Specialized replication mechanisms maintain genome stability at human centromeres.

Area of Science:

• Genetics
• Cell Biology
• Cancer Research

Background:

• Centromere instability, characterized by whole-arm chromosome aneuploidy and translocations, is frequent in tumors.
• The underlying causes of centromere fragility and the mechanisms maintaining its integrity are not well understood.

Purpose of the Study:

• To investigate the impact of replication stress on centromere integrity.
• To elucidate the molecular mechanisms governing centromere replication and stability.

Main Methods:

• Induction of replication stress in cellular models.
• Analysis of centromeric breakage during mitosis.
• Locus-specific proteomics to identify centromeric proteins.
• Investigation of DNA replication and repair pathways at centromeres.

Main Results:

• Replication stress promotes centromeric breakage in mitosis via spindle forces and endonucleases.
• Centromeric replication dynamics differ from the rest of the genome, with specialized proteins involved.
• The translesion synthesis pathway is crucial for sustaining centromere replication and integrity.
• Prolonged stress leads to centromeric ruptures and translocations, observed in ovarian cancer models.

Conclusions:

• Centromere fragility under replication stress contributes to chromosomal abnormalities in cancer.
• Unique replisome dynamics and specialized DNA repair pathways are essential for centromere stability.
• Understanding these mechanisms offers insights into cancer karyotype evolution and potential therapeutic targets.