The shieldin complex mediates 53BP1-dependent DNA repair

• Published in: Nature (London) Vol. 560; no. 7716; pp. 117 - 121
• Main Authors: Noordermeer, Sylvie M., Adam, Salomé, Setiaputra, Dheva, Barazas, Marco, Pettitt, Stephen J., Ling, Alexanda K., Olivieri, Michele, Álvarez-Quilón, Alejandro, Moatti, Nathalie, Zimmermann, Michal, Annunziato, Stefano, Krastev, Dragomir B., Song, Feifei, Brandsma, Inger, Frankum, Jessica, Brough, Rachel, Sherker, Alana, Landry, Sébastien, Szilard, Rachel K., Munro, Meagan M., McEwan, Andrea, Goullet de Rugy, Théo, Lin, Zhen-Yuan, Hart, Traver, Moffat, Jason, Gingras, Anne-Claude, Martin, Alberto, van Attikum, Haico, Jonkers, Jos, Lord, Christopher J., Rottenberg, Sven, Durocher, Daniel
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.08.2018; Nature Publishing Group
• Subjects: 13; 13/1; 14; 14/35; 38/47; 42; 42/109; 45; 45/70; 631/208/211; 631/337/1427/2122; 64/60; 82/58; 82/83; Adenosine diphosphate; Animals; Biotechnology; BRCA1 protein; Cancer; Cell Line; Chromatin; Class switching; CRISPR; CRISPR-Cas Systems; Deoxyribonucleic acid; DNA; DNA Breaks, Double-Stranded; DNA damage; DNA Repair; DNA, Single-Stranded - genetics; Domains; Female; Gene expression; Genes; Genes, BRCA1; Genomes; Homologous recombination; Homology; Humanities and Social Sciences; Humans; Immunoglobulin Class Switching - genetics; Immunoglobulins; Integrated software; Ionizing radiation; Letter; Mass spectrometry; Mice; Models, Biological; Monosaccharides; multidisciplinary; Multiprotein Complexes - chemistry; Multiprotein Complexes - deficiency; Multiprotein Complexes - genetics; Multiprotein Complexes - metabolism; Mutation; Non-homologous end joining; Nuclease; Poly(ADP-ribose); Poly(ADP-ribose) polymerase; Poly(ADP-ribose) Polymerase Inhibitors - pharmacology; Protein binding; Proteins; Proteomics; Repair; Restoration; Ribose; Science; Science (multidisciplinary); Scientific imaging; Single-stranded DNA; Telomere-Binding Proteins - metabolism; Tumor Suppressor p53-Binding Protein 1 - metabolism; Tumor Suppressor Protein p53 - deficiency; Tumors
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-018-0340-7

53BP1 is a chromatin-binding protein that regulates the repair of DNA double-strand breaks by suppressing the nucleolytic resection of DNA termini 1 , 2 . This function of 53BP1 requires interactions with PTIP 3 and RIF1 4 – 9 , the latter of which recruits REV7 (also known as MAD2L2) to break sites 10 , 11 . How 53BP1-pathway proteins shield DNA ends is currently unknown, but there are two models that provide the best potential explanation of their action. In one model the 53BP1 complex strengthens the nucleosomal barrier to end-resection nucleases 12 , 13 , and in the other 53BP1 recruits effector proteins with end-protection activity. Here we identify a 53BP1 effector complex, shieldin, that includes C20orf196 (also known as SHLD1), FAM35A (SHLD2), CTC-534A2.2 (SHLD3) and REV7. Shieldin localizes to double-strand-break sites in a 53BP1- and RIF1-dependent manner, and its SHLD2 subunit binds to single-stranded DNA via OB-fold domains that are analogous to those of RPA1 and POT1. Loss of shieldin impairs non-homologous end-joining, leads to defective immunoglobulin class switching and causes hyper-resection. Mutations in genes that encode shieldin subunits also cause resistance to poly(ADP-ribose) polymerase inhibition in BRCA1-deficient cells and tumours, owing to restoration of homologous recombination. Finally, we show that binding of single-stranded DNA by SHLD2 is critical for shieldin function, consistent with a model in which shieldin protects DNA ends to mediate 53BP1-dependent DNA repair. The 53BP1 effector complex shieldin is involved in non-homologous end-joining and immunoglobulin class switching, and acts to protect DNA ends to facilitate the repair of DNA by 53BP1.