Chromosomal Integrity after UV Irradiation Requires FANCD2-Mediated Repair of Double Strand Breaks

PLoS Genet. 2016 Jan 14;12(1):e1005792. doi: 10.1371/journal.pgen.1005792. eCollection 2016 Jan.

Abstract

Fanconi Anemia (FA) is a rare autosomal recessive disorder characterized by hypersensitivity to inter-strand crosslinks (ICLs). FANCD2, a central factor of the FA pathway, is essential for the repair of double strand breaks (DSBs) generated during fork collapse at ICLs. While lesions different from ICLs can also trigger fork collapse, the contribution of FANCD2 to the resolution of replication-coupled DSBs generated independently from ICLs is unknown. Intriguingly, FANCD2 is readily activated after UV irradiation, a DNA-damaging agent that generates predominantly intra-strand crosslinks but not ICLs. Hence, UV irradiation is an ideal tool to explore the contribution of FANCD2 to the DNA damage response triggered by DNA lesions other than ICL repair. Here we show that, in contrast to ICL-causing agents, UV radiation compromises cell survival independently from FANCD2. In agreement, FANCD2 depletion does not increase the amount of DSBs generated during the replication of UV-damaged DNA and is dispensable for UV-induced checkpoint activation. Remarkably however, FANCD2 protects UV-dependent, replication-coupled DSBs from aberrant processing by non-homologous end joining, preventing the accumulation of micronuclei and chromatid aberrations including non-homologous chromatid exchanges. Hence, while dispensable for cell survival, FANCD2 selectively safeguards chromosomal stability after UV-triggered replication stress.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromatids / genetics
  • Chromatids / radiation effects
  • Chromosomal Instability / radiation effects
  • Chromosomes / genetics
  • Chromosomes / radiation effects
  • DNA Breaks, Double-Stranded / drug effects
  • DNA Damage / radiation effects
  • DNA End-Joining Repair / genetics
  • DNA End-Joining Repair / radiation effects
  • DNA Repair / genetics*
  • DNA Repair / radiation effects
  • DNA Replication / genetics*
  • DNA Replication / radiation effects
  • Fanconi Anemia / genetics*
  • Fanconi Anemia / pathology
  • Fanconi Anemia Complementation Group D2 Protein / genetics*
  • Genomic Instability / genetics
  • Genomic Instability / radiation effects
  • Humans
  • RNA, Small Interfering
  • Ultraviolet Rays

Substances

  • Fanconi Anemia Complementation Group D2 Protein
  • RNA, Small Interfering

Grants and funding

VG, GS and JLB are researchers from the National Council of Scientific and Technological Research (CONICET) and MDG and AR from the Nuclear Regulation Authority (ARN). MBF and MBV are supported by fellowships from CONICET. Grants supporting this research are PICT2012-1371 and PICT2013-1049 http://www.foncyt.mincyt.gov.ar/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.