PhD Studentship in the Regulation of Mre11-Rad50-Nbs1 (MRN) Complex Disassembly in Response to Ionising Radiation

Project Description:

MRE11-RAD50-NBS1 (MRN) is a central DNA double strand break (DSB) repair complex that processes DSB ends for efficient DNA Damage Response (DDR) and DNA repair. Alterations in the MRN complex are present in the cancer-prone disorders like ataxia telangiectasia-like disorder. Germline variants of the MRN complex genes have been linked to the development of breast cancer, and reduced MRN complex expression has been observed in many cancers. Thus, understanding how the MRN complex is regulated is paramount for identifying potential radio-sensitising cancer therapies.

We have recently shown that the ubiquitin-dependent ATPase p97 is one of the central components in DNA repair (Singh et al., EMBO J 2019, Krastev et al. Nature Cell Biology, 2021) and regulation of MRN complex disassembly (Kilgas et al. Cell Reports, 2021). p97 binds ubiquitinated MRN complex and removes it - by its ATPase activity - from chromatin. Thus, p97 prevents MRN complex hyper-accumulation at the sites of DSB. Inactivation of p97 leads to MRN complex hyperaccumulation and consequently cell killing due to uncontrolled DNA end resection. By using a xenograft mouse model, we further demonstrated that this mechanism can be explored for cancer therapy. Namely, chemical inactivation of p97 prevents tumour growth when combined with ionizing radiation. To have effective chemo-radiotherapy based on our model, we still have to understand the molecular details of how p97 regulates MRN complex disassembly. By using the state-of-the art quantitative mass-spectrometry, you will identify the p97-associated proteins which regulate MRN complex disassembly after Ionizing Radiation. The identified components will be further biochemically and cell biologically characterised by using various well-established assays in our group such as confocal microscopy, DNA repair reporter assays, recruitment of proteins to sites of DNA lesion in living cells. Finally, your results will be evaluated in various tumour patient materials.

Training Opportunities: Training in all state-of-the-art technologies including Quantitative Mass-Spectrometry, CRISPR/Cas9 gene editing, Confocal Microscopy, FACS, DNA combing, DNA repair and High-Throughput live cell imaging and analysis.

Relevant Publications:

Singh, A.N., Oehler, J., Torrecilla, I., Kilgas, S., Li, S., Vaz, B., Guérillon, C., Fielden, J., Hernandez‐ Carralero, E., Cabrera, E. and Tullis, I.D., 2019. The p97–Ataxin 3 complex regulates homeostasis of the DNA damage response E3 ubiquitin ligase RNF 8. The EMBO journal, 38(21), p.e102361. Kilgas, S., Singh, A.N., Paillas, S., Then, C.K., Torrecilla, I., Nicholson, J., Browning, L., Vendrell, I., Konietzny, R., Kessler, B.M. and Kiltie, A.E., 2021. p97/VCP inhibition causes excessive MRE11- dependent DNA end resection promoting cell killing after ionizing radiation. Cell reports, 35(8). Krastev, D.B., Li, S., Sun, Y., Wicks, A.J., Hoslett, G., Weekes, D., Badder, L.M., Knight, E.G., Marlow, R., Pardo, M.C. and Yu, L., 2022. The ubiquitin-dependent ATPase p97 removes cytotoxic trapped PARP1 from chromatin. Nature cell biology, 24(1), pp.62-73.

Funding: competition funded.

Entry Requirements and How to Apply: first-class or strong upper second-class undergraduate degree (or predicted) in a biological, medical, mathematical or physical science or international equivalent.

Enquire: Professor Kristijan Ramadan: kristijan.ramadan@oncology.ox.ac.uk Project Link - Dept Oncology website General Enquiries: graduate.studies@oncology.ox.ac.uk 

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