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

Centromere identity is defined and maintained epigenetically by the presence of the histone variant CENP-A. How centromeric CENP-A position is specified and precisely maintained through DNA replication is not fully understood. The recently released Telomere-to-Telomere (T2T-CHM13) genome assembly containing the first complete human centromere sequences provides a new resource for examining CENP-A position. Mapping CENP-A position in clones of the same cell line to T2T-CHM13 identified highly similar CENP-A position following multiple cell divisions. In contrast, centromeric CENP-A epialleles were evident at several centromeres of different human cell lines, demonstrating the location of CENP-A enrichment and site of kinetochore recruitment varies among human cells. Across the cell cycle, CENP-A molecules deposited in G1 phase are maintained at their precise position through DNA replication. Thus, despite CENP-A dilution during DNA replication, CENP-A is precisely reloaded onto the same sequences within the daughter centromeres, maintaining unique centromere identity among human cells.