Regulation of CK1 substrate specificity during DNA repair

/Abstract CK1 enzymes are conserved, ubiquitous serine/threonine kinases. They phosphorylate substrates in a variety of cellular signaling pathways and are frequently misregulated in cancer and other pathologies, yet the mechanisms that regulate their activity and choice of substrates are poorly understood. It is vital to elucidate the biochemical basis for CK1 substrate specificity in order to learn how these kinases contribute to cellular signaling and, ultimately, to design specific therapeutic interventions for human disease. In addition to phosphorylating their substrates, CK1s autophosphorylate themselves on multiple residues, and this alters their structure and function. The central hypothesis of this proposal is that occupancy of different autophosphorylation sites on CK1 influences which substrates are preferred, which may be a mechanism to direct kinase activity to a specific pathway in response to cellular conditions. To test this hypothesis, we will investigate how autophosphorylation impacts the substrate specificity of CK1s from the fission yeast Schizosaccharomyces pombe during DNA repair. First, we will determine how autophosphorylation site occupancy changes in response to DNA damage and how autophosphorylation state affects the efficiency of DNA repair in vivo in S. pombe. Second, we will biochemically characterize the rates by which different autophosphorylated forms of CK1 act on a known DNA repair substrate in vitro. Third, we will validate a new substrate that is involved in DNA repair and test whether it is preferentially targeted by the same autophosphorylated form of CK1, as our hypothesis would predict. Successful completion of these aims will both refine our model for the regulation of CK1 substrate specificity and deepen our understanding of how CK1 contributes to DNA repair, filling two important knowledge gaps. Project Number: 1R15GM164980-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of General Medical Sciences (NIGMS) | Principal Investigator: Sierra Cullati | Institution: WESTERN WASHINGTON UNIVERSITY, BELLINGHAM, WA | Award Amount: $481,808 | Activity Code: R15 | Study Section: Macromolecular Structure and Function A Study Section[MSFA] View on NIH RePORTER: https://reporter.nih.gov/project-details/11360619