Several large multi-protein death signalling platforms play a key role in determining cell death or survival. Caspase-8, a key regulator of cell fate, is activated within these complexes - e.g. the Death-Inducing Signalling Complex (DISC), Necrosome and Ripoptosome. Despite these signalling platforms playing a role in determining the tissue response to toxic insult (e.g. drug-induced liver injury), the mechanisms underlying their assembly and regulation is still poorly understood.
Recruitment of Procaspase-8 to the adaptor molecule FADD is mediated via Death Effector Domain (DED) interactions. Subsequently, multiple Procaspase-8 molecules are required to interact via their tDEDs to form a helical Caspase-8-activating chain. c-FLIP isoforms and Caspase-10, which are key regulators of procaspase-8 activation, are recruited to the complex via a co-operative/hierarchical binding mechanism involving Procaspase-8 (Hughes et al. 2016 Mol. Cell; Horn et al. 2017 Cell Rep). The ratio of c-FLIPL/S to Procaspase-8 is a critical regulator of Caspase-8 activation within tDED oligomers and crucially defines how c-FLIP isoforms differentially control cell fate, predicting c-FLIPS blocks Caspase-8 activation by disrupting tDED triple helix assembly. Using negative-stain Electron Microscopy (EM) and Cryo-EM, we have recently visualized the 3D structural architecture of the core FADD:Caspase-8 complex (Fox et al. 2021 Nat Commun). However, the mechanisms whereby other tDED proteins such as cFLIPL/S or Caspase-10 interact with/regulate this core FADD:Caspase-8 complex remains to be determined.
This project will explore the molecular assembly and regulation of FADD:Caspase-8 signalling platforms by other key tDED regulators (e.g. c-FLIP, Caspase-10). Co-expression of recombinant full-length proteins, together with negative-stain transmission electron microscopy (TEM) will be used to gain new insights on the molecular architecture of FADD:Caspase-8 complexes. Using the FEI TALOS Cryo-EM within the MRC Toxicology Unit, we will solve their structure and validate key interactions using structure-guided mutagenesis linked to signalling output.
The successful candidate will be supervised by Prof. M MacFarlane, MRC Toxicology Unit and will include collaboration with other leading laboratories with expertise in structural biology across Cambridge as well as access to core Cryo-EM facilities within the School of Biological Sciences.
Potential applicants should have a strong interest in cell death regulation, protein biochemistry and the application of multi-disciplinary approaches to uncover novel biology.
The Medical Research Council (MRC) Toxicology Unit is a leading International Research Institute within the School of Biological Sciences, University of Cambridge. The Unit delivers mechanistic toxicology research, pursuing hypothesis-driven toxicological questions with a particular focus on the study of the causal links between exposure to endogenous and exogenous toxicants, molecular initiating events and adverse outcome pathways. The Unit's overall aims are to carry out pioneering research which leads to improved health and to train and mentor the next generation of toxicologists.
The Unit provides a supportive learning environment designed to meet the scientific and transferable skills required for an internationally competitive career. Our PhD Programme aims to train the scientific leaders of the future, giving them rewarding research projects with access to world-class facilities and expertise. Students receive toxicology-specific training in the Unit and through the Integrated Toxicology Training Partnership (ITTP).
Students are registered for their PhD with the Graduate School of Life Sciences at the University of Cambridge and have membership of a University of Cambridge College.
The ideal candidate will have excellent academic abilities (a good 2.1 honours degree or equivalent undergraduate degree) combined with strong communication and team working skills in order to make the most of interdisciplinary training opportunities.
To apply please visit the Toxicology Unit website and follow the instructions provided: Applications | MRC Toxicology Unit (cam.ac.uk)
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