Histone chaperone FACT is essential to overcome replication stress in mammalian cells

Oncogene. 2020 Jul;39(28):5124-5137. doi: 10.1038/s41388-020-1346-9. Epub 2020 Jun 12.


The histone chaperone FACT is upregulated during mammary tumorigenesis and necessary for the viability and growth of breast tumor cells. We established that only proliferating tumor cells are sensitive to FACT knockdown, suggesting that FACT functions during DNA replication in tumor cells but not in normal cells. We hypothesized that the basal level of replication stress defines the FACT dependence of cells. Using genetic and chemical tools, we demonstrated that FACT is needed to overcome replication stress. In the absence of FACT during replication stress, the MCM2-7 helicase dissociates from chromatin, resulting in the absence of ssDNA accumulation, RPA binding, and activation of the ATR/CHK1 checkpoint response. Without this response, stalled replication forks are not stabilized, and new origin firing cannot be prevented, leading to the accumulation of DNA damage and cell death. Thus, we propose a novel role for FACT as a factor preventing helicase dissociation from chromatin during replication stress.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Ataxia Telangiectasia Mutated Proteins / metabolism
  • Cell Line
  • Cells, Cultured
  • Checkpoint Kinase 1 / metabolism
  • Chromatin / genetics
  • Chromatin / metabolism
  • DNA Damage*
  • DNA Replication / genetics*
  • DNA, Single-Stranded / genetics
  • DNA, Single-Stranded / metabolism
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • High Mobility Group Proteins / genetics*
  • High Mobility Group Proteins / metabolism
  • Histone Chaperones / genetics*
  • Histone Chaperones / metabolism
  • Humans
  • MCF-7 Cells
  • Mice, Knockout
  • Minichromosome Maintenance Proteins / genetics
  • Minichromosome Maintenance Proteins / metabolism
  • RNA Interference
  • Replication Protein A / metabolism
  • Transcriptional Elongation Factors / genetics*
  • Transcriptional Elongation Factors / metabolism


  • Chromatin
  • DNA, Single-Stranded
  • DNA-Binding Proteins
  • High Mobility Group Proteins
  • Histone Chaperones
  • Replication Protein A
  • SSRP1 protein, human
  • Transcriptional Elongation Factors
  • ATR protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • Checkpoint Kinase 1
  • Minichromosome Maintenance Proteins