Alternative pathways for the repair of RAG-induced DNA breaks Journal Article
| Authors: | Weinstock, D. M.; Jasin, M. |
| Article Title: | Alternative pathways for the repair of RAG-induced DNA breaks |
| Abstract: | RAG1 and RAG2 cleave DNA to generate blunt signal ends and hairpin coding ends at antigen receptor loci in lymphoid cells. During V(D)J recombination, repair of these RAG-generated double-strand breaks (DSBs) by the nonhomologous end-joining (NHEJ) pathway contributes substantially to the antigen receptor diversity necessary for immune system function, although recent evidence also supports the ability of RAG-generated breaks to undergo homology-directed repair (HDR). We have determined that RAG-generated chromosomal breaks can be repaired by pathways other than NHEJ in mouse embryonic stem (ES) cells, although repair by these pathways occurs at a significantly lower frequency than NHEJ. HDR frequency was estimated to be ≥40-fold lower than NHEJ frequency for both coding end and signal end reporters. Repair by single-strand annealing was estimated to occur at a comparable or lower frequency than HDR. As expected, V(D)J recombination was substantially impaired in cells deficient for the NHEJ components Ku70, XRCC4, and DNA-PKcs. Concomitant with decreased NHEJ, RAG-induced HDR was increased in each of the mutants, including cells lacking DNA-PKcs, which has been implicated in hairpin opening. HDR was increased to the largest extent in Ku70-/- cells, implicating the Ku70/80 DNA end-binding protein in regulating pathway choice. Thus, RAG-generated DSBs are typically repaired by the NHEJ pathway in ES cells, but in the absence of NHEJ components, a substantial fraction of breaks can be efficiently channeled into alternative pathways in these cells. Copyright © 2006, American Society for Microbiology. All Rights Reserved. |
| Keywords: | controlled study; dna binding protein; human cell; genetics; dna-binding proteins; mouse; animal; cytology; metabolism; animals; mice; dna repair; immune system; embryo; embryonic stem cell; homeodomain proteins; stem cell; dna strand breakage; dna; genetic recombination; immunoglobulin gene; recombination, genetic; stem cells; chromosome breakage; homeodomain protein; sequence homology; rag1 protein; rag2 protein; dna binding; vdj recombinases; lymphocyte antigen receptor; dna cleavage; lymphoid cell; recombinase; genes, immunoglobulin; rag 1 protein; rag-1 protein; rag2 protein, mouse; homology directed repair; non homologous end joining pathway |
| Journal Title: | Molecular and Cellular Biology |
| Volume: | 26 |
| Issue: | 1 |
| ISSN: | 0270-7306 |
| Publisher: | American Society for Microbiology |
| Date Published: | 2006-01-01 |
| Start Page: | 131 |
| End Page: | 139 |
| Language: | English |
| DOI: | 10.1128/mcb.26.1.131-139.2006 |
| PUBMED: | 16354685 |
| PROVIDER: | scopus |
| PMCID: | PMC1317616 |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 30" - "Export Date: 4 June 2012" - "CODEN: MCEBD" - "Source: Scopus" |
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