Potent, selective, and subunit‐dependent activation of TRPC5 channels by a xanthine derivative

作者：Aisling Minard, Claudia Bauer, Eulashini Chuntharpursat‐Bon, Isabelle B. Pickles, David J. Wright, Melanie J. Ludlow, Matthew Burnham, Stuart L. Warriner, David J. Beech, Katsuhiko Muraki, Robin S. Bon · 发表于：British Journal of Pharmacology · 年份：2019 · DOI：10.1111/bph.14791 · 被引用次数：47 · 研究领域：Ion Channels and Receptors、Ion channel regulation and function、Magnesium in Health and Disease

Background and Purpose The TRPC1, TRPC4, and TRPC5 proteins form homotetrameric or heterotetrameric, calcium‐permeable cation channels that are involved in various disease states. Recent research has yielded specific and potent xanthine‐based TRPC1/4/5 inhibitors. Here, we investigated the possibility of xanthine‐based activators of these channels. Experimental Approach An analogue of the TRPC1/4/5 inhibitor Pico145, AM237, was synthesized and its activity was investigated using HEK cells overexpressing TRPC4, TRPC5, TRPC4–C1, TRPC5–C1, TRPC1:C4 or TRPC1:C5 channels, and in A498 cells expressing native TRPC1:C4 channels. TRPC1/4/5 channel activities were assayed by measuring intracellular concentration of Ca 2+ ([Ca 2+ ] i ) and by patch‐clamp electrophysiology. Selectivity of AM237 was tested against TRPC3, TRPC6, TRPV4, or TRPM2 channels. Key Results AM237 potently activated TRPC5:C5 channels (EC 50 15–20 nM in [Ca 2+ ] i assay) and potentiated their activation by sphingosine‐1‐phosphate but suppressed activation evoked by (−)‐englerin A (EA). In patch‐clamp studies, AM237 activated TRPC5:C5 channels, with greater effect at positive voltages, but with lower efficacy than EA. Pico145 competitively inhibited AM237‐induced TRPC5:C5 activation. AM237 did not activate TRPC4:C4, TRPC4–C1, TRPC5–C1, TRPC1:C5, and TRPC1:C4 channels, or native TRPC1:C4 channels in A498 cells, but potently inhibited EA‐dependent activation of these channels with IC 50 values ranging from 0.9 to 7 nM....