UV-dependent interaction between Cep164 and XPA mediates localization of Cep164 at sites of DNA damage and UV sensitivity.

DNA damage response plays a critical role in the maintenance of genomic stability. In response to UV damage, ataxia telangiectasia mutated and rad3 related kinase (ATR)-mediated checkpoint and nucleotide excision repair (NER) machinery are activated. A centrosomal protein, Cep164, has been identified as a chromatin binding mediator protein functioning in ATR-mediated checkpoint activation upon UV damage. However, it was not clear whether there is cross talk between Cep164 and NER machinery. We show that Cep164 knockdown compromises the cell survival upon UV damage. Cep164 localizes to cyclobutane pyrimidine dimmers (CPD), one of the major DNA lesions induced by UV irradiation. Binding of Cep164 to the region of exon 4 to intron 9 within p53 gene, known as a pyrimidine-rich region as well as a photoproduct formation region upon UV damage, increases 2.5-fold upon UV irradiation. Recruitment of Cep164 to CPD sites or photoproduct formation region requires a NER factor, Xeroderma pigmentosum group A (XPA). Furthermore, UV irradiation significantly enhances the interaction between Cep164 and XPA. Cep164 binds to amino acids 4-97 of XPA, a region required for UV resistance. Importantly, co-localization of Cep164 and CPD is aberrant in XPA-deficient fibroblasts complemented with XPA(Delta10-88) mutant. In addition, UV-induced CHK1 phosphorylation is impaired in these cells. These findings provide mechanistic insights for the recruitment of Cep164 mediator protein to DNA damage sites and reveal a critical juncture between checkpoint pathways and repair systems.