| First Author | Weinstock DM | Year | 2006 |
| Journal | Mol Cell Biol | Volume | 26 |
| Issue | 1 | Pages | 131-9 |
| PubMed ID | 16354685 | Mgi Jnum | J:104162 |
| Mgi Id | MGI:3611407 | Doi | 10.1128/MCB.26.1.131-139.2006 |
| Citation | Weinstock DM, et al. (2006) Alternative Pathways for the Repair of RAG-Induced DNA Breaks. Mol Cell Biol 26(1):131-9 |
| abstractText | 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. |
