Research Opportunities

Whipworms (Trichuris trichiura) are intestinal parasites that infect hundreds of millions of people worldwide and cause trichuriasis, a major Neglected Tropical Disease. Whipworms live preferentially in the caecum of their hosts and have a unique life cycle strategy where they establish a multi-intracellular niche within the intestinal epithelia (IE). In this niche, whipworms can remain for years causing chronic infections by modulating intestinal inflammation. During IBD the IE is damaged and recent findings identified a pivotal role of the IE in the maintenance of inflammation. IBD is rare in countries where trichuriasis is endemic, suggesting that the control of inflammation evolved by whipworms in order to persist in their epithelial niche during chronic infections may have beneficial effects for its host by limiting bystander inflammatory pathologies. Current IBD therapies using live parasitic worms, including whipworms (T. trichiura and T. suis), worm secretions and worm-derived synthetic molecules are being trialled to treat IBD.  However, the effects of whipworms on the IE during IBD are poorly understood. Intestinal organoids are in vitro multicellular clusters resulting from stem cell self-renewal and organization that closely recapitulate the composition and architecture of the IE. We have shown that murine caecal organoids (caecaloids) stimulated with extracellular vesicles purified from adult T. muris (mouse whipworm) excretory-secretory (ES) products show a downregulation of genes normally involved in virus responses, specifically type-1 interferon signalling. This data led us to hypothesise that the anti-inflammatory effects of whipworm infections as IBD therapy are partly mediated by direct effects on the IE.

For this PhD project, we will adapt our murine caecal organoid-whipworm model to human organoids and T. trichiura. We will generate intestinal organoids from biopsies of IBD patients, healthy controls and individuals experimentally infected with T. trichiura in human challenge infections. These studies will offer insights on the inflammatory and stem cell remodelling pathways modulated by whipworms in the IE and will lead to the dissection of the molecular mechanisms promoting whipworm persistence in the host but also with beneficial effects for therapies on IBD.

The Phosphoinositide 3-kinases (PI3Ks) are a family of lipid kinases that control diverse signalling pathways affecting gene-transcription, cellular adhesion and trafficking, autophagy and metabolism via the generation of PIP3. While some of these readouts are controlled by the evolutionarily conserved PI3K-AKT-FOXO, PI3K-AKT-mTOR axes, there is a diverse network of PI3K effectors that are less well studied, especially in lymphocytes, but which nonetheless can have profound effects on lymphocyte biology. We have recently used CRISPR/Cas9 to perform a targeted screen of PI3K effectors by generating a library that specifically targets PIP3-binding proteins. Screening for genes that affect T cell adhesion, we identified RASA3 as a key protein linking PI3K to the activation of the integrin LFA-1 and found that RASA3 is critical for T cell migration, homeostasis and responses to immunization. We have now generated extended CRISPR/Cas9 libraries that target the entire PI3K-ome (including the kinases, phosphatases and all known effector proteins). Potential projects include designing and implementing new screens for downstream readouts of PI function, including autophagy, endocytosis, regulation of humoral immunity in vivo or other readouts, and/or understanding how RASA3 regulates T cell function and the signaling pathways involving this key regulator of immune cell migration.

Lymphocytes respond to infection by rapidly increasing and decreasing the expression of many genes in a highly regulated manner. This regulation requires the integration of transcription, mRNA decay and translation. We are only just beginning to understand how these processes are integrated with each other. The host labs are studying how the multiprotein CCR4-NOT complex and its associated RNA binding proteins control gene expression. By combining structural and molecular biology approaches with cellular immunology and mouse models of immune responses we offer a broad training experience and the opportunity to discover fundamental mechanisms of gene regulation in the immune system.

References:
A functional screen of RNA binding proteins identifies genes that promote or limit the accumulation of CD138+ plasma cells Turner, D. J., Saveliev, A., Salerno, F., Matheson, L. S., Screen, M., Lawson, H., Wotherspoon, D., Kranc, K. R., and Turner, M. (2022).. eLife, 11, e72313. PMID: 35451955; PMCID: PMC9106329; DOI: 10.7554/eLife.72313

Reconstitution of recombinant human CCR4-NOT reveals molecular insights into regulated deadenylation.  Raisch, T., Chang, C.T., Levdansky, Y., Muthukumar, S., Raunser, S., Valkov, E. (2019). Nature Communications 10: 3173.  

RNA-binding proteins control gene expression and cell fate in the immune system.  Turner, M., and Dìaz-Muñoz, M.D. (2018) Nature Immunology 19:120-129.

The posterior Lateral Line primordium is a group of about a hundred cells that migrates under the skin, from the ear to the tip of the tail, periodically forming and depositing sensory organs called neuromasts, to spearhead formation of the zebrafish Lateral Line sensory system. In recent years, this relatively simple and accessible system has emerged as an attractive model for understanding various aspects of morphogenesis in the developing embryo, including the guidance of cell migration, tissue patterning and organ formation. The goal is to use a combination of cellular, molecular, genetic and biomechanical manipulations coupled with live imaging, image processing and the development of multi-scale computational models to understand the self-organization of cell-fate, morphogenesis and migration of the lateral line primordium. Specific focus will be on developing tools and methods for investigating, imaging, quantifying and modelling the mechanics of collective migration, morphogenesis of epithelial rosettes and the intercellular and intracellular signaling networks that coordinate lateral line primordium development.

I founded a new ultra-high field (7T) MRI physics group in Cambridge in autumn 2017. We develop cutting-edge methods for studying the human brain and body using Cambridge’s state-of-the-art Siemens Terra 7T MRI scanner. My group have active collaborations with clinicians in clinical neurosciences, psychiatry, oncology, and cardiology (Papworth), and with experts in cognitive neuroscience. I welcome PhD students to join the group. The following are areas of strong interest from our community, which would be suitable to develop a PhD project in discussion with me.

(i) Developing new spectroscopic imaging pulse sequences to map neurochemical profiles across the whole brain in a single scan. We have hardware available to apply these methods to study metabolites containing 1H (e.g. NAA, creatine, GABA, GSH) or 31P (e.g. PCr, ATP, in vivo pH mapping) or 13C (e.g. labelled glucose or succinate).
(ii) Developing new methods for neuroimaging, particularly for imaging blood flow in small vessel disease, or for rapid, motion-corrected fMRI in deep brain nuclei.
(iii) Developing new metabolic imaging methods for use in the human body. These would use a new multinuclear (1H and 31P) whole-body coil being built for me by Tesla Dynamic Coils (Netherlands). This could be developed in collaboration with colleagues at Papworth and Radiology for studies in the heart.
(iv) Imaging of metabolism by 2H deuterium metabolic imaging (DMI). 

Repetition priming (RP) is a basic form of memory, whereby prior exposure to a stimulus facilitates or biases subsequent responses to that stimulus. From a neuropsychological perspective, RP is interesting because it can occur without awareness, and despite the damage to the medial temporal lobe (MTL) system that produces amnesia. Many functional neuroimaging studies using fMRI and MEG/EEG have investigated the brain regions and neuronal dynamics associated with RP. However, the results are complex, depending on several important variables, and suggesting multiple underlying neural mechanisms. Recent computational models provide some insight, and the proposed project will extend these models to a broader range of neuroimaging data, including existing data from intracranial recording in human and non-human primates.

Population genomic approaches across diverse species have traditionally used short read sequence data to investigate population structure and signatures of selection. In the recent past, long reads are more traditionally used to build reference genomes to which the short read data can be aligned and evaluated. However, the cost of long read sequencing as well as the DNA input required to generate high quality long read data is dropping rapidly. We foresee a future where population genomics transitions to long read data.

Using these emerging technologies, this project will begin to evaluate what new insights are gained for the Anopheles gambiae species complex, a set of mosquito species famous as the vector of malaria and known to exhibit porous species boundaries and abundant structural variation.  We anticipate that long-read approaches for haplotype phasing and structural variant discovery will enable much clearer resolution of gene flow within species, introgression between species, and alleles under directional or balancing selection.  Insights gained from this project are likely to influence approaches taken for other species that are known to have similar complexities (e.g., Heliconius butterflies, African cichlid fishes).

This project will involve developing and applying new computational methods for analysing long-read sequencing data in an Anopheles population genomics context. The collaborating laboratories at the Sanger Institute and NHGRI are experts in these respective areas and well-suited to provide the appropriate mentorship.

The opportunistic human pathogen, Pseudomonas aeruginosa, is a commonly-found inhabitant in the airways of patients with chronic respiratory ailments such as COPD and cystic fibrosis (CF). Short chain fatty acids (SCFAs) such as acetate and propionate accumulate to high levels in the airways of these patients. In mutants of P. aeruginosa that are unable to catabolise SCFAs, these compounds are toxic and lead to cessation of growth. In this project, we aim to use fragment-based drug discovery to identify inhibitors of the key enzymes involved in propionate catabolism (PrpB and PrpC) and acetate assimilation (AceA). We have recently solved the x-ray crystal structure of each enzyme, and are supported by the Diamond Light Source to initiate a FBDD programme. Challenges will be to identify high affinity binders with specificity for the intended targets. Cell permeability and efflux of the “hits” will need to be investigated, as will “off target” effects, cytotoxicity to mammalian cells, and likely resistance mechanisms. Species specificity of inhibition will be examined in an in vitro polymicrobial system recently developed in the lab.   

We are interested in the transmission of bacterial pathogens and AMR determinants at multiple scales from the within-hospital level to global networks. Projects are possible on many large-scale datasets, primarily using population genomic and phylogenetic approaches to investigate these processes.

We have the largest world-wide collection of patients suffering from rare-inherited immunodeficiency that have been whole-genome sequenced (1500+ cases). Using established analytical expertise the candidate will use novel methods to interrogate and filter potential genetic mutations, we will identify novel candidate genetic loci in patients grouped by disease phenotype or familial relationship. Candidate genetic loci will be investigated using CRISPR-editing of patient derived material (lymphoblastoid, fibroblast and iPS cell lines). Confirmatory studies at mRNA, protein and functional level will be carried out to validate the link between variant and disease.

1. Models of ion channel regulation in single cells and small circuits
2. Modelling robust neuromodulation
3. Regulation and control of neural activity and circuit dynamics

The project aims to develop and exploit high transconductance organic electrochemical transistor-based bio-sensors and ultra-low power thin-film electronics as emerging ICT tools with perfect fit to the targeted application domain. The proposed sensors and interfaces will provide unprecedented ability to detect and monitor small metabolites both in vitro and in vivo, to map immunometabolism of organs and tissues, and to test new drugs in situ.

In this project, we will investigate how different stimuli including IgG-immune complexes and TLR ligands affect the ability of DCs to influence T cell autocrine complement regulation. This is of relevance to our understanding of how inflammation is propagated in autoimmunity and for vaccination boost strategies.