372 4913Laboratory of Molecular Biology and Immunology, National Institute on Aging, NIH, Baltimore, MD USA ,grid.21107.350000 0001 2171 9311Graduate Program in Immunology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Mark A. Hutchinson
- grid.419475.a0000 0000 9372 4913Laboratory of Molecular Biology and Immunology, National Institute on Aging, NIH, Baltimore, MD USA
| | - Patricia J. Gearhart
- grid.419475.a0000 0000 9372 4913Laboratory of Molecular Biology and Immunology, National Institute on Aging, NIH, Baltimore, MD USA
| | - Robert W. Maul
- grid.419475.a0000 0000 9372 4913Laboratory of Molecular Biology and Immunology, National Institute on Aging, NIH, Baltimore, MD USA
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Ursin RL, Dhakal S, Liu H, Jayaraman S, Park HS, Powell HR, Sherer ML, Littlefield KE, Fink AL, Ma Z, Mueller AL, Chen AP, Seddu K, Woldetsadik YA, Gearhart PJ, Larman HB, Maul RW, Pekosz A, Klein SL. Greater Breadth of Vaccine-Induced Immunity in Females than Males Is Mediated by Increased Antibody Diversity in Germinal Center B Cells. mBio 2022; 13:e0183922. [PMID: 35856618 PMCID: PMC9426573 DOI: 10.1128/mbio.01839-22] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 07/01/2022] [Indexed: 11/20/2022] Open
Abstract
Inactivated influenza vaccines induce greater antibody responses in females than males among both humans and mice. To test the breadth of protection, we used recombinant mouse-adapted A/California/2009 (maA/Cal/09) H1N1 viruses containing mutations at one (1M), two (2M), or three (3M) antigenic sites, in addition to a virus containing the 1M mutation and a substitution of the Ca2 antigenic site (Sub) with one derived from an H5 hemagglutinin (HA) to challenge mice of both sexes. Following maA/Cal/09 vaccination, females produced greater virus-specific, class-switched total IgG and IgG2c antibodies against the vaccine and all mutant viruses, and antibodies from females recognized a greater number of unique, linear HA epitopes than did antibodies from males. While females had greater neutralizing antibody titers against the vaccine virus, both sexes showed a lower neutralization capacity against mutant viruses. After virus challenge, vaccinated females had lower pulmonary virus titers and reduced morbidity than males for the 1M and 2M viruses, but not the Sub virus. Females generated greater numbers of germinal center (GC) B cells containing superior somatic hypermutation (SHM) frequencies than vaccinated males. Deletion of activation-induced cytidine deaminase (Aicda) eliminated female-biased immunity and protection against the 2M virus. Harnessing methods to improve GC B cell responses and frequencies of SHM, especially in males, should be considered in the development of universal influenza vaccines. IMPORTANCE Adult females develop greater antibody responses to influenza vaccines than males. We hypothesized that female-biased immunity and protection would be dependent on the extent of virus diversity as well as molecular mechanisms in B cells which constrain the breadth of epitope recognition. We developed a panel of mouse-adapted (ma) A/Cal/09 viruses that had mutations in the immunodominant hemagglutinin. Following vaccination against maA/Cal/09, females were better able to neutralize maA/Cal/09 than males, but neutralization of mutant maA/Cal/09 viruses was equally poor in both sexes, despite vaccinated females being better protected against these viruses. Vaccinated females benefited from the greater production of class-switched, somatically hypermutated antibodies generated in germinal center B cells, which increased recognition of more diverse maA/Cal/09 hemagglutinin antigen epitopes. Female-biased protection against influenza infection and disease after vaccination is driven by differential mechanisms in males versus females and should be considered in the design of novel vaccine platforms.
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Affiliation(s)
- Rebecca L. Ursin
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Santosh Dhakal
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Hsuan Liu
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Sahana Jayaraman
- Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Han-Sol Park
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Harrison R. Powell
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Morgan L. Sherer
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Kirsten E. Littlefield
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Ashley L. Fink
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Zexu Ma
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Alice L. Mueller
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Allison P. Chen
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Kumba Seddu
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Yishak A. Woldetsadik
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Patricia J. Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - H. Benjamin Larman
- Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Robert W. Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Andrew Pekosz
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Sabra L. Klein
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
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7
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Taylor JA, Hutchinson MA, Gearhart PJ, Maul RW. Arterial antibodies promote atherosclerotic plaque development in mice. The Journal of Immunology 2022. [DOI: 10.4049/jimmunol.208.supp.48.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Abstract
Atherosclerosis is characterized by the progressive buildup of cholesterol-rich plaques within the arterial wall. Plaques activate the immune system, of which B cells play a major role. Antibodies bind autoantigens released from necrotic cells and form immune complexes to increase inflammation. We isolated aorta-associated B cells from atherosclerotic ApoE-deficient mice on a high-fat diet and performed single cell sequencing of the B cell receptors to obtain antibody pairs. 32 over-represented antibodies were identified and then expressed in Expi293F cells. Epitope determination of these antibodies was performed against a human proteome array, and 15 potential autoantigens bound the monoclonal antibodies with significant affinity and specificity. The 12 most-promising antigens were scrutinized for their location in plaque tissue by immunohistochemistry using the cognate antibodies. Nine of these relevant antigens were then successfully synthesized using the pET bacterial expression system, and purified proteins were used to interrogate antibodies in human and mouse sera by ELISA. Mice were then immunized with the 5 best antigens to confirm their immunogenicity. The relevant antigens and antibodies are now being tested to see if they will protect or promote atherosclerosis development, and if they can be used as biomarkers in human disease.
This research was supported in part by the Intramural Research Program of the NIH, National Institute on Aging.
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Affiliation(s)
- Joshua A Taylor
- 1LMBI, NIA, NIH
- 2Graduate Program in Immunology, Johns Hopkins Univ. Sch. of Med
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8
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Heltzel JHM, Maul RW, Yang W, Gearhart PJ. Promoter Proximity Defines Mutation Window for V H and V Κ Genes Rearranged to Different J Genes. J Immunol 2022; 208:2220-2226. [PMID: 35418469 PMCID: PMC9050841 DOI: 10.4049/jimmunol.2101002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 02/21/2022] [Indexed: 05/03/2023]
Abstract
Somatic hypermutation induced by activation-induced deaminase (AID) occurs at high densities between the Ig V gene promoter and intronic enhancer, which encompasses DNA encoding the rearranged V gene exon and J intron. It has been proposed that proximity between the promoter and enhancer defines the boundaries of mutation in V regions. However, depending on the J gene used, the distance between the promoter and enhancer is quite variable and may result in differential targeting around the V gene. To examine the effect of distance in mutation accumulation, we sequenced 320 clones containing different endogenous rearranged V genes in the IgH and Igκ loci from Peyer's patch B cells of mice. Clones were grouped by their use of different J genes. Distances between the V gene and enhancer ranged from ∼2.3 kb of intron DNA for rearrangements using J1, ∼2.0 kb for rearrangements using J2, ∼1.6 kb for rearrangements using J3 (H) or 4 (κ), and 1.1 kb for rearrangements using J4 (H) or 5 (κ). Strikingly, >90% of intron mutations occurred within 1 kb downstream of the J gene for both H and κ clones, regardless of which J gene was used. Thus, there is no evidence that the intron sequence or enhancer plays a role in determining the extent of mutation. The results indicate that V region intron mutations are targeted by their proximity to the promoter, suggesting they result from AID interactions with RNA polymerase II over a 1-kb region.
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Affiliation(s)
- Justin H M Heltzel
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD
| | - William Yang
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD
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9
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Ticas Rodas CJ, Greer BD, Maul RW, Gearhart PJ. Follicular B cells from old mice are hyper-responsive and produce non-specific antibodies. The Journal of Immunology 2022. [DOI: 10.4049/jimmunol.208.supp.112.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Immunosenescence is the increase in immune defects that occurs during aging. To identify any intrinsic defects in old B lymphocytes, we devised a transfer system to introduce follicular B cells from old mice (FOO, >22 months) or young mice (FOY, 8–12 weeks) into young mMT mice which have no B cells. Using this system, we observed that, compared to FOY cells, FOO cells do not produce antigen-specific antibodies to nitrophenyl (NP)-chicken gamma globulin after immunization. Examination of the germinal center (GC) response shows that FOO cells produced increased numbers of GC B cells which have divided faster than their FOY counterparts, but they have significantly decreased NP+ λ+ antigen-specificity. To understand the differences between FOO and FOY cells, single-cell RNAseq was performed on naïve and day 14 GC B cells. Comparing naïve populations revealed very few differences with only 387 differentially expressed genes between FOO and FOY cells. Interestingly, Ccr6 was upregulated in the FOO cells, suggesting that the cells were pre-activated before transfer into mMT mice. Antibody repertoire analysis also confirmed the lack of antigen-specificity in FOO cells, as the canonical NP-specific IgH V-gene, 1–72, was utilized in fewer cells and had zero instances of the CDR2 W33L mutation known to increase affinity. Taken together, old mice produce B cells which are pre-activated and hyper-responsive upon immunization, causing a lack of proper selection and affinity maturation in the GC.
This research was supported in part by the Intramural Research Program of the NIH, National Institute on Aging.
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10
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Butler TJ, Estep KN, Sommers JA, Maul RW, Moore AZ, Bandinelli S, Cucca F, Tuke MA, Wood AR, Bharti SK, Bogenhagen DF, Yakubovskaya E, Garcia-Diaz M, Guilliam TA, Byrd AK, Raney KD, Doherty AJ, Ferrucci L, Schlessinger D, Ding J, Brosh RM. Mitochondrial genetic variation is enriched in G-quadruplex regions that stall DNA synthesis in vitro. Hum Mol Genet 2021; 29:1292-1309. [PMID: 32191790 DOI: 10.1093/hmg/ddaa043] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 01/27/2020] [Accepted: 03/18/2020] [Indexed: 01/08/2023] Open
Abstract
As the powerhouses of the eukaryotic cell, mitochondria must maintain their genomes which encode proteins essential for energy production. Mitochondria are characterized by guanine-rich DNA sequences that spontaneously form unusual three-dimensional structures known as G-quadruplexes (G4). G4 structures can be problematic for the essential processes of DNA replication and transcription because they deter normal progression of the enzymatic-driven processes. In this study, we addressed the hypothesis that mitochondrial G4 is a source of mutagenesis leading to base-pair substitutions. Our computational analysis of 2757 individual genomes from two Italian population cohorts (SardiNIA and InCHIANTI) revealed a statistically significant enrichment of mitochondrial mutations within sequences corresponding to stable G4 DNA structures. Guided by the computational analysis results, we designed biochemical reconstitution experiments and demonstrated that DNA synthesis by two known mitochondrial DNA polymerases (Pol γ, PrimPol) in vitro was strongly blocked by representative stable G4 mitochondrial DNA structures, which could be overcome in a specific manner by the ATP-dependent G4-resolving helicase Pif1. However, error-prone DNA synthesis by PrimPol using the G4 template sequence persisted even in the presence of Pif1. Altogether, our results suggest that genetic variation is enriched in G-quadruplex regions that impede mitochondrial DNA replication.
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Affiliation(s)
- Thomas J Butler
- Translational Gerontology Branch, National Institute on Aging, Baltimore, MD 21224, USA
| | - Katrina N Estep
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Joshua A Sommers
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Ann Zenobia Moore
- Translational Gerontology Branch, National Institute on Aging, Baltimore, MD 21224, USA
| | | | - Francesco Cucca
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Monserrato 09042, Italy
| | - Marcus A Tuke
- Genetics of Complex Traits, University of Exeter Medical School, Exeter EX1 2LU, UK
| | - Andrew R Wood
- Genetics of Complex Traits, University of Exeter Medical School, Exeter EX1 2LU, UK
| | - Sanjay Kumar Bharti
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD 21224, USA
| | - Daniel F Bogenhagen
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794-8651, USA
| | - Elena Yakubovskaya
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794-8651, USA
| | - Miguel Garcia-Diaz
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794-8651, USA
| | - Thomas A Guilliam
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Alicia K Byrd
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Kevin D Raney
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Aidan J Doherty
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Luigi Ferrucci
- Translational Gerontology Branch, National Institute on Aging, Baltimore, MD 21224, USA
| | - David Schlessinger
- Laboratory of Genetics and Genomics, National Institute on Aging, Baltimore, MD 21224, USA
| | - Jun Ding
- Translational Gerontology Branch, National Institute on Aging, Baltimore, MD 21224, USA
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD 21224, USA
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11
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Hutchinson MA, Park HS, Zanotti KJ, Alvarez-Gonzalez J, Zhang J, Zhang L, Telljohann R, Wang M, Lakatta EG, Gearhart PJ, Maul RW. Auto-Antibody Production During Experimental Atherosclerosis in ApoE-/- Mice. Front Immunol 2021; 12:695220. [PMID: 34305930 PMCID: PMC8299997 DOI: 10.3389/fimmu.2021.695220] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 06/21/2021] [Indexed: 12/22/2022] Open
Abstract
Current models stipulate that B cells and antibodies function during atherosclerosis in two distinct ways based on antibody isotype, where IgM is protective and IgG is inflammatory. To examine this model, we generated ApoE-/- Aid-/- mice, which are unable to produce IgG antibodies due to the absence of activation-induced deaminase (AID) but maintain high plasma cholesterol due to the absence of apolipoprotein E (APOE). We saw a dramatic decrease in plaque formation in ApoE-/- Aid-/- mice compared to ApoE-/- mice. Rigorous analysis of serum antibodies revealed both ApoE-/- and ApoE-/- Aid-/- mice had substantially elevated titers of IgM antibodies compared to C57BL/6J controls, suggesting a more complex dynamic than previously described. Analysis of antigen specificity demonstrated that ApoE-/- Aid-/- mice had elevated titers of antibodies specific to malondialdehyde-oxidized low density lipoprotein (MDA-oxLDL), which has been shown to block macrophage recruitment into plaques. Conversely, ApoE-/- mice showed low levels of MDA-oxLDL specificity, but had antibodies specific to numerous self-proteins. We provide evidence for a hierarchical order of antibody specificity, where elevated levels of MDA-oxLDL specific IgM antibodies inhibit plaque formation. If the level of MDA-oxLDL specific IgM is insufficient, self-reactive IgM and IgG antibodies are generated against debris within the arterial plaque, resulting in increased inflammation and further plaque expansion.
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Affiliation(s)
- Mark A. Hutchinson
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Han-Sol Park
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Kimberly J. Zanotti
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Juan Alvarez-Gonzalez
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Jing Zhang
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Li Zhang
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Richard Telljohann
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Mingyi Wang
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Edward G. Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Patricia J. Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, NIH, Baltimore, MD, United States
| | - Robert W. Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, NIH, Baltimore, MD, United States
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12
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Alvarez-Gonzalez J, Yasgar A, Maul RW, Rieffer AE, Crawford DJ, Salamango DJ, Dorjsuren D, Zakharov AV, Jansen DJ, Rai G, Marugan J, Simeonov A, Harris RS, Kohli RM, Gearhart PJ. Small Molecule Inhibitors of Activation-Induced Deaminase Decrease Class Switch Recombination in B Cells. ACS Pharmacol Transl Sci 2021; 4:1214-1226. [PMID: 34151211 DOI: 10.1021/acsptsci.1c00064] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Indexed: 11/30/2022]
Abstract
Activation-induced deaminase (AID) not only mutates DNA within the immunoglobulin loci to generate antibody diversity, but it also promotes development of B cell lymphomas. To tame this mutagen, we performed a quantitative high-throughput screen of over 90 000 compounds to see if AID activity could be mitigated. The enzymatic activity was assessed in biochemical assays to detect cytosine deamination and in cellular assays to measure class switch recombination. Three compounds showed promise via inhibition of switching in a transformed B cell line and in murine splenic B cells. These compounds have similar chemical structures, which suggests a shared mechanism of action. Importantly, the inhibitors blocked AID, but not a related cytosine DNA deaminase, APOBEC3B. We further determined that AID was continually expressed for several days after B cell activation to induce switching. This first report of small molecules that inhibit AID can be used to gain regulatory control over base editors.
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Affiliation(s)
- Juan Alvarez-Gonzalez
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, United States
| | - Adam Yasgar
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, United States
| | - Amanda E Rieffer
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Daniel J Crawford
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Daniel J Salamango
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Dorjbal Dorjsuren
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Alexey V Zakharov
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Daniel J Jansen
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Ganesha Rai
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Juan Marugan
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Anton Simeonov
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Rahul M Kohli
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, United States
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13
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Maul RW, Catalina MD, Kumar V, Bachali P, Grammer AC, Wang S, Yang W, Hasni S, Ettinger R, Lipsky PE, Gearhart PJ. Transcriptome and IgH Repertoire Analyses Show That CD11c hi B Cells Are a Distinct Population With Similarity to B Cells Arising in Autoimmunity and Infection. Front Immunol 2021; 12:649458. [PMID: 33815408 PMCID: PMC8017342 DOI: 10.3389/fimmu.2021.649458] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 02/24/2021] [Indexed: 01/14/2023] Open
Abstract
A distinct B cell population marked by elevated CD11c expression is found in patients with systemic lupus erythematosus (SLE). Cells with a similar phenotype have been described during chronic infection, but variable gating strategies and nomenclature have led to uncertainty of their relationship to each other. We isolated CD11chi cells from peripheral blood and characterized them using transcriptome and IgH repertoire analyses. Gene expression data revealed the CD11chi IgD+ and IgD- subsets were highly similar to each other, but distinct from naive, memory, and plasma cell subsets. Although CD11chi B cells were enriched in some germinal center (GC) transcripts and expressed numerous negative regulators of B cell receptor (BCR) activation, they were distinct from GC B cells. Gene expression patterns from SLE CD11chi B cells were shared with other human diseases, but not with mouse age-associated B cells. IgH V-gene sequencing analysis showed IgD+ and IgD- CD11chi B cells had somatic hypermutation and were clonally related to each other and to conventional memory and plasma cells. However, the IgH repertoires expressed by the different subsets suggested that defects in negative selection during GC transit could contribute to autoimmunity. The results portray a pervasive B cell population that accumulates during autoimmunity and chronic infection and is refractory to BCR signaling.
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Affiliation(s)
- Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Michelle D Catalina
- AMPEL BioSolutions LLC, Charlottesville, VA, United States.,RILITE Foundation, Charlottesville, VA, United States
| | - Varsha Kumar
- Research and Early Development, Respiratory and Immunology, BioPharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, United States
| | - Prathyusha Bachali
- AMPEL BioSolutions LLC, Charlottesville, VA, United States.,RILITE Foundation, Charlottesville, VA, United States
| | - Amrie C Grammer
- AMPEL BioSolutions LLC, Charlottesville, VA, United States.,RILITE Foundation, Charlottesville, VA, United States
| | - Shu Wang
- Viela Bio, Gaithersburg, MD, United States
| | - William Yang
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Sarfaraz Hasni
- Lupus Clinical Research Program, Office of the Clinical Director, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD, United States
| | | | - Peter E Lipsky
- AMPEL BioSolutions LLC, Charlottesville, VA, United States.,RILITE Foundation, Charlottesville, VA, United States
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
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14
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Jones BG, Sealy RE, Penkert RR, Surman SL, Birshtein BK, Xu B, Neale G, Maul RW, Gearhart PJ, Hurwitz JL. From Influenza Virus Infections to Lupus: Synchronous Estrogen Receptor α and RNA Polymerase II Binding Within the Immunoglobulin Heavy Chain Locus. Viral Immunol 2020; 33:307-315. [PMID: 32105583 DOI: 10.1089/vim.2019.0144] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Males and females respond to pathogens differently and exhibit significantly different frequencies of autoimmune disease. For example, vaccinated adult females control influenza virus better than males, but females suffer systemic lupus erythematosus at a 9:1 frequency compared to males. Numerous explanations have been offered for these sex differences, but most have involved indirect mechanisms by which estrogen, a nuclear hormone, modifies cell barriers or immunity. In search of a direct mechanism, we examined the binding of estrogen receptor α (ERα), a class I nuclear hormone receptor, to the immunoglobulin heavy chain locus. Here, we show that in purified murine B cells, ERα and RNA polymerase II (RNA Pol II) exhibit extraordinarily similar DNA binding patterns. We further demonstrate that ERα preferentially binds adenosine-cytidine (AC)-repeats in the immunoglobulin heavy chain locus when supplemental estrogen is added to purified, lipopolysaccharide-activated B cells. Based on these and previous data, we hypothesize that (i) estrogen guides the binding of ERα and its RNA Pol II partner within the locus, which in turn instructs sterile transcription and class switch recombination (CSR), (ii) ERα binding to AC-repeats modifies the DNA architecture and loops associated with CSR, and (iii) by these mechanisms, estrogen instructs antibody expression. By targeting ERα-DNA interactions in the immunoglobulin heavy chain locus, clinicians may ultimately enhance antibody responses in the context of infectious diseases and reduce antibody responses in the context of allergic or autoimmune reactions.
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Affiliation(s)
- Bart G Jones
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Robert E Sealy
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Rhiannon R Penkert
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Sherri L Surman
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Barbara K Birshtein
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Beisi Xu
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Geoffrey Neale
- Hartwell Center for Bioinformatics and Biotechnology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Robert W Maul
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Patricia J Gearhart
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Julia L Hurwitz
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.,Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee, USA
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15
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Jones BG, Sealy RE, Penkert RR, Surman SL, Maul RW, Neale G, Xu B, Gearhart PJ, Hurwitz JL. Complex sex-biased antibody responses: estrogen receptors bind estrogen response elements centered within immunoglobulin heavy chain gene enhancers. Int Immunol 2020; 31:141-156. [PMID: 30407507 DOI: 10.1093/intimm/dxy074] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 11/02/2018] [Indexed: 01/10/2023] Open
Abstract
Nuclear hormone receptors including the estrogen receptor (ERα) and the retinoic acid receptor regulate a plethora of biological functions including reproduction, circulation and immunity. To understand how estrogen and other nuclear hormones influence antibody production, we characterized total serum antibody isotypes in female and male mice of C57BL/6J, BALB/cJ and C3H/HeJ mouse strains. Antibody levels were higher in females compared to males in all strains and there was a female preference for IgG2b production. Sex-biased patterns were influenced by vitamin levels, and by antigen specificity toward influenza virus or pneumococcus antigens. To help explain sex biases, we examined the direct effects of estrogen on immunoglobulin heavy chain sterile transcript production among purified, lipopolysaccharide-stimulated B cells. Supplemental estrogen in B-cell cultures significantly increased immunoglobulin heavy chain sterile transcripts. Chromatin immunoprecipitation analyses of activated B cells identified significant ERα binding to estrogen response elements (EREs) centered within enhancer elements of the immunoglobulin heavy chain locus, including the Eµ enhancer and hypersensitive site 1,2 (HS1,2) in the 3' regulatory region. The ERE in HS1,2 was conserved across animal species, and in humans marked a site of polymorphism associated with the estrogen-augmented autoimmune disease, lupus. Taken together, the results highlight: (i) the important targets of ERα in regulatory regions of the immunoglobulin heavy chain locus that influence antibody production, and (ii) the complexity of mechanisms by which estrogen instructs sex-biased antibody production profiles.
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Affiliation(s)
- Bart G Jones
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Danny Thomas Place, Memphis, USA
| | - Robert E Sealy
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Danny Thomas Place, Memphis, USA
| | - Rhiannon R Penkert
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Danny Thomas Place, Memphis, USA
| | - Sherri L Surman
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Danny Thomas Place, Memphis, USA
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Geoff Neale
- Hartwell Center for Bioinformatics & Biotechnology, St. Jude Children's Research Hospital, Memphis, USA
| | - Beisi Xu
- Computational Biology, St. Jude Children's Research Hospital, Memphis, USA
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Julia L Hurwitz
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Danny Thomas Place, Memphis, USA.,Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, USA
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16
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Jones BG, Penkert RR, Surman SL, Sealy RE, Pelletier S, Xu B, Neale G, Maul RW, Gearhart PJ, Hurwitz JL. Matters of life and death: How estrogen and estrogen receptor binding to the immunoglobulin heavy chain locus may influence outcomes of infection, allergy, and autoimmune disease. Cell Immunol 2019; 346:103996. [PMID: 31703914 DOI: 10.1016/j.cellimm.2019.103996] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/20/2019] [Accepted: 10/24/2019] [Indexed: 12/21/2022]
Abstract
Sex hormones are best known for their influences on reproduction, but they also have profound influences on the immune response. Examples of sex-specific differences include: (i) the relatively poor control of influenza virus infections in males compared to females, (ii) allergic asthma, an IgE-associated hypersensitivity reaction that is exacerbated in adolescent females compared to males, and (iii) systemic lupus erythematosus, a life-threatening autoimmune disease with a 9:1 female:male bias. Here we consider how estrogen and estrogen receptor α (ERα) may influence the immune response by modifying class switch recombination (CSR) and immunoglobulin expression patterns. We focus on ERα binding to enhancers (Eμ and the 3' regulatory region) and switch sites (Sµ and Sε) in the immunoglobulin heavy chain locus. Our preliminary data from ChIP-seq analyses of purified, activated B cells show estrogen-mediated changes in the positioning of ERα binding within and near Sµ and Sε. In the presence of estrogen, ERα is bound not only to estrogen response elements (ERE), but also to adenosine-cytidine (AC)-repeats and poly adenosine (poly A) sequences, in some cases within constant region gene introns. We propose that by binding these sites, estrogen and ERα directly participate in the DNA loop formation required for CSR. We further suggest that estrogen regulates immunoglobulin expression patterns and can thereby influence life-and-death outcomes of infection, hypersensitivity, and autoimmune disease.
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Affiliation(s)
- Bart G Jones
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Rhiannon R Penkert
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Sherri L Surman
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Robert E Sealy
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Stephane Pelletier
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Beisi Xu
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Geoff Neale
- Hartwell Center for Bioinformatics & Biotechnology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Robert W Maul
- National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Patricia J Gearhart
- National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - J L Hurwitz
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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17
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Ragonnaud E, Moritoh K, Bodogai M, Gusev F, Garaud S, Chen C, Wang X, Baljinnyam T, Becker KG, Maul RW, Willard-Gallo K, Rogaev E, Biragyn A. Tumor-Derived Thymic Stromal Lymphopoietin Expands Bone Marrow B-cell Precursors in Circulation to Support Metastasis. Cancer Res 2019; 79:5826-5838. [PMID: 31575547 DOI: 10.1158/0008-5472.can-19-1058] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 07/29/2019] [Accepted: 09/23/2019] [Indexed: 12/21/2022]
Abstract
Immature B cells in the bone marrow emigrate into the spleen during adult lymphopoiesis. Here, we report that emigration is shifted to earlier B-cell stages in mice with orthotopic breast cancer, spontaneous ovarian cancer, and possibly in human breast carcinoma. Using mouse and human bone marrow aspirates and mouse models challenged with highly metastatic 4T1 breast cancer cells, we demonstrated that this was the result of secretion of thymic stromal lymphopoietin (TSLP) by cancer cells. First, TSLP downregulated surface expression of bone marrow (BM) retention receptors CXCR4 and VLA4 in B-cell precursors, increasing their motility and, presumably, emigration. Then, TSLP supported peripheral survival and proliferation of BM B-cell precursors such as pre-B-like cells. 4T1 cancer cells used the increased pool of circulating pre-B-like cells to generate metastasis-supporting regulatory B cells. As such, the loss of TSLP expression in cancer cells alone or TSLPR deficiency in B cells blocked both accumulation of pre-B-like cells in circulation and cancer metastasis, implying that the pre-B cell-TSLP axis can be an attractive therapeutic target. SIGNIFICANCE: Cancer cells induce premature emigration of B-cell precursors from the bone marrow to generate regulatory B cells.
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Affiliation(s)
- Emeline Ragonnaud
- Immunoregulation Section, National Institute on Aging, Baltimore, Maryland
| | - Kanako Moritoh
- Immunoregulation Section, National Institute on Aging, Baltimore, Maryland
| | - Monica Bodogai
- Immunoregulation Section, National Institute on Aging, Baltimore, Maryland
| | - Fedor Gusev
- Department of Genomics and Human Genetics, Institute of General Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Soizic Garaud
- Molecular Immunology Unit, Jules Bordet Institute, Université Libre de Bruxelles, Brussels, Belgium
| | - Chen Chen
- Immunoregulation Section, National Institute on Aging, Baltimore, Maryland
| | - Xin Wang
- Immunoregulation Section, National Institute on Aging, Baltimore, Maryland
| | | | - Kevin G Becker
- Gene Expression and Genomics Unit, National Institute on Aging, Baltimore, Maryland
| | - Robert W Maul
- Antibody Diversity Section, Laboratory of Immunology and Molecular Biology, National Institute on Aging, Baltimore, Maryland
| | - Karen Willard-Gallo
- Center for Genetics and Genetic Technologies, Faculty of Biology, Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
| | - Evgeny Rogaev
- Department of Genomics and Human Genetics, Institute of General Genetics, Russian Academy of Sciences, Moscow, Russia
- Center for Genetics and Genetic Technologies, Faculty of Biology, Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia
- Department of Psychiatry, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Arya Biragyn
- Immunoregulation Section, National Institute on Aging, Baltimore, Maryland.
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18
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Russell Knode LM, Park HS, Maul RW, Gearhart PJ. B cells from young and old mice switch isotypes with equal frequencies after ex vivo stimulation. Cell Immunol 2019; 345:103966. [PMID: 31447053 DOI: 10.1016/j.cellimm.2019.103966] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 08/16/2019] [Accepted: 08/17/2019] [Indexed: 02/07/2023]
Abstract
To determine whether old B cells have the same capacity to switch isotypes as young cells, we purified splenic follicular, marginal zone, and age-associated B cell subsets from C57BL/6 mice. Cells were stimulated in culture with interleukin 4 and either lipopolysaccharide or anti-CD40, and switching to IgG1 was measured by flow cytometry of surface immunoglobulin. The results show that switching was robust in follicular and marginal zone B cells from old mice and was comparable to their young counterparts. However, age-associated B cells from old mice switched poorly relative to the other subsets. Expression of activation-induced deaminase, which initiates switching, was quantified by qPCR of mRNA, and it was equal between young and old follicular B cells. Thus, in this ex vivo system, the follicular and marginal zone cells from young and old mice behaved similarly, showing that the molecular machinery to perform switching is intact in old B cells.
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Affiliation(s)
- Lisa M Russell Knode
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, United States
| | - Han-Sol Park
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, United States
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, United States
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, United States.
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19
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Zhu WS, Naler L, Maul RW, Sallin MA, Sen JM. Immune system development and age-dependent maintenance in Klotho-hypomorphic mice. Aging (Albany NY) 2019; 11:5246-5257. [PMID: 31386628 PMCID: PMC6682518 DOI: 10.18632/aging.102121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 07/20/2019] [Indexed: 12/12/2022]
Abstract
Circulating Klotho peptide hormone has anti-aging activity and affects tissue maintenance. Hypomorphic mutant Klotho [kl/kl] mice on C57BL/6xC3H, BALB/c and 129 genetic backgrounds, show decreased Klotho expression that correlate with accelerated aging including pre-mature death due to abnormally high levels of serum vitamin D. These mice also show multiple impairments in the immune system. However, it remains unresolved if the defects in the immune system stem from decreased Klotho expression or high vitamin D levels in the serum. Transfer of the kl/kl allele to pure C57BL/6 genetic background [B6-kl/kl] significantly reduced expression of Klotho at all ages. Surprisingly, B6-kl/kl mice showed normalized serum vitamin D levels, amelioration of severe aging-related phenotypes and normal lifespan. This paper reports a detailed analysis of the immune system in B6-kl/kl mice in the absence of detrimental levels of serum vitamin D. Remarkably, the data reveal that in the absence of overt systemic stress, such as abnormally high vitamin D levels, reduced expression of Klotho does not have a major effect on the generation and maintenance of the immune system.
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Affiliation(s)
- Wandi Sandra Zhu
- National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.,Current address: Department of Immunology and Microbiology, University of California San Francisco, San Francisco, CA 94143, USA
| | - Lynette Naler
- National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.,Current address: Department of Chemical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Robert W Maul
- National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Michelle A Sallin
- National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Jyoti Misra Sen
- National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.,Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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20
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Zanotti KJ, Maul RW, Yang W, Gearhart PJ. DNA Breaks in Ig V Regions Are Predominantly Single Stranded and Are Generated by UNG and MSH6 DNA Repair Pathways. J Immunol 2019; 202:1573-1581. [PMID: 30665938 DOI: 10.4049/jimmunol.1801183] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 12/16/2018] [Indexed: 11/19/2022]
Abstract
Antibody diversity is initiated by activation-induced deaminase (AID), which deaminates cytosine to uracil in DNA. Uracils in the Ig gene loci can be recognized by uracil DNA glycosylase (UNG) or mutS homologs 2 and 6 (MSH2-MSH6) proteins, and then processed into DNA breaks. Breaks in switch regions of the H chain locus cause isotype switching and have been extensively characterized as staggered and blunt double-strand breaks. However, breaks in V regions that arise during somatic hypermutation are poorly understood. In this study, we characterize AID-dependent break formation in JH introns from mouse germinal center B cells. We used a ligation-mediated PCR assay to detect single-strand breaks and double-strand breaks that were either staggered or blunt. In contrast to switch regions, V regions contained predominantly single-strand breaks, which peaked 10 d after immunization. We then examined the pathways used to generate these breaks in UNG- and MSH6-deficient mice. Surprisingly, both DNA repair pathways contributed substantially to break formation, and in the absence of both UNG and MSH6, the frequency of breaks was severely reduced. When the breaks were sequenced and mapped, they were widely distributed over a 1000-bp intron region downstream of JH3 and JH4 exons and were unexpectedly located at all 4 nt. These data suggest that during DNA repair, nicks are generated at distal sites from the original deaminated cytosine, and these repair intermediates could generate both faithful and mutagenic repair. During mutagenesis, single-strand breaks would allow entry for low-fidelity DNA polymerases to generate somatic hypermutation.
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Affiliation(s)
- Kimberly J Zanotti
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
| | - William Yang
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
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21
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Pape KA, Maul RW, Dileepan T, Paustian AS, Gearhart PJ, Jenkins MK. Naive B Cells with High-Avidity Germline-Encoded Antigen Receptors Produce Persistent IgM + and Transient IgG + Memory B Cells. Immunity 2018; 48:1135-1143.e4. [PMID: 29884459 DOI: 10.1016/j.immuni.2018.04.019] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 02/20/2018] [Accepted: 04/17/2018] [Indexed: 12/11/2022]
Abstract
Although immune memory often lasts for life, this is not the case for certain vaccines in some individuals. We sought a mechanism for this phenomenon by studying B cell responses to phycoerythrin (PE). PE immunization of mouse strains with Ighb immunoglobulin (Ig) variable heavy chain (VH) genes elicited affinity-matured switched Ig memory B cells that declined with time, while the comparable population from an Igha strain was numerically stable. Ighb strains had larger numbers of PE-specific naive B cells and generated smaller germinal center responses and larger numbers of IgM memory cells than the Igha strain. The properties of PE-specific B cells in Ighb mice correlated with usage of a single VH that afforded high-affinity PE binding in its germline form. These results suggest that some individuals may be genetically predisposed to generate non-canonical memory B cell responses to certain antigens because of avid antigen binding via germline-encoded VH elements.
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Affiliation(s)
- Kathryn A Pape
- Department of Microbiology and Immunology, Center for Immunology, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224 USA
| | - Thamotharampillai Dileepan
- Department of Microbiology and Immunology, Center for Immunology, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | | | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224 USA
| | - Marc K Jenkins
- Department of Microbiology and Immunology, Center for Immunology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
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22
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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23
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Castiblanco DP, Maul RW, Russell Knode LM, Gearhart PJ. Co-Stimulation of BCR and Toll-Like Receptor 7 Increases Somatic Hypermutation, Memory B Cell Formation, and Secondary Antibody Response to Protein Antigen. Front Immunol 2017; 8:1833. [PMID: 29312329 PMCID: PMC5742111 DOI: 10.3389/fimmu.2017.01833] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 12/05/2017] [Indexed: 12/18/2022] Open
Abstract
The goal of immunization is to produce both a flood of antibodies to neutralize antigen and memory cells to accelerate the secondary response. To enhance the generation of memory B cells, we examined the effect of co-engaging BCR and toll-like receptor (TLR) 7 receptors by immunizing mice with a hapten-protein antigen, NP-CGG, and a ligand, R837 (imiquimod). During the early and late primary responses, there was no augmentation with R837 on the number of germinal center B cells or serum antibody. However, in the niche of germinal centers, R837 increased somatic hypermutation in the canonical VH1-72 gene that encodes NP-specific antibody. Increased mutation was not due to enhanced expression of activation-induced deaminase, but was likely a result of selection for high-affinity B cells with altered codons in the gene. This correlated with the appearance of antigen-specific B cells with a memory phenotype, which was intrinsic to TLR7 on B cells. To determine if these memory cells produced a recall response after a secondary challenge, spleen cells from mice that were immunized with NP-CGG and R837 were adoptively transferred into muMT recipients, and boosted with NP-CGG. Cells from mice that initially received both antigen and R837 generated a robust increase in germinal center B cells, plasmablasts, plasma cells, and serum antibody, compared with their cohorts who received antigen alone. These results support the use of co-immunization with TLR7 ligands to promote vigorous memory B cell responses to protein antigens.
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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, United States
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Lisa M Russell Knode
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
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24
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Alvarez-Gonzalez JA, Crawford DJ, Maul RW, Kohli RM, Gearhart PJ. Inhibiting a mutagen: mitigating Activation-Induced Deaminase activity. The Journal of Immunology 2017. [DOI: 10.4049/jimmunol.198.supp.195.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Activation-Induced Deaminase (AID) is a cytosine deaminase which converts cytosine into uracil within stretches of ssDNA. The presence of uracil in DNA initiates a cascade of mutagenic DNA repair to introduce point mutations and DNA double strand breaks. Specific targeting of AID to the immunoglobulin heavy chain loci (Igh) promotes mutagenesis in the antibody variable region for somatic hypermutation (SHM) or switch regions leading to class switch recombination (CSR). However, AID also plays a role in accumulating unnecessary mutations across the genome. Mis-targeting of AID results in the initiation of tumor development and leads to greater drug resistance among cancer cells when continually expressed. To identify an AID inhibitor, we screened ~400,000 compounds in conjunction with the NCATS core facility at NIH. Using FRET based analysis of cytosine deamination, we have identified approximately 150 potential inhibitors of AID catalytic activity. To confirm biological function, we have examined the compounds’ effects on CSR in an in vitro murine B-cell activation assay. Of 30 confirmed inhibitor candidates, we have selected the top 7 to proceed with further characterization to determine if they prevent uracil accumulation in primary mouse cells after ex vivo stimulation. Using these approaches, we hope to identify a small molecule with great efficacy and low toxicity for use as a molecular probe to further characterize AID’s intricacies, or even as a therapeutic.
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25
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Hutchinson MA, Maul RW, Gearhart PJ. Aortic B cells: Identifying antibodies specific for atherosclerosis in mice. The Journal of Immunology 2017. [DOI: 10.4049/jimmunol.198.supp.195.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Atherosclerosis is characterized by the development of arterial plaques containing lipid deposits and immune cells, such as B cells. Once recruited to the site of inflammation, B cells become activated and form germinal centers within the adventitia of the artery adjacent to the plaque. To determine if these B cells produce antibodies specific for atherosclerosis, abdominal aortas were collected, and germinal center B cells were isolated by flow cytometry. We characterized their heavy and light chain repertoires by next generation sequencing to compare non-diseased (C57BL/6) and diseased (ApoE−/−) tissues. Furthermore, the aortic repertoires were compared to the germinal center repertoires from spleens taken from the same mice to address whether local (aortic) and systemic (spleen) B cell responses were similar. Preliminary results suggest that all the splenic repertoires were similar, independent of diet or disease. However, aortic repertoires from ApoE−/− mice indicated that some VH and Vk genes were overexpressed, suggesting selection for particular antigens. We therefore performed single cell analysis and identified over 100 VH and Vk gene pairs, with different frequencies of expression and somatic hypermutation. Antibody gene pairs will then be cloned and expressed in culture using HEK293A cells. The purified recombinant antibodies will be used to identify antigens specific to atherosclerosis by protein array. These results may be useful in creating potential vaccines for its prevention, as well as treatment via antibody immunotherapy.
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26
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Maul RW, MacCarthy T, Frank EG, Donigan KA, McLenigan MP, Yang W, Saribasak H, Huston DE, Lange SS, Woodgate R, Gearhart PJ. DNA polymerase ι functions in the generation of tandem mutations during somatic hypermutation of antibody genes. J Exp Med 2016; 213:1675-83. [PMID: 27455952 PMCID: PMC4995076 DOI: 10.1084/jem.20151227] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 06/01/2016] [Indexed: 11/04/2022] Open
Abstract
DNA polymerase ι (Pol ι) is an attractive candidate for somatic hypermutation in antibody genes because of its low fidelity. To identify a role for Pol ι, we analyzed mutations in two strains of mice with deficiencies in the enzyme: 129 mice with negligible expression of truncated Pol ι, and knock-in mice that express full-length Pol ι that is catalytically inactive. Both strains had normal frequencies and spectra of mutations in the variable region, indicating that loss of Pol ι did not change overall mutagenesis. We next examined if Pol ι affected tandem mutations generated by another error-prone polymerase, Pol ζ. The frequency of contiguous mutations was analyzed using a novel computational model to determine if they occur during a single DNA transaction or during two independent events. Analyses of 2,000 mutations from both strains indicated that Pol ι-compromised mice lost the tandem signature, whereas C57BL/6 mice accumulated significant amounts of double mutations. The results support a model where Pol ι occasionally accesses the replication fork to generate a first mutation, and Pol ζ extends the mismatch with a second mutation.
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Affiliation(s)
- Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
| | - Thomas MacCarthy
- Department of Applied Mathematics and Statistics, State University of New York, Stony Brook, NY 11794
| | - Ekaterina G Frank
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD 20850
| | - Katherine A Donigan
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD 20850
| | - Mary P McLenigan
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD 20850
| | - William Yang
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
| | - Huseyin Saribasak
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
| | - Donald E Huston
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD 20850
| | - Sabine S Lange
- Department of Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center Science Park, Smithville, TX 78957
| | - Roger Woodgate
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD 20850
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
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27
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Hurwitz JL, Jones BG, Sealy RE, Xu B, Fan Y, Partridge JF, Maul RW, Gearhart PJ, Penkert R. Hotspots for hormone response elements in Sα switch regions of immunoglobulin heavy chain loci; how estrogen may influence class switch recombination (CSR) and IgA/IgG isotype expression by activated B cells. The Journal of Immunology 2016. [DOI: 10.4049/jimmunol.196.supp.198.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
B cell immune responses differ between genders. To investigate mechanisms responsible for these differences, we activated murine B cells with mitogens in vitro in the presence or absence of hormones. We found that additions of estradiol and thyroid hormones to mitogen-activated B cell cultures altered IgA/IgG expression patterns. Chromatin immunoprecipitation (ChIP) analyses then showed that estrogen receptor (ER) associated with the anti-apoptotic bcl-2 gene in LPS-stimulated murine B cells, but the interaction was inhibited by estrogen, possibly explaining variant isotype expression patterns. In search of additional mechanisms, we queried mouse and human immunoglobulin heavy chain switch (S) regions for potential hormone response elements (HRE). In both human and mouse loci, the DNA sequences of Sμ and Sα encompassed an extraordinary number of HRE. For example, there were more than 70 potential estrogen response elements (ERE, G/AG/AT/CT/CG/AnnnTGAC/GC) in Sα regions of both human and mouse loci, yet not a single ERE in Sγ2. Results suggest that hormones impact antibody isotype expression by both indirect and direct mechanisms; they might alter B cell growth, but might also up- and down-regulate class switch recombination (CSR) by direct receptor interactions with Sμ and Sα.
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28
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Hurwitz JL, Penkert RR, Xu B, Fan Y, Partridge JF, Maul RW, Gearhart PJ. Hotspots for Vitamin-Steroid-Thyroid Hormone Response Elements Within Switch Regions of Immunoglobulin Heavy Chain Loci Predict a Direct Influence of Vitamins and Hormones on B Cell Class Switch Recombination. Viral Immunol 2016; 29:132-6. [PMID: 26741514 DOI: 10.1089/vim.2015.0104] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Vitamin A deficiencies are common throughout the world and have a significant negative influence on immune protection against viral infections. Mouse models demonstrate that the production of IgA, a first line of defense against viruses at mucosal sites, is inhibited in the context of vitamin A deficiency. In vitro, the addition of vitamin A to activated B cells can enhance IgA expression, but downregulate IgE. Previous reports have demonstrated that vitamin A modifies cytokine patterns, and in so doing may influence antibody isotype expression by an indirect mechanism. However, we have now discovered hundreds of potential response elements among Sμ, Sɛ, and Sα switch sites within immunoglobulin heavy chain loci. These hotspots appear in both mouse and human loci and include targets for vitamin receptors and related proteins (e.g., estrogen receptors) in the nuclear receptor superfamily. Full response elements with direct repeats are relatively infrequent or absent in Sγ regions although half-sites are present. Based on these results, we pose a hypothesis that nuclear receptors have a direct effect on the immunoglobulin heavy chain class switch recombination event. We propose that vitamin A may alter S site accessibility to activation-induced deaminase and nonhomologous end-joining machinery, thereby influencing the isotype switch, antibody production, and protection against viral infections at mucosal sites.
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Affiliation(s)
- Julia L Hurwitz
- 1 Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, Tennessee.,2 Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Rhiannon R Penkert
- 1 Department of Infectious Diseases, St. Jude Children's Research Hospital , Memphis, Tennessee
| | - Beisi Xu
- 3 Department of Computational Biology, St. Jude Children's Research Hospital , Memphis, Tennessee
| | - Yiping Fan
- 3 Department of Computational Biology, St. Jude Children's Research Hospital , Memphis, Tennessee
| | - Janet F Partridge
- 4 Department of Pathology, St. Jude Children's Research Hospital , Memphis, Tennessee
| | - Robert W Maul
- 5 National Institute on Aging, National Institutes of Health , Baltimore, Maryland
| | - Patricia J Gearhart
- 5 National Institute on Aging, National Institutes of Health , Baltimore, Maryland
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29
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Maul RW, Saribasak H, Cao Z, Gearhart PJ. Topoisomerase I deficiency causes RNA polymerase II accumulation and increases AID abundance in immunoglobulin variable genes. DNA Repair (Amst) 2015; 30:46-52. [PMID: 25869824 DOI: 10.1016/j.dnarep.2015.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 03/03/2015] [Accepted: 03/09/2015] [Indexed: 10/23/2022]
Abstract
Activation-induced deaminase (AID) is a DNA cytosine deaminase that diversifies immunoglobulin genes in B cells. Recent work has shown that RNA polymerase II (Pol II) accumulation correlates with AID recruitment. However, a direct link between Pol II and AID abundance has not been tested. We used the DT40 B-cell line to manipulate levels of Pol II by decreasing topoisomerase I (Top1), which relaxes DNA supercoiling in front of the transcription complex. Top1 was decreased by stable transfection of a short hairpin RNA against Top1, which produced an accumulation of Pol II in transcribed genes, compared to cells transfected with sh-control RNA. The increased Pol II density enhanced AID recruitment to variable genes in the λ light chain locus, and resulted in higher levels of somatic hypermutation and gene conversion. It has been proposed by another lab that AID itself might directly suppress Top1 to increase somatic hypermutation. However, we found that in both AID(+/+) and AID(-/-) B cells from DT40 and mice, Top1 protein levels were identical, indicating that the presence or absence of AID did not decrease Top1 expression. Rather, our results suggest that the mechanism for increased diversity when Top1 is reduced is that Pol II accumulates and recruits AID to variable genes.
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Affiliation(s)
- Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, United States
| | - Huseyin Saribasak
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, United States
| | - Zheng Cao
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, United States
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, United States.
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Vallabhaneni H, Zhou F, Maul RW, Sarkar J, Yin J, Lei M, Harrington L, Gearhart PJ, Liu Y. Defective repair of uracil causes telomere defects in mouse hematopoietic cells. J Biol Chem 2015; 290:5502-11. [PMID: 25572391 DOI: 10.1074/jbc.m114.607101] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Uracil in the genome can result from misincorporation of dUTP instead of dTTP during DNA synthesis, and is primarily removed by uracil DNA glycosylase (UNG) during base excision repair. Telomeres contain long arrays of TTAGGG repeats and may be susceptible to uracil misincorporation. Using model telomeric DNA substrates, we showed that the position and number of uracil substitutions of thymine in telomeric DNA decreased recognition by the telomere single-strand binding protein, POT1. In primary mouse hematopoietic cells, uracil was detectable at telomeres, and UNG deficiency further increased uracil loads and led to abnormal telomere lengthening. In UNG-deficient cells, the frequencies of sister chromatid exchange and fragility in telomeres also significantly increased in the absence of telomerase. Thus, accumulation of uracil and/or UNG deficiency interferes with telomere maintenance, thereby underscoring the necessity of UNG-initiated base excision repair for the preservation of telomere integrity.
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Affiliation(s)
| | - Fang Zhou
- From the Laboratory of Molecular Gerontology
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Jaya Sarkar
- From the Laboratory of Molecular Gerontology
| | - Jinhu Yin
- From the Laboratory of Molecular Gerontology
| | - Ming Lei
- National Center for Protein Science Shanghai, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Lea Harrington
- Department of Medicine, Institute for Research in Immunology and Cancer, University of Montréal, Montréal, Québec H3C 3J7, Canada
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, NIA, National Institutes of Health, Baltimore, Maryland 21224,
| | - Yie Liu
- From the Laboratory of Molecular Gerontology,
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Zanotti KJ, Maul RW, Castiblanco DP, Yang W, Choi YJ, Fox JT, Myung K, Saribasak H, Gearhart PJ. ATAD5 deficiency decreases B cell division and Igh recombination. J Immunol 2014; 194:35-42. [PMID: 25404367 DOI: 10.4049/jimmunol.1401158] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mammalian ATPase family AAA domain-containing protein 5 (ATAD5) and its yeast homolog enhanced level of genomic instability 1 are responsible for unloading proliferating cell nuclear antigen from newly synthesized DNA. Prior work in HeLa and yeast cells showed that a decrease in ATAD5 protein levels resulted in accumulation of chromatin-bound proliferating cell nuclear antigen, slowed cell division, and increased genomic instability. In this study, B cells from heterozygous (Atad5(+/m)) mice were used to examine the effects of decreased cell proliferation on Ab diversity. ATAD5 haploinsufficiency did not change the frequency or spectrum of somatic hypermutation in Ab genes, indicating that DNA repair and error-prone DNA polymerase η usage were unaffected. However, immunized Atad5(+/m) mice had decreased serum IgG1 Abs, demonstrating a functional effect on class switch recombination. The mechanism of this altered immune response was then examined following ex vivo stimulation of splenic B cells, where Atad5(+/m) cells accumulated in the S phase of the cell cycle and had reduced proliferation compared with wild-type cells. These haploinsufficient cells underwent a significant decline in activation-induced deaminase expression, resulting in decreased switch region DNA double-strand breaks and interchromosomal translocations in the Igh locus. Class switch recombination to several isotypes was also reduced in Atad5(+/m) cells, although the types of end-joining pathways were not affected. These results describe a defect in DNA replication that affects Igh recombination via reduced cell division.
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Affiliation(s)
- Kimberly J Zanotti
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - Diana P Castiblanco
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - William Yang
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - Yong Jun Choi
- Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jennifer T Fox
- Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892
| | - Kyungjae Myung
- Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892
| | - Huseyin Saribasak
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224; and
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Maul RW, Cao Z, Venkataraman L, Giorgetti CA, Press JL, Denizot Y, Du H, Sen R, Gearhart PJ. Spt5 accumulation at variable genes distinguishes somatic hypermutation in germinal center B cells from ex vivo-activated cells. ACTA ACUST UNITED AC 2014; 211:2297-306. [PMID: 25288395 PMCID: PMC4203944 DOI: 10.1084/jem.20131512] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Variable (V) genes of immunoglobulins undergo somatic hypermutation by activation-induced deaminase (AID) to generate amino acid substitutions that encode antibodies with increased affinity for antigen. Hypermutation is restricted to germinal center B cells and cannot be recapitulated in ex vivo-activated splenic cells, even though the latter express high levels of AID. This suggests that there is a specific feature of antigen activation in germinal centers that recruits AID to V genes which is absent in mitogen-activated cultured cells. Using two Igh knock-in mouse models, we found that RNA polymerase II accumulates in V regions in B cells after both types of stimulation for an extended distance of 1.2 kb from the TATA box. The paused polymerases generate abundant single-strand DNA targets for AID. However, there is a distinct accumulation of the initiating form of polymerase, along with the transcription cofactor Spt5 and AID, in the V region from germinal center cells, which is totally absent in cultured cells. These data support a model where mutations are prevalent in germinal center cells, but not in ex vivo cells, because the initiating form of polymerase is retained, which affects Spt5 and AID recruitment.
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Affiliation(s)
- Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
| | - Zheng Cao
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
| | | | | | - Joan L Press
- Department of Biology, Brandeis University, Waltham, MA 02454
| | - Yves Denizot
- Centre National de la Recherche Scientifique UMR 7276, Université de Limoges, 87025 Limoges, France
| | - Hansen Du
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
| | - Ranjan Sen
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
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Maul RW, Gearhart PJ. Refining the Neuberger model: Uracil processing by activated B cells. Eur J Immunol 2014; 44:1913-6. [PMID: 24920531 PMCID: PMC4126077 DOI: 10.1002/eji.201444813] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 06/02/2014] [Accepted: 06/03/2014] [Indexed: 01/07/2023]
Abstract
During the immune response, B cells undergo a programed mutagenic cascade to promote increased affinity and expanded antibody function. The two processes, somatic hypermutation (SHM) and class switch recombination (CSR), are initiated by the protein activation-induced deaminase (AID), which converts cytosine to uracil in the immunoglobulin loci. The presence of uracil in DNA promotes DNA mutagenesis though a subset of DNA repair proteins. Two distinct mechanisms have been proposed to control uracil processing. The first is through base removal by uracil DNA glycosylase (UNG), and the second is through detection by the mismatch repair (MMR) complex MSH2/6. In a study published in this issue of European Journal of Immunology, Dingler et al. [Eur. J. Immunol. 2014. 44: 1925-1935] examine uracil processing in B cells in the absence of UNG and SMUG1 glycosylases. Similar to UNG, SMUG1 is an uracil glycosylase which can remove the uracil base. While Smug1(-/-) mice show no clear deficiency in SHM or CSR, Ung(-/-) Smug1(-/-) mice display exacerbated phenotypes, suggesting a back-up role for SMUG1 in antibody diversity. This new information expands the model of uracil processing in B cells and raises several interesting questions about the dynamic relationship between base excision repair and MMR.
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Affiliation(s)
- Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
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Saribasak H, Maul RW, Cao Z, Yang WW, Schenten D, Kracker S, Gearhart PJ. DNA polymerase ζ generates tandem mutations in immunoglobulin variable regions. ACTA ACUST UNITED AC 2012; 209:1075-81. [PMID: 22615128 PMCID: PMC3371727 DOI: 10.1084/jem.20112234] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Genetic inactivation of the genes encoding several low-fidelity DNA polymerases indicates that DNA polymerase ζ inserts tandem double-base substitutions in the immunoglobulin variable region in mouse B cells. Low-fidelity DNA polymerases introduce nucleotide substitutions in immunoglobulin variable regions during somatic hypermutation. Although DNA polymerase (pol) η is the major low-fidelity polymerase, other DNA polymerases may also contribute. Existing data are contradictory as to whether pol ζ is involved. We reasoned that the presence of pol η may mask the contribution of pol ζ, and therefore we generated mice deficient for pol η and heterozygous for pol ζ. The frequency and spectra of hypermutation was unaltered between Polζ+/− Polη−/− and Polζ+/+ Polη−/− clones. However, there was a decrease in tandem double-base substitutions in Polζ+/− Polη−/− cells compared with Polζ+/+ Polη−/− cells, suggesting that pol ζ generates tandem mutations. Contiguous mutations are consistent with the biochemical property of pol ζ to extend a mismatch with a second mutation. The presence of this unique signature implies that pol ζ contributes to mutational synthesis in vivo. Additionally, data on tandem mutations from wild type, Polζ+/−, Polζ−/−, Ung−/−, Msh2−/−, Msh6−/−, and Ung−/− Msh2−/− clones suggest that pol ζ may function in the MSH2–MSH6 pathway.
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Affiliation(s)
- Huseyin Saribasak
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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Saribasak H, Maul RW, Cao Z, McClure RL, Yang W, McNeill DR, Wilson DM, Gearhart PJ. XRCC1 suppresses somatic hypermutation and promotes alternative nonhomologous end joining in Ighgenes. J Biophys Biochem Cytol 2011. [DOI: 10.1083/jcb1952oia2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Saribasak H, Maul RW, Cao Z, McClure RL, Yang W, McNeill DR, Wilson DM, Gearhart PJ. XRCC1 suppresses somatic hypermutation and promotes alternative nonhomologous end joining in Igh genes. ACTA ACUST UNITED AC 2011; 208:2209-16. [PMID: 21967769 PMCID: PMC3201205 DOI: 10.1084/jem.20111135] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
As revealed using mice heterozygous for the base excision repair (BER) protein XRCC1, BER and mutagenic repair pathways can simultaneously compete for access to single-strand breaks induced by activation-induced deaminase. Activation-induced deaminase (AID) deaminates cytosine to uracil in immunoglobulin genes. Uracils in DNA can be recognized by uracil DNA glycosylase and abasic endonuclease to produce single-strand breaks. The breaks are repaired either faithfully by DNA base excision repair (BER) or mutagenically to produce somatic hypermutation (SHM) and class switch recombination (CSR). To unravel the interplay between repair and mutagenesis, we decreased the level of x-ray cross-complementing 1 (XRCC1), a scaffold protein involved in BER. Mice heterozygous for XRCC1 showed a significant increase in the frequencies of SHM in Igh variable regions in Peyer’s patch cells, and of double-strand breaks in the switch regions during CSR. Although the frequency of CSR was normal in Xrcc1+/− splenic B cells, the length of microhomology at the switch junctions decreased, suggesting that XRCC1 also participates in alternative nonhomologous end joining. Furthermore, Xrcc1+/− B cells had reduced Igh/c-myc translocations during CSR, supporting a role for XRCC1 in microhomology-mediated joining. Our results imply that AID-induced single-strand breaks in Igh variable and switch regions become substrates simultaneously for BER and mutagenesis pathways.
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Affiliation(s)
- Huseyin Saribasak
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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Pape KA, Taylor JJ, Maul RW, Gearhart PJ, Jenkins MK. Different B cell populations mediate early and late memory during an endogenous immune response. Science 2011; 331:1203-7. [PMID: 21310965 DOI: 10.1126/science.1201730] [Citation(s) in RCA: 423] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Memory B cells formed in response to microbial antigens provide immunity to later infections; however, the inability to detect rare endogenous antigen-specific cells limits current understanding of this process. Using an antigen-based technique to enrich these cells, we found that immunization with a model protein generated B memory cells that expressed isotype-switched immunoglobulins (swIg) or retained IgM. The more numerous IgM(+) cells were longer lived than the swIg(+) cells. However, swIg(+) memory cells dominated the secondary response because of the capacity to become activated in the presence of neutralizing serum immunoglobulin. Thus, we propose that memory relies on swIg(+) cells until they disappear and serum immunoglobulin falls to a low level, in which case memory resides with durable IgM(+) reserves.
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Affiliation(s)
- Kathryn A Pape
- Department of Microbiology, Center for Immunology, University of Minnesota Medical School, Minneapolis, MN 55455, USA
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Maul RW, Saribasak H, Martomo SA, McClure RL, Yang W, Vaisman A, Gramlich HS, Schatz DG, Woodgate R, Wilson DM, Gearhart PJ. Uracil residues dependent on the deaminase AID in immunoglobulin gene variable and switch regions. Nat Immunol 2010; 12:70-6. [PMID: 21151102 DOI: 10.1038/ni.1970] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 11/12/2010] [Indexed: 11/09/2022]
Abstract
Activation-induced deaminase (AID) initiates diversity of immunoglobulin genes through deamination of cytosine to uracil. Two opposing models have been proposed for the deamination of DNA or RNA by AID. Although most data support DNA deamination, there is no physical evidence of uracil residues in immunoglobulin genes. Here we demonstrate their presence by determining the sensitivity of DNA to digestion with uracil DNA glycosylase (UNG) and abasic endonuclease. Using several methods of detection, we identified uracil residues in the variable and switch regions. Uracil residues were generated within 24 h of B cell stimulation, were present on both DNA strands and were found to replace mainly cytosine bases. Our data provide direct evidence for the model that AID functions by deaminating cytosine residues in DNA.
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Affiliation(s)
- Robert W Maul
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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Abstract
Activation-induced deaminase (AID) is a B-cell-specific enzyme required for initiating the mechanisms of affinity maturation and isotype switching of antibodies. AID functions by deaminating cytosine to uracil in DNA, which initiates a cascade of events resulting in mutations and strand breaks in the immunoglobulin loci. There is an intricate interplay between faithful DNA repair and mutagenic DNA repair during somatic hypermutation, in that some proteins from accurate repair pathways are also involved in mutagenesis. One factor that shifts the balance from faithful to mutagenic repair is the genomic sequence of the switch regions. Indeed, the sequence of the switch mu region is designed to maximize AID access to increase the abundance of clustered dU bases. The frequency and proximity of these dU nucleotides then in turn inhibit faithful repair and promote strand breaks.
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Affiliation(s)
- Robert W Maul
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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Kohli RM, Maul RW, Guminski AF, McClure RL, Gajula KS, Saribasak H, McMahon MA, Siliciano RF, Gearhart PJ, Stivers JT. Local sequence targeting in the AID/APOBEC family differentially impacts retroviral restriction and antibody diversification. J Biol Chem 2010; 285:40956-64. [PMID: 20929867 DOI: 10.1074/jbc.m110.177402] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nucleic acid cytidine deaminases of the activation-induced deaminase (AID)/APOBEC family are critical players in active and innate immune responses, playing roles as target-directed, purposeful mutators. AID specifically deaminates the host immunoglobulin (Ig) locus to evolve antibody specificity, whereas its close relative, APOBEC3G (A3G), lethally mutates the genomes of retroviral pathogens such as HIV. Understanding the basis for the target-specific action of these enzymes is essential, as mistargeting poses significant risks, potentially promoting oncogenesis (AID) or fostering drug resistance (A3G). AID prefers to deaminate cytosine in WRC (W = A/T, R = A/G) motifs, whereas A3G favors deamination of CCC motifs. This specificity is largely dictated by a single, divergent protein loop in the enzyme family that recognizes the DNA sequence. Through grafting of this substrate-recognition loop, we have created enzyme variants of A3G and AID with altered local targeting to directly evaluate the role of sequence specificity on immune function. We find that grafted loops placed in the A3G scaffold all produced efficient restriction of HIV but that foreign loops in the AID scaffold compromised hypermutation and class switch recombination. Local targeting, therefore, appears alterable for innate defense against retroviruses by A3G but important for adaptive antibody maturation catalyzed by AID. Notably, AID targeting within the Ig locus is proportionally correlated to its in vitro ability to target WRC sequences rather than non-WRC sequences. Although other mechanisms may also contribute, our results suggest that local sequence targeting by AID/APOBEC3 enzymes represents an elegant example of co-evolution of enzyme specificity with its target DNA sequence.
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Affiliation(s)
- Rahul M Kohli
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Abstract
In response to an assault by foreign organisms, peripheral B cells can change their antibody affinity and isotype by somatically mutating their genomic DNA. The ability of a cell to modify its DNA is exceptional in light of the potential consequences of genetic alterations to cause human disease and cancer. Thus, as expected, this mechanism of antibody diversity is tightly regulated and coordinated through one protein, activation-induced deaminase (AID). AID produces diversity by converting cytosine to uracil within the immunoglobulin loci. The deoxyuracil residue is mutagenic when paired with deoxyguanosine, since it mimics thymidine during DNA replication. Additionally, B cells can manipulate the DNA repair pathways so that deoxyuracils are not faithfully repaired. Therefore, an intricate balance exists which is regulated at multiple stages to promote mutation of immunoglobulin genes, while retaining integrity of the rest of the genome. Here we discuss and summarize the current understanding of how AID functions to cause somatic hypermutation.
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Affiliation(s)
- Robert W Maul
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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Kohli RM, Abrams SR, Gajula KS, Maul RW, Gearhart PJ, Stivers JT. A portable hot spot recognition loop transfers sequence preferences from APOBEC family members to activation-induced cytidine deaminase. J Biol Chem 2009; 284:22898-904. [PMID: 19561087 DOI: 10.1074/jbc.m109.025536] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Enzymes of the AID/APOBEC family, characterized by the targeted deamination of cytosine to generate uracil within DNA, mediate numerous critical immune responses. One family member, activation-induced cytidine deaminase (AID), selectively introduces uracil into antibody variable and switch regions, promoting antibody diversity through somatic hypermutation or class switching. Other family members, including APOBEC3F and APOBEC3G, play an important role in retroviral defense by acting on viral reverse transcripts. These enzymes are distinguished from one another by targeting cytosine within different DNA sequence contexts; however, the reason for these differences is not known. Here, we report the identification of a recognition loop of 9-11 amino acids that contributes significantly to the distinct sequence motifs of individual family members. When this recognition loop is grafted from the donor APOBEC3F or 3G proteins into the acceptor scaffold of AID, the mutational signature of AID changes toward that of the donor proteins. These loop-graft mutants of AID provide useful tools for dissecting the biological impact of DNA sequence preferences upon generation of antibody diversity, and the results have implications for the evolution and specialization of the AID/APOBEC family.
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Affiliation(s)
- Rahul M Kohli
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Rajagopal D, Maul RW, Ghosh A, Chakraborty T, Khamlichi AA, Sen R, Gearhart PJ. Immunoglobulin switch µ sequence causes RNA polymerase II accumulation and reduces dA hypermutation. J Biophys Biochem Cytol 2009. [DOI: 10.1083/jcb1854oia9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Rajagopal D, Maul RW, Ghosh A, Chakraborty T, Khamlichi AA, Sen R, Gearhart PJ. Immunoglobulin switch mu sequence causes RNA polymerase II accumulation and reduces dA hypermutation. ACTA ACUST UNITED AC 2009; 206:1237-44. [PMID: 19433618 PMCID: PMC2715057 DOI: 10.1084/jem.20082514] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Repetitive DNA sequences in the immunoglobulin switch μ region form RNA-containing secondary structures and undergo hypermutation by activation-induced deaminase (AID). To examine how DNA structure affects transcription and hypermutation, we mapped the position of RNA polymerase II molecules and mutations across a 5-kb region spanning the intronic enhancer to the constant μ gene. For RNA polymerase II, the distribution was determined by nuclear run-on and chromatin immunoprecipitation assays in B cells from uracil-DNA glycosylase (UNG)–deficient mice stimulated ex vivo. RNA polymerases were found at a high density in DNA flanking both sides of a 1-kb repetitive sequence that forms the core of the switch region. The pileup of polymerases was similar in unstimulated and stimulated cells from Ung−/− and Aid−/−Ung−/− mice but was absent in cells from mice with a deletion of the switch region. For mutations, DNA was sequenced from Ung−/− B cells stimulated in vivo. Surprisingly, mutations of A nucleotides, which are incorporated by DNA polymerase η, decreased 10-fold before the repetitive sequence, suggesting that the polymerase was less active in this region. We propose that altered DNA structure in the switch region pauses RNA polymerase II and limits access of DNA polymerase η during hypermutation.
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Affiliation(s)
- Deepa Rajagopal
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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Abstract
Somatic hypermutation of immunoglobulin (Ig) genes occurs at a frequency that is a million times greater than the mutation in other genes. Mutations occur in variable genes to increase antibody affinity, and in switch regions before constant genes to cause switching from IgM to IgG. Hypermutation is initiated in activated B cells when the activation-induced deaminase protein deaminates cytosine in DNA to uracil. Uracils can be processed by either a mutagenic pathway to produce mutations or a non-mutagenic pathway to remove mutations. In the mutagenic pathway, we first studied the role of mismatch repair proteins, MSH2, MSH3, MSH6, PMS2 and MLH1, since they would recognize mismatches. The MSH2-MSH6 heterodimer is involved in hypermutation by binding to U:G and other mismatches generated during repair synthesis, but the other proteins are not necessary. Second, we analysed the role of low-fidelity DNA polymerases eta, iota and theta in synthesizing mutations, and conclude that polymerase eta is the dominant participant by generating mutations at A:T base pairs. In the non-mutagenic pathway, we examined the role of the Cockayne syndrome B protein that interacts with other repair proteins. Mice deficient in this protein had normal hypermutation and class switch recombination, showing that it is not involved.
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Affiliation(s)
- Huseyin Saribasak
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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46
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Abstract
Why women are more susceptible to autoimmune diseases is not completely clear, but new data suggest that the hormone estrogen may play an important role. A new study now shows that estrogen activates the expression of activation-induced deaminase (AID), a protein that drives antibody diversification by deaminating cytosine in DNA to uracil. If estrogen increases the level of AID, increased mutations could transform benign antibodies into anti-self pariahs. AID might also contribute to cancer--particularly in breast tissue, which is highly responsive to estrogen--by introducing mutations and strand breaks into the genome.
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Affiliation(s)
- Robert W Maul
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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47
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Abstract
Escherichia coli strains expressing the mutant beta159-sliding clamp protein (containing both a G66E and a G174A substitution) are temperature sensitive for growth and display altered DNA polymerase (pol) usage. We selected for suppressors of the dnaN159 allele able to grow at 42 degrees C, and identified four intragenic suppressor alleles. One of these alleles (dnaN780) contained only the G66E substitution, while a second (dnaN781) contained only the G174A substitution. Genetic characterization of isogenic E. coli strains expressing these alleles indicated that certain phenotypes were dependent upon only the G174A substitution, while others required both the G66E and G174A substitutions. In order to understand the individual contributions of the G66E and the G174A substitution to the dnaN159 phenotypes, we utilized biochemical approaches to characterize the purified mutant beta159 (G66E and G174A), beta780 (G66E) and beta781 (G174A) clamp proteins. The G66E substitution conferred a more pronounced effect on pol IV replication than it did pol II or pol III, while the G174A substitution conferred a greater effect on pol III and pol IV than it did pol II. Taken together, these findings indicate that pol II, pol III and pol IV interact with distinct, albeit overlapping surfaces of the beta clamp.
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Affiliation(s)
- Robert W Maul
- Department of Biochemistry, School of Medicine and Biomedical Sciences, University at Buffalo, SUNY, Buffalo, New York 14214, USA
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48
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Maul RW, Sanders LH, Lim JB, Benitez R, Sutton MD. Role of Escherichia coli DNA polymerase I in conferring viability upon the dnaN159 mutant strain. J Bacteriol 2007; 189:4688-95. [PMID: 17449610 PMCID: PMC1913439 DOI: 10.1128/jb.00476-07] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The Escherichia coli dnaN159 allele encodes a mutant form of the beta-sliding clamp (beta159) that is impaired for interaction with the replicative DNA polymerase (Pol), Pol III. In addition, strains bearing the dnaN159 allele require functional Pol I for viability. We have utilized a combination of genetic and biochemical approaches to characterize the role(s) played by Pol I in the dnaN159 strain. Our findings indicate that elevated levels of Pol I partially suppress the temperature-sensitive growth phenotype of the dnaN159 strain. In addition, we demonstrate that the beta clamp stimulates the processivity of Pol I in vitro and that beta159 is impaired for this activity. The reduced ability of beta159 to stimulate Pol I in vitro correlates with our finding that single-stranded DNA (ssDNA) gap repair is impaired in the dnaN159 strain. Taken together, these results suggest that (i) the beta clamp-Pol I interaction may be important for proper Pol I function in vivo and (ii) in the absence of Pol I, ssDNA gaps may persist in the dnaN159 strain, leading to lethality of the dnaN159 DeltapolA strain.
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Affiliation(s)
- Robert W Maul
- Department of Biochemistry, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, 3435 Main Street, Buffalo, NY 14214, USA
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49
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Abstract
The Escherichia coli beta sliding clamp protein is proposed to play an important role in effecting switches between different DNA polymerases during replication, repair, and translesion DNA synthesis. We recently described how strains bearing the dnaN159 allele, which encodes a mutant form of the beta clamp (beta159), display a UV-sensitive phenotype that is suppressed by inactivation of DNA polymerase IV (M. D. Sutton, J. Bacteriol. 186:6738-6748, 2004). As part of an ongoing effort to understand mechanisms of DNA polymerase management in E. coli, we have further characterized effects of the dnaN159 allele on polymerase usage. Three of the five E.coli DNA polymerases (II, IV, and V) are regulated as part of the global SOS response. Our results indicate that elevated expression of the dinB-encoded polymerase IV is sufficient to result in conditional lethality of the dnaN159 strain. In contrast, chronically activated RecA protein, expressed from the recA730 allele, is lethal to the dnaN159 strain, and this lethality is suppressed by mutations that either mitigate RecA730 activity (i.e., DeltarecR), or impair the activities of DNA polymerase II or DNA polymerase V (i.e., DeltapolB or DeltaumuDC). Thus, we have identified distinct genetic requirements whereby each of the three different SOS-regulated DNA polymerases are able to confer lethality upon the dnaN159 strain, suggesting the presence of multiple mechanisms by which the actions of the cell's different DNA polymerases are managed in vivo.
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Affiliation(s)
- Robert W Maul
- Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, 14214, USA
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50
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Sutton MD, Duzen JM, Maul RW. Mutant forms of theEscherichia coliβ sliding clamp that distinguish between its roles in replication and DNA polymerase V-dependent translesion DNA synthesis. Mol Microbiol 2005; 55:1751-66. [PMID: 15752198 DOI: 10.1111/j.1365-2958.2005.04500.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Escherichia colibeta sliding clamp is proposed to play an important role in regulating DNA polymerase traffic at the replication fork. As part of an ongoing effort to understand how organisms manage the actions of their multiple DNA polymerases, we examined the ability of several mutant forms of the beta clamp to function in DNA polymerase V- (pol V-) dependent translesion DNA synthesis (TLS) in vivo. Our results indicate that a dnaN159 strain, which expresses a temperature sensitive form of the beta clamp, was impaired for pol V-dependent TLS at the permissive temperature of 37 degrees C. This defect was complemented by a plasmid that expressed near-physiological levels of the wild-type clamp. Using a dnaN159 mutant strain, together with various plasmids expressing mutant forms of the clamp, we determined that residues H148 through R152, which comprise a portion of a solvent exposed loop, as well as position P363, which is located in the C-terminal tail of the beta clamp, are critically important for pol V-dependent TLS in vivo. In contrast, these same residues appear to be less critical for pol III-dependent replication. Taken together, these findings indicate that: (i) the beta clamp plays an essential role in pol V-dependent TLS in vivo and (ii) pol III and pol V interact with non-identical surfaces of the beta clamp.
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Affiliation(s)
- Mark D Sutton
- Department of Biochemistry, School of Medicine and Biomedical Sciences, University at Buffalo, SUNY, 3435 Main Street, 140 Farber Hall, Buffalo, NY 14214, USA.
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