SLX4 interacts with RTEL1 to prevent transcription-mediated DNA replication perturbations

Area of Science:

• Molecular Biology
• Genetics
• Cancer Research

Background:

• The SLX4 tumor suppressor is a key scaffold protein involved in genome maintenance pathways like homologous recombination and DNA crosslink repair.
• The DNA helicase RTEL1 has known roles in genome stability, but its interaction with SLX4 was previously uncharacterized.
• SLX4 and RTEL1 were considered to have independent and potentially antagonistic functions in genome protection.

Purpose of the Study:

• To investigate a potential direct interaction between the SLX4 tumor suppressor and the RTEL1 DNA helicase.
• To determine the functional significance of the SLX4-RTEL1 interaction in genome protection and DNA replication.
• To explore the role of this interaction in preventing conflicts between DNA replication and transcription.

Main Methods:

• Identification and characterization of mutations in SLX4 and RTEL1 associated with cancer and Hoyeraal-Hreidarsson syndrome, respectively.
• Analysis of SLX4-RTEL1 complex formation and co-localization with active RNA polymerase II at nascent DNA.
• Assessment of DNA replication defects in cells with disrupted SLX4-RTEL1 interaction, with and without transcription inhibition.

Main Results:

• An unexpected direct interaction between SLX4 and RTEL1 was identified, challenging previous assumptions of independent functions.
• Specific cancer- and syndrome-associated mutations were found to disrupt SLX4-RTEL1 complex formation.
• Disruption of the SLX4-RTEL1 interaction leads to DNA replication defects, which can be rescued by inhibiting transcription, indicating a role in preventing replication-transcription conflicts.

Conclusions:

• SLX4 and RTEL1 form a complex that plays a critical role in preventing replication-transcription conflicts.
• This interaction is essential for maintaining genome stability, particularly in unstressed cellular conditions.
• The function of SLX4 in this complex is independent of its known nuclease scaffold activity.