scholarly journals Editing Anti-DNA B Cells by Vλx

2004 ◽  
Vol 199 (3) ◽  
pp. 337-346 ◽  
Author(s):  
Yijin Li ◽  
Yoram Louzoun ◽  
Martin Weigert
Keyword(s):  
B Cells ◽  
Dna Binding ◽  
Transgenic Mice ◽  
Heavy Chain ◽  
Light Chain ◽  
Gene Replacement ◽  
Light Chains ◽  
Alternative Pathways ◽  
Self Tolerance ◽  
V Gene

Receptor editing is performed by replacement of Vκ genes that contribute to autoreactivity. In addition, the Cκ locus can be deleted by Vκ rearrangement to intronic or 3′ of Cκ RS sequences (also referred to as κ deletion elements). B cells that delete the Cκ can then express λ light chains. However, the λ locus, either of man or mouse, does not allow V gene replacement. Nor does it appear to be deleted. Therefore, editing of autoreactive λ B cells may require alternative pathways. We have found that in anti-DNA heavy chain transgenic mice (tgs) VH3H9/56R, B cells that express anti-DNA receptors comprised of λ1 in association with an anti-DNA heavy chain often coexpress a κ chain that prevents DNA binding. We speculate that such isotypically included cells may have low anti-DNA receptor densities, a feature that may lead to self-tolerance. Here we describe a mechanism of preventing DNA binding by expression of a rarely used member of the Vλ family, Vλx. The λx B cells of the tgs also express CD25 and may represent B cells that have exhausted light chain editing possibilities.

scholarly journals A Mouse with a Monoclonal Primary lmmunoglobulin Repertoire not Further Diversified by V-Gene Replacement

1999 ◽  
Vol 7 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Marilia Cascalho ◽  
Denise A. Martin ◽  
Jamie Wong ◽  
Queenie Lam ◽  
Matthias Wabl ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Heavy Chain ◽  
Light Chain ◽  
Gene Replacement ◽  
Genes Encoding ◽  
V Gene ◽  
Immunoglobulin Repertoire ◽  
Or Gene

We have generated a monoclonal B-cell mouse by introducing homozygous, nonfunctional RAG-2 alleles and aλ1 light-chain transgene into the quasi-monoclonal (QM) mouse, which contains a “knocked-in” VHDJHrearrangement. Thus, this mouse, which we call MonoB, is devoid of T cells and contains preformed heavy- and light-chain genes encoding immunoglobulin with an anti-NP specificity. The MonoB mouse allows us to examine immunoglobulin diversity in the absence of processes mediated by V(D)J recombination and T cells. Here we report that not only is the MonoB's primary immunoglobulin repertoire monoclonal, but also that its secondary repertoire is not further diversified by V-gene replacement or gene conversion. Among 99 heavy-chain and 41λlight-chain genes from peripheral B cells of the MonoB mouse, there were no V-gene replacements. When compared to the QM mouse, which has RAG activity, and for which V-gene replacement is the major diversifying mechanism, these data suggest that V-gene replacement is mediated by V(D)J recombination and not by other recombination systems.

Evidence for Non-Random Immunoglobulin VH Gene and Light Chain Isotype Usage in Follicular Non-Hodgkin’s Lymphoma.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2408-2408
Author(s):  
Christopher B. Yohn ◽  
Charles P. Van Beveren ◽  
Xi Y. Mu ◽  
Peter Shier ◽  
Gregg J. Silverman ◽  
...  
Keyword(s):  
Gene Expression ◽  
B Cells ◽  
B Cell ◽  
Light Chain ◽  
Light Chains ◽  
B Cell Malignancies ◽  
Gene Usage ◽  
Vh Gene ◽  
V Gene ◽  
Peripheral B Cells

Abstract Background: Antibody diversity is generated by recombination of individual immunoglobulin (Ig) gene segments and subsequent somatic diversification driven by antigen recognition. In the repertoire of expressed B cell receptors (BCR) among normal peripheral B cells, variable heavy (VH) gene segments are not equally represented. The ratio of kappa to lambda light chain usage is also skewed; the normal κ/λ is 1.5. Investigation of the BCR repertoire may provide clues to the genesis of B cell malignancies, as suggested in chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL). BCR V gene identification during the production of recombinant antibodies used in our ongoing PhII and PhIII FavId® (idiotype/KLH) immunotherapy studies has enabled us to analyze V gene usage from 475 B cell follicular lymphoma (FL) tissue samples. This study reports the results of VH gene and κ/λ gene expression in this FL sample collection. Methods: Ig heavy chain (HC) and light chain (LC) isotypes from B cell FL samples were identified by flow cytometry. VH and VL regions were sequenced from gene specific cDNA libraries prepared from these samples. VH gene usage and κ/λ ratios were compared to frequencies determined for normal peripheral B cells isolated from six healthy volunteers as well as published reports for normal peripheral B cells and other B cell malignancies. Results: Compared to VH gene family usage determined for normal B cells, VH3 usage is higher (68% vs. 42%), VH1 usage is lower (7.8% vs. 22%) and VH4 usage is equivalent (22% vs. 26%) in our cohort of FL patients while VH2, 5, 6 and 7 are infrequently used in both populations. Usage of the VH3 genes within FL derived sequences also depends upon isotype, in that this gene family is preferentially associated with the IgM HC isotype relative to IgG (76% and 57% respectively). Additionally, the combined usage of the specific genes VH3-23 and VH3-48 in our patient collection accounts for over 29% of all VH genes - compared to 9% among normal B cells. These VH gene usages also differ from reports of VH gene expression among CLL and MCL patients. With respect to LC usage, VH3 isolates are associated with a normal κ/λ ratio of 1.6 while VH4 gene isolates are preferentially associated with λ light chains with a κ/λ ratio of 0.9. Finally, FL B cells expressing the IgM HC isotype preferentially co-express κ light chains (κ/λ ratio of 2.4) while IgG expressing cells preferentially utilize λ chains (κ/λ ratio of 0.6). Conclusions: Non-random V gene and LC expression among patients with FL is noted. These distortions in Ig gene expression suggest that lymphomagenesis in FL may be associated with B cell stimulation by common antigens. A program to investigate the epitopes recognized by FL derived BCRs via binding of recombinant FL derived antibodies to protein arrays containing common auto-antigens is currently underway.

scholarly journals Critical roles of the immunoglobulin intronic enhancers in maintaining the sequential rearrangement of IgH and Igk loci

2006 ◽  
Vol 203 (7) ◽  
pp. 1721-1732 ◽  
Author(s):  
Matthew A. Inlay ◽  
Tongxiang Lin ◽  
Heather H. Gao ◽  
Yang Xu
Keyword(s):  
B Cells ◽  
Developmental Stage ◽  
Heavy Chain ◽  
Light Chain ◽  
Matrix Attachment Region ◽  
Cis Elements ◽  
Wild Type ◽  
Intronic Enhancer ◽  
Attachment Region

V(D)J recombination of immunoglobulin (Ig) heavy (IgH) and light chain genes occurs sequentially in the pro– and pre–B cells. To identify cis-elements that dictate this order of rearrangement, we replaced the endogenous matrix attachment region/Igk intronic enhancer (MiEκ) with its heavy chain counterpart (Eμ) in mice. This replacement, denoted EμR, substantially increases the accessibility of both Vκ and Jκ loci to V(D)J recombinase in pro–B cells and induces Igk rearrangement in these cells. However, EμR does not support Igk rearrangement in pre–B cells. Similar to that in MiEκ−/− pre–B cells, the accessibility of Vκ segments to V(D)J recombinase is considerably reduced in EμR pre–B cells when compared with wild-type pre–B cells. Therefore, Eμ and MiEκ play developmental stage-specific roles in maintaining the sequential rearrangement of IgH and Igk loci by promoting the accessibility of V, D, and J loci to the V(D)J recombinase.

scholarly journals Positive and negative selection of antigen-specific B cells in transgenic mice expressing variant forms of the VH1 (T15) heavy chain

2000 ◽  
Vol 12 (6) ◽  
pp. 873-885 ◽  
Author(s):  
James J. Kenny ◽  
Eric G. Derby ◽  
Jeffrey A. Yoder ◽  
Shawn A. Hill ◽  
Randy T. Fischer ◽  
...  
Keyword(s):  
B Cells ◽  
Transgenic Mice ◽  
Heavy Chain ◽  
Negative Selection ◽  
Selection Of

Self-Tolerance in B-Cells from Different Lines of Lysozyme Double-Transgenic Mice

1989 ◽  
pp. 377-384 ◽  
Author(s):  
A. Basten ◽  
R. A. Brink ◽  
D. Y. Mason ◽  
J. Crosbie ◽  
C. C. Goodnow
Keyword(s):  
B Cells ◽  
Transgenic Mice ◽  
Self Tolerance ◽  
Double Transgenic Mice

Morphometry and muscle gene expression in hypertrophied hearts from polyomavirus large T antigen transgenic mice

1995 ◽  
Vol 269 (1) ◽  
pp. H86-H95 ◽  
Author(s):  
E. Holder ◽  
B. Mitmaker ◽  
L. Alpert ◽  
L. Chalifour
Keyword(s):  
Transgenic Mice ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Troponin I ◽  
T Antigen ◽  
Large T Antigen ◽  
Cross Sectional

Transgenic mice expressing polyomavirus large T antigen (PVLT) in cardiomyocytes develop a cardiac hypertrophy in adulthood. Morphometric analysis identified cardiomyocytes enlarged up to ninefold in cross-sectional area in the adult transgenic hearts compared with normal age-matched nontransgenic hearts. Most enlarged cardiomyocytes were found in the subendocardium, whereas normal-sized cardiomyocytes were localized to the midmyocardium. Transgenic hearts did not express detectable skeletal muscle actin mRNA or protein, or skeletal troponin I isoform mRNA. Some, but not all, transgenic hearts expressed an increase in the beta-myosin heavy chain mRNA. All five transgenic mice tested had increased expression of atrial natriuretic factor (ANF) mRNA. Whereas normal hearts expressed three myosin light chain proteins of 19, 16, and 15 kDa, we found that the 19-kDa myosin light chain was not observed in the transgenic hearts. We conclude that adult, PVLT-expressing, transgenic mice developed enlarged cardiomyocytes with an increase in beta-myosin heavy chain and ANF mRNA expression, but a widespread skeletal isoform usage was not present in these transgenic mice. The adult transgenic hearts thus display histological and molecular changes similar to those found in hypertrophy induced by a pressure overload in vivo.

scholarly journals Fate of surrogate light chains in B lineage cells.

1996 ◽  
Vol 183 (2) ◽  
pp. 421-429 ◽  
Author(s):  
K Lassoued ◽  
H Illges ◽  
K Benlagha ◽  
M D Cooper
Keyword(s):  
B Cells ◽  
Cell Surface ◽  
Light Chain ◽  
Light Chains ◽  
Receptor Complex ◽  
Surrogate Light Chain ◽  
Heavy Chains ◽  
Receptor Component ◽  
B Lineage ◽  
Receptor Assembly

Biosynthesis of the immunoglobulin (Ig) receptor components and their assembly were examined in cell lines representative of early stages in human B lineage development. In pro-B cells, the nascent surrogate light chain proteins form a complex that transiently associates in the endoplasmic reticulum with a spectrum of unidentified proteins (40, 60, and 98 kD) and Bip, a heat shock protein family member. Lacking companion heavy chains, the surrogate light chains in pro-B cells do not associate with either the Ig(alpha) or Ig(beta) signal transduction units, undergo rapid degradation, and fail to reach the pro-B cell surface. In pre-B cells, by contrast, a significant portion of the surrogate light chain proteins associate with mu heavy chains, Ig(alpha), and Ig(beta) to form a stable receptor complex with a relatively long half-life. Early in this assembly process, Bip/GRP78, calnexin, GRP94, and a protein of approximately 17 kD differentially bind to the nascent mu heavy chains. The 17-kD intermediate is gradually replaced by the surrogate light chain protein complex, and the Ig(alpha) and Ig(beta) chains bind progressively to the mu heavy chains during the complex and relatively inefficient process of pre-B receptor assembly. The results suggest that, in humans, heavy chain association is essential for surrogate light chain survival and transport to the cell surface as an integral receptor component.

scholarly journals Changes in Locus-specific V(D)J Recombinase Activity Induced by Immunoglobulin Gene Products during B Cell Development

1997 ◽  
Vol 185 (4) ◽  
pp. 609-620 ◽  
Author(s):  
Andrei Constantinescu ◽  
Mark S. Schlissel
Keyword(s):  
B Cells ◽  
B Cell ◽  
Heavy Chain ◽  
Light Chain ◽  
Immunoglobulin Heavy Chain ◽  
Cell Development ◽  
B Cell Development ◽  
Allelic Exclusion ◽  
Chain Locus ◽  
Heavy Chain Locus

The process of V(D)J recombination is crucial for regulating the development of B cells and for determining their eventual antigen specificity. Here we assess the developmental regulation of the V(D)J recombinase directly, by monitoring the double-stranded DNA breaks produced in the process of V(D)J recombination. This analysis provides a measure of recombinase activity at immunoglobulin heavy and light chain loci across defined developmental stages spanning the process of B cell development. We find that expression of a complete immunoglobulin heavy chain protein is accompanied by a drastic change in the targeting of V(D)J recombinase activity, from being predominantly active at the heavy chain locus in pro-B cells to being exclusively restricted to the light chain loci in pre-B cells. This switch in locus-specific recombinase activity results in allelic exclusion at the immunoglobulin heavy chain locus. Allelic exclusion is maintained by a different mechanism at the light chain locus. We find that immature, but not mature, B cells that already express a functional light chain protein can undergo continued light chain gene rearrangement, by replacement of the original rearrangement on the same allele. Finally, we find that the developmentally regulated targeting of V(D)J recombination is unaffected by enforced rapid transit through the cell cycle induced by an Eμ-myc transgene.

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