TRPC5 channel sensitivities to antioxidants and hydroxylated stilbenes.
Transient receptor potential canonical 5 (TRPC5) forms cationic channels that are polymodal sensors of factors including oxidized phospholipids, hydrogen peroxide, and reduced thioredoxin. The aim of this study was to expand knowledge of the chemical-sensing capabilities of TRPC5 by investigating dietary antioxidants. Human TRPC5 channels were expressed in HEK 293 cells and studied by patch clamp and intracellular Ca(2+) recording. GFP- and HA-tagged channels were used to quantify plasma membrane localization. Gallic acid and vitamin C suppressed TRPC5 activity if it was evoked by exogenous hydrogen peroxide or lanthanide ions but not by lysophosphatidylcholine or carbachol. Catalase mimicked the effects, suggesting that lanthanide-evoked activity depended on endogenous hydrogen peroxide. Trans-resveratrol, by contrast, inhibited all modes of TRPC5, and its effect was additive with that of vitamin C, suggesting antioxidant-independent action. The IC(50) was ∼10 μM. Diethylstilbestrol, a related hydroxylated stilbene, inhibited TRPC5 with a similar IC(50), but its action contrasted sharply with that of resveratrol in outside-out membrane patches where diethylstilbestrol caused strong and reversible inhibition and resveratrol had no effect, suggesting indirect modulation by resveratrol. Resveratrol did not affect channel surface density, but its effect was calcium-sensitive, indicating an action via a calcium-dependent intermediate. The data suggest previously unrecognized chemical-sensing properties of TRPC5 through multiple mechanisms: (i) inhibition by scavengers of reactive oxygen species because a mode of TRPC5 activity depends on endogenous hydrogen peroxide; (ii) direct channel blockade by diethylstilbestrol; and (iii) indirect, antioxidant-independent inhibition by resveratrol.
Multidisciplinary Cardiovascular Research Centre, Institute of Membrane and Systems Biology, Faculty of Biological Sciences, and Faculty of Medicine and Health, University of Leeds, Leeds LS2 9JT, United Kingdom.
Jacqueline
J
Naylor
Eman
E
Al-Shawaf
Lynn
L
McKeown
Paul T
PT
Manna
Karen E
KE
Porter
David
D
O'Regan
Katsuhiko
K
Muraki
David J
DJ
Beech
D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D016166:Free Radical Scavengers / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D013267:Stilbenes / Q000494:pharmacology*; D050052:TRPC Cation Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D016166:Free Radical Scavengers; D013267:Stilbenes; D050052:TRPC Cation Channels; C491780:TRPC5 protein, human; D006861:Hydrogen Peroxide; D002118:Calcium