Old players in new posts: the role of P53, ATM and DNAPK in DNA damage-related ubiquitylation-dependent removal of S2P RNAPII

DNA double-strand breaks are the most deleterious lesions for the cells, therefore understanding the macromolecular interactions in the DNA repair-related mechanisms is essential. DNA damage triggers transcription silencing at the damage site, leading to the removal of the elongating RNA polymerase II (S2P RNAPII) from this locus, which provides accessibility for the repair factors to the lesion. Ataxia-telangiectasia mutated (ATM) and DNA-dependent protein kinase (DNAPK) are the two main regulatory kinases of homologous recombination and non-homologous end joining, respectively. Although these kinases are involved in the activation of different repair pathways, they have common target proteins, such as P53. We previously demonstrated that following transcription block, P53 plays a pivotal role in transcription elongation process by interacting with S2P RNAPII. In the current study, we reveal that P53, ATM and DNAPK are involved in the fine-tune regulation of the ubiquitin-proteasome system-related degradation of S2P RNAPII. However, they act differently in this process: P53 delays the removal of S2P RNAPII, while ATM and DNAPK participate in the activation of members of E3 ligase complexes involved in the ubiquitylation of S2P RNAPII. We also demonstrate that WW domain-containing protein 2 (WWP2) and Cullin-3 (CUL3) are interaction partners of S2P RNAPII, thus forming a complex with the transcribing RNAPII complex. Simple SummaryTo ensure the proper repair following DNA double-strand breaks, the eviction of the arrested elongating RNA polymerase II (S2P RNAPII) is required. Here, we report an emerging role of P53, Ataxia-telangiectasia mutated (ATM) and DNA-dependent protein kinase (DNAPK) in the ubiquitin-proteasome system-dependent removal of S2P RNAPII. We also identified interactions between S2P RNAPII and WW domain-containing protein 2 (WWP2) or Cullin-3 (CUL3) (members of E3 ligase complexes), which are involved in the ubiquitylation of S2P RNAPII following DNA damage. Furthermore, the RNAPII-E3 ligase complex interactions are mediated by P53, ATM and DNAPK, which suggests potential participation of all three proteins in the effective resolution of transcription block at the damage site. Altogether, our results provide a better comprehension of the molecular background of transcription elongation block-related DNA repair processes and highlight an indispensable function of P53, ATM and DNAPK in these mechanisms.