Histone Acetylation Dynamics and Epigenome Duplication

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Eukaryotic genomes exist in a complex and dynamic 3-dimensional structure that provides important regulatory information controlling gene expression programs essential for the maintenance of cell identity. Genome structure is also critical for packaging the genome in the nucleus and preserving genome stability. Genome structure is primarily dictated by its' association with the histone proteins to form chromatin. The post- translational modifications on histones play a key role in determining genome structure as they regulate the association of non-histone proteins with genomic DNA. An important challenge for eukaryotes is the epigenetic inheritance of the histone modification patterns that govern genome structure following DNA replication and cell division. This proposal seeks to identify fundamental mechanisms that regulate the epigenetic inheritance of histone modification patterns. Following passage of a replication fork, newly replicated DNA is packaged into chromatin that contains a 1:1 mixture of parental histones and newly synthesized histones. The retention of modification patterns on parental histones provides the spatial memory for the duplication of specific chromatin states. The key step in epigenetic inheritance is the transfer of the parental modification patterns to the neighboring new histones. Our work is based on the hypothesis that the new histones play a critical regulatory role in the epigenetic inheritance of chromatin states. The current proposal is based on my lab's identification of previously unknown links between the dynamic acetylation of newly synthesized histones and the epigenetic inheritance of specific chromatin states and the restoration of 3-dimensional genome architecture following DNA replication. The experiments proposed here will characterize the effect of new histone acetylation on the structure and composition of chromatin and identify factors and pathways that function with new histone acetylation to regulate the epigenetic inheritance of chromatin states. In addition, we will characterize a previously unanticipated role of new histone acetylation in the epigenetic inheritance of 3-dimensional genome architecture through regulation of the interactions between chromatin and the nuclear lamina.