Dong, J., Panchakshari, R. A., Zhang, T., Zhang, Y., Hu, J., Volpi, S. A., Meyers, R. M., Ho, Y. J., Du, Z., Robbiani, D. F., Meng, F., Gostissa, M., Nussenzweig, M. C., Manis, J. P., Alt, F. W. (September 2015) Orientation-specific joining of AID-initiated DNA breaks promotes antibody class switching. Nature, 525 (7567). pp. 134-9. ISSN 1476-4687 (Electronic)0028-0836 (Linking)
Abstract
During B-cell development, RAG endonuclease cleaves immunoglobulin heavy chain (IgH) V, D, and J gene segments and orchestrates their fusion as deletional events that assemble a V(D)J exon in the same transcriptional orientation as adjacent Cmu constant region exons. In mice, six additional sets of constant region exons (CHs) lie 100-200 kilobases downstream in the same transcriptional orientation as V(D)J and Cmu exons. Long repetitive switch (S) regions precede Cmu and downstream CHs. In mature B cells, class switch recombination (CSR) generates different antibody classes by replacing Cmu with a downstream CH (ref. 2). Activation-induced cytidine deaminase (AID) initiates CSR by promoting deamination lesions within Smu and a downstream acceptor S region; these lesions are converted into DNA double-strand breaks (DSBs) by general DNA repair factors. Productive CSR must occur in a deletional orientation by joining the upstream end of an Smu DSB to the downstream end of an acceptor S-region DSB. However, the relative frequency of deletional to inversional CSR junctions has not been measured. Thus, whether orientation-specific joining is a programmed mechanistic feature of CSR as it is for V(D)J recombination and, if so, how this is achieved is unknown. To address this question, we adapt high-throughput genome-wide translocation sequencing into a highly sensitive DSB end-joining assay and apply it to endogenous AID-initiated S-region DSBs in mouse B cells. We show that CSR is programmed to occur in a productive deletional orientation and does so via an unprecedented mechanism that involves in cis Igh organizational features in combination with frequent S-region DSBs initiated by AID. We further implicate ATM-dependent DSB-response factors in enforcing this mechanism and provide an explanation of why CSR is so reliant on the 53BP1 DSB-response factor.
| Item Type: | Paper |
|---|---|
| Subjects: | organs, tissues, organelles, cell types and functions > cell types and functions > cell types > B cells organs, tissues, organelles, cell types and functions > cell types and functions > cell types > B cells organs, tissues, organelles, cell types and functions > cell types and functions > cell types > B cells bioinformatics > genomics and proteomics > genetics & nucleic acid processing > DNA, RNA structure, function, modification |
| CSHL Authors: | |
| Communities: | CSHL labs > Hammell M. lab School of Biological Sciences > Publications |
| Depositing User: | Matt Covey |
| Date: | 3 September 2015 |
| Date Deposited: | 18 Sep 2015 15:42 |
| Last Modified: | 15 Jul 2021 18:59 |
| PMCID: | PMC4592165 |
| Related URLs: | |
| URI: | https://repository.cshl.edu/id/eprint/31876 |
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