DNA2 enables growth by restricting recombination-restarted replication

Area of Science:

• Genetics
• Molecular Biology
• Cell Biology

Background:

• DNA2 is a nuclease-helicase essential for genome stability and cell proliferation across species.
• Mutations in DNA2 cause primordial dwarfism syndromes, while cancer cells overexpress it.
• The precise roles of DNA2 in cell proliferation and disease pathogenesis are not fully understood.

Purpose of the Study:

• To elucidate the mechanism by which DNA2 prevents cell proliferation defects.
• To understand the molecular basis of DNA2-linked genetic disorders.
• To investigate the role of DNA2 in regulating DNA replication and checkpoint activation.

Main Methods:

• Utilized yeast and human cell models.
• Investigated DNA2's function in suppressing homologous recombination at stalled replication forks.
• Analyzed DNA synthesis, RPA-bound single-stranded DNA accumulation, and cell-cycle progression upon DNA2 depletion.

Main Results:

• DNA2 suppresses homologous recombination-restarted replication and checkpoint activation at stalled forks.
• Loss of DNA2 leads to recombination-dependent DNA synthesis and RPA-ssDNA accumulation in G2 phase.
• DNA2 deprivation triggers the DNA damage checkpoint, causing ATR-p21-dependent cell-cycle exit.

Conclusions:

• DNA2 is essential for cell proliferation by restricting recombination at stalled replication forks, preventing cellular senescence.
• Replication fork processing to limit recombination is critical for avoiding senescence.
• This mechanism provides a framework for understanding growth failure in DNA2-linked primordial dwarfism.