Analysis of Drosophila Insulator Protein Function in Replication Timing and the Osmotic Stress Response

Chromatin insulators contribute to the three-dimensional organization of the eukaryotic genome. Insulators and their associated proteins form boundaries between differing chromatin environments, regulate enhancer-promoter interactions, and contribute to the formation of distal genomic contacts. Growing evidence suggests chromatin insulators play roles in cellular processes that extend beyond genome organization alone. The collection of work presented here investigates the involvement of insulators in the timing of DNA replication, the nuclear response to osmotic stress, and the maintenance of genome stability. Chapter 1 characterizes a novel component of Su(Hw) insulator protein complex in Drosophila melanogaster and its contributions to insulator function, genome stability, and the replication timing program. Chapter 2 analyzes conserved properties of the osmotic stress response pathway in Drosophila and human nuclei. Chapter 3 identifies a role for Su(Hw) in maintenance of genome stability and DNA repair in response to DNA damage accumulated during replication. These findings provide evidence that chromatin insulators play a multifaceted role in cellular function that intersects with their role on genome organization.