Deconstructing the molecular basis of cytokine signalling. (360G-Wellcome-101609_Z_13_Z)

How signalling specificity is transmitted by cross-reactive receptors is a fundamental unresolved problem in cell biology. This research proposal aims to elucidate the molecular basis of ligand discrimination by cross-reactive receptors, using shared cytokine receptors as a model system. I plan to take a forward genetic approach, using a non-mammalian cell line, virtually devoid of any ongoing cytokine signalling, to define the relationship between ligands, receptors and active modulators of IL- 2/IL-15 cytokine signalling. Using step-wise reconstitution of signalling components, I will recapitulate cytokine-signalling in insect cells which will allow us to probe if ligand-receptor affinity drives signalling identity. Taking advantage of this reconstitution system I will be able to quantify the proximal signalling induced by a panel of engineered IL-2 and IL-15 cytokines, observe the dynamics of receptor subunits diffusion at the cell membrane and produce a structure of JAK1 bound to th e entire IL-2 receptor complex. This research plan will generate a novel framework for understanding receptor triggering mechanisms and serve as a paradigm for determining the basis of ligand discrimination by cross-reactive receptors. Elucidating receptor signalling mechanisms for key cytokines such as IL-2 and IL-15 could similarly guide development of more precise and effective therapeutic strategies.