Figure 7.

A Model for Transcription and Its Global Control by the Free RNAPII Pool

Simplified model, illustrating how RNAPII levels in WT, K₁₂₆₈R, and Cockayne syndrome cells regulate the global transcriptional response to UV irradiation. mRNA, green lines; DNA lesions, purple stars. Top panels denote transcriptional shutdown, bottom panels restart. Repair of transcription-blocking DNA lesions is slower in K₁₂₆₈R cells, and little TC-NER occurs in CSB cells, partly because CSB protein is required for it, but also because TC-NER requires RNAPII, which is depleted in these cells. Combined with other mechanisms (e.g., Epanchintsev et al., 2017), such depletion means that transcription shutdown is more rapid in CSB cells (shown as thin green lines).