scholarly journals Positive and Negative Regulation of  V(D)J Recombination by the E2A Proteins

1999 ◽  
Vol 189 (2) ◽  
pp. 289-300 ◽  
Author(s):  
Gretchen Bain ◽  
William J. Romanow ◽  
Karen Albers ◽  
Wendy L. Havran ◽  
Cornelis Murre
Keyword(s):  
Adult Development ◽  
Signal Sequence ◽  
Gene Segment ◽  
Cell Receptor ◽  
Recombination Reaction ◽  
Gene Products ◽  
Antigen Receptors ◽  
Dna Breaks ◽  
Thymocyte Development ◽  
Temporal Regulation

A key feature of B and T lymphocyte development is the generation of antigen receptors through the rearrangement and assembly of the germline variable (V), diversity (D), and joining (J) gene segments. However, the mechanisms responsible for regulating developmentally ordered gene rearrangements are largely unknown. Here we show that the E2A gene products are essential for the proper coordinated temporal regulation of V(D)J rearrangements within the T cell receptor (TCR) γ and δ loci. Specifically, we show that E2A is required during adult thymocyte development to inhibit rearrangements to the γ and δ V regions that normally recombine almost exclusively during fetal thymocyte development. The continued rearrangement of the fetal Vγ3 gene segment in E2A-deficient adult thymocytes correlates with increased levels of Vγ3 germline transcripts and increased levels of double-stranded DNA breaks at the recombination signal sequence bordering Vγ3. Additionally, rearrangements to a number of Vγ and Vδ gene segments used predominately during adult development are significantly reduced in E2A-deficient thymocytes. Interestingly, at distinct stages of T lineage development, both the increased and decreased rearrangement of particular Vδ gene segments is highly sensitive to the dosage of the E2A gene products, suggesting that the concentration of the E2A proteins is rate limiting for the recombination reaction involving these Vδ regions.

scholarly journals Structure of Nonhairpin Coding-End DNA Breaks in Cells Undergoing V(D)J Recombination

1998 ◽  
Vol 18 (4) ◽  
pp. 2029-2037 ◽  
Author(s):  
Mark S. Schlissel
Keyword(s):  
Receptor Gene ◽  
Cell Receptor ◽  
Recombination Reaction ◽  
Immunoglobulin Gene ◽  
Dna Breaks ◽  
Strand Breaks ◽  
Recombination Signal Sequences ◽  
Nuclease Digestion ◽  
Dna Ends ◽  
In Cells

ABSTRACT The V(D)J recombinase recognizes a pair of immunoglobulin or T-cell receptor gene segments flanked by recombination signal sequences and introduces double-strand breaks, generating two signal ends and two coding ends. Broken coding ends were initially identified as covalently closed hairpin DNA molecules. Before recombination, however, the hairpins must be opened and the ends must be modified by nuclease digestion and N-region addition. We have now analyzed nonhairpin coding ends associated with various immunoglobulin gene segments in cells undergoing V(D)J recombination. We found that these broken DNA ends have different nonrandom 5′-strand deletions which were characteristic for each locus examined. These deletions correlate well with the sequence characteristics of coding joints involving these gene segments. In addition, unlike broken signal ends, these nonhairpin coding-end V(D)J recombination reaction intermediates have 3′ overhanging ends. We discuss the implications of these results for models of how sequence modifications occur during coding-joint formation.

scholarly journals T-cell receptor alpha locus V(D)J recombination by-products are abundant in thymocytes and mature T cells.

1996 ◽  
Vol 16 (2) ◽  
pp. 609-618 ◽  
Author(s):  
F Livak ◽  
D G Schatz
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Signal Sequence ◽  
Cell Receptor ◽  
Recombination Reaction ◽  
Dna Molecules ◽  
Coding Region ◽  
Recombination Signal ◽  
By Products

In addition to the assembled coding regions of immunoglobulin and T-cell receptor (TCR) genes, the V(D)J recombination reaction can in principle generate three types of by-products in normal developing lymphocytes: broken DNA molecules that terminate in a recombination signal sequence or a coding region (termed signal or coding end molecules, respectively) and DNA molecules containing fused recombination signal sequences (termed reciprocal products). Using a quantitative Southern blot analysis of the murine TCR alpha locus, we demonstrate that substantial amounts of signal end molecules and reciprocal products, but not coding end molecules, exist in thymocytes, while peripheral T cells contain substantial amounts of reciprocal products. At the 5' end of the J alpha locus, 20% of thymus DNA exists as signal end molecules. An additional 30 to 40% of the TCR alpha/delta locus exists as remarkably stable reciprocal products throughout T-cell development, with the consequence that the TCR C delta region is substantially retained in alpha beta committed T cells. The disappearance of the broken DNA molecules occurs in the same developmental transition as termination of expression of the recombination activating genes, RAG-1 and RAG-2. These findings raise important questions concerning the mechanism of V(D)J recombination and the maintenance of genome integrity during lymphoid development.

scholarly journals The T-Cell Receptor β Variable Gene Promoter Is Required for Efficient Vβ Rearrangement but Not Allelic Exclusion

2004 ◽  
Vol 24 (16) ◽  
pp. 7015-7023 ◽  
Author(s):  
Chun Jeih Ryu ◽  
Brian B. Haines ◽  
Hye Ran Lee ◽  
Yun Hee Kang ◽  
Dobrin D. Draganov ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
Dna Sequences ◽  
Signal Sequence ◽  
Gene Segment ◽  
Gene Promoter ◽  
Simian Virus 40 ◽  
Cell Receptor ◽  
Allelic Exclusion ◽  
Variable Gene

ABSTRACT To investigate the role of promoters in regulating variable gene rearrangement and allelic exclusion, we constructed mutant mice in which a 1.2-kb region of the Vβ13 promoter was either deleted (P13−/−) or replaced with the simian virus 40 minimal promoter plus five copies of Gal4 DNA sequences (P13R/R). In P13−/− mice, cleavage, rearrangement, and transcription of Vβ13, but not the flanking Vβ gene segments, were significantly inhibited. In P13R/R mice, inhibition of Vβ13 rearrangement was less severe and was not associated with any apparent reduction in Vβ13 cleavage. Expression of a T-cell receptor (TCR) transgene blocked cleavages at the normal Vβ13-recombination signal sequence junction and Vβ13 coding joint formation of both wild-type and mutant Vβ13 alleles. However, a low level of aberrant Vβ13 cleavage was consistently detected, especially in TCR transgenic P13R/R mice. These findings suggest that the variable gene promoter is required for promoting local recombination accessibility of the associated Vβ gene segment. Although the promoter is dispensable for allelic exclusion, it appears to suppress aberrant Vβ cleavages during allelic exclusion.

scholarly journals Genetic Modulation of T Cell Receptor Gene Segment Usage during Somatic Recombination

2000 ◽  
Vol 192 (8) ◽  
pp. 1191-1196 ◽  
Author(s):  
Ferenc Livak ◽  
Douglas B. Burtrum ◽  
Lee Rowen ◽  
David G. Schatz ◽  
Howard T. Petrie
Keyword(s):  
T Cell ◽  
T Cell Receptor ◽  
Receptor Gene ◽  
Gene Segment ◽  
Cell Receptor ◽  
Antigen Receptors ◽  
Synaptic Complex ◽  
Recombination Signal Sequences ◽  
Germline Genes ◽  
Cluster Gene

Lymphocyte antigen receptors are not encoded by germline genes, but rather are produced by combinatorial joining between clusters of gene segments in somatic cells. Within a given cluster, gene segment usage during recombination is thought to be largely random, with biased representation in mature T lymphocytes resulting from protein-mediated selection of a subset of the total repertoire. Here we show that T cell receptor Dβ and Jβ gene segment usage is not random, but is patterned at the time of recombination. The hierarchy of gene segment usage is independent of gene segment proximity, but rather is influenced by the ability of the flanking recombination signal sequences (RSS) to bind the recombinase and/or to form a paired synaptic complex. Importantly, the relative frequency of gene segment usage established during recombination is very similar to that found after protein-mediated selection, suggesting that in addition to targeting recombinase activity, the RSS may have evolved to bias the naive repertoire in favor of useful gene products.

scholarly journals B-cell repertoire responses to varicella-zoster vaccination in human identical twins

2014 ◽  
Vol 112 (2) ◽  
pp. 500-505 ◽  
Author(s):  
Chen Wang ◽  
Yi Liu ◽  
Mary M. Cavanagh ◽  
Sabine Le Saux ◽  
Qian Qi ◽  
...  
Keyword(s):  
B Cell ◽  
Germ Line ◽  
Twin Pair ◽  
Gene Segment ◽  
Cell Receptor ◽  
Identical Twins ◽  
Antigen Receptors ◽  
Cell Repertoire ◽  
Varicella Zoster ◽  
B Cell Repertoire

Adaptive immune responses in humans rely on somatic genetic rearrangements of Ig and T-cell receptor loci to generate diverse antigen receptors. It is unclear to what extent an individual’s genetic background affects the characteristics of the antibody repertoire used in responding to vaccination or infection. We studied the B-cell repertoires and clonal expansions in response to attenuated varicella-zoster vaccination in four pairs of adult identical twins and found that the global antibody repertoires of twin pair members showed high similarity in antibody heavy chain V, D, and J gene segment use, and in the length and features of the complementarity-determining region 3, a major determinant of antigen binding. These twin similarities were most pronounced in the IgM-expressing B-cell pools, but were seen to a lesser extent in IgG-expressing B cells. In addition, the degree of antibody somatic mutation accumulated in the B-cell repertoire was highly correlated within twin pair members. Twin pair members had greater numbers of shared convergent antibody sequences, including mutated sequences, suggesting similarity among memory B-cell clonal lineages. Despite these similarities in the memory repertoire, the B-cell clones used in acute responses to ZOSTAVAX vaccination were largely unique to each individual. Taken together, these results suggest that the overall B-cell repertoire is significantly shaped by the underlying germ-line genome, but that stochastic or individual-specific effects dominate the selection of clones in response to an acute antigenic stimulus.

scholarly journals Allelic variations in the human T cell receptor V beta 6.7 gene products.

1990 ◽  
Vol 171 (1) ◽  
pp. 221-230 ◽  
Author(s):  
Y Li ◽  
P Szabo ◽  
M A Robinson ◽  
B Dong ◽  
D N Posnett
Keyword(s):  
Immune Responses ◽  
T Cell Receptor ◽  
Cell Receptor ◽  
Gene Products ◽  
Human T Cell ◽  
Direct Demonstration ◽  
Disease Associations ◽  
V Genes ◽  
V Gene ◽  
Allelic Variations

Polymorphisms of human TCR gene products have been suggested by the description of a mAb, OT145, that identifies a subset of TCRs in some individuals but not in others (6). Here we demonstrate that this mAb detects a TCR allotype of the V beta 6.7 gene. Two allelic products of this V gene differ by two nonconservative amino acid substitutions. The mAb OT145 appears to react with V beta 6.7 a gene products ("+" allele), but not with V beta 6.7b gene products ("-" allele). This represents the first direct demonstration that TCR V gene allotypes exist and provides a possible explanation for immune responses under the control of TCR V genes and for disease associations with TCR V genes.

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