Orientation-specific joining of AID-initiated DNA breaks promotes antibody class switching

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)

URL: http://www.ncbi.nlm.nih.gov/pubmed/26308889
DOI: 10.1038/nature14970

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
Watson School > Publications
Depositing User: Matt Covey
Date: 3 September 2015
Date Deposited: 18 Sep 2015 15:42
Last Modified: 03 Jan 2019 21:09
Related URLs:
URI: http://repository.cshl.edu/id/eprint/31876

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