Rad52 competes with Ku70/Ku86 for binding to S-region DSB ends to modulate antibody class-switch DNA recombination.
Antibody class-switch DNA recombination (CSR) is initiated by AID-introduced DSBs in the switch (S) regions targeted for recombination, as effected by Ku70/Ku86-mediated NHEJ. Ku-deficient B cells, however, undergo (reduced) CSR through an alternative(A)-NHEJ pathway, which introduces microhomologies in S-S junctions. As microhomology-mediated end-joining requires annealing of single-strand DNA ends, we addressed the contribution of single-strand annealing factors HR Rad52 and translesion DNA polymerase θ to CSR. Compared with their Rad52+/+counterparts, which display normal CSR, Rad52-/-B cells show increased CSR, fewer intra-Sμ region recombinations, no/minimal microhomologies in S-S junctions, decreased c-Myc/IgH translocations and increased Ku70/Ku86 recruitment to S-region DSB ends. Rad52 competes with Ku70/Ku86 for binding to S-region DSB ends. It also facilitates a Ku-independent DSB repair, which favours intra-S region recombination and mediates, particularly in Ku absence, inter-S-S recombination, as emphasized by the significantly greater CSR reduction in Rad52-/-versus Rad52+/+B cells on Ku86 knockdown.
Department of Microbiology, Immunology and Molecular Genetics, University of Texas School of Medicine, UT Health Science Center, San Antonio, Texas 78229, USA.
Hong
H
Zan
Department of Microbiology, Immunology and Molecular Genetics, University of Texas School of Medicine, UT Health Science Center, San Antonio, Texas 78229, USA.
Connie
C
Tat
Department of Microbiology, Immunology and Molecular Genetics, University of Texas School of Medicine, UT Health Science Center, San Antonio, Texas 78229, USA.
Zhifang
Z
Qiu
Department of Microbiology, Immunology and Molecular Genetics, University of Texas School of Medicine, UT Health Science Center, San Antonio, Texas 78229, USA.
Julia R
0000-0002-7549-0812
JR
Taylor
Department of Microbiology, Immunology and Molecular Genetics, University of Texas School of Medicine, UT Health Science Center, San Antonio, Texas 78229, USA.
Justin A
JA
Guerrero
Department of Microbiology, Immunology and Molecular Genetics, University of Texas School of Medicine, UT Health Science Center, San Antonio, Texas 78229, USA.
Tian
T
Shen
Department of Microbiology, Immunology and Molecular Genetics, University of Texas School of Medicine, UT Health Science Center, San Antonio, Texas 78229, USA.
Paolo
P
Casali
D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D003564:Cytidine Deaminase / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair / Q000235:genetics / Q000276:immunology*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D017578:Immunoglobulin Class Switching / Q000235:genetics* / Q000276:immunology; D007134:Immunoglobulin Switch Region / Q000235:genetics; D000072200:Ku Autoantigen / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D034741:RNA, Small Interfering / Q000378:metabolism; D051721:Rad52 DNA Repair and Recombination Protein / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D059767:Recombinational DNA Repair / Q000276:immunology*; D013449:Sulfonamides; D000097462:DNA Polymerase theta; D000098830:AICDA (Activation-Induced Cytidine Deaminase); D000096926:Benzenesulfonamides
D003564:Cytidine Deaminase; D004259:DNA-Directed DNA Polymerase; D000072200:Ku Autoantigen; D034741:RNA, Small Interfering; D051721:Rad52 DNA Repair and Recombination Protein; D013449:Sulfonamides; D000097462:DNA Polymerase theta; D000098830:AICDA (Activation-Induced Cytidine Deaminase); C497194:RAD52 protein, human; C497196:Rad52 protein, mouse; C007563:1,2-di-(4-sulfamidophenyl)-4-butylpyrazolidine-3,5-dione; D000096926:Benzenesulfonamides; C106893:XRCC5 protein, human; C000606512:Xrcc5 protein, mouse; C000606509:Xrcc6 protein, human; C000606510:Xrcc6 protein, mouse