Epigenetic centromere identity is precisely maintained through DNA replication but is uniquely specified among human...

Area of Science:

• Epigenetics
• Molecular Biology
• Genomics

Background:

• Centromere identity is epigenetically determined by the histone variant CENP-A.
• The precise localization and maintenance of CENP-A through DNA replication remain incompletely understood.
• Recent advancements in genome sequencing, including the Telomere-to-Telomere (T2T) assembly, offer new tools to study centromeric DNA.

Purpose of the Study:

• To investigate the precise positioning and maintenance of centromeric CENP-A through DNA replication.
• To leverage the complete human centromere sequences from the T2T assembly to analyze CENP-A localization.
• To understand how centromere identity is maintained across cell divisions and among different cell types.

Main Methods:

• Mapping CENP-A positions to the T2T human genome assembly.
• Analyzing CENP-A localization in clones from the same cell line.
• Comparing CENP-A epialleles across different human cell lines.
• Tracking CENP-A dynamics throughout the cell cycle.

Main Results:

• CENP-A position is highly conserved across multiple cell divisions within the same cell line.
• Variations in CENP-A enrichment and kinetochore recruitment sites (epialleles) exist among different human cell lines.
• CENP-A deposited in G1 phase remains in its precise location during DNA replication.
• CENP-A is accurately reloaded onto the same DNA sequences in daughter centromeres after replication.

Conclusions:

• Centromere identity is robustly maintained through precise CENP-A reloading onto specific DNA sequences during replication.
• While centromere identity is stable within a cell lineage, variations can occur between different human cell types.
• This study provides critical insights into the epigenetic mechanisms governing centromere identity and inheritance.