Abstract
The Transient Receptor Potential Ankyrin 1 cation channel (TRPA1) is a broadly-tuned chemosensor expressed in nociceptive neurons. Multiple TRPA1 agonists are chemically unrelated non-electrophilic compounds, for which the mechanisms of channel activation remain unknown. Here, we assess the hypothesis that such chemicals activate TRPA1 by inducing mechanical perturbations in the plasma membrane. We characterized the activation of mouse TRPA1 by non-electrophilic alkylphenols (APs) of different carbon chain lengths in the para position of the aromatic ring. Having discarded oxidative stress and the action of electrophilic mediators as activation mechanisms, we determined whether APs induce mechanical perturbations in the plasma membrane using dyes whose fluorescence properties change upon alteration of the lipid environment. APs activated TRPA1, with potency increasing with their lipophilicity. APs increased the generalized polarization of Laurdan fluorescence and the anisotropy of the fluorescence of 1,6-diphenyl-1,3,5-hexatriene (DPH), also according to their lipophilicity. Thus, the potency of APs for TRPA1 activation is an increasing function of their ability to induce lipid order and membrane rigidity. These results support the hypothesis that TRPA1 senses non-electrophilic compounds by detecting the mechanical alterations they produce in the plasma membrane. This may explain how structurally unrelated non-reactive compounds induce TRPA1 activation and support the role of TRPA1 as an unspecific sensor of potentially noxious compounds.
Highlights
Animal survival strongly relies on constant monitoring of the external chemical environment that allows the trigger of adequate protective reactions against potentially noxious stimuli
Noting that many non-electrophilic agonists of Transient Receptor Potential Ankyrin 1 cation channel (TRPA1) are amphiphilic, these findings suggest that the channel is activated by mechanical perturbations produced by compound insertion in the plasma membrane
We found that APs are TRPA1 agonists, via a mechanism that is not mediated by oxidative stress, nor by covalent modification of key cysteine residues involved in the activation by electrophilic compounds
Summary
Animal survival strongly relies on constant monitoring of the external chemical environment that allows the trigger of adequate protective reactions against potentially noxious stimuli. The plot of the average amplitude of the responses of CHO-mTRPA1 cells as a function of the concentration of the APs corroborates that the effects were concentration-dependent and illustrates difference in sensitivity of mTRPA1 for these compounds (Figure 6a) Each of these experimental data sets were fit with Hill functions, yielding the corresponding. This simple model does not account for the distinct efficacies and Hill coefficients obtained from the fits of the concentration dependencies of the different APs (Figure 6a; data not shown) Taken together, this demonstrates that the differences in lipophilicity across APs are not sufficient to explain the distinct effects of these compounds on mTRPA1. We assessed the ability of APs to alter the lipid environment, using fluorescence-based methods to evaluate membrane order, fluidity, and integrity
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
