Deciphering complexities in ghrelin receptor signalling to enhance understanding of appetite regulation (360G-Wellcome-224155_Z_21_Z)

This fellowship focusses on the growth hormone secretagogue receptor-1a (GHSR1a), a G protein-coupled receptor (GPCR) that binds the orexigenic hormone ghrelin, and is an attractive pharmacological target to regulate appetite. I hypothesise that efforts to target GHSR1a have poor outcomes as GHSR1a signalling is complex, involving GPCR heterodimerisation, interacting proteins and dynamic spatiotemporal signalling. I postulate these mechanisms exist to facilitate GHSR1a’s role as a ‘hub’ at arcuate neurons, where physiological signals are integrated to regulate appetite. Understanding these mechanisms could define new therapeutic targets for obesity and undernutrition. My fellowship will explore GHSR1a signalling in detail. Aim 1 and 2 will address: how GHSR1a interacts with other GPCRs at membranes; how this modulates signalling; if heterodimers form in hypothalamic brain tissue; and whether this affects ghrelin-mediated physiological functions. Aim 3, will identify proteins that interact with GHSR1a and how they affect GHSR1a signalling. Aim 4 will determine how interacting proteins affect GHSR1a trafficking, and whether GHSR1a can continue to signal from intracellular sites once internalised. State-of-the-art kinetic signalling assays (cAMP Glosensor, calflux, NanoBiT-BRET, HTRF); advanced microscopy (TIRF microscopy with single-particle tracking, HILO, single-molecule pull-down); quantitative proteomics (peroxidase-catalysed proximity labelling); and animal models will be utilised to achieve these aims.