Understanding the Immunoglobulin Locus Specificity of Hypermutation

2011 ◽  
pp. 311-326 ◽  
Author(s):  
Vera Batrak ◽  
Artem Blagodatski ◽  
Jean-Marie Buerstedde
Keyword(s):  
Immunoglobulin Locus ◽  
Locus Specificity

Gene replacement with one-sided homologous recombination

1992 ◽  
Vol 12 (1) ◽  
pp. 360-367
Author(s):  
N Berinstein ◽  
N Pennell ◽  
C A Ottaway ◽  
M J Shulman
Keyword(s):  
Homologous Recombination ◽  
Dna Sequences ◽  
Mammalian Cells ◽  
Target Gene ◽  
Gene Replacement ◽  
Immunoglobulin Genes ◽  
Nonhomologous Recombination ◽  
Immunoglobulin Locus ◽  
Chromosomal Sequences ◽  
Dna Vectors

Homologous recombination is now routinely used in mammalian cells to replace endogenous chromosomal sequences with transferred DNA. Vectors for this purpose are traditionally constructed so that the replacement segment is flanked on both sides by DNA sequences which are identical to sequences in the chromosomal target gene. To test the importance of bilateral regions of homology, we measured recombination between transferred and chromosomal immunoglobulin genes when the transferred segment was homologous to the chromosomal gene only on the 3' side. In each of the four recombinants analyzed, the 5' junction was unique, suggesting that it was formed by nonhomologous, i.e., random or illegitimate, recombination. In two of the recombinants, the 3' junction was apparently formed by homologous recombination, while in the other two recombinants, the 3' junction as well as the 5' junction might have involved a nonhomologous crossover. As reported previously, we found that the frequency of gene targeting increases monotonically with the length of the region of homology. Our results also indicate that targeting with fragments bearing one-sided homology can be as efficient as with fragments with bilateral homology, provided that the overall length of homology is comparable. The frequency of these events suggests that the immunoglobulin locus is particularly susceptible to nonhomologous recombination. Vectors designed for one-sided homologous recombination might be advantageous for some applications in genetic engineering.

scholarly journals DNA Polymerase η Is Involved in Hypermutation Occurring during Immunoglobulin Class Switch Recombination

2004 ◽  
Vol 199 (2) ◽  
pp. 265-270 ◽  
Author(s):  
Ahmad Faili ◽  
Said Aoufouchi ◽  
Sandra Weller ◽  
Françoise Vuillier ◽  
Anne Stary ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Dna Sequences ◽  
Tandem Repeats ◽  
Somatic Hypermutation ◽  
Cytidine Deaminase ◽  
Class Switch Recombination ◽  
Class Switch ◽  
Mutation Pattern ◽  
Immunoglobulin Locus ◽  
V Gene

Base substitutions, deletions, and duplications are observed at the immunoglobulin locus in DNA sequences involved in class switch recombination (CSR). These mutations are dependent upon activation-induced cytidine deaminase (AID) and present all the characteristics of the ones observed during V gene somatic hypermutation, implying that they could be generated by the same mutational complex. It has been proposed, based on the V gene mutation pattern of patients with the cancer-prone xeroderma pigmentosum variant (XP-V) syndrome who are deficient in DNA polymerase η (pol η), that this enzyme could be responsible for a large part of the mutations occurring on A/T bases. Here we show, by analyzing switched memory B cells from two XP-V patients, that pol η is also an A/T mutator during CSR, in both the switch region of tandem repeats as well as upstream of it, thus suggesting that the same error-prone translesional polymerases are involved, together with AID, in both processes.

scholarly journals Epigenome engineering: new technologies for precision medicine

2020 ◽  
Vol 48 (22) ◽  
pp. 12453-12482
Author(s):  
Agustin Sgro ◽  
Pilar Blancafort
Keyword(s):  
Tumor Suppressor Genes ◽  
New Technologies ◽  
Molecular Medicine ◽  
New Era ◽  
Epigenome Editing ◽  
Promising Strategy ◽  
Technological Advances ◽  
Covalent Modifications ◽  
Reversible Covalent ◽  
Locus Specificity

Abstract Chromatin adopts different configurations that are regulated by reversible covalent modifications, referred to as epigenetic marks. Epigenetic inhibitors have been approved for clinical use to restore epigenetic aberrations that result in silencing of tumor-suppressor genes, oncogene addictions, and enhancement of immune responses. However, these drugs suffer from major limitations, such as a lack of locus selectivity and potential toxicities. Technological advances have opened a new era of precision molecular medicine to reprogram cellular physiology. The locus-specificity of CRISPR/dCas9/12a to manipulate the epigenome is rapidly becoming a highly promising strategy for personalized medicine. This review focuses on new state-of-the-art epigenome editing approaches to modify the epigenome of neoplasms and other disease models towards a more ‘normal-like state’, having characteristics of normal tissue counterparts. We highlight biomolecular engineering methodologies to assemble, regulate, and deliver multiple epigenetic effectors that maximize the longevity of the therapeutic effect, and we discuss limitations of the platforms such as targeting efficiency and intracellular delivery for future clinical applications.

scholarly journals Induction of Immunoglobulin Heavy-Chain Transcription through the Transcription Factor Bright Requires TFII-I

2006 ◽  
Vol 26 (12) ◽  
pp. 4758-4768 ◽  
Author(s):  
Jaya Rajaiya ◽  
Jamee C. Nixon ◽  
Neil Ayers ◽  
Zana P. Desgranges ◽  
Ananda L. Roy ◽  
...  
Keyword(s):  
Transcription Factor ◽  
B Lymphocytes ◽  
Heavy Chain ◽  
In Vitro Model ◽  
Model System ◽  
Interaction Domain ◽  
Tyrosine Residues ◽  
Immunoglobulin Locus ◽  
Vitro Model

ABSTRACT Bright/ARID3a/Dril1, a member of the ARID family of transcription factors, is expressed in a highly regulated fashion in B lymphocytes, where it enhances immunoglobulin transcription three- to sixfold. Recent publications from our lab indicated that functional, but not kinase-inactive, Bruton's tyrosine kinase (Btk) is critical for Bright activity in an in vitro model system, yet Bright itself is not appreciably tyrosine phosphorylated. These data suggested that a third protein, and Btk substrate, must contribute to Bright-enhanced immunoglobulin transcription. The ubiquitously expressed transcription factor TFII-I was identified as a substrate for Btk several years ago. In this work, we show that TFII-I directly interacts with human Bright through amino acids in Bright's protein interaction domain and that specific tyrosine residues of TFII-I are essential for Bright-induced activity of an immunoglobulin reporter gene. Moreover, inhibition of TFII-I function in a B-cell line resulted in decreased heavy-chain transcript levels. These data suggest that Bright functions as a three-component protein complex in the immunoglobulin locus and tie together previous data indicating important roles for Btk and TFII-I in B lymphocytes.

scholarly journals Biallelic Germline Transcription at the κ Immunoglobulin Locus

2003 ◽  
Vol 197 (6) ◽  
pp. 743-750 ◽  
Author(s):  
Nandita Singh ◽  
Yehudit Bergman ◽  
Howard Cedar ◽  
Andrew Chess
Keyword(s):  
B Cells ◽  
Chromatin Structure ◽  
Replication Timing ◽  
Allelic Exclusion ◽  
Antigen Receptors ◽  
Germline Transcription ◽  
Immature B Cells ◽  
Recombination Activating Gene ◽  
Immunoglobulin Locus

Rearrangement of antigen receptor genes generates a vast array of antigen receptors on lymphocytes. The establishment of allelic exclusion in immunoglobulin genes requires differential treatment of the two sequence identical alleles. In the case of the κ immunoglobulin locus, changes in chromatin structure, methylation, and replication timing of the two alleles are all potentially involved in regulating rearrangement. Additionally, germline transcription of the κ locus which precedes rearrangement has been proposed to reflect an opening of the chromatin structure rendering it available for rearrangement. As the initial restriction of rearrangement to one allele is critical to the establishment of allelic exclusion, a key question is whether or not germline transcription at the κ locus is monoallelic or biallelic. We have used a sensitive reverse transcription-polymerase chain reaction (RT-PCR) assay and an RNA–fluorescence in situ hybridization (FISH) to show that germline transcription of the κ locus is biallelic in wild-type immature B cells and in recombination activating gene (RAG)−/−, μ+ B cells. Therefore, germline transcription is unlikely to dictate which allele will be rearranged first and rather reflects a general opening on both alleles that must be accompanied by a mechanism allowing one of the two alleles to be rearranged first.

scholarly journals Locus specificity and instability of mutations induced in Drosophila melanogasler by natural and synthetic polynucleotides

1991 ◽  
Vol 7 (5) ◽  
pp. 86-97
Author(s):  
S. M. Gershenson ◽  
Yu. N. Alexandrov ◽  
T. V. Shandala ◽  
M. G. Aizenzon ◽  
R. P. Subbota
Keyword(s):  
Locus Specificity ◽  
Natural And Synthetic
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