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CAF-1 promotes efficient PrimPol recruitment to nascent DNA for single-stranded DNA gap formation

Joshua Straka1, Jude B Khatib1, Lindsey Pale1

  • 1Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.

Nucleic Acids Research
|November 18, 2024
PubMed

Insights

The CAF-1-ASF1 pathway promotes single-stranded DNA (ssDNA) gap accumulation at replication forks, impacting chemosensitivity in homologous recombination (HR)-deficient tumors. This process relies on CAF-1

Area of Science:

  • Cellular Biology
  • Molecular Oncology
  • DNA Replication and Repair

Background:

  • Single-stranded DNA (ssDNA) gap accumulation at replication forks is linked to chemosensitivity in homologous recombination (HR)-deficient tumors.
  • The histone chaperone CAF-1 (Chromatin Assembly Factor 1) is known to protect stalled replication forks in HR-deficient cells.
  • CAF-1's role in preventing ssDNA gap accumulation and its impact on chemosensitivity require further elucidation.

Purpose of the Study:

  • To investigate the role of the CAF-1-ASF1 pathway in regulating ssDNA gap accumulation at replication forks.
  • To determine whether CAF-1's nucleosome deposition function or its localization is critical for ssDNA gap formation.
  • To explore the relationship between CAF-1, PrimPol recruitment, and ssDNA gap generation in both wild-type and BRCA-deficient cells.

Main Methods:

  • Assessed ssDNA gap accumulation in wild-type and BRCA-deficient cells with varying CAF-1 and ASF1A expression.
  • Investigated the localization of CAF-1 to replication forks using immunofluorescence.
  • Examined the recruitment of PrimPol to nascent DNA in the presence or absence of functional CAF-1.

Main Results:

  • The CAF-1-ASF1 pathway promotes ssDNA gap accumulation independently of CAF-1's nucleosome deposition activity.
  • CAF-1's localization to replication forks is crucial for promoting ssDNA gap accumulation.
  • CAF-1 is essential for the efficient recruitment of PrimPol (primase-polymerase) to nascent DNA, a process linked to ssDNA gap generation.

Conclusions:

  • CAF-1 plays an unexpected role in regulating PrimPol recruitment and subsequent ssDNA gap generation at replication forks.
  • Chemoresistance in HR-deficient cells lacking CAF-1 or ASF1A is associated with suppressed ssDNA gaps, not just fork protection.
  • This study identifies a novel mechanism by which CAF-1 influences DNA replication stress response and potential therapeutic strategies.

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