BPS2026 – Structural basis of cold and menthol sensing by TRPM8

The transient receptor potential melastatin 8 (TRPM8) channel is the primary detector of environmental cold in mammals, where it contributes to thermoregulation, nociception, and the cooling relief induced by menthol. Dysregulated TRPM8 activity has been implicated in neuropathic pain, migraine, and certain cancers, making it a potential therapeutic target. Although cryo-electron microscopy (cryo-EM) has yielded multiple ligand-bound TRPM8 structures, the molecular mechanism by which cold activates the channel remain unresolved. More broadly, how thermoTRP channels couple thermal and chemical stimuli to gating has remained a fundamental question in sensory biology. Here, we report multiple cryo-EM structures of TRPM8 under cooling and menthol stimulation, capturing conformational snapshots along the channel-opening trajectory, which we validate through extensive electrophysiological experiments with pore accessibility scanning. First, cooling elicits marked rearrangements of the pore domain, including helical extension and rotation of the gating forming S6 helix, as well as tilting of the pore helix toward the pore axis. Second, menthol engages the voltage-sensor-like domain through dynamic binding interactions that drive opening, providing structural insight into its specificity for TRPM8. Third, cold- and menthol-dependent activation converge on overlapping yet nonidentical pathways, with cold primarily driving late-stage conformational changes. We further identify a “cold spot” that is uniquely central to cold activation and functions to mitigate desensitization. Together, these findings define the structural basis of polymodal TRPM8 gating and advance a principle for TRP channel thermosensation.