Enhanced frequency of transcription pre-initiation complexes assembly after exposure to UV irradiation results in increased repair activity and reduced probabilities for mutagenesis

In order to survive from genotoxic challenges, cells need to adjust efficiently gene expression patterns. Recruitment of Pol II at promoters of active genes and assembly of pre-initiation complex (PIC) is the first step of gene transcription. In this study we employed time- and inhibitor- resolved experiments in order to uncover the dynamics of Pol II recruitment at promoters in UV-treated and control cells. We found that de novo recruitment of the available Pol II molecules at active promoters not only persists upon UV at all times tested (2 hours and 6 hours post UV treatment) but occurs significantly faster in the early phase of recovery (2 hours) than in unexposed human fibroblasts at the majority of active genes.