Transcription-coupled nucleotide excision repair is coordinated by ubiquitin and SUMO in response to ultraviolet irradiation

Nucleic Acids Res. 2020 Jan 10;48(1):231-248. doi: 10.1093/nar/gkz977.


Cockayne Syndrome (CS) is a severe neurodegenerative and premature aging autosomal-recessive disease, caused by inherited defects in the CSA and CSB genes, leading to defects in transcription-coupled nucleotide excision repair (TC-NER) and consequently hypersensitivity to ultraviolet (UV) irradiation. TC-NER is initiated by lesion-stalled RNA polymerase II, which stabilizes the interaction with the SNF2/SWI2 ATPase CSB to facilitate recruitment of the CSA E3 Cullin ubiquitin ligase complex. However, the precise biochemical connections between CSA and CSB are unknown. The small ubiquitin-like modifier SUMO is important in the DNA damage response. We found that CSB, among an extensive set of other target proteins, is the most dynamically SUMOylated substrate in response to UV irradiation. Inhibiting SUMOylation reduced the accumulation of CSB at local sites of UV irradiation and reduced recovery of RNA synthesis. Interestingly, CSA is required for the efficient clearance of SUMOylated CSB. However, subsequent proteomic analysis of CSA-dependent ubiquitinated substrates revealed that CSA does not ubiquitinate CSB in a UV-dependent manner. Surprisingly, we found that CSA is required for the ubiquitination of the largest subunit of RNA polymerase II, RPB1. Combined, our results indicate that the CSA, CSB, RNA polymerase II triad is coordinated by ubiquitin and SUMO in response to UV irradiation. Furthermore, our work provides a resource of SUMO targets regulated in response to UV or ionizing radiation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Transformed
  • Cell Line, Tumor
  • DNA Helicases / genetics*
  • DNA Helicases / metabolism
  • DNA Repair Enzymes / genetics*
  • DNA Repair Enzymes / metabolism
  • DNA Repair*
  • Epithelial Cells / cytology
  • Epithelial Cells / metabolism
  • Epithelial Cells / radiation effects
  • Fibroblasts / cytology
  • Fibroblasts / metabolism
  • Fibroblasts / radiation effects
  • Gene Expression Regulation
  • Gene Regulatory Networks
  • Humans
  • Osteoblasts / cytology
  • Osteoblasts / metabolism
  • Osteoblasts / radiation effects
  • Poly-ADP-Ribose Binding Proteins / genetics*
  • Poly-ADP-Ribose Binding Proteins / metabolism
  • Protein Processing, Post-Translational*
  • RNA Polymerase II / genetics
  • RNA Polymerase II / metabolism
  • Small Ubiquitin-Related Modifier Proteins / genetics*
  • Small Ubiquitin-Related Modifier Proteins / metabolism
  • Sumoylation
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism
  • Transcription, Genetic*
  • Ubiquitin / genetics*
  • Ubiquitin / metabolism
  • Ubiquitination
  • Ultraviolet Rays


  • ERCC8 protein, human
  • Poly-ADP-Ribose Binding Proteins
  • SUMO2 protein, human
  • Small Ubiquitin-Related Modifier Proteins
  • Transcription Factors
  • Ubiquitin
  • RNA Polymerase II
  • DNA Helicases
  • ERCC6 protein, human
  • DNA Repair Enzymes