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

Paradoxical activation of the protein kinase-transcription factor ERK5 by ERK5 kinase inhibitors.
Lochhead PA, Tucker JA, Tatum NJ, Wang J, Oxley D, Kidger AM, Johnson VP, Cassidy MA, Gray NS, Noble MEM, Cook SJ

The dual protein kinase-transcription factor, ERK5, is an emerging drug target in cancer and inflammation, and small-molecule ERK5 kinase inhibitors have been developed. However, selective ERK5 kinase inhibitors fail to recapitulate ERK5 genetic ablation phenotypes, suggesting kinase-independent functions for ERK5. Here we show that ERK5 kinase inhibitors cause paradoxical activation of ERK5 transcriptional activity mediated through its unique C-terminal transcriptional activation domain (TAD). Using the ERK5 kinase inhibitor, Compound 26 (ERK5-IN-1), as a paradigm, we have developed kinase-active, drug-resistant mutants of ERK5. With these mutants, we show that induction of ERK5 transcriptional activity requires direct binding of the inhibitor to the kinase domain. This in turn promotes conformational changes in the kinase domain that result in nuclear translocation of ERK5 and stimulation of gene transcription. This shows that both the ERK5 kinase and TAD must be considered when assessing the role of ERK5 and the effectiveness of anti-ERK5 therapeutics.

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Nature communications, 11, 1, 13 Mar 2020

DOI: 10.1038/s41467-020-15031-3

PMID: 32170057

Macroautophagy is repressed during mitosis - seeing is believing.
Odle RI, Cook SJ

For the last two decades there has been wide ranging debate about the status of macroautophagy during mitosis. Because metazoan cells undergo an "open" mitosis in which the nuclear envelope breaks down, it has been proposed that macroautophagy must be inhibited to maintain genome integrity. While many studies have agreed that the number of autophagosomes is greatly reduced in cells undergoing mitosis, there has been no consensus on whether this reflects decreased autophagosome synthesis or increased autophagosome degradation. Reviewing the literature we were concerned that many studies relied too heavily on autophagy assays that were simply not appropriate for a relatively brief event such as mitosis. Using highly dynamic omegasome markers we have recently shown unequivocally that autophagosome synthesis is repressed at the onset of mitosis and is restored once cell division is complete. This is accomplished by CDK1, the master regulator of mitosis, taking over the function of MTORC1, to ensure autophagy is repressed during mitosis.

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Autophagy, 1, 1, 20 Feb 2020

DOI: 10.1080/15548627.2020.1725405

PMID: 32079445

Dual-mechanism ERK1/2 inhibitors exploit a distinct binding mode to block phosphorylation and nuclear accumulation of ERK1/2.
Kidger AM, Munck JM, Saini HK, Balmanno K, Minihane E, Courtin A, Graham B, O'Reilly M, Odle R, Cook SJ

The RAS-regulated RAF-MEK1/2-ERK1/2 signalling pathway is frequently deregulated in cancer due to activating mutations of growth factor receptors, RAS or BRAF. Both RAF and MEK1/2 inhibitors are clinically approved and various ERK1/2 inhibitors (ERKi) are currently undergoing clinical trials. To date ERKi display two distinct mechanisms of action (MoA); catalytic ERKi solely inhibit ERK1/2 catalytic activity, whereas dual mechanism ERKi additionally prevent the activating phosphorylation of ERK1/2 at its T-E-Y motif by MEK1/2. These differences may impart significant differences in biological activity because T-E-Y phosphorylation is the signal for nuclear entry of ERK1/2, allowing them to access many key transcription factor targets. Here, we characterised the MoA of five ERKi and examined their functional consequences in terms of ERK1/2 signalling, gene expression and anti-proliferative efficacy. We demonstrate that catalytic ERKi promote a striking nuclear accumulation of p-ERK1/2 in KRAS mutant cell lines. In contrast, dual mechanism ERKi exploit a distinct binding mode to block ERK1/2 phosphorylation by MEK1/2, exhibit superior potency and prevent the nuclear accumulation of ERK1/2. Consequently, dual-mechanism ERKi exhibit more durable pathway inhibition and enhanced suppression of ERK1/2-dependent gene expression compared to catalytic ERKi, resulting in increased efficacy across BRAF and RAS mutant cell lines.

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Molecular cancer therapeutics, 1, 1, 20 Nov 2019

DOI: 10.1158/1535-7163.MCT-19-0505

PMID: 31748345

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Keywords

stress responses
ras