Many environmental agents, such as UV-irradiation, induce the formation bulky DNA lesions throughout the genome. Yet, DNA damages occurring in transcribed strands of active genes are repaired much faster than those in the rest of the genome, by a dedicated pathway called Transcription-Coupled Nucleotide Excision Repair (TC-NER).
TC-NER is initiated when transcribing RNA polymerase II (RNAPII) encounters the DNA damage, and stalls. This results in the recruitment of the Cockayne Syndrome B (CSB) protein to the stalled RNAPII, which then triggers the downstream steps of the repair reaction.
Inactivating mutations in CSB protein disable TC-NER and cause a severe, autosomal-recessive disorder Cockayne Syndrome. However, we recently found that the lack of functional CSB also results in unstable RNAPII protein upon DNA damage. Thus, is TC-NER absent in these patients because CSB is not functional, or because the sensor of the DNA damage, RNAPII, is depleted? To answer that, we stabilised RNAPII protein in CSB-deficient cells, and surprisingly, this rescued the ability to repair DNA damage, despite lacking CSB. This strongly suggests that an “alternative”, CSB-independent TC-NER pathway exists in human cells. Indeed, such a pathway has been detected in yeast and Drosophila, but the mechanisms are poorly understood. Successful PhD candidate will investigate the mechanisms of alternative-TC-NER in human and yeast cells, using state-of-the-art CRISPR screens, biochemistry, molecular biology, cell biology and genome-wide transcription and repair profiling.
References
Tufegdzic Vidakovic, A., Mitter, R., Kelly, G.P., Neumann, M., Harreman, M., Rodriguez-Martinez, M., Herlihy, A., Weems, J.C., Boeing, S., Encheva, V., et al. (2020)
Regulation of the RNAPII Pool Is Integral to the DNA Damage Response.
Cell 180: 1245-1261 e1221.
Tufegdzic Vidakovic, A., Harreman, M., Dirac-Svejstrup, A.B., Boeing, S., Roy, A., Encheva, V., Neumann, M., Wilson, M., Snijders, A.P., and Svejstrup, J.Q. (2019)
Analysis of RNA polymerase II ubiquitylation and proteasomal degradation.
Methods 159-160: 146-156.