Human CtIP mediates cell cycle control of DNA end resection and double strand break repair

J Biol Chem. 2009 Apr 3;284(14):9558-65. doi: 10.1074/jbc.M808906200. Epub 2009 Feb 7.

Abstract

In G(0) and G(1), DNA double strand breaks are repaired by nonhomologous end joining, whereas in S and G(2), they are also repaired by homologous recombination. The human CtIP protein controls double strand break (DSB) resection, an event that occurs effectively only in S/G(2) and that promotes homologous recombination but not non-homologous end joining. Here, we mutate a highly conserved cyclin-dependent kinase (CDK) target motif in CtIP and reveal that mutating Thr-847 to Ala impairs resection, whereas mutating it to Glu to mimic constitutive phosphorylation does not. Moreover, we show that unlike cells expressing wild-type CtIP, cells expressing the Thr-to-Glu mutant resect DSBs even after CDK inhibition. Finally, we establish that Thr-847 mutations to either Ala or Glu affect DSB repair efficiency, cause hypersensitivity toward DSB-generating agents, and affect the frequency and nature of radiation-induced chromosomal rearrangements. These results suggest that CDK-mediated control of resection in human cells operates by mechanisms similar to those recently established in yeast.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Carrier Proteins / chemistry
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Cycle* / drug effects
  • Cell Line, Tumor
  • Conserved Sequence
  • Cyclin-Dependent Kinases / antagonists & inhibitors
  • Cyclin-Dependent Kinases / metabolism
  • DNA / genetics*
  • DNA / metabolism*
  • DNA Damage / genetics*
  • DNA Repair / genetics*
  • Endodeoxyribonucleases
  • Genomic Instability
  • Humans
  • Molecular Sequence Data
  • Mutation / genetics
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Protein Kinase Inhibitors / pharmacology
  • Sequence Alignment

Substances

  • Carrier Proteins
  • Nuclear Proteins
  • Protein Kinase Inhibitors
  • DNA
  • Cyclin-Dependent Kinases
  • Endodeoxyribonucleases
  • RBBP8 protein, human