The Replisome Mediates A-NHEJ Repair of Telomeres Lacking POT1-TPP1 Independently of MRN Function

Cell Rep. 2019 Dec 10;29(11):3708-3725.e5. doi: 10.1016/j.celrep.2019.11.012. Epub 2019 Dec 10.

Abstract

Telomeres use shelterin to protect chromosome ends from activating the DNA damage sensor MRE11-RAD50-NBS1 (MRN), repressing ataxia-telangiectasia, mutated (ATM) and ATM and Rad3-related (ATR) dependent DNA damage checkpoint responses. The MRE11 nuclease is thought to be essential for the resection of the 5' C-strand to generate the microhomologies necessary for alternative non-homologous end joining (A-NHEJ) repair. In the present study, we uncover DNA damage signaling and repair pathways engaged by components of the replisome complex to repair dysfunctional telomeres. In cells lacking MRN, single-stranded telomeric overhangs devoid of POT1-TPP1 do not recruit replication protein A (RPA), ATR-interacting protein (ATRIP), and RAD 51. Rather, components of the replisome complex, including Claspin, Proliferating cell nuclear antigen (PCNA), and Downstream neighbor of SON (DONSON), initiate DNA-PKcs-mediated p-CHK1 activation and A-NHEJ repair. In addition, Claspin directly interacts with TRF2 and recruits EXO1 to newly replicated telomeres to promote 5' end resection. Our data indicate that MRN is dispensable for the repair of dysfunctional telomeres lacking POT1-TPP1 and highlight the contributions of the replisome in telomere repair.

Keywords: A-NHEJ repair; DNA damage; MRE11-RAD50-NBS1; POT1; TRF2; replisome; telomere.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acid Anhydride Hydrolases / metabolism
  • Adaptor Proteins, Signal Transducing / metabolism
  • Aminopeptidases / deficiency
  • Aminopeptidases / metabolism
  • Animals
  • Cell Cycle Proteins / metabolism
  • Cell Line, Tumor
  • Cells, Cultured
  • Checkpoint Kinase 1 / metabolism
  • DNA End-Joining Repair*
  • DNA Repair Enzymes / metabolism
  • DNA-Binding Proteins / metabolism
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / metabolism*
  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / deficiency
  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / metabolism
  • Exodeoxyribonucleases / metabolism
  • HEK293 Cells
  • Humans
  • MRE11 Homologue Protein / metabolism
  • Mice
  • Multienzyme Complexes / genetics
  • Multienzyme Complexes / metabolism*
  • Proliferating Cell Nuclear Antigen / metabolism
  • Serine Proteases / deficiency
  • Serine Proteases / metabolism
  • Shelterin Complex
  • Telomere / genetics
  • Telomere / metabolism*
  • Telomere-Binding Proteins / deficiency
  • Telomere-Binding Proteins / metabolism
  • Telomeric Repeat Binding Protein 2 / metabolism

Substances

  • ACD protein, human
  • Acd protein, mouse
  • Adaptor Proteins, Signal Transducing
  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • Mre11a protein, mouse
  • Multienzyme Complexes
  • Nijmegen breakage syndrome 1 protein, mouse
  • POT1 protein, mouse
  • Proliferating Cell Nuclear Antigen
  • Shelterin Complex
  • TRF2 protein, mouse
  • Telomere-Binding Proteins
  • Telomeric Repeat Binding Protein 2
  • claspin protein, mouse
  • Checkpoint Kinase 1
  • Chek1 protein, mouse
  • DNA synthesome
  • DNA-Directed DNA Polymerase
  • Exo1 protein, mouse
  • Exodeoxyribonucleases
  • MRE11 Homologue Protein
  • Serine Proteases
  • Aminopeptidases
  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases
  • Acid Anhydride Hydrolases
  • Rad50 protein, mouse
  • DNA Repair Enzymes