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Abstract
Heavy chain diseases (HCDs) are B-cell proliferative disorders characterized by the production of monoclonal, incomplete, immunoglobulin (Ig) heavy chains (HCs) without associated light chains (LCs). These abnormal HCs are produced as a consequence of HC gene alterations in the neoplastic B cells. HC gene alterations will also impact on surface HC, which is part of the B-cell receptor (BCR), a crucial player in lymphocyte activation by antigen. The selective advantage conferred to mutant cells by abnormal BCR without an antigen-binding domain may be explained by activation of ligand-independent signaling, in analogy to what has been shown for mutated oncogenic growth factor receptors. Here we review data obtained from mouse models showing abnormal, constitutive activity of HCD-BCR, and we discuss the possible mechanism involved, namely, aberrant spontaneous self-aggregation. This self-aggregation might occur as a consequence of escape from the chaperone immunoglobulin binding protein (BiP) and from the anti-aggregation effect of LC association. The concept of misfolding-induced signaling elaborated here may extend to other pathologies termed conformational diseases.
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2
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Corcos D. Immunoglobulin transport in the absence of light chains. Trends Biochem Sci 2010; 35:593; author reply 594. [PMID: 20728360 DOI: 10.1016/j.tibs.2010.07.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 07/26/2010] [Accepted: 07/27/2010] [Indexed: 10/19/2022]
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3
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Tolar P, Pierce SK. A conformation-induced oligomerization model for B cell receptor microclustering and signaling. Curr Top Microbiol Immunol 2010; 340:155-69. [PMID: 19960313 PMCID: PMC3400257 DOI: 10.1007/978-3-642-03858-7_8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The B cell receptor (BCR) generates both antigen-independent and dependent intracellular signals that are essential for B cell development and antibody responses against pathogens. However, the molecular mechanisms underlying the initiation of BCR signaling are not understood completely yet. The advent of new imaging technologies is allowing the earliest events in B cell signaling to be viewed both in vivo in lymphoid tissues and in vitro in living cells, in real-time, down to the single molecule level. Here we review recent progress in the use of these technologies to decipher the earliest events that follow B cell antigen recognition. Based on recent data using these techniques, we propose a model for the initiation of BCR signaling in which the binding of antigen induces a conformational change in the BCR's extracellular domains leading to BCR oligomerization and signaling. We conclude that testing this model will require an in-depth understanding of the unique structural and organizational features of the BCR in the plasma membrane of living B cells in the presence and absence of antigen.
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Affiliation(s)
- Pavel Tolar
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852
| | - Susan K. Pierce
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852
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4
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The constant region of the membrane immunoglobulin mediates B cell-receptor clustering and signaling in response to membrane antigens. Immunity 2009; 30:44-55. [PMID: 19135393 DOI: 10.1016/j.immuni.2008.11.007] [Citation(s) in RCA: 186] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2008] [Revised: 09/12/2008] [Accepted: 11/04/2008] [Indexed: 11/20/2022]
Abstract
B cells are activated in vivo after the B cell receptors (BCRs) bind to antigens captured on the surfaces of antigen-presenting cells. Antigen binding results in BCR microclustering and signaling; however, the molecular nature of the signaling-active BCR clusters is not well understood. Using single-molecule imaging techniques, we provide evidence that within microclusters, the binding of monovalent membrane antigens results in the assembly of immobile signaling-active BCR oligomers. The oligomerization depends on interactions between the membrane-proximal Cmicro4 domains of the membrane immunoglobulin that are both necessary and sufficient for assembly. Antigen-bound BCRs that lacked the Cmicro4 domain failed to cluster and signal, and conversely, Cmicro4 domains alone clustered spontaneously and activated B cells. These results support a unique mechanism for the initiation of BCR signaling in which antigen binding induces a conformational change in the Fc portion of the BCR, revealing an interface that promotes BCR clustering.
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5
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Zou X, Smith JA, Corcos D, Matheson LS, Osborn MJ, Brüggemann M. Removal of the BiP-retention domain in Cmicro permits surface deposition and developmental progression without L-chain. Mol Immunol 2008; 45:3573-9. [PMID: 18584871 DOI: 10.1016/j.molimm.2008.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 04/25/2008] [Accepted: 05/07/2008] [Indexed: 01/16/2023]
Abstract
Nascent, full length, immunoglobulin (Ig) heavy (H)-chains are post-translationally associated with H-chain-binding protein (BiP or GRP78) in the endoplasmic reticulum (ER). The first constant (C) domain, CH1 of a C gene (Cmu, Cgamma, Calpha), is important for this interaction. The contact is released upon BiP replacement by conventional Ig light (L)-chain (kappa or lambda). Incomplete or mutated H-chains with removed variable (VH) and/or C(H)1 domain, as found in H-chain disease (HCD), can preclude stable BiP interaction. Progression in development after the preB cell stage is dependent on surface expression of IgM when association of a micro H-chain with a L-chain overcomes the retention by BiP. We show that IgM lacking the BiP-binding domain is displayed on the cell surface and elicits a signal that allows developmental progression even without the presence of L-chain. The results are reminiscent of single chain Ig secretion in camelids where developmental processes leading to the generation of fully functional H-chain-only antibodies are not understood. Furthermore, in the mouse the largest secondary lymphoid organ, the spleen, is not required for H-chain-only Ig expression and the CD5 survival signal may be obsolete for cells expressing truncated IgM.
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Affiliation(s)
- Xiangang Zou
- The Babraham Institute, Babraham, Cambridge CB22 3AT, United Kingdom
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6
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Geraldes P, Rebrovich M, Herrmann K, Wong J, Jäck HM, Wabl M, Cascalho M. Ig Heavy Chain Promotes Mature B Cell Survival in the Absence of Light Chain. THE JOURNAL OF IMMUNOLOGY 2007; 179:1659-68. [PMID: 17641032 DOI: 10.4049/jimmunol.179.3.1659] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Survival of mature B cells is thought to depend on the BCR signaling (BCR) because ablation of either H chain (HC) expression or BCR signaling causes B cells to rapidly disappear. Whether a complete BCR is required for survival of mature B cells is not known. To address this question, we generated a mouse in which we can repress the expression of a transgenic Ig L chain (IgL) by doxycycline (IgL-repressible mouse). Repression of IgL abrogated expression. Surprisingly, however, IgL-negative B cells survived longer than 14 wk, expressed signal-competent HC on the cell's surface, and active unfolded protein response factors. Like postgerminal center B cells, IgL-negative B cells were small lymphocytes, not dividing and expressed Bcl-6. Our results indicate that expression of unpaired HC, as it may occur as a consequence of Ag ligation, somatic hypermutation, or receptor editing, facilitates the survival of cells either by inducing receptor signaling or by inducing unfolded protein response and/or the expression of survival genes such as Bcl-6.
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Affiliation(s)
- Pedro Geraldes
- Transplantation Biology Program, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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7
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Lapter S, Livnat I, Faerman A, Zipori D. Structure and implied functions of truncated B-cell receptor mRNAs in early embryo and adult mesenchymal stem cells: Cdelta replaces Cmu in mu heavy chain-deficient mice. Stem Cells 2006; 25:761-70. [PMID: 17124007 DOI: 10.1634/stemcells.2006-0582] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Stem cells exhibit a promiscuous gene expression pattern. We show herein that the early embryo and adult MSCs express B-cell receptor component mRNAs. To examine possible bearings of these genes on the expressing cells, we studied immunoglobulin mu chain-deficient mice. Pregnant mu chain-deficient females were found to produce a higher percentage of defective morulae compared with control females. Structure analysis indicated that the mu mRNA species found in embryos and in mesenchyme consist of the constant region of the mu heavy chain that encodes a recombinant 50-kDa protein. In situ hybridization localized the constant mu gene expression to loose mesenchymal tissues within the day-12.5 embryo proper and the yolk sac. In early embryo and in adult mesenchyme from mu-deficient mice, delta replaced mu chain, implying a possible requirement of these alternative molecules for embryo development and mesenchymal functions. Indeed, overexpression of the mesenchymal-truncated mu heavy chain in 293T cells resulted in specific subcellular localization and in G(1) growth arrest. The lack of such occurrence following overexpression of a complete, rearranged form of mu chain suggests that the mesenchymal version of this mRNA may possess unique functions.
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Affiliation(s)
- Smadar Lapter
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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8
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Janssens R, Dekker S, Hendriks RW, Panayotou G, van Remoortere A, San JKA, Grosveld F, Drabek D. Generation of heavy-chain-only antibodies in mice. Proc Natl Acad Sci U S A 2006; 103:15130-5. [PMID: 17015837 PMCID: PMC1586177 DOI: 10.1073/pnas.0601108103] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have generated transgenic mice containing hybrid llama/human antibody loci that contain two llama variable regions and the human D, J, and Cmu and/or Cgamma constant regions. Such loci rearrange productively and rescue B cell development efficiently without LC rearrangement. Heavy-chain-only antibodies (HCAb) are expressed at high levels, provided that the CH1 domain is deleted from the constant regions. HCAb production does not require an IgM stage for effective pre-B cell signaling. Antigen-specific heavy-chain-only IgM or IgGs are produced upon immunization. The IgG is dimeric, whereas IgM is multimeric. The chimeric HCAb loci are subject to allelic exclusion, but several copies of the transgenic locus can be rearranged and expressed successfully on the same allele in the same cell. Such cells are not subject to negative selection. The mice produce a full antibody repertoire and provide a previously undescribed avenue to produce specific human HCAb in the future.
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Affiliation(s)
| | | | - Rudi W. Hendriks
- Immunology, ErasmusMC, P.O. Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - George Panayotou
- Biomedical Sciences Research Center, Alexander Fleming, Varkiza 16602, Greece; and
| | - Alexandra van Remoortere
- Department of Parasitology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | | | - Frank Grosveld
- *Departments of Cell Biology and
- To whom correspondence should be addressed. E-mail:
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9
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Zou X, Smith JA, Nguyen VK, Ren L, Luyten K, Muyldermans S, Brüggemann M. Expression of a Dromedary Heavy Chain-Only Antibody and B Cell Development in the Mouse. THE JOURNAL OF IMMUNOLOGY 2005; 175:3769-79. [PMID: 16148123 DOI: 10.4049/jimmunol.175.6.3769] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
In mature B cells of mice and most mammals, cellular release of single H chain Abs without L chains is prevented by H chain association with Ig-specific chaperons in the endoplasmic reticulum. In precursor B cells, however, surface expression of mu-H chain in the absence of surrogate and conventional L chain has been identified. Despite this, Ag-specific single H chain Ig repertoires, using mu-, gamma-, epsilon-, or alpha-H chains found in conventional Abs, are not produced. Moreover, removal of H chain or, separately, L chain (kappa/lambda) locus core sequences by gene targeting has prevented B cell development. In contrast, H chain-only Abs are produced abundantly in Camelidae as H2 IgG without the C(H)1 domain. To test whether H chain Abs can be produced in mice, and to investigate how their expression affects B cell development, we introduced a rearranged dromedary gamma2a H chain into the mouse germline. The dromedary transgene was expressed as a naturally occurring Ag-specific disulphide-linked homodimer, which showed that B cell development can be instigated by expression of single H chains without L chains. Lymphocyte development and B cell proliferation was accomplished despite the absence of L chain from the BCR complex. Endogenous Ig could not be detected, although V(D)J recombination and IgH/L transcription was unaltered. Furthermore, crossing the dromedary H chain mice with mice devoid of all C genes demonstrated without a doubt that a H chain-only Ab can facilitate B cell development independent of endogenous Ig expression, such as mu- or delta-H chain, at early developmental stages.
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Affiliation(s)
- Xiangang Zou
- Protein Technologies Laboratory, The Babraham Institute, Babraham, Cambridge, United Kingdom
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10
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Malynn BA, Shaw AC, Young F, Stewart V, Alt FW. Truncated immunoglobulin Dmu causes incomplete developmental progression of RAG-deficient pro-B cells. Mol Immunol 2002; 38:547-56. [PMID: 11750656 DOI: 10.1016/s0161-5890(01)00085-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Early stages of B cell development are dependent on the expression of a pre-B cell receptor (BCR), composed of a mu heavy chain (HC) in association with surrogate light chain (SLC) proteins and the signaling molecules, Igalpha and Igbeta. During the formation of the variable region of the mu chain by somatic gene rearrangement, a truncated form of the mu protein (called Dmu) is sometimes produced by the rearrangement of a D(H) segment to a J(H) segment using one of three reading frames (designated rf2). When a Dmu protein is formed, subsequent B cell development is blocked by down-regulation of further HC rearrangements, so that a full-length muHC cannot be formed. In this study, we demonstrate that in recombinase activating gene (RAG)-2-deficient B220(+) CD43(+) pro-B cells in which B lymphopoiesis has been arrested at fraction C, transgenic expression of Dmu promoted partial developmental progression to fraction C', but was unable to mediate the pro-B to pre-B cell transition to fraction D effected by full-length muHC protein. These data suggest that the intracellular signaling pathways engaged by the Dmu pre-BCR are insufficient to facilitate the expansion and/or survival of pre-B cells, and are distinct from those engaged by the pre-BCR-containing full-length muHC.
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Affiliation(s)
- Barbara A Malynn
- The Center for Blood Research, Harvard Medical School, Boston, MA 02115, USA
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11
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Corcos D, Grandien A, Vazquez A, Dunda O, Lorès P, Bucchini D. Expression of a V region-less B cell receptor confers a tolerance-like phenotype on transgenic B cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:3083-9. [PMID: 11207259 DOI: 10.4049/jimmunol.166.5.3083] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Neoplastic B cells from H chain disease patients express a truncated B cell receptor (BCR), comprising a membrane Ig that lacks part of its extracellular domain. It has been speculated that deletion of the Ag binding domain would confer a constitutive activity on the BCR, as it has been shown for oncogenic growth factor receptors. A V region-less BCR has constitutive activity, because in transgenic mice it causes inhibition of endogenous H chain gene rearrangements and relieves the requirement for surrogate L chain in pre-B cell development. However, it has been speculated that normal Ag receptors also display constitutive activity. Here we show that transgenic B cells expressing a membrane H chain disease protein on their surface are phenotypically and functionally similar to B cells developing in the presence of their cognate Ag and that cells with normal levels of mutant BCR are eliminated in spleen via a bcl-2 sensitive pathway while progressing toward the mature stage. In contrast, cells with lower levels of mutant receptors develop as mature B cells. These findings support the view that the truncated BCR has a constitutive activity that mimics ligand binding, in analogy to what has been shown for oncogenic growth factor receptors.
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MESH Headings
- Animals
- Apoptosis/genetics
- Apoptosis/immunology
- B-Lymphocyte Subsets/cytology
- B-Lymphocyte Subsets/immunology
- B-Lymphocyte Subsets/metabolism
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cells, Cultured
- Clonal Anergy/genetics
- Crosses, Genetic
- Gene Rearrangement, B-Lymphocyte, Light Chain
- Humans
- Immune Tolerance/genetics
- Immunoglobulin Light Chains/biosynthesis
- Immunoglobulin Light Chains/genetics
- Immunoglobulin mu-Chains/biosynthesis
- Immunoglobulin mu-Chains/genetics
- Immunophenotyping
- Lymphocyte Activation/genetics
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Transgenic
- Proto-Oncogene Proteins c-bcl-2/genetics
- Proto-Oncogene Proteins c-bcl-2/physiology
- Receptors, Antigen, B-Cell/biosynthesis
- Receptors, Antigen, B-Cell/deficiency
- Receptors, Antigen, B-Cell/genetics
- T-Lymphocytes/immunology
- Transgenes/immunology
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Affiliation(s)
- D Corcos
- Institut Cochin de Génétique Moléculaire, Institut National de la Santé et de la Recherche Médicale Unité 257, Paris, France.
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12
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Abstract
We investigate the role of the antigen-specific B cell receptor (BCR) in the establishment and maintenance of the peripheral B cell pools. We studied the fate of a population of transgenic B cells expressing a BCR without V region (Tg(deltaVmu)). We found that the Tg(deltaVmu) B cells can populate the peripheral B cell pools in the absence of other B cells, but when in the presence of a second population of non-transgenic B cells, they are virtually absent from the mature B cell compartments. By studying the rate of accumulation of 5-bromo-2'-deoxyuridine we show that the peripheral Tg(deltaVmu) B cells have a shorter life-span compared to non-transgenic B cells. By directly comparing the fate of two populations of transgenic B cells, either lacking or expressing a V region, we were able to assign the poorest competitive ability and the short peripheral survival of the Tg(delatVmu) B cells to the lack of an antigen-binding site. The results obtained support the involvement of the V region in the persistence of peripheral B cell populations.
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Affiliation(s)
- M M Rosado
- Laboratoire des Dynamiques Lymphocytaires, CNRS URA1961, Institut Pasteur, Paris, France
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13
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Horne MC, Roth PE, DeFranco AL. Assembly of the truncated immunoglobulin heavy chain D mu into antigen receptor-like complexes in pre-B cells but not in B cells. Immunity 1996; 4:145-58. [PMID: 8624805 DOI: 10.1016/s1074-7613(00)80679-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Rearrangements of the IgH locus with JH joined to reading frame 2 of DH are greatly underrepresented in B cells. These rearrangements encode the truncated heavy chain D mu. In pre-B cells, we found D mu protein expressed on the cell surface and assembled into a complex with surrogate light chains, Ig alpha, and Ig beta. Cross-linking of either mu m- or D mu m- containing pre-B cell receptors triggered signal transduction reactions. In contrast, when expressed in mature B cell lines, D mu was not detected on the cell surface and did not efficiently bind kappa immunoglobulin light chains, but did associate with Ig alpha and Ig beta. These results characterize the interactions of D mu chain with other components of the B cell antigen receptor complex and suggest possible mechanisms by which D mu expression may interfere with B cell development.
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Affiliation(s)
- M C Horne
- Department of Microbiology, University of California, San Francisco 94143-0552, USA
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14
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Affiliation(s)
- H Karasuyama
- Department of Immunology, The Tokyo Metropolitan Institute of Medical Science, Japan
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15
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Corcos D, Dunda O, Butor C, Cesbron JY, Lorès P, Bucchini D, Jami J. Pre-B-cell development in the absence of lambda 5 in transgenic mice expressing a heavy-chain disease protein. Curr Biol 1995; 5:1140-8. [PMID: 8548286 DOI: 10.1016/s0960-9822(95)00230-2] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Heavy-chain diseases (HCDs) are human lymphoproliferative neoplasias that are characterized by the secretion of truncated immunoglobulin heavy chains devoid of light chains. We have previously proposed--by analogy to the process by which mutated growth factor receptors can be oncogenic--that because the genetic defects in HCDs result in the production of abnormal membrane-associated heavy chains lacking an antigen-binding domain, these abnormal B-cell antigen receptors might engage in ligand-independent signalling. Normal pre-B-cell development requires the presence of the pre-B-cell receptor, formed by the association of mu heavy chains with two polypeptides--so-called surrogate light chains, Vpre-B and lambda 5--that are homologous to the variable and constant portions of immunoglobulin light chains, respectively. To assess whether amino-terminal truncation of membrane-associated heavy chains results in their constitutive activation, we have examined the ability of a HCD-associated mu protein to promote pre-B-cell development in transgenic mice. RESULTS When the mu HCD transgene is introduced into SCID mice, CD43- pre-B cells develop normally. To determine whether this pre-B-cell development requires surrogate light chains, we backcrossed mice expressing full-length or truncated mu transgenes with lambda 5-deficient mice. Our results show that the truncated heavy chain, but not the normal chain, is able to promote pre-B-cell development in the absence of lambda 5. We also show that truncated mu chains spontaneously aggregate at the surface of bone marrow cells. CONCLUSIONS Expression of the truncated mu heavy chain overrides a tightly controlled step of pre-B-cell development, which strongly suggests that a constitutive signal is delivered by the truncated mu chain disease protein. The self-aggregation of mu chain disease proteins might account for this constitutive activation. We conclude that amino-terminal truncation of heavy chains could play a role in the genesis of HCD neoplasia if it occurs at an appropriate stage of B-cell differentiation, namely in a mature B cell.
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Affiliation(s)
- D Corcos
- Institut Cochin de Génétique Moléculaire, Unité INSERM 257, Paris, France
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16
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Chang Y, Bosma GC, Bosma MJ. Development of B cells in scid mice with immunoglobulin transgenes: implications for the control of V(D)J recombination. Immunity 1995; 2:607-16. [PMID: 7796294 DOI: 10.1016/1074-7613(95)90005-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The inability of scid pro-B cells to progress to the pre-B and B cell stages is believed to be caused by a defective recombinase activity that fails to resolve chromosomal breaks resulting from attempted V(D)J recombination. In support of this model, we report that certain immunoglobulin transgenes, specifically those which strongly inhibit endogenous VH-to-DJH and V kappa-to-J kappa rearrangement in wild-type mice, allow scid pro-B cells to progress to the pre-B and B cell stages. This rescue of scid B cell differentiation is associated with a dramatic reduction in expression of the recombination activation genes, RAG1 and RAG2, and with reduced transcription of the kappa locus.
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Affiliation(s)
- Y Chang
- Fox Chase Cancer Center, Institute for Cancer Research, Philadelphia, Pennsylvania 19111, USA
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17
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Levinson DA, Campos-Torres J, Leder P. Molecular characterization of transgene-induced immunodeficiency in B-less mice using a novel quantitative limiting dilution polymerase chain reaction method. J Exp Med 1993; 178:317-29. [PMID: 8315387 PMCID: PMC2191084 DOI: 10.1084/jem.178.1.317] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
B-less mice express a human immunoglobulin (Ig) lambda transgene that induces a severe deficiency of both immature pre-B and mature B lymphocytes. To understand this perturbation in B lymphopoiesis, we have devised a sensitive limiting dilution polymerase chain reaction assay that quantitates specific Ig rearrangements and thus quantitates B lineage cells at various stages of differentiation within unfractionated bone marrow. We find that there are significantly reduced frequencies of both VH-to-DJH and VK-to-JK rearrangements in the transgenic strain, whereas the frequency of D-to-JH rearrangements approximates that of wild type. Since Ig gene rearrangements occur in a stepwise fashion in which D-to-JH joining precedes that of VH-to-DJH and VK-to-JK, these results indicate that the major block of B lymphocyte development in the B-less strain occurs after D-to-JH rearrangement. Interestingly, sequence analysis of residual VHDJH junctions from transgenic pre-B lymphocytes reveals that an abnormally high proportion of these are out of frame and therefore nonproductive. Taken together, these data suggest that early expression of the transgenic lambda protein specifically prevents the development of a normal-sized population of precursor B lymphocytes coexpressing functional IgH. The transgene-induced immunodeficiency appears to arise by a precocious maturation process in which precursors bypass a developmental stage associated with cellular expansion.
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Affiliation(s)
- D A Levinson
- Department of Genetics, Harvard Medical School, Boston, Massachusetts
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18
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Borst J, Brouns GS, de Vries E, Verschuren MC, Mason DY, van Dongen JJ. Antigen receptors on T and B lymphocytes: parallels in organization and function. Immunol Rev 1993; 132:49-84. [PMID: 8349297 DOI: 10.1111/j.1600-065x.1993.tb00837.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- J Borst
- Division of Immunology, The Netherlands Cancer Institute, Amsterdam
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