The regulation of Mre11-Rad50-Nbs1 (MRN) complex disassembly in response to ionising radiation
About the research:
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.
We have a dynamic and vibrant environment in the lab. Our lab currently trains 1 master student, 4 DPhil students and 4 post-doctoral researchers. The lab has expertise in biochemistry, molecular and cell biology, ionizing radiation and cancer research coupled to state-of-the-art technologies such as Quantitative Mass-Spectrometry, CRISPR/Cas9 gene editing, Confocal Microscopy, FACS, DNA combing, DNA repair and High-Throughput image analysis. You, as a PhD/DPhil student will get an excellent training in the aforementioned laboratory technologies. The most importantly, once you obtain your PhD/DPhil in our group, you will become an independent and competitive scientist on the market. As evident, all our students have so far secured their next-destination jobs at the most prestigious scientific institutions worldwide, such as Oxford, Cambridge, Swiss Federal Institute of Technology (ETH-Zurich), the Curie Institute-Paris or pharma companies. Please check our websites for further details or contact Prof Ramadan directly. Follow us on tweeter: https://twitter.com/Kramadan2
- Abhay Narayan Singh, Judith Oehler, Ignacio Torrecilla, Bruno Vaz, Claire Guerillon, John Fielden, Iain D.C. Tullis, Mayura Meerang, Paul R Barber, Raimundo Freire, Jason Parsons, Borislav Vojnovic, Niels Mailand and Kristijan Ramadan*. Homeostasis of the E3-ubiquitin ligase RNF8 by the p97-Ataxin 3 complex preserves genome stability. EMBO J, 2019 (* corresponding author).
- Dragomir B. Krastev, Shudong Li, Yilun Sun, Andrew Wicks, Gwendoline Hoslett, Daniel Weekes, Luned M. Badder, Eleanor G. Knight, Rebecca Marlow, Mercedes Pardo Calvo4, Lu Yu, Tanaji T. Talele, Jiri Bartek, Jyoti Choudhary, Yves Pommier, Stephen J. Pettitt1*, Andrew N.J. Tutt*, Kristijan Ramadan*, Christopher J. Lord*. The ubiquitin dependent ATPase p97 removes cytotoxic trapped PARP1 from chromatin. Nature Cell Biology, 2021, accepted (*corresponding authors).
- Kilgas S, Singh AN, Paillas S, Then CK, Torrecilla I, Nicholson J, Browning L, Vendrell I, Konietzny R, Kessler BM, Kiltie AE*, Ramadan K*. p97/VCP inhibition causes excessive MRE11-dependent DNA end resection promoting cell killing after ionizing radiation. Cell Rep. 2021 May 25;35(8):109153. doi: 10.1016/j.celrep.2021.109153. (* corresponding authors).