Polycarcin V induces DNA damage response and enables the profiling of DNA-binding proteins

Abstract

Polycarcin V, a light-dependent DNA intercalating agent, shows promising therapeutic effects for psoriasis, and its light-activatable chemical probe derivative enabled the identification of 311 DNA-binding proteins which is significant for new biology discovery. To maintain genomic integrity and avoid diseases, the DNA damage response (DDR) not only detects and repairs DNA lesions, but also contributes to the resistance to DNA-damaging chemotherapeutics. Targeting the DDR plays a significant role in drug discovery using the principle of synthetic lethality. The incomplete current knowledge of the DDR encouraged us to develop new strategies to identify and study its components and pathways. Polycarcin V, belonging to the C-aryl glycoside natural products, is a light-activatable DNA intercalating agent which causes DNA damage by forming a covalent [2+2] cycloadduct with thymine residue under 365-450 nm light irradiation in a DNA sequence independent manner. Taking advantage of the light-activatable feature and temporal control of DDR, we designed and synthesized polycarcin V-based bifunctional chemical probes, including one that crosslinks DNA to DNA-binding protein to explore the DDR induced by polycarcin V and uncover novel DNA-protein interactions. Utilizing this chemical probe and ABPP-SILAC, we identified 311 DNA-binding proteins, including known DDR factors and additional proteins that may be of interest in discovering new biology. We validated our approach by showing that our probe could specifically crosslink proteins involved in nucleotide excision repair (NER) that repair bulky DNA adducts. Our studies showed that the [2+2] cycloadduct formed by polycarcin V could indeed be repaired by NER in vivo. As a DNA damaging agent, polycarcin V or its drug-like derivative plus blue light showed promising properties for psoriasis treatment, suggesting that it may itself hold promise for clinic applications.