Objective

TRP channels are non-selective cation channels that are sensitive to a wide variety of chemical and physical stimuli, such as temperature, physical force and dietary chemicals. For example, capsaicin and noxious heat activate TRPV1 channels, while menthol and noxious cold activate TRPM8 channels. TRP channels all consist of tetramers of TRP proteins. Our research focuses on the closely related TRPC4 and TRPC5 channels, including heteromeric C1/C4 and C1/C5 channels, which are emerging as potential therapeutic targets for the treatment of anxiety disorders, renal cancer and cardiovascular inflammation. However, target validation studies and drug discovery of these channels is impeded by the lack of potent and channel-specific inhibitors. Yet the lack of understanding of the mode-of-action of small molecule inhibitors of TRPC4/5 currently prevents rational design of such inhibitors. In this project, we use a combination of chemical, biochemical and biophysical approaches to identify the mode-of-action of small molecule TRPC4/5 inhibitors. We initially determined SAR and selectivity of TRPC4/5 inhibitors against a panel of ion channels – by calcium imaging and electrophysiology – which allowed us to select two promising series of TRPC4/5 inhibitors for more detailed studies. Utilising these inhibitors we were able to develop chemical probes incorporating diazirine photocrosslinkers and are currently using these in experiments to identify a binding site.