Elucidating factors that modulate mammalian DNA repair to improve genome editing

Project Summary/Abstract Genome editing is an exciting avenue for treating common and rare genetic diseases, and the advent of CRISPR/Cas technologies has accelerated the development of this therapeutic option. These therapies rely on cellular DNA repair machinery to install their edits, so changes in the balance between DNA repair pathways result in different editing patterns. This dependency on endogenous DNA repair has led to considerable variability in editing efficiency between cell types or even among targets in the same cell. Thus, a long-term goal of my laboratory is to investigate factors that modify the efficacy of genome editing and to develop strategies that address these shortcomings. Histone modifications play a role in many cellular processes, including transcriptional regulation and DNA repair. Recent evidence found that histone modifications correlate with biases for specific DNA repair pathways. However, given their role in multiple processes, interpreting the effects of individual histone modifications has been challenging. I will dissect these effects to define the role of histone modifications in the repair of double-strand breaks by innovating a platform that recruits histone modifiers to thousands of break sites in parallel. This work will determine whether histone modifications influence DNA repair and uncover properties of the target site that predict these effects. For genome editing to reach its therapeutic potential, precise control of DNA repair is required. I will identify peptides from the human proteome that alter the repair of double-strand breaks. To do this, I will adapt a peptide screening platform I developed to investigate DNA repair. The peptides will reveal critical protein-protein interactions and other methods for altering DNA repair. The completion of these projects will significantly advance our understanding of mammalian DNA repair and has the potential to improve genome editing therapies.