Multiple DSB Resection Activities Redundantly Promote Alternative End Joining-Mediated Class Switch Recombination
Alternative end joining (A-EJ) catalyzes substantial level of antibody class switch recombination (CSR) in B cells deficient for classical non-homologous end joining, featuring increased switch (S) region DSB resection and junctional microhomology (MH). While resection has been suggested to initiate...
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Frontiers Media S.A.
2021
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oai:doaj.org-article:783e94bec6534c0ba59ab903e0bf080f2021-12-01T20:04:11ZMultiple DSB Resection Activities Redundantly Promote Alternative End Joining-Mediated Class Switch Recombination2296-634X10.3389/fcell.2021.767624https://doaj.org/article/783e94bec6534c0ba59ab903e0bf080f2021-11-01T00:00:00Zhttps://www.frontiersin.org/articles/10.3389/fcell.2021.767624/fullhttps://doaj.org/toc/2296-634XAlternative end joining (A-EJ) catalyzes substantial level of antibody class switch recombination (CSR) in B cells deficient for classical non-homologous end joining, featuring increased switch (S) region DSB resection and junctional microhomology (MH). While resection has been suggested to initiate A-EJ in model DSB repair systems using engineered endonucleases, the contribution of resection factors to A-EJ-mediated CSR remains unclear. In this study, we systematically dissected the requirement for individual DSB resection factors in A-EJ-mediated class switching with a cell-based assay system and high-throughput sequencing. We show that while CtIP and Mre11 both are mildly required for CSR in WT cells, they play more critical roles in mediating A-EJ CSR, which depend on the exonuclease activity of Mre11. While DNA2 and the helicase/HRDC domain of BLM are required for A-EJ by mediating long S region DSB resection, in contrast, Exo1’s resection-related function does not play any obvious roles for class switching in either c-NHEJ or A-EJ cells, or mediated in an AID-independent manner by joining of Cas9 breaks. Furthermore, ATM and its kinase activity functions at least in part independent of CtIP/Mre11 to mediate A-EJ switching in Lig4-deficient cells. In stark contrast to Lig4 deficiency, 53BP1-deficient cells do not depend on ATM/Mre11/CtIP for residual joining. We discuss the roles for each resection factor in A-EJ-mediated CSR and suggest that the extent of requirements for resection is context dependent.Xikui SunXikui SunJingning BaiJingning BaiJiejie XuJiejie XuXiaoli XiMingyu GuMingyu GuChengming ZhuHongman XueChun ChenJunchao DongJunchao DongJunchao DongFrontiers Media S.A.articleDNA double-strand breaks repairalternative end joiningclass switch recombinationDSB end resectionmicrohomologyBiology (General)QH301-705.5ENFrontiers in Cell and Developmental Biology, Vol 9 (2021) |
| institution |
DOAJ |
| collection |
DOAJ |
| language |
EN |
| topic |
DNA double-strand breaks repair alternative end joining class switch recombination DSB end resection microhomology Biology (General) QH301-705.5 |
| spellingShingle |
DNA double-strand breaks repair alternative end joining class switch recombination DSB end resection microhomology Biology (General) QH301-705.5 Xikui Sun Xikui Sun Jingning Bai Jingning Bai Jiejie Xu Jiejie Xu Xiaoli Xi Mingyu Gu Mingyu Gu Chengming Zhu Hongman Xue Chun Chen Junchao Dong Junchao Dong Junchao Dong Multiple DSB Resection Activities Redundantly Promote Alternative End Joining-Mediated Class Switch Recombination |
| description |
Alternative end joining (A-EJ) catalyzes substantial level of antibody class switch recombination (CSR) in B cells deficient for classical non-homologous end joining, featuring increased switch (S) region DSB resection and junctional microhomology (MH). While resection has been suggested to initiate A-EJ in model DSB repair systems using engineered endonucleases, the contribution of resection factors to A-EJ-mediated CSR remains unclear. In this study, we systematically dissected the requirement for individual DSB resection factors in A-EJ-mediated class switching with a cell-based assay system and high-throughput sequencing. We show that while CtIP and Mre11 both are mildly required for CSR in WT cells, they play more critical roles in mediating A-EJ CSR, which depend on the exonuclease activity of Mre11. While DNA2 and the helicase/HRDC domain of BLM are required for A-EJ by mediating long S region DSB resection, in contrast, Exo1’s resection-related function does not play any obvious roles for class switching in either c-NHEJ or A-EJ cells, or mediated in an AID-independent manner by joining of Cas9 breaks. Furthermore, ATM and its kinase activity functions at least in part independent of CtIP/Mre11 to mediate A-EJ switching in Lig4-deficient cells. In stark contrast to Lig4 deficiency, 53BP1-deficient cells do not depend on ATM/Mre11/CtIP for residual joining. We discuss the roles for each resection factor in A-EJ-mediated CSR and suggest that the extent of requirements for resection is context dependent. |
| format |
article |
| author |
Xikui Sun Xikui Sun Jingning Bai Jingning Bai Jiejie Xu Jiejie Xu Xiaoli Xi Mingyu Gu Mingyu Gu Chengming Zhu Hongman Xue Chun Chen Junchao Dong Junchao Dong Junchao Dong |
| author_facet |
Xikui Sun Xikui Sun Jingning Bai Jingning Bai Jiejie Xu Jiejie Xu Xiaoli Xi Mingyu Gu Mingyu Gu Chengming Zhu Hongman Xue Chun Chen Junchao Dong Junchao Dong Junchao Dong |
| author_sort |
Xikui Sun |
| title |
Multiple DSB Resection Activities Redundantly Promote Alternative End Joining-Mediated Class Switch Recombination |
| title_short |
Multiple DSB Resection Activities Redundantly Promote Alternative End Joining-Mediated Class Switch Recombination |
| title_full |
Multiple DSB Resection Activities Redundantly Promote Alternative End Joining-Mediated Class Switch Recombination |
| title_fullStr |
Multiple DSB Resection Activities Redundantly Promote Alternative End Joining-Mediated Class Switch Recombination |
| title_full_unstemmed |
Multiple DSB Resection Activities Redundantly Promote Alternative End Joining-Mediated Class Switch Recombination |
| title_sort |
multiple dsb resection activities redundantly promote alternative end joining-mediated class switch recombination |
| publisher |
Frontiers Media S.A. |
| publishDate |
2021 |
| url |
https://doaj.org/article/783e94bec6534c0ba59ab903e0bf080f |
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