Ethanol inhibits cold-menthol receptor TRPM8 by modulating its interaction with membrane phosphatidylinositol 4,5-bisphosphate.
Ethanol has opposite effects on two members of the transient receptor potential (TRP) family of ion channels: it inhibits the cold-menthol receptor TRPM8, whereas it potentiates the activity of the heat- and capsaicin-gated vanilloid receptor TRPV1. Both thermosensitive cation channels are critically regulated by the membrane lipid, phosphatidylinositol 4,5-bisphosphate (PIP(2)). The effects of this phospholipid on TRPM8 and TRPV1 are also functionally opposite: PIP(2) is necessary for the activation of TRPM8 but it constitutively inhibits TRPV1. This parallel led us to investigate the possible role of PIP(2) in the ethanol-induced modulation of rat TRPM8, heterologously expressed in HEK293T cells. In this study, we characterize the effects of ethanol (0.1-10%) on whole-cell currents produced by menthol and by low temperature (< 17 degrees C). We show that the inclusion of PIP(2) in the intracellular solution results in a strong reduction in the ethanol-induced inhibition of menthol-evoked responses. Conversely, intracellular dialysis with anti-PIP(2) antibody or with the PIP(2) scavenger, poly L-lysine, enhanced the ethanol-induced inhibition of TRPM8. A 20 min pre-incubation with wortmannin caused a modest decrease in inhibition produced by 1% ethanol, indicating that the ethanol-induced inhibition is not mediated by lipid kinases. These findings suggest that ethanol inhibits TRPM8 by weakening the PIP(2)-TRPM8 channel interaction; a similar mechanism may contribute to the ethanol-mediated modulation of some other PIP(2)-sensitive TRP channels.
Benedikt
Jan
J
Department of Cellular Neurophysiology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Teisinger
Jan
J
Vyklicky
Ladislav
L
Vlachova
Viktorie
V
D000409:Alanine / Q000235:genetics; D000730:Androstadienes / Q000494:pharmacology; D001120:Arginine / Q000235:genetics; D002460:Cell Line / Q000648:ultrastructure; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D003080:Cold Temperature; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004347:Drug Interactions; D004558:Electric Stimulation / Q000379:methods; D000431:Ethanol / Q000494:pharmacology*; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D008610:Menthol / Q000494:pharmacology; D016296:Mutagenesis / Q000502:physiology; D018408:Patch-Clamp Techniques / Q000379:methods; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000494:pharmacology*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D050053:TRPM Cation Channels / Q000378:metabolism*; D014162:Transfection / Q000379:methods; D000077191:Wortmannin
D000730:Androstadienes; D002492:Central Nervous System Depressants; D019269:Phosphatidylinositol 4,5-Diphosphate; D010726:Phosphodiesterase Inhibitors; D050053:TRPM Cation Channels; C425966:TRPM8 protein, human; D008610:Menthol; D000431:Ethanol; D001120:Arginine; D000409:Alanine; D000077191:Wortmannin