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Xanthine-Based Photoaffinity Probes Allow Assessment of Ligand Engagement by TRPC5 Channels

preprint
revised on 27.02.2020 and posted on 28.02.2020 by Claudia Bauer, Aisling Minard, Isabelle Pickles, Matthew Burnham, Nikil Kapur, David Beech, Stephen Muench, Megan Wright, Stuart Warriner, Robin Bon
TRPC1/4/5 cation channels are emerging drug targets for the treatment of, amongst others, central nervous system (CNS) disorders, kidney disease, and cardiovascular and metabolic disease. Various small-molecule TRPC1/4/5 modulators have been reported, including highly potent xanthine derivatives that can distinguish between specific TRPC1/4/5 tetramers. However, there is a paucity of information about their binding mode, which limits the ability to develop them further as chemical probes of specific TRPC1/4/5 channels for use in fundamental biological studies and drug discovery programmes. Here, we report the development of a set of potent xanthine-based photoaffinity probes that functionally mimic the xanthines Pico145 and AM237, respectively. Using these probes, we have developed a quantitative photoaffinity labelling protocol for TRPC5 channels. Our results provide the first direct evidence that xanthines modulate TRPC5 channels through a direct binding interaction with TRPC5 protein, and the first quantitative method for the assessment of binding interactions of TRPC5 and small molecules. Our method may allow the study of the mode-of-action of other TRPC1/4/5 modulators, and the identification of small molecule binding sites of TRPC1/4/5 channels.

Funding

BB/P020208/1

Understanding potent small-molecule inhibition of TRPC1/4/5 channels

British Heart Foundation

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BB/L015676/1

The molecular basis of biological mechanisms

Wellcome Trust

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History

Email Address of Submitting Author

r.bon@leeds.ac.uk

Institution

University of Leeds

Country

UK

ORCID For Submitting Author

0000-0003-1733-3680

Declaration of Conflict of Interest

The authors declare no conflict of interest.

Version Notes

ChemRxiv V1.2 (More details added in Supplementary Info, including on LED photocrosslinker design)

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