Next-Generation Sequencing Enables Spatiotemporal Resolution of Human Centromere Replication Timing

Area of Science:

• Genomics
• Cell Biology
• Molecular Biology

Background:

• Centromeres are crucial for genome integrity and chromosome segregation during cell division.
• The repetitive, heterochromatic nature of centromeres has hindered their analysis and inclusion in genome assemblies and replication timing studies.

Purpose of the Study:

• To establish experimental methods for determining centromere replication timing.
• To resolve the replication timing of centromeres in human cell lines using the hg38 reference genome.

Main Methods:

• Sequencing of G₁- and S-phase cells from five human cell lines.
• Alignment of sequence reads to the hg38 human reference genome.
• Inference of DNA replication timing profiles for centromeric regions.

Main Results:

• Centromere replication was determined to occur during mid-to-late S phase across all tested cell lines.
• Replication timing in centromeric regions exhibited greater variability between cell lines than genome-wide variations.

Conclusions:

• The study successfully inferred centromere replication timing profiles, resolving a long-standing question.
• The findings highlight the potential of updated genome references and sequencing methods for studying heterochromatic regions like centromeres.
• Observed variability suggests cell-specific regulation of centromere replication timing.