LRR1-mediated replisome disassembly promotes DNA replication by recycling replisome components

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• DNA replication requires replisome disassembly after fork convergence.
• CMG helicase (CDC45-MCM-GINS) unloading is critical for replisome disassembly.
• CRL2LRR1 initiates CMG unloading in model organisms.

Purpose of the Study:

• To investigate the role of LRR1 in human CMG helicase unloading.
• To determine the consequences of impaired CMG unloading on DNA replication and cell division.
• To assess the therapeutic potential of targeting CRL2LRR1 in cancer.

Main Methods:

• CRISPR-Cas9 mediated gene knockout of LRR1 in human cells.
• Chromatin immunoprecipitation to assess protein binding.
• Flow cytometry to analyze cell cycle progression.
• Western blotting to detect protein levels.

Main Results:

• Human cells lacking LRR1 accumulate chromatin-bound replisome components.
• Failure to unload CMG helicases reduces DNA replication rate and blocks recycling.
• CMG helicase persistence on chromatin activates the ATR-mediated G2/M checkpoint, blocking mitosis.
• LRR1 is essential for human cell division.

Conclusions:

• LRR1 is crucial for CMG helicase unloading and replisome disassembly in human cells.
• Impaired replisome disassembly leads to replication stress and cell cycle arrest.
• CRL2LRR1 activity is required for cancer cell proliferation, representing a potential therapeutic target.