title: RPA accumulation during class switch recombination represents 5'-3' DNA-end resection during the S-G2/M phase of the cell cycle.
abstract: Activation-induced cytidine deaminase (AID) promotes chromosomal translocations by inducing DNA double-strand breaks (DSBs) at immunoglobulin (Ig) genes and oncogenes in the G1 phase. RPA is a single-stranded DNA (ssDNA)-binding protein that associates with resected DSBs in the S phase and facilitates the assembly of factors involved in homologous repair (HR), such as Rad51. Notably, RPA deposition also marks sites of AID-mediated damage, but its role in Ig gene recombination remains unclear. Here, we demonstrate that RPA associates asymmetrically with resected ssDNA in response to lesions created by AID, recombination-activating genes (RAG), or other nucleases. Small amounts of RPA are deposited at AID targets in G1 in an ATM-dependent manner. In contrast, recruitment in the S-G2/M phase is extensive, ATM independent, and associated with Rad51 accumulation. In the S-G2/M phase, RPA increases in nonhomologous-end-joining-deficient lymphocytes, where there is more extensive DNA-end resection. Thus, most RPA recruitment during class switch recombination represents salvage of unrepaired breaks by homology-based pathways during the S-G2/M phase of the cell cycle.
authors.affiliation: Genomics & Immunity, NIAMS, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Arito
authors.initials: A
authors.lastname: Yamane
authors.forename: Davide F
authors.initials: DF
authors.lastname: Robbiani
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Resch
authors.forename: Anne
authors.initials: A
authors.lastname: Bothmer
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Nakahashi
authors.forename: Thiago
authors.initials: T
authors.lastname: Oliveira
authors.forename: Philipp C
authors.initials: PC
authors.lastname: Rommel
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Brown
authors.forename: Andre
authors.initials: A
authors.lastname: Nussenzweig
authors.forename: Michel C
authors.initials: MC
authors.lastname: Nussenzweig
authors.forename: Rafael
authors.initials: R
authors.lastname: Casellas
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D003564:Cytidine Deaminase / Q000378:metabolism; D053960:DNA Breaks; D053903:DNA Breaks, Double-Stranded; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D016195:G2 Phase / Q000235:genetics*; D056426:Genetic Loci; D006657:Histones / Q000378:metabolism; D017578:Immunoglobulin Class Switching / Q000235:genetics*; D051379:Mice; D008954:Models, Biological; D011485:Protein Binding / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051135:Rad51 Recombinase / Q000378:metabolism; D011995:Recombination, Genetic; D051716:Replication Protein A / Q000378:metabolism*; D016196:S Phase / Q000235:genetics*; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D006657:Histones; D051716:Replication Protein A; D025521:Tumor Suppressor Proteins; C475961:gamma-H2AX protein, mouse; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases; D051135:Rad51 Recombinase; D003564:Cytidine Deaminase