Replication-independent endogenous DNA double-strand breaks in Saccharomyces cerevisiae model

PLoS One. 2013 Aug 19;8(8):e72706. doi: 10.1371/journal.pone.0072706. eCollection 2013.

Abstract

Without exposure to any DNA-damaging agents, non-dividing eukaryotic cells carry endogenous DNA double-strand breaks (EDSBs), or Replication-Independent (RIND)-EDSBs. In human cells, RIND-EDSBs are enriched in the methylated heterochromatic areas of the genome and are repaired by an ATM-dependent non-homologous end-joining pathway (NHEJ). Here, we showed that Saccharomyces cerevisiae similarly possess RIND-EDSBs. Various levels of EDSBs were detected during different phases of the cell cycle, including G0. Using a collection of mutant yeast strains, we investigated various DNA metabolic and DNA repair pathways that might be involved in the maintenance of RIND-EDSB levels. We found that the RIND-EDSB levels increased significantly in yeast strains lacking proteins involved in NHEJ DNA repair and in suppression of heterochromatin formation. RIND-EDSB levels were also upregulated when genes encoding histone deacetylase, endonucleases, topoisomerase, and DNA repair regulators were deleted. In contrast, RIND-EDSB levels were downregulated in the mutants that lack chromatin-condensing proteins, such as the high-mobility group box proteins, and Sir2. Likewise, RIND-EDSB levels were also decreased in human cells lacking HMGB1. Therefore, we conclude that the genomic levels of RIND-EDSBs are evolutionally conserved, dynamically regulated, and may be influenced by genome topology, chromatin structure, and the efficiency of DNA repair systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle
  • Chromosomes, Fungal / metabolism
  • DNA Breaks, Double-Stranded*
  • DNA Repair
  • DNA Replication*
  • DNA, Fungal / metabolism
  • Genes, Fungal
  • HMGB1 Protein / metabolism
  • HeLa Cells
  • Heterochromatin / metabolism
  • Humans
  • Long Interspersed Nucleotide Elements / genetics
  • Models, Biological*
  • Molecular Weight
  • Mutation / genetics
  • Polymerase Chain Reaction
  • RNA, Small Interfering / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Stress, Physiological

Substances

  • DNA, Fungal
  • HMGB1 Protein
  • Heterochromatin
  • RNA, Small Interfering

Grants and funding

This work was supported by the Discovery-Based Development Grant and the Research Chair Grant 2011 from the National Science and Technology Development Agency (NSTDA), Thailand; by the Four Seasons Hotel Bangkok's 4th Cancer Care charity fun run in coordination with the Thai Red Cross Society; and by Chulalongkorn University under the office of the Higher Education Commission. Funding for the open access charge was provided by Chulalongkorn University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.