Real-time characterisation of neuropeptide binding to a membrane receptor involved in pain and ischemic stroke

ended

Under physiological conditions, localized acidification of brain tissue serves as neuronal signal that get synaptically transduced via acid-sensing ion channels (ASIC1a). Local acidosis has, however, also been linked to some of the most prevalent neurological disorders such as chronic pain, ischemic stroke and psychiatric diseases. ASIC1a has thus emerged as drug target with great potential, but no drugs are currently available that specifically target the channels under pathological conditions. A few known neuropeptides modulate ASIC1a and could thus serve as scaffolds for a new generation of ASIC1a-selective drugs to, for example, treat pain without the typical downsides of opioids. Advances have, however, been hampered by the limited understanding of detailed protein-peptide interactions. Thus, the aim of the proposed project is to directly characterize the binding of the neuropeptide Big Dynorphin to ASIC1a in real time. Here, I will use a unique in-house developed high-sensitivity fluorescence patch-clamp electrophysiology setup and establish a protocol for a FRET-based ligand-binding assay. Together with site-directed mutagenesis, this approach will be able to identify state-dependent binding sites and key interactions, and allow direct analysis of binding affinity and kinetics under pathological conditions; all in intact membranes and with unprecedented (microsecond) temporal resolution. This information will aid future design of ASIC inhibitors with the potential to treat chronic pain and ischemia. The technology developed for this work will also enable ligand-binding studies of other membrane proteins in living cells and with high temporal resolution and will thus be of great potential value for a broad field. The project will expand my existing electrophysiology skills and add highly versatile expertise in fluorescent measurements. I thus anticipate my project to have significant personal and scientific impact beyond the scope of this proposal.