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The vanilloid receptor TRPV1 plays a well-established functional role in the detection of a range of chemical and thermal noxious stimuli, such as those associated with tissue inflammation and the resulting pain. TRPV1 activation results in membrane depolarization, but may also trigger intracellular Ca2+-signalling events. In a proteomic screen for proteins associated with the C-terminal sequence of TRPV1, we identifiedβ-tubulin as a specific TRPV1-interacting protein. We demonstrate that the TRPV1 C-terminal tail is capable of binding tubulin dimers, as well as of binding polymerized microtubules. The interaction is Ca2+-sensitive, and affects microtubule properties, such as microtubule sensitivity towards low temperatures and nocodazole. Our data thus provide compelling evidence for the interaction of TRPV1 with the cytoskeleton. The Ca2+-sensitivity of this interaction suggests that the microtubule cytoskeleton at the cell membrane may be a downstream effector of TRPV1 activation. [ABSTRACT FROM AUTHOR]

1: TRPM8 (CMR1) is a Ca2+-permeable channel, which can be activated by low temperatures, menthol, eucalyptol and icilin. It belongs to the transient receptor potential (TRP) family, and therefore is related to vanilloid receptor type-1 (VR1, TRPV1). We tested whether substances which are structurally related to menthol, or which produce a cooling sensation, could activate TRPM8, and compared the responses of TRPM8 and VR1 to these ligands. 2: The effects of 70 odorants and menthol-related substances on recombinant mouse TRPM8 (mTRPM8), expressed in HEK293 cells, were examined using a FLIPR® assay. In all, 10 substances (linalool, geraniol, hydroxycitronellal, WS-3, WS-23, FrescolatMGA, FrescolatML, PMD38, CoolactP and Cooling Agent 10) were found to be agonists. 3: The EC50 values of the agonists defined their relative potencies: icilin (0.2±0.1?µM)>FrescolatML (3.3±1.5?µM) > WS-3 (3.7±1.7?µM) >(-)menthol (4.1±1.3?µM) >frescolatMAG (4.8±1.1?µM) > cooling agent 10 (6±2.2?µM) >(+)menthol (14.4±1.3?µM) > PMD38 (31±1.1?µM) > WS-23 (44±7.3?µM) > Coolact P (66±20?µM) > geraniol (5.9±1.6?mM) > linalool (6.7±2.0?mM) > eucalyptol (7.7±2.0?mM) > hydroxycitronellal (19.6±2.2?mM). 4: Known VR1 antagonists (BCTC, thio-BCTC and capsazepine) were also able to block the response of TRPM8 to menthol (IC50: 0.8±1.0, 3.5±1.1 and 18±1.1?µM, respectively). 5: The Ca2+ response of hVR1-transfected HEK293 cells to the endogenous VR1 agonist N-arachidonoyl-dopamine was potentiated by low pH. In contrast, menthol- and icilin-activated TRPM8 currents were suppressed by low pH. 6: In conclusion, in the present study, we identified 10 new agonists and three antagonists of TRPM8. We found that, in contrast to VR1, TRPM8 is inhibited rather than potentiated by protons.British Journal of Pharmacology (2004) 141, 737-745. doi:10.1038/sj.bjp.0705652 [ABSTRACT FROM AUTHOR]

The Vanilloid Receptor 1 is a heat-sensitive, nonselective cation channel expressed by primary sensory neurons involved in nociception. To find and study potential interacting proteins of VR1 we cloned the full N- and C-termini without transmembrane sequences of VR1 into the bacterial expression vector pMALc2x. We here report the expression and purification of the VR1 fragments fused to the maltose binding protein (MBP). In addition, we assessed the subcellular targeting of N- and C-terminal VR1 fragments expressed in the cell line F-11. This cell line has recently been shown to be particularly suited for the expression of VR1 (1). Preliminary data suggest that the VR1 N-terminal fragment is targeted to membranes despite the lack of predicted transmembrane regions. [ABSTRACT FROM AUTHOR]