A Damage-Independent Role for 53BP1 that Impacts Break Order and Igh Architecture during Class Switch Recombination.
During class switch recombination (CSR), B cells replace the Igh Cμ or δ exons with another downstream constant region exon (CH), altering the antibody isotype. CSR occurs through the introduction of AID-mediated double-strand breaks (DSBs) in switch regions and subsequent ligation of broken ends. Here, we developed an assay to investigate the dynamics of DSB formation in individual cells. We demonstrate that the upstream switch region Sμ is first targeted during recombination and that the mechanism underlying this control relies on 53BP1. Surprisingly, regulation of break order occurs through residual binding of 53BP1 to chromatin before the introduction of damage and independent of its established role in DNA repair. Using chromosome conformation capture, we show that 53BP1 mediates changes in chromatin architecture that affect break order. Finally, our results explain how changes in Igh architecture in the absence of 53BP1 could promote inversional rearrangements that compromise CSR.
Department of Pathology, New York University School of Medicine, New York, NY 10016, USA. Electronic address: pereip02@nyumc.org.
Pedro P
PP
Rocha
Department of Pathology, New York University School of Medicine, New York, NY 10016, USA; Department of Biology, New York University, New York, NY 10003, USA.
Ramya
R
Raviram
Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
Yi
Y
Fu
Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
JungHyun
J
Kim
Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
Vincent M
VM
Luo
Department of Pathology, New York University School of Medicine, New York, NY 10016, USA.
Arafat
A
Aljoufi
Department of Developmental Genetics, New York University School of Medicine, New York, NY 10016, USA.
Emily
E
Swanzey
Ludwig Maximilians University and Munich Center for Integrated Protein Science (CiPSM), Biomedical Center, Planegg-Martinsried 80336, Germany.
Alessandra
A
Pasquarella
Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
Alessia
A
Balestrini
Simons Center for Data Analysis, New York, NY 10010, USA.
Emily R
ER
Miraldi
Department of Biology, New York University, New York, NY 10003, USA; Department of Computer Science, Courant Institute of Mathematical Sciences, New York, NY 10012, USA; Simons Center for Data Analysis, New York, NY 10010, USA.
Richard
R
Bonneau
Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
John
J
Petrini
Ludwig Maximilians University and Munich Center for Integrated Protein Science (CiPSM), Biomedical Center, Planegg-Martinsried 80336, Germany.
Gunnar
G
Schotta
Department of Pathology, New York University School of Medicine, New York, NY 10016, USA. Electronic address: jane.skok@nyumc.org.
Jane A
JA
Skok
D000818:Animals; D001483:Base Sequence; D002843:Chromatin / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D017578:Immunoglobulin Class Switching / Q000235:genetics*; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D051379:Mice; D011485:Protein Binding; D011995:Recombination, Genetic; D059010:Single-Cell Analysis; D000071857:Tumor Suppressor p53-Binding Protein 1 / Q000378:metabolism*
D002843:Chromatin; D007143:Immunoglobulin Heavy Chains; C498302:Trp53bp1 protein, mouse; D000071857:Tumor Suppressor p53-Binding Protein 1