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FAN1-mediated translesion synthesis and POLQ/HELQ-mediated end joining generate interstrand crosslink-induced

Jip Verschuren1, Robin van Schendel1, Ivo van Bostelen1

  • 1Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.

Nature Communications
|March 14, 2025
PubMed

Insights

DNA interstrand crosslink (ICL) repair can cause mutations. This study reveals two main ICL repair pathways in C. elegans: one causing single nucleotide changes and another causing deletions, highlighting the impact on genetic integrity.

Area of Science:

  • Molecular Biology
  • Genetics
  • DNA Repair

Background:

  • Cells possess specialized pathways to repair DNA interstrand crosslinks (ICLs).
  • The precise impact of these ICL repair mechanisms on genetic integrity is not fully understood.
  • Understanding ICL repair is crucial for comprehending genome stability.

Purpose of the Study:

  • To investigate the mutagenic outcomes of psoralen-induced ICL repair in the model organism C.elegans.
  • To identify the specific molecular players and mechanisms involved in ICL-induced mutagenesis.
  • To elucidate the role of DNA replication and specific repair factors in ICL repair fidelity.

Main Methods:

  • Utilized the animal model C.elegans to study psoralen-induced DNA interstrand crosslinks (ICLs).
  • Employed genetic approaches to disrupt key DNA repair genes, including POLH, REV1/3, POLQ, HELQ, FANCD2, FANCI, TRAIP, and FAN1.
  • Analyzed the types and frequencies of mutations (single nucleotide polymorphisms and deletions) resulting from ICL repair in wild-type and mutant strains.

Main Results:

  • Identified two distinct mutagenic ICL repair pathways: translesion synthesis (TLS) mediated by POLH and REV1/3, and end joining involving POLQ or HELQ.
  • TLS pathways resulted in single nucleotide polymorphisms (SNVs), while end joining pathways led to deletions.
  • Disruption of TRAIP significantly altered the ICL repair profile, implicating DNA replication in deletion formation, but did not affect SNV formation.
  • TRAIP-deficient cells showed SNV formation dependent on the Fanconi anemia-associated nuclease FAN1.

Conclusions:

  • Psoralen ICL repair in C.elegans can be mutagenic through distinct TLS and end-joining mechanisms.
  • TRAIP plays a critical role in regulating ICL repair, particularly in preventing deletions during DNA replication.
  • FAN1 is essential for SNV formation during ICL repair, independent of TRAIP function.

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