Publication highlights

This paper is a continuation of our major research theme on how dividing stem cells in the CNS are able to resist environmental stresses that shut down proliferation in most other developing tissues. It reports the first identification, in any species, of lipid droplets as protectors of stem cells. We discovered that hypoxia induces lipid droplets in the neural stem cell niche and that these protect the neural stem cells themselves from damaging polyunsaturated fatty acid (PUFA) peroxidation reactions. This study laid the foundation for our current mechanistic studies into the antioxidant functions of lipid droplets during development and tumorigenesis.

This paper provided the first evidence that stem cells in the adult mouse hippocampus are heterogeneous in their behaviour, with most stem cells differentiating and leaving the niche after they have become active but a small fraction returning to a shallow state of quiescence. These “resting cells” have an essential role in the long-term maintenance of an active stem cell pool.

Improving chemotherapies against intracellular pathogens requires an understanding of how antibiotic distribution within infected cells affects efficacy. In this work, we developed an approach to visualise antibiotics in human macrophages infected with the tubercle bacillus. We showed that the antitubercular (anti-TB) drug bedaquiline accumulated in host lipid droplets, which seemed to act as an antibiotic reservoir that could be transferred to bacteria during host lipid consumption. Indeed, alterations in host lipid droplet content affected the anti-TB activity of bedaquiline against intracellular bacilli.

This paper established that intestinal epithelial cells use BTNL/Btnl molecules to select for and regulate tissue-specific gamma delta T cell compartments. It established a biological mechanism by which epithelial cells communicate with local T cells at steady-state (“normality sensing”). Following on from our prototypic discovery of such a mechanism in mouse skin, the work established conservation of the process across tissues as well as across species. The system is unperturbed by microbial colonisation.

This paper shows how temporal information in the zebrafish embryo is transformed into a spatial pattern. We demonstrate how the Nodal signalling gradient is formed in the early zebrafish embryo and show that its size and shape are determined by a temporal signal activation window created by a microRNA-mediated delay in the translation of Lefty, a Nodal antagonist. This paper was important as it not only challenged the long-held view in the field that the Nodal gradient was formed by a reaction–diffusion mechanism, but highlighted the importance of signalling duration in gradient formation.

Here we describe our discovery that preservation of specific cellular geometry across a range of cell sizes is essential for correct division site positioning and survival, demonstrating the organismal-level function for scaling.

How inflammatory programmes are tuned to recruit sufficient numbers of neutrophils to clear microbes of different size remained unknown. Furthermore, neutrophils were not thought to serve as major regulators of inflammation in vivo. We showed that reactive oxygen species localisation allows neutrophils to regulate their own recruitment by setting the appropriate level of cytokine production.

We addressed the hypothesis that impairment of neuroprotective astrocytic mechanisms are disrupted in ALS using in vivo models, and patient-specific iPSCs. We found that EphB1, a neuronal signal, can induce a neuroprotective astrocyte phenotype through the EphrinB1 receptor / JAK-STAT pathway and that this response fails in ALS astrocytes.

We report a new and powerful metabolic anti-stress mechanism, ‘Lysine harvesting’, that protects microbial cells in stress situations. We noticed that extracellular lysine is taken up to reach concentrations up to 100x higher than those required for growth. Uptake is dependent on the polyamine pathway, connected via promiscuous metabolic reactions, and triggers a reprogramming of redox metabolism: NADPH is channelled into glutathione metabolism, leading to a large increase in glutathione, lower levels of reactive oxygen species and increased oxidant tolerance. Therefore, nutrient uptake occurs not only to enable cell growth, but allows cells to reconfigure their metabolism to preventatively mount stress protection.

Conventional dendritic cells (cDCs) originate from a committed precursor in bone marrow (BM) that exits via the blood as a pre-cDC to seed tissues with the cDC1 and cDC2 subsets. We used a multi-colour genetic tracing mouse model to analyse colonisation of tissues by pre-cDC. We found that cDCs in tissues comprise clones mostly composed of a single cDC subset and that ‘flu infection causes an efflux of pre-cDCs from BM and influx into the lungs. The latter finding indicates that cDCpoiesis is responsive to emergency need, which suggests previously undiscovered communication between tissues and cDC progenitors in BM.

In this paper, we uncovered a potent mechanism of cancer immune evasion, namely cyclooxygenase (COX)-dependent secretion of prostaglandin E2 (PGE2) by tumour cells. We further showed that the growth of PGE2-secreting tumours in mice can be reversed by a combination of checkpoint blockade immunotherapy and COX inhibitors, suggesting that COX inhibition might be a useful addition to both conventional and immune-based therapy of cancer. This paper led to seven clinical trials worldwide to test combinations of prostaglandin E2 inhibition with checkpoint blockade cancer therapies.

Protein ubiquitination is a key regulatory mechanism and E3 ubiquitin ligases are the key mediators of ubiquitination providing specificity to the process. In this study we describe the application of fragment-based covalent ligand screening to target the active site of an E3 ubiquitin ligase (HOIP) for which previously no specific inhibitors were known. Combining chemical biology, X-ray crystallography, chemoproteomics and cell biology we were able to identify a covalent binder for HOIP that now forms the basis for further inhibitor development. This study illustrates more generally the power of fragment-based covalent ligand screening to identify lead compounds against challenging targets.

Here we determined the structure by single particle cryo-EM of capsid assembly in an endogenous retrovirus. This is the first atomic resolution structure of a closed capsid shell, which in retroviruses packages and protects the genome. By studying 4 different types of symmetric assemblies, we discovered how the underlying Fullerene geometry is achieved by the CA protein forming both pentamers and hexamers and found structural rules by which invariant pentamers and structurally plastic hexamers associate to form the unique polyhedral structures.

Our previous work showed how stromal fibroblasts lead the collective invasion of cancer cells, and documented how remodelling of the extracellular matrix was important for this behaviour. Following our observation of direct cell-cell contacts between cancer cells and fibroblasts, we hypothesised that the two cells might be mechanically coupled; therefore, we began collaborating with Xavi Trepat (IBEC Barcelona), who is a world leader in the mechanics of multi-cellular systems. By biophysical measurements and a range of conventional cell and molecular biology manipulations, we demonstrated that fibroblasts actively ‘pull’ cancer cells into the surrounding extracellular matrix.