2. Academic Validation
  3. DNA Repair Network Analysis Reveals Shieldin as a Key Regulator of NHEJ and PARP Inhibitor Sensitivity

DNA Repair Network Analysis Reveals Shieldin as a Key Regulator of NHEJ and PARP Inhibitor Sensitivity

  • Cell. 2018 May 3;173(4):972-988.e23. doi: 10.1016/j.cell.2018.03.050.
Rajat Gupta 1,  Kumar Somyajit 2,  Takeo Narita 1,  Elina Maskey 1,  Andre Stanlie 3,  Magdalena Kremer 4,  Dimitris Typas 2,  Michael Lammers 5,  Niels Mailand 2,  Andre Nussenzweig 3,  Jiri Lukas 2,  Chunaram Choudhary 6
Affiliations

Affiliations

  • 1 Proteomics Program, the Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark.
  • 2 Protein Signaling Program, the Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark.
  • 3 Laboratory of Genome Integrity, NIH, Bethesda, MD 20892, USA.
  • 4 Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Joseph-Stelzmann-Str. 26, University of Cologne, 50931 Cologne, Germany.
  • 5 Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Joseph-Stelzmann-Str. 26, University of Cologne, 50931 Cologne, Germany; Institute for Biochemistry, Synthetic and Structural Biochemistry, Felix-Hausdorff-Str. 4, University of Greifswald, 17487 Greifswald, Germany.
  • 6 Proteomics Program, the Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark; Center for Chromosome Stability (CCS), Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark. Electronic address: chuna.choudhary@cpr.ku.dk.
PMID: 29656893 DOI: 10.1016/j.cell.2018.03.050
Abstract

Repair of damaged DNA is essential for maintaining genome integrity and for preventing genome-instability-associated diseases, such as Cancer. By combining proximity labeling with quantitative mass spectrometry, we generated high-resolution interaction neighborhood maps of the endogenously expressed DNA repair factors 53BP1, BRCA1, and MDC1. Our spatially resolved interaction maps reveal rich network intricacies, identify shared and bait-specific interaction modules, and implicate previously concealed regulators in this process. We identified a novel vertebrate-specific protein complex, shieldin, comprising REV7 plus three previously uncharacterized proteins, RINN1 (CTC-534A2.2), RINN2 (FAM35A), and RINN3 (C20ORF196). Recruitment of shieldin to DSBs, via the ATM-RNF8-RNF168-53BP1-RIF1 axis, promotes NHEJ-dependent repair of intrachromosomal breaks, immunoglobulin class-switch recombination (CSR), and fusion of unprotected telomeres. Shieldin functions as a downstream effector of 53BP1-RIF1 in restraining DNA end resection and in sensitizing BRCA1-deficient cells to PARP inhibitors. These findings have implications for understanding cancer-associated PARPi resistance and the evolution of antibody CSR in higher vertebrates.

Keywords

53BP1; BRCA1; DNA damage repair; NHEJ; PARP inhibitors; antibody class-switch recombination; proteomics; proximity labeling; shieldin; telomere maintenance.

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