Proteomic discovery of DEK and NUMA1 as new players in UV-induced DNA damage repair mechanisms.

Ultraviolet (UV)-induced DNA lesions threaten genomic stability and are associated with skin carcinogenesis. These lesions are primarily repaired by the nucleotide excision repair (NER) pathway. However, alternative repair mechanisms and regulators are emerging as critical contributors to managing UV lesions. Here, we used a click chemistry-based proteomic approach to identify DEK and NUMA1 as novel regulators of UV-induced DNA lesion repair. Depletion of DEK or NUMA1 resulted in delayed UV lesion repair and increased cellular UV sensitivity. This was accompanied by delayed recruitment of XPF to UV-damaged sites. Notably, abnormal accumulation of proliferating cell nuclear antigen (PCNA) at UV lesions was observed in DEK- or NUMA1-depleted cells. This PCNA accumulation was not entirely dependent on NER, as it also involved contributions from apurinic/apyrimidinic endonuclease 1 (APE1), a key protein in base excision repair (BER). Co-depletion experiments revealed an epistatic relationship between DEK or NUMA1 and APE1, but not with XPA, suggesting an impaired BER in DEK- or NUMA1-depleted cells, possibly due to excessive PCNA accumulation. Our findings suggest that DEK and NUMA1 facilitate efficient UV lesion removal by promoting proper NER activity and regulating APE1-mediated long-patch BER, highlighting the collaborative roles of NER and BER in UV lesion repair.