scholarly journals Alternative end-joining catalyzes class switch recombination in the absence of both Ku70 and DNA ligase 4

2010 ◽  
Vol 207 (2) ◽  
pp. 417-427 ◽  
Author(s):  
Cristian Boboila ◽  
Catherine Yan ◽  
Duane R. Wesemann ◽  
Mila Jankovic ◽  
Jing H. Wang ◽  
...  
Keyword(s):  
B Cells ◽  
Class Switch Recombination ◽  
Strand Break ◽  
Nonhomologous End Joining ◽  
Dna Ligase ◽  
End Joining ◽  
Dsb Repair ◽  
Class Switch ◽  
Dna Double Strand Break ◽  
Alternative End Joining

The classical nonhomologous end-joining (C-NHEJ) DNA double-strand break (DSB) repair pathway employs the Ku70/80 complex (Ku) for DSB recognition and the XRCC4/DNA ligase 4 (Lig4) complex for ligation. During IgH class switch recombination (CSR) in B lymphocytes, switch (S) region DSBs are joined by C-NHEJ to form junctions either with short microhomologies (MHs; “MH-mediated” joins) or no homologies (“direct” joins). In the absence of XRCC4 or Lig4, substantial CSR occurs via “alternative” end-joining (A-EJ) that generates largely MH-mediated joins. Because upstream C-NHEJ components remain in XRCC4- or Lig4-deficient B cells, residual CSR might be catalyzed by C-NHEJ using a different ligase. To address this, we have assayed for CSR in B cells deficient for Ku70, Ku80, or both Ku70 and Lig4. Ku70- or Ku80-deficient B cells have reduced, but still substantial, CSR. Strikingly, B cells deficient for both Ku plus Lig4 undergo CSR similarly to Ku-deficient B cells, firmly demonstrating that an A-EJ pathway distinct from C-NHEJ can catalyze CSR end-joining. Ku-deficient or Ku- plus Lig4-deficient B cells are also biased toward MH-mediated CSR joins; but, in contrast to XRCC4- or Lig4-deficient B cells, generate substantial numbers of direct CSR joins. Our findings suggest that more than one form of A-EJ can function in CSR.

scholarly journals Redundant function of DNA ligase 1 and 3 in alternative end-joining during immunoglobulin class switch recombination

2016 ◽  
Vol 113 (5) ◽  
pp. 1261-1266 ◽  
Author(s):  
Shahnaz Masani ◽  
Li Han ◽  
Katheryn Meek ◽  
Kefei Yu
Keyword(s):  
Class Switch Recombination ◽  
Strand Break ◽  
Nonhomologous End Joining ◽  
Dna Ligase ◽  
End Joining ◽  
Dna Ligases ◽  
Class Switch ◽  
Dna Double Strand Break ◽  
Absolute Requirement ◽  
Alternative End Joining

Nonhomologous end-joining (NHEJ) is the major DNA double-strand break (DSB) repair pathway in mammals and resolves the DSBs generated during both V(D)J recombination in developing lymphocytes and class switch recombination (CSR) in antigen-stimulated B cells. In contrast to the absolute requirement for NHEJ to resolve DSBs associated with V(D)J recombination, DSBs associated with CSR can be resolved in NHEJ-deficient cells (albeit at a reduced level) by a poorly defined alternative end-joining (A-EJ) pathway. Deletion of DNA ligase IV (Lig4), a core component of the NHEJ pathway, reduces CSR efficiency in a mouse B-cell line capable of robust cytokine-stimulated CSR in cell culture. Here, we report that CSR levels are not further reduced by deletion of either of the two remaining DNA ligases (Lig1 and nuclear Lig3) in Lig4−/− cells. We conclude that in the absence of Lig4, Lig1, and Lig3 function in a redundant manner in resolving switch region DSBs during CSR.

scholarly journals Ligase I and ligase III mediate the DNA double-strand break ligation in alternative end-joining

2016 ◽  
Vol 113 (5) ◽  
pp. 1256-1260 ◽  
Author(s):  
Guangqing Lu ◽  
Jinzhi Duan ◽  
Sheng Shu ◽  
Xuxiang Wang ◽  
Linlin Gao ◽  
...  
Keyword(s):  
Strand Break ◽  
Chromosome Translocation ◽  
Nonhomologous End Joining ◽  
Dna Ligase ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Dna Double Strand Break ◽  
Alternative End Joining ◽  
Class Switching Recombination

In eukaryotes, DNA double-strand breaks (DSBs), one of the most harmful types of DNA damage, are repaired by homologous repair (HR) and nonhomologous end-joining (NHEJ). Surprisingly, in cells deficient for core classic NHEJ factors such as DNA ligase IV (Lig4), substantial end-joining activities have been observed in various situations, suggesting the existence of alternative end-joining (A-EJ) activities. Several putative A-EJ factors have been proposed, although results are mostly controversial. By using a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system, we generated mouse CH12F3 cell lines in which, in addition to Lig4, either Lig1 or nuclear Lig3, representing the cells containing a single DNA ligase (Lig3 or Lig1, respectively) in their nucleus, was completely ablated. Surprisingly, we found that both Lig1- and Lig3-containing complexes could efficiently catalyze A-EJ for class switching recombination (CSR) in the IgH locus and chromosomal deletions between DSBs generated by CRISPR/Cas9 in cis-chromosomes. However, only deletion of nuclear Lig3, but not Lig1, could significantly reduce the interchromosomal translocations in Lig4−/− cells, suggesting the unique role of Lig3 in catalyzing chromosome translocation. Additional sequence analysis of chromosome translocation junction microhomology revealed the specificity of different ligase-containing complexes. The data suggested the existence of multiple DNA ligase-containing complexes in A-EJ.

scholarly journals HMCES Functions in the Alternative End-Joining Pathway of the DNA DSB Repair during Class Switch Recombination in B Cells

2020 ◽  
Vol 77 (5) ◽  
pp. 1154 ◽  
Author(s):  
Vipul Shukla ◽  
Levon Halabelian ◽  
Sanjana Balagere ◽  
Daniela Samaniego-Castruita ◽  
Douglas E. Feldman ◽  
...  
Keyword(s):  
B Cells ◽  
Class Switch Recombination ◽  
End Joining ◽  
Dsb Repair ◽  
Class Switch ◽  
Alternative End Joining

scholarly journals HMCES Functions in the Alternative End-Joining Pathway of the DNA DSB Repair during Class Switch Recombination in B Cells

2020 ◽  
Vol 77 (2) ◽  
pp. 384-394.e4 ◽  
Author(s):  
Vipul Shukla ◽  
Levon Halabelian ◽  
Sanjana Balagere ◽  
Daniela Samaniego-Castruita ◽  
Douglas E. Feldman ◽  
...  
Keyword(s):  
B Cells ◽  
Class Switch Recombination ◽  
End Joining ◽  
Dsb Repair ◽  
Class Switch ◽  
Alternative End Joining

scholarly journals RAD-51-Dependent and -Independent Roles of a Caenorhabditis elegans BRCA2-Related Protein during DNA Double-Strand Break Repair

2005 ◽  
Vol 25 (8) ◽  
pp. 3127-3139 ◽  
Author(s):  
Julie S. Martin ◽  
Nicole Winkelmann ◽  
Mark I. R. Petalcorin ◽  
Michael J. McIlwraith ◽  
Simon J. Boulton
Keyword(s):  
Caenorhabditis Elegans ◽  
Strand Break ◽  
Double Strand Break ◽  
Nonhomologous End Joining ◽  
Related Protein ◽  
End Joining ◽  
Dsb Repair ◽  
Phenotypic Differences ◽  
Dna Double Strand Break ◽  
Radiation Induced

ABSTRACT The BRCA2 tumor suppressor is implicated in DNA double-strand break (DSB) repair by homologous recombination (HR), where it regulates the RAD51 recombinase. We describe a BRCA2-related protein of Caenorhabditis elegans (CeBRC-2) that interacts directly with RAD-51 via a single BRC motif and that binds preferentially to single-stranded DNA through an oligonucleotide-oligosaccharide binding fold. Cebrc-2 mutants fail to repair meiotic or radiation-induced DSBs by HR due to inefficient RAD-51 nuclear localization and a failure to target RAD-51 to sites of DSBs. Genetic and cytological comparisons of Cebrc-2 and rad-51 mutants revealed fundamental phenotypic differences that suggest a role for Cebrc-2 in promoting the use of an alternative repair pathway in the absence of rad-51 and independent of nonhomologous end joining (NHEJ). Unlike rad-51 mutants, Cebrc-2 mutants also accumulate RPA-1 at DSBs, and abnormal chromosome aggregates that arise during the meiotic prophase can be rescued by blocking the NHEJ pathway. CeBRC-2 also forms foci in response to DNA damage and can do so independently of rad-51. Thus, CeBRC-2 not only regulates RAD-51 during HR but can also function independently of rad-51 in DSB repair processes.

scholarly journals DNA-dependent protein kinase in nonhomologous end joining: a lock with multiple keys?

2007 ◽  
Vol 179 (2) ◽  
pp. 183-186 ◽  
Author(s):  
Eric Weterings ◽  
David J. Chen
Keyword(s):  
Protein Kinase ◽  
Strand Break ◽  
Nonhomologous End Joining ◽  
End Joining ◽  
Dsb Repair ◽  
Dependent Protein Kinase ◽  
Dna Molecule ◽  
Dna Double Strand Break ◽  
Dependent Protein ◽  
Multiple Keys

The DNA-dependent protein kinase (DNA-PK) is one of the central enzymes involved in DNA double-strand break (DSB) repair. It facilitates proper alignment of the two ends of the broken DNA molecule and coordinates access of other factors to the repair complex. We discuss the latest findings on DNA-PK phosphorylation and offer a working model for the regulation of DNA-PK during DSB repair.

scholarly journals Alternative end-joining catalyzes class switch recombination in the absence of both Ku70 and DNA ligase 4

2013 ◽  
Vol 210 (3) ◽  
pp. 641-641 ◽  
Author(s):  
Cristian Boboila ◽  
Catherine Yan ◽  
Duane R. Wesemann ◽  
Mila Jankovic ◽  
Jing H. Wang ◽  
...  
Keyword(s):  
Class Switch Recombination ◽  
Dna Ligase ◽  
End Joining ◽  
Class Switch ◽  
Alternative End Joining

scholarly journals Alternative end-joining catalyzes class switch recombination in the absence of both Ku70 and DNA ligase 4

2010 ◽  
Vol 188 (4) ◽  
pp. i7-i7
Author(s):  
Cristian Boboila ◽  
Catherine Yan ◽  
Duane R. Wesemann ◽  
Mila Jankovic ◽  
Jing H. Wang ◽  
...  
Keyword(s):  
Class Switch Recombination ◽  
Dna Ligase ◽  
End Joining ◽  
Class Switch ◽  
Alternative End Joining
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