GSE52789
UVB induces a major genome-wide rearrangement of RNA polymerase II at transcribed human genes
Abstract  Background: Faithful transcription of DNA is constantly threatened by different endogenous and environmental genotoxic effects. Transcription coupled repair has been described to quickly remove DNA lesions from the transcribed strand of active genes, permitting rapid resumption of blocked transcription. This repair mechanism has been well characterized in the past using individual target genes. However, the precise mechanism by which RNA polymerase II (Pol II) transcription is affected following UV irradiation during the repair processes genome-wide is not well understood.  Results: We investigated the effect of a non-lethal dose of UVB on global DNA-bound Pol II distribution in human cells. We find that about 90% of the promoters of expressed genes show reduced Pol II occupancy 2-4 hours following UVB irradiation, and that the presence of Pol II is restored to “normal”, or higher, levels 5-6 hours after irradiation. We also identified a smaller set of genes, where the presence of Pol II at the promoter regions does not decrease after UVB irradiation, but often increases throughout the entire transcription units. Interestingly, at promoters, where Pol II promoter clearance occurs, TFIIH but not TBP follows the behavior of Pol II suggesting that at these genes TFIIH may be sequestered for DNA repair upon UVB treatment.  Conclusions: Thus, our study reveals a global negative regulatory mechanism that targets Pol II transcription initiation on the large majority of transcribed genes following sublethal UVB irradiation, and a small subset of genes (including regulators of repair, cell growth and survival), where Pol II escapes this negative regulation. Overall design: Following genome-wide RNA Polymerase II redistribution over time upon UVB irradiation