Project 1: Cellular requirements for Pol theta

PROJECT 1 SUMMARY Loss of Pol θ is tolerated in normal cells but is lethal in many cancers, making it an attractive target for cancer therapy. Unfortunately, the cellular contexts that drive this synthetic lethality still remain unclear. Here we will investigate cellular requirements for repair by mammalian DNA polymerase θ (Pol θ), the defining enzyme for repair of DNA double-strand breaks by polymerase theta-mediated end joining (TMEJ). Project 1 (“Cellular requirements for Pol θ”) is part of a Program Project titled, “Polymerase theta, genome instability, and cancer”. We will address the significance of recently described interactions between Pol θ and elements of the genome replication machinery, including Pol δ and PCNA, in Aim 1. We will in Aim 2 investigate how cellular regulation of Pol θ activity effects requirements for Pol θ, focusing on perturbations relevant to cancer therapy and the DNA damage response. We will explore in Aim 3 the molecular determinants for Pol θ requirement in cellular resistance to inhibitors of the type 1 Topoisomerase, an agent used in chemotherapy. This project together will extend recent exiting work from our team to characterize mechanisms behind Pol θ activity in response to replication stress, and how this differs relative to mechanisms for repair of chromosome breaks generated by other sources.