scholarly journals An ontogenetic switch drives the positive and negative selection of B cells

2020 ◽  
Vol 117 (7) ◽  
pp. 3718-3727 ◽  
Author(s):  
Xijin Xu ◽  
Mukta Deobagkar-Lele ◽  
Katherine R. Bull ◽  
Tanya L. Crockford ◽  
Adam J. Mead ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
Negative Selection ◽  
Ectopic Expression ◽  
Cell Development ◽  
B Cell Development ◽  
Bone Marrow Analysis ◽  
Self Antigen ◽  
Selection Of

Developing B cells can be positively or negatively selected by self-antigens, but the mechanisms that determine these outcomes are incompletely understood. Here, we show that a B cell intrinsic switch between positive and negative selection during ontogeny is determined by a change from Lin28b to let-7 gene expression. Ectopic expression of a Lin28b transgene in murine B cells restored the positive selection of autoreactive B-1 B cells by self-antigen in adult bone marrow. Analysis of antigen-specific immature B cells in early and late ontogeny identified Lin28b-dependent genes associated with B-1 B cell development, including Arid3a and Bhleh41, and Lin28b-independent effects are associated with the presence or absence of self-antigen. These findings identify cell intrinsic and extrinsic determinants of B cell fate during ontogeny and reconcile lineage and selection theories of B cell development. They explain how changes in the balance of positive and negative selection may be able to adapt to meet the immunological needs of an individual during its lifetime.

scholarly journals Conditional antibody expression to avoid central B cell deletion in humanized HIV-1 vaccine mouse models

2020 ◽  
Vol 117 (14) ◽  
pp. 7929-7940
Author(s):  
Ming Tian ◽  
Kelly McGovern ◽  
Hwei-Ling Cheng ◽  
Peyton Waddicor ◽  
Lisa Rieble ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Mouse Models ◽  
Negative Selection ◽  
Cell Development ◽  
B Cell Development ◽  
Affinity Maturation ◽  
Variable Regions ◽  
Conditional Expression ◽  
Hiv 1

HIV-1 vaccine development aims to elicit broadly neutralizing antibodies (bnAbs) against diverse viral strains. In some HIV-1–infected individuals, bnAbs evolved from precursor antibodies through affinity maturation. To induce bnAbs, a vaccine must mediate a similar antibody maturation process. One way to test a vaccine is to immunize mouse models that express human bnAb precursors and assess whether the vaccine can convert precursor antibodies into bnAbs. A major problem with such mouse models is that bnAb expression often hinders B cell development. Such developmental blocks may be attributed to the unusual properties of bnAb variable regions, such as poly-reactivity and long antigen-binding loops, which are usually under negative selection during primary B cell development. To address this problem, we devised a method to circumvent such B cell developmental blocks by expressing bnAbs conditionally in mature B cells. We validated this method by expressing the unmutated common ancestor (UCA) of the human VRC26 bnAb in transgenic mice. Constitutive expression of the VRC26UCA led to developmental arrest of B cell progenitors in bone marrow; poly-reactivity of the VRC26UCA and poor pairing of the VRC26UCA heavy chain with the mouse surrogate light chain may contribute to this phenotype. The conditional expression strategy bypassed the impediment to VRC26UCA B cell development, enabling the expression of VRC26UCA in mature B cells. This approach should be generally applicable for expressing other bnAbs that are under negative selection during B cell development.

scholarly journals Essential role of EBF1 in the generation and function of distinct mature B cell types

2012 ◽  
Vol 209 (4) ◽  
pp. 775-792 ◽  
Author(s):  
Bojan Vilagos ◽  
Mareike Hoffmann ◽  
Abdallah Souabni ◽  
Qiong Sun ◽  
Barbara Werner ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Intracellular Signaling ◽  
Ectopic Expression ◽  
Cell Types ◽  
Cell Development ◽  
B Cell Development ◽  
Cell Stage ◽  
Cell Immunity ◽  
Cell Commitment

The transcription factor EBF1 is essential for lineage specification in early B cell development. In this study, we demonstrate by conditional mutagenesis that EBF1 is required for B cell commitment, pro–B cell development, and subsequent transition to the pre–B cell stage. Later in B cell development, EBF1 was essential for the generation and maintenance of several mature B cell types. Marginal zone and B-1 B cells were lost, whereas follicular (FO) and germinal center (GC) B cells were reduced in the absence of EBF1. Activation of the B cell receptor resulted in impaired intracellular signaling, proliferation and survival of EBF1-deficient FO B cells. Immune responses were severely reduced upon Ebf1 inactivation, as GCs were formed but not maintained. ChIP- and RNA-sequencing of FO B cells identified EBF1-activated genes that encode receptors, signal transducers, and transcriptional regulators implicated in B cell signaling. Notably, ectopic expression of EBF1 efficiently induced the development of B-1 cells at the expense of conventional B cells. These gain- and loss-of-function analyses uncovered novel important functions of EBF1 in controlling B cell immunity.

Ectopic Expression of HDAC9 in Murine Lymphoid System Leads to Altered Lymphocyte Numbers and Proliferation as Well as Predisposition to Tumorigenesis.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 376-376
Author(s):  
Veronica S. Gil ◽  
Louise M.C. Howell ◽  
Jenny Yeung ◽  
Kevin R. Petrie ◽  
Adrian Smith ◽  
...  
Keyword(s):  
Gene Expression ◽  
B Cells ◽  
Transgenic Mice ◽  
B Cell ◽  
Ectopic Expression ◽  
Cell Development ◽  
B Cell Development ◽  
Gene Promoters ◽  
Marginal Zone B Cells ◽  
Lymphoid System

Abstract Reversible acetylation of lysine residues on histone tails is associated with changes to chromatin structure and plays a key role in regulation of gene expression. In this process, histone hypoacetylation is generally associated with gene silencing and pharmacological inhibition of histone deacetylases (HDACs) leads usually to activation of gene expression. Decreased histone acetylation is a hallmark of cancer cells and increased HDAC expression or their mistargetting to specific gene promoters has been associated with a variety of tumors. In the past we have identified and cloned class IIa HDAC9. The HDAC9 gene is located in chromosome 7p21, which is frequently amplified in B-cell tumours such as mantle cell lymphoma (MCL) and in B-cell non-Hodgkin’s lymphoma cell lines. Consistently, initial analysis of patient samples and/or publicly available microarray data highlighted high levels of HDAC9 expression in chronic lymphocytic leukemia, folicullar lymphoma and MCL. Within the normal lymphoid system, HDAC9 is co-expressed with BCL-6 in germinal center B-cells (∼60% of cells). HDAC9 is also expressed in marginal zone B cells and a fraction of CD38 or CD27 positive subepithelial tonsilar cells. In order to examine the role of HDAC9 in the lymphoid development and pathogenesis of lymphoid malignancies we used Ig heavy chain enhancer (Eμ), which drives gene expression from early stages of B-cell development, to ectopically express HDAC9 in transgenic mice. Hemizygous and homozygous mice expressing Flag epitope tagged human HDAC9 (fHDAC9) transgene display throughout their lifespan altered B-cell development. Immunophenotypic analysis of B-cells isolated from bone marrow (BM) revealed an absence of cells expressing the pre-B/immature-B cell markers normally associated with C-E Hardy’s fractions. In vitro functional clonogenic assays for IL-7 responsive BM-derived B-cell progenitors demonstrated an increase (∼50%) in colony numbers in the transgenic BM. Moreover, morphologic and flow cytometric analyses of the transgenic colonies, but not those derived from normal BM, revealed the presence of granulocyte/macrophage colony forming units expressing the HDAC9 transgene, suggesting a lympho-myeloid lineage switch. This correlates with the finding that extramedullary myelopoiesis occurs in a fraction of mice presenting splenomegaly (44%). Furthermore, a subgroup of homozygous Eμ-fHDAC9 mice (n=16) developed tumours (81%) at middle age, and present with enlarged lymph nodes (6%) and abnormal hematopoietic elements in peripheral blood and BM. Taken together these data suggest that HDAC9 plays a role in B-cell maturation and its ectopic expression in early B-cells leads to perturbation of normal B-cell development, possibly predisposing transgenic mice to tumorigenesis.

scholarly journals The B29 (Immunoglobulin β-Chain) Gene Is a Genetic Target for Early B-Cell Factor

1999 ◽  
Vol 19 (1) ◽  
pp. 392-401 ◽  
Author(s):  
Peter Åkerblad ◽  
Maria Rosberg ◽  
Tomas Leanderson ◽  
Mikael Sigvardsson
Keyword(s):  
Transcription Factor ◽  
B Cells ◽  
B Cell ◽  
B Lymphocyte ◽  
Ectopic Expression ◽  
Cell Receptor ◽  
Cell Development ◽  
B Cell Development ◽  
Chain Gene ◽  
Early B Cell Factor

ABSTRACT Early B-cell factor (EBF) is a transcription factor suggested as essential for early B-lymphocyte development by findings in mice where the coding gene has been inactivated by homologous disruption. This makes the identification of genetic targets for this transcription factor pertinent for the understanding of early B-cell development. The lack of B29 transcripts, coding for the β subunit of the B-cell receptor complex, in pro-B cells from EBF-deficient mice suggested that B29 might be a genetic target for EBF. We here present data suggesting that EBF interacts with three independent sites within the mouse B29 promoter. Furthermore, ectopic expression of EBF in HeLa cells activated a B29promoter-controlled reporter construct 13-fold and induced a low level of expression from the endogenous B29 gene. Finally, mutations in the EBF binding sites diminished B29 promoter activity in pre-B cells while the same mutations did not have as striking an effect on the promoter function in B-cell lines of later differentiation stages. These data suggest that the B29gene is a genetic target for EBF in early B-cell development.

The MiR-23a MicroRNA Cluster Inhibits B Cell Development.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1465-1465
Author(s):  
Jason Mullenix ◽  
Kimi Y Kong ◽  
Kristin Severns Owens ◽  
Jason Rogers ◽  
Shannon FitzPatrick ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
Conflicts Of Interest ◽  
Myeloid Cells ◽  
Mature Mirnas ◽  
Cell Development ◽  
B Cell Development

Abstract Abstract 1465 Poster Board I-488 The miR-23a microRNA (miRNAs) cluster inhibits both [ITALIC]in vitro[/ITALIC] and [ITALIC]in vivo[/ITALIC] B cell development. When murine hematopoietic progenitor cells expressing the 23a cluster miRNAs were cultured in B cell promoting conditions we observed over a five-fold decrease in the generation of CD19+ B cells compared to control cultures. Conversely, we observed over a five-fold increase in CD11b+ myeloid cells. When irradiated mice were transplanted with bone marrow expressing the miR-23a cluster we observed a two-fold decrease in bone marrow and splenic B cells, 8 weeks post-transplant compared to control mice. The miR-23a cluster codes for a single pri-transcript, which when processed yields three mature miRNAs: miR-23a, miR-27a, and miR-24-2. All three mature miRNAs are more abundant in myeloid cells compared to other hematopoietic cells. In vitro miR-24 alone is necessary and sufficient to inhibit B cell development. The promoter for the cluster contains conserved binding sites for the essential myeloid transcription factors PU.1 and C/EBP alpha. Chromatin immunoprecipitations demonstrated that PU.1 and C/EBP alpha are associated with the promoter in myeloid cells. In addition, C/EBP alpha is bound to several highly conserved regions upstream of the promoter. Both PU.1 and C/EBP alpha promote myeloid development at the expense of lymphopoiesis. Our work suggests that the miR-23a cluster may be a critical downstream target of PU.1 and C/EBP alpha in the specification of myeloid cell fate. Although miRNAs have been identified downstream of PU.1 and C/EBP alpha in mediating the development of monocytes and granulocytes, the 23a cluster is the first downstream miRNA target implicated in the regulating lymphoid cell fate acquisition. We are currently identifying targets of miR-24 that may mediate the inhibitory effect on B lymphopoiesis. Disclosures No relevant conflicts of interest to declare.

scholarly journals Conditional Selection of B Cells in Mice With an Inducible B Cell Development

2018 ◽  
Vol 9 ◽  
Author(s):  
Elias Hobeika ◽  
Marcel Dautzenberg ◽  
Ella Levit-Zerdoun ◽  
Roberta Pelanda ◽  
Michael Reth
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Development ◽  
B Cell Development ◽  
Conditional Selection ◽  
Selection Of

scholarly journals Notch 1–Deficient Common Lymphoid Precursors Adopt a B Cell Fate in the Thymus

2001 ◽  
Vol 194 (7) ◽  
pp. 1003-1012 ◽  
Author(s):  
Anne Wilson ◽  
H. Robson MacDonald ◽  
Freddy Radtke
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
De Novo ◽  
T Cell Development ◽  
Cell Development ◽  
B Cell Development ◽  
Notch 1 ◽  
Corticomedullary Junction

We have recently reported that Notch 1, a member of the Notch multigene family, is essential for the development of murine T cells. Using a mouse model in which Notch 1 is inactivated in bone marrow (BM) precursors we have shown that B cells instead of T cells are found in the thymus of BM chimeras. However, it is not clear whether these B cells develop by default from a common lymphoid precursor due to the absence of Notch 1 signaling, or whether they arise as a result of perturbed migration of BM-derived B cells and/or altered homeostasis of normal resident thymic B cells. In this report we show that Notch 1–deficient thymic B cells resemble BM B cells in phenotype and turnover kinetics and are located predominantly in the medulla and corticomedullary junction. Peripheral blood lymphocyte analysis shows no evidence of recirculating Notch1−/− BM B cells. Furthermore, lack of T cell development is not due to a failure of Notch1−/− precursors to home to the thymus, as even after intrathymic reconstitution with BM cells, B cells instead of T cells develop from Notch 1–deficient precursors. Taken together, these results provide evidence for de novo ectopic B cell development in the thymus, and support the hypothesis that in the absence of Notch 1 common lymphoid precursors adopt the default cell fate and develop into B cells instead.

scholarly journals Positive Selection of Anti–Thy-1 Autoreactive B-1 Cells and Natural Serum Autoantibody Production Independent from Bone Marrow B Cell Development

2003 ◽  
Vol 197 (1) ◽  
pp. 87-99 ◽  
Author(s):  
Kyoko Hayakawa ◽  
Masanao Asano ◽  
Susan A. Shinton ◽  
Ming Gui ◽  
Li-Jun Wen ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
Positive Selection ◽  
B Cell ◽  
Cell Development ◽  
B Cell Development ◽  
Immunoglobulin M ◽  
Autoantibody Production ◽  
Serum Autoantibody ◽  
Self Antigen

A natural serum autoantibody specific for the Thy-1 glycoprotein (anti–Thy-1 autoantibody [ATA]) is produced by B-1 cells that are positively selected by self-antigen. Here, using ATAμκ transgenic mice we show that cells with this B cell receptor are negatively selected during bone marrow (BM) development. In a Thy-1 null environment, BM ATA B cells progress to a normal follicular stage in spleen. However, in a self-antigen–positive environment, development is arrested at an immature stage in the spleen, concomitant with induction of CD5. Such cells are tolerant and short-lived, different from B-1. Nonetheless, ATA-positive selection was evident by self-antigen–dependent high serum ATA production, comprising ∼90% of serum immunoglobulin M in ATAμκ mice. Splenectomy did not eliminate ATA production and transfer of tolerant splenic B cells did not induce it. These findings demonstrate that B-1 positive selection, resulting in the production of natural serum ATA, arises independently from the major pathway of BM B cell development and selection.

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