When a segment of the template strand of DNA is damaged due to factors such as UV radiation, a lesion is created that would effectively block the passage of RNA polymerase II during transcription.
When such stalling occurs, a mammalian cell would usually deploy various transcription-coupled repair factor, such as the XP group of proteins to give provide a proper basis of the lesion and to orient other enzymes in. The endonuclease would cut out the damaged bases, and the DNA polymerase and DNA ligase would, respectively, add the new bases and correctly anchor them onto the template strand.
I fully realize that during the process in which the RNA polymerase II was stalled to the arrival of the transcription-coupled repair factors, some sort of cell signaling must have occurred. However, I could not find any sources that would tell me the specificity of such phenomenon. Therefore, I hope this forum could explain such matter.
Thank you very much!