Simon Cook

Research Summary

One of the keys to understanding lifelong health is to understand the signalling pathways that operate inside cells and govern key fate decisions such as cell death, cell survival, cell division or cell senescence (collectively cell longevity).  These signalling pathways involve enzymes called ‘protein kinases’ that attach phosphate groups to specific cellular proteins, thereby controlling their activity, location or abundance. In this way protein kinases orchestrate the cellular response to growth factors, nutrient availability or stress and damage.

Ageing results in part from the imbalance between cellular damage, accrued throughout life, and the progressive decline in stress response and repair pathways. We are interested in how protein kinases function in stress responses, the removal of damaged cellular components (e.g. autophagy, see also Nicholas Ktistakis and Oliver Florey) and the control of cellular lifespan. We believe this will enhance our understanding of how the normal declines in these processes drive ageing.

Signalling pathways are frequently de-regulated in certain age-related diseases – notably in cancer, inflammation and neurodegeneration – and many protein kinases are attractive drug targets. Consequently we translate our basic knowledge of signalling through collaborations with charities and pharmaceutical companies (e.g. AstraZeneca and MISSION Therapeutics).

Latest Publications

Inhibitory feedback control of NF-κB signalling in health and disease.
Prescott JA, Mitchell JP, Cook SJ

Cells must adapt to changes in their environment to maintain cell, tissue and organismal integrity in the face of mechanical, chemical or microbiological stress. Nuclear factor-κB (NF-κB) is one of the most important transcription factors that controls inducible gene expression as cells attempt to restore homeostasis. It plays critical roles in the immune system, from acute inflammation to the development of secondary lymphoid organs, and also has roles in cell survival, proliferation and differentiation. Given its role in such critical processes, NF-κB signalling must be subject to strict spatiotemporal control to ensure measured and context-specific cellular responses. Indeed, deregulation of NF-κB signalling can result in debilitating and even lethal inflammation and also underpins some forms of cancer. In this review, we describe the homeostatic feedback mechanisms that limit and 're-set' inducible activation of NF-κB. We first describe the key components of the signalling pathways leading to activation of NF-κB, including the prominent role of protein phosphorylation and protein ubiquitylation, before briefly introducing the key features of feedback control mechanisms. We then describe the array of negative feedback loops targeting different components of the NF-κB signalling cascade including controls at the receptor level, post-receptor signalosome complexes, direct regulation of the critical 'inhibitor of κB kinases' (IKKs) and inhibitory feedforward regulation of NF-κB-dependent transcriptional responses. We also review post-transcriptional feedback controls affecting RNA stability and translation. Finally, we describe the deregulation of these feedback controls in human disease and consider how feedback may be a challenge to the efficacy of inhibitors.

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The Biochemical journal, 478, 13, 16 Jul 2021

PMID: 34269817

Inhibition of RAF dimers: it takes two to tango.
Cook FA, Cook SJ

The RAS-regulated RAF-MEK1/2-ERK1/2 pathway promotes cell proliferation and survival and RAS and BRAF proteins are commonly mutated in cancer. This has fuelled the development of small molecule kinase inhibitors including ATP-competitive RAF inhibitors. Type I and type I½ ATP-competitive RAF inhibitors are effective in BRAFV600E/K-mutant cancer cells. However, in RAS-mutant cells these compounds instead promote RAS-dependent dimerisation and paradoxical activation of wild-type RAF proteins. RAF dimerisation is mediated by two key regions within each RAF protein; the RKTR motif of the αC-helix and the NtA-region of the dimer partner. Dimer formation requires the adoption of a closed, active kinase conformation which can be induced by RAS-dependent activation of RAF or by the binding of type I and I½ RAF inhibitors. Binding of type I or I½ RAF inhibitors to one dimer partner reduces the binding affinity of the other, thereby leaving a single dimer partner uninhibited and able to activate MEK. To overcome this paradox two classes of drug are currently under development; type II pan-RAF inhibitors that induce RAF dimer formation but bind both dimer partners thus allowing effective inhibition of both wild-type RAF dimer partners and monomeric active class I mutant RAF, and the recently developed "paradox breakers" which interrupt BRAF dimerisation through disruption of the αC-helix. Here we review the regulation of RAF proteins, including RAF dimers, and the progress towards effective targeting of the wild-type RAF proteins.

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Biochemical Society transactions, 1, 1, 24 Dec 2020

PMID: 33367512

CDK1, the Other 'Master Regulator' of Autophagy.
Odle RI, Florey O, Ktistakis NT, Cook SJ

Autophagy and cap-dependent mRNA translation are tightly regulated by the mechanistic target of rapamycin complex 1 (mTORC1) signalling complex in response to nutrient availability. However, the regulation of these processes, and mTORC1 itself, is different during mitosis, and this has remained an area of significant controversy; for example, studies have argued that autophagy is either repressed or highly active during mitosis. Recent studies have shown that autophagy initiation is repressed, and cap-dependent mRNA translation is maintained during mitosis despite mTORC1 activity being repressed. This is achieved in large part by a switch from mTORC1- to cyclin-dependent kinase 1 (CDK1)-mediated regulation. Here, we review the history and recent advances and seek to present a unifying model to inform the future study of autophagy and mTORC1 during mitosis.

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Trends in cell biology, 1, 1, 30 Nov 2020

PMID: 33272830

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Keywords

stress responses
ras

bioRxiv Manuscripts

DNA REPLICATION DURING ACUTE MEK INHIBITION DRIVES ACQUISITION OF RESISTANCE THROUGH AMPLIFICATION OF THE BRAF ONCOGENE
Prasanna Channathodiyil, Anne Segonds-Pichon, Paul D. Smith, Simon J. Cook, Jonathan Houseley
bioRxiv 2021.03.23.436572
https://doi.org/10.1101/2021.03.23.436572