RFWD3 and translesion DNA polymerases contribute to PCNA modification-dependent DNA damage tolerance

DNA damage tolerance pathways are regulated by proliferating cell nuclear antigen (PCNA) modifications at lysine 164. Translesion DNA synthesis by DNA polymerase eta (Pol eta) is well studied, but less is known about Pol.-independent mechanisms. Illudin S and its derivatives induce alkyl DNA adducts, which are repaired by transcription-coupled nucleotide excision repair (TC-NER). We demonstrate that in addition to TC-NER, PCNA modification at K164 plays an essential role in cellular resistance to these compounds by overcoming replication blockages, with no requirement for Pol eta. Pol kappa and RING finger and WD repeat domain 3 (RFWD3) contribute to tolerance, and are both dependent on PCNA modifications. Although RFWD3 is a FANC protein, we demonstrate that it plays a role in DNA damage tolerance independent of the FANC pathway. Finally, we demonstrate that RFWD3-mediated cellular survival after UV irradiation is dependent on PCNA modifications but is independent of Pol eta. Thus, RFWD3 contributes to PCNA modification-dependent DNA damage tolerance in addition to translesion DNA polymerases.

Automated summary

PCNA modifications at K164 play a crucial role in DNA damage tolerance pathways by overcoming replication blockages and enhancing cellular resistance to alkylating compounds. Polκ and RFWD3 contribute to tolerance and their contributions are dependent on PCNA modifications, but independent of Polη.