TRPM8 voltage sensor mutants reveal a mechanism for integrating thermal and chemical stimuli.
TRPM8, a member of the transient receptor potential (TRP) channel superfamily, is expressed in thermosensitive neurons, in which it functions as a cold and menthol sensor. TRPM8 and most other temperature-sensitive TRP channels (thermoTRPs) are voltage gated; temperature and ligands regulate channel opening by shifting the voltage dependence of activation. The mechanisms and structures underlying gating of thermoTRPs are currently poorly understood. Here we show that charge-neutralizing mutations in transmembrane segment 4 (S4) and the S4-S5 linker of human TRPM8 reduce the channel's gating charge, which indicates that this region is part of the voltage sensor. Mutagenesis-induced changes in voltage sensitivity translated into altered thermal sensitivity, thereby establishing the strict coupling between voltage and temperature sensing. Specific mutations in this region also affected menthol affinity, which indicates a direct interaction between menthol and the TRPM8 voltage sensor. Based on these findings, we present a Monod-Wyman-Changeux-type model explaining the combined effects of voltage, temperature and menthol on TRPM8 gating.
Voets
Thomas
T
Laboratory of Ion Channel Research, Division of Physiology, Department of Molecular Cell Biology, Campus Gasthuisberg O&N1, KU Leuven, Herestraat 49 bus 802, B-3000 Leuven, Belgium. thomas.voets@med.kuleuven.be
Owsianik
Grzegorz
G
Janssens
Annelies
A
Talavera
Karel
K
Nilius
Bernd
B
D000465:Algorithms; D002460:Cell Line; D002678:Chimera / Q000235:genetics / Q000502:physiology; D003627:Data Interpretation, Statistical; D004594:Electrophysiology; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology; D008024:Ligands; D008610:Menthol / Q000494:pharmacology; D016296:Mutagenesis; D009154:Mutation / Q000502:physiology*; D011869:Radioligand Assay; D015398:Signal Transduction / Q000235:genetics* / Q000502:physiology*; D013268:Stimulation, Chemical; D050053:TRPM Cation Channels / Q000235:genetics* / Q000502:physiology*; D013696:Temperature
D008024:Ligands; D050053:TRPM Cation Channels; C425966:TRPM8 protein, human; D008610:Menthol