PHOSREP: Investigating the regulation of DNA repair by the BOD1L1-PP2A-B56 phosphatase complex

Despite recent advances in targeted therapies, ionising radiation and genotoxic chemotherapy remain mainstays in the treatment of cancer. These treatments are responsible for the majority of cures achieved in the clinic, and kill cancer cells by causing catastrophic levels of DNA lesions in the cellular genome, leading to cell death. To counteract the toxic nature of unrepaired DNA lesions, cells possess overlapping pathways for responding to and repairing DNA lesions, collectively termed the DNA Damage Response (DDR). The DDR is regulated by a number of protein modifications, including phosphorylation.

The poorly characterised large nuclear protein BOD1L1 has been identified by the Higgs lab to have multiple roles in the DDR, and is key to the repair of lesions induced by both ionising radiation and genotoxic chemotherapies. Separately, I recently identified that BOD1L1 interacts with and suppresses activity of the protein phosphatase PP2A via its regulatory subunit B56.

Phosphatases remove phosphate molecules from other proteins in order to change their structure or activity, and are vital to ensure timely and accurate DNA repair. We hypothesise that this new function of BOD1L1 is involved in regulation of the DDR.

In this proposal, named PHOSREP, we will investigate the relationship between BOD1L1, the PP2A-B56 complex and the DDR using cutting-edge proximity-labelling approaches combined with phospho-proteomic mass spectrometry, single molecule analyses and DNA repair assays. We will characterise the binding of BOD1L1 and PP2A-B56, determine which protein components of the DDR are regulated by BOD1L1-PP2A-B56 at/near DNA lesions, and determine the importance of these changes in repairing DNA damage caused by ionising radiation/genotoxic chemotherapy.

PHOSREP will enhance our fundamental understanding of DNA repair, clarify mechanisms of cancer treatment sensitivity/resistance, and improve the use of genotoxic therapies in the clinic.