Inheritance of the CENP-A chromatin domain is spatially and temporally constrained at human centromeres.
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BACKGROUND: Chromatin containing the histone variant CENP-A (CEN chromatin) exists as an essential domain at every centromere and heritably marks the location of kinetochore assembly. The size of the CEN chromatin domain on alpha satellite DNA in humans has been shown to vary according to underlying array size. However, the average amount of CENP-A reported at human centromeres is largely consistent, implying the genomic extent of CENP-A chromatin domains more likely reflects variations in the number of CENP-A subdomains and/or the density of CENP-A nucleosomes within individual subdomains. Defining the organizational and spatial properties of CEN chromatin would provide insight into centromere inheritance via CENP-A loading in G1 and the dynamics of its distribution between mother and daughter strands during replication. RESULTS: Using a multi-color protein strategy to detect distinct pools of CENP-A over several cell cycles, we show that nascent CENP-A is equally distributed to sister centromeres. CENP-A distribution is independent of previous or subsequent cell cycles in that centromeres showing disproportionately distributed CENP-A in one cycle can equally divide CENP-A nucleosomes in the next cycle. Furthermore, we show using extended chromatin fibers that maintenance of the CENP-A chromatin domain is achieved by a cycle-specific oscillating pattern of new CENP-A nucleosomes next to existing CENP-A nucleosomes over multiple cell cycles. Finally, we demonstrate that the size of the CENP-A domain does not change throughout the cell cycle and is spatially fixed to a similar location within a given alpha satellite DNA array. CONCLUSIONS: We demonstrate that most human chromosomes share similar patterns of CENP-A loading and distribution and that centromere inheritance is achieved through specific placement of new CENP-A near existing CENP-A as assembly occurs each cell cycle. The loading pattern fixes the location and size of the CENP-A domain on individual chromosomes. These results suggest that spatial and temporal dynamics of CENP-A are important for maintaining centromere identity and genome stability.
Published Version (Please cite this version)10.1186/s13072-016-0071-7
Publication InfoRoss, JE; Sullivan, Beth Ann; & Woodlief, KS (2016). Inheritance of the CENP-A chromatin domain is spatially and temporally constrained at human centromeres. Epigenetics Chromatin, 9. pp. 20. 10.1186/s13072-016-0071-7. Retrieved from http://hdl.handle.net/10161/12389.
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Associate Professor of Molecular Genetics and Microbiology
Research in the Sullivan Lab is focused on chromosome organization, with a specific emphasis on the genomics and epigenetics of the chromosomal locus called the centromere and the formation and fate of chromosome abnormalities that are associated with birth defects, reproductive abnormalities, and cancer. The centromere is a specialized chromosomal site involved in chromosome architecture and movement, kinetochore function, heterochromatin assembly, and sister chromatid cohesion.Our