Centromeric chromatin pliability and memory at a human neocentromere

Area of Science:

• Epigenetics and Chromatin Biology
• Molecular Biology
• Genetics

Background:

• Centromeres are crucial for chromosome segregation during mitosis.
• Centromeric chromatin structure, particularly the presence of CENP-A, is vital for kinetochore assembly and function.
• Neocentromeres provide a model to study centromere formation and epigenetic regulation.

Purpose of the Study:

• To investigate the impact of histone acetylation on CENP-A binding and replication timing at human neocentromeres.
• To determine the reversibility of observed epigenetic changes and their effect on neocentromere function.
• To assess the role of replication timing domains in centromere function.

Main Methods:

• Treatment of human neocentromeres with Trichostatin A (TSA) to induce histone hyperacetylation.
• Analysis of CENP-A binding domain shifts using genomic mapping techniques.
• Assessment of replication timing using established methods.
• Evaluation of mitotic fidelity and neocentromere function.

Main Results:

• TSA-induced hyperacetylation caused a reversible 320 kb shift in the CENP-A binding domain.
• A reduction in CENP-A density and abolition of a delayed replication timing domain were observed.
• No deleterious effects on mitosis or neocentromere function were detected.
• Observed changes were fully reversible upon TSA removal, indicating epigenetic memory.

Conclusions:

• Centromeric chromatin exhibits plasticity in response to epigenetic modifications like histone acetylation.
• Regions of delayed replication timing are not essential for centromere function.
• Epigenetic memory at the neocentromeric site ensures the stable inheritance of chromatin organization.