Elucidating inhibitory signalling in T cell activation using optogenetics
Principal Supervisor: Prof John JamesLink opens in a new window
Co-supervisor: Orkun Soyer
PhD project title: Elucidating inhibitory signalling in T cell activation using optogenetics
University of Registration: University of Warwick
My group’s research focuses on the intracellular signalling of T cells, an essential white blood cell type of the adaptive immune response, which detect infected cells and coordinate their removal. Although the signalling proteins of T cells have been almost completely identified, there is much that remains to be discovered about how the properties of T cells emerge when these components are incorporated into a signalling network. My group’s overall aim is to understand how the network dynamics of T cell receptor signalling orchestrate an immune response. Our central hypothesis is that modulation of the temporal and spatial dynamics of receptor-mediated signalling can instruct different fates at the level of gene transcription and cellular function.
Current approaches to investigate intracellular signalling invariably disrupt a point in the network, either by genetic or pharmacological ablation, and compare cell function afterwards, often at just a single time-point. However, the intervention can never be made without perturbing the whole network due to its interconnected nature, which often leads to misleading results. As an alternative strategy, we investigate intracellular signalling by providing quantitative and dynamic cellular inputs to the intact network and then measure the corresponding outputs to infer details about the underlying system.
Being able to directly control the dynamics of intracellular signalling is essential for the success of this approach. My group has recently developed light-controlled receptors (optogenetics), which can provide both spatial and temporal control over T cell signalling within the physiologically relevant context of a presenting cell conjugate. This receptor utilises a LOV2 domain, which changes conformation when exposed to blue light, to drive the separation of the intracellular signalling motifs from the extracellular receptor, thus disrupting signalling in a reversible manner. This control over the tempo of TCR signalling through optogenetics offers a unique means to probe the dynamics of T cell signalling.
In one potential PhD project, we will explore how inhibitory receptors expressed by T cells affect the downstream output response. It has been suggested that these inhibitory receptors only control one part of the signalling network, but this result has been hard to verify. The outcome has important consequences, as many of the 'checkpoint' inhibitors currently used for treatments for cancer patients target inhibitory receptors, such as PD-1, so knowing how they work at the fundamental level is required to improve their clinical function. To address this limitation, we will develop and implement new tools using the techniques described above, to investigate this hypothesis at the molecular level.
The first main objective of the proposed research would be to map how the information from PD‑1 receptor binding is decoded by the T cell intracellular signalling network, with the expectation of identifying parts of the signalling network that could be controlled by new drugs or therapies. Secondly, we will expand this approach to understand the mechanism of action for a diverse range of inhibitory receptors expressed by T cells, to look for common features between their function.
Harris MJ, Fuyal M, James JR. Quantifying persistence in the T-cell signaling network using an optically controllable antigen receptor Molecular Systems Biology (2021) 17:e10091
JR James Tuning ITAM multiplicity on T-cell receptors can control potency and selectivity to ligand density Science Signaling (2018) 11:eaan1088
BBSRC Strategic Research Priority: Understanding the rules of life – Immunology.
Techniques that will be undertaken during the project:
Molecular biology and cloning
Spinning-disk confocal microscopy
Quantitative Western analysis
Contact: Prof John JamesLink opens in a new window