The essential roles of checkpoint kinase 1 in DNA damage checkpoint response

The DNA damage checkpoint response is a critical surveillance mechanism to ensure that the genome is accurately replicated before undergoing cell division. Defects in cell cycle checkpoints are a significant underlying cause of genomic instability, which drives the development of cancer. Checkpoint kinases are central in the response to oncogene activation, chemo- and radiotherapy-induced DNA damage and replicative stress. As a result, many inhibitors targeting this pathway have been developed, yet none are in clinical use due to adverse side effects in normal cell survival, particularly during cellular differentiation and haematopoiesis. The lack of clarity surrounding the checkpoint response poses a challenge in developing checkpoint inhibitors without dose-limiting toxicity.

My research focuses on investigating the essential functions of Checkpoint kinase 1 (Chk1) in healthy non-cancer cells, both in the presence and absence of DNA damage, using proximity labelling and spatial proteomics techniques. By tagging Chk1 with APEX2, identification of Chk1 interactors in a native physiological setting of the human hTERT-immortalized Retinal Pigment Epithelial-1 (RPE-1) cell line is achieved. The spatial proteome map of the RPE-1 cell line established through Localisation of Organelle Proteins by Isotope Tagging after Differential ultraCentrifugation (LOPIT-DC), provides additional validation and information on Chk1 interactors, especially those within the nucleus. Additionally, it reveals the dynamics of protein re-localization in response to DNA damage, offering a valuable and comprehensive understanding of the checkpoint response. Comprehending the role of checkpoint kinases in genome maintenance and cell division will provide fundamental insights for developing innovative approaches to target enzymes of the DNA damage response pathways in cancer patients.