Biology subjects

Talavera, K.

Publications and source records attributed to Talavera, K..

6 recordsLinked to original sources

bioRxiv2026

Cinnamaldehyde interacts with the local anesthetic pocket of the NaV 1.5 channel

Cinnamaldehyde (CA) is extensively used as flavorant and in traditional medicine. CA is com-monly used in pain research as specific agonist of TRPA1, a polymodal cation channel expressed in nociceptive primary sensory neurons. However, we previously showed that CA inhibits the L-type Ca2+ channel in cardiac and smooth muscle cells, raising the possibility that other ion channels can be modulated by this compound as well. Here, we investigated whether CA exhibits affects the activity on the cardiac NaV1.5 channel. We used the whole-cell patch-clamp technique to record Na+ currents in HEK293T cells expressing the human NaV1.5 channel, as well as in cells expressing hNaV1.5 channels baring mutation in the binding pocket of local anesthetics (LA). Our results show that CA exhibit LA-like actions on hNaV1.5 channels: CA blocks hNaV1.5 currents in a tonic and voltage-dependent fashion. Residues F1760 and Y1767 are important for the blockade of NaV1.5 by CA and a double point mutation F1760A/Y1767A abolishes the blockade of INa by CA. We conclude that CA and LID share common structural determinants for the inhibition of Na+ channels and that CA has LA-like actions.

pharmacology and toxicology↗

bioRxiv2026

Chemical transfection reagents induce intracellular Ca2+ signals in TRPA1-expressing cells

Transient receptor potential ankyrin 1 (TRPA1) is a polymodal sensory ion channel whose activity is influenced not only by chemical ligands but also by the physical properties of the plasma membrane. This raises the possibility that membrane-active compounds used routinely in cell biology may alter TRPA1 function. We investigated the acute effects of two widely used chemical transfection reagents, Lipofectamine 3000 and Mirus TransIT-293, on intracellular Ca2+; signaling and TRPA1 activity. For this, we monitored intracellular Ca2+; dynamics using ratiometric Fura-2 imaging in CHO cells stably expressing mouse TRPA1 (CHO-mTRPA1), parental CHO-WT cells, and primary mouse dorsal root ganglion (DRG) neurons. Transfection reagent preparations were applied at different concentrations under controlled temperature and low-flow conditions. The contribution of TRPA1 and Ca2+; influx was assessed using the selective TRPA1 inhibitor HC-030031 and the broad-spectrum Ca2+; channel blocker ruthenium red. We found that Lipofectamine 3000 induced concentration-dependent, irregular Ca2+; transients in CHO-mTRPA1 cells, while simultaneously inhibiting the constitutive TRPA1-dependent Ca2+; activity observed under basal conditions. Its inhibitory effect was evident at concentrations below those producing substantial cellular activation and was rapidly reversible after washout. At higher concentrations, Lipofectamine-induced Ca2+; responses were only partially suppressed by TRPA1 inhibition, indicating the involvement of additional mechanisms. Consistent with this, Lipofectamine also induced Ca2+; transients in CHO-WT cells and primary DRG neurons, where both extracellular Ca2+; influx and intracellular Ca2+; mobilization contributed to the responses. Analysis of the components of the Lipofectamine 3000 formulation further revealed distinct effects of Lipofectamine and the P3000 enhancer. Mirus TransIT-293 similarly induced Ca2+; transients in CHO-mTRPA1 cells and DRG neurons. In CHO-mTRPA1 cells, its response was concentration-dependent and strongly reduced by HC-030031, whereas the response in DRG neurons showed little sensitivity to TRPA1 inhibition. We conclude that chemical transfection reagents can acutely alter intracellular Ca2+; homeostasis and modulate TRPA1 activity. Their effects involve both TRPA1-dependent and TRPA1-independent mechanisms and differ substantially between formulations and cell types. These findings identify membrane-active transfection reagents as previously underappreciated modulators of sensory ion-channel function and highlight their potential to influence the interpretation of experiments performed in transfected cells.

cell biology↗

bioRxiv2026

Direct analytical estimation of thermodynamic parameters of thermo-TRP channels

A subset of Transient Receptor Potential (TRP) channels display very steep temperature dependences and play key roles in thermosensation. To characterize the properties of these thermoTRP channels, two-state close-open gating models were developed for TRPM8, TRPV1, TRPM4, TRPM5, TRPA1 and TRPM3. In this study, we met the recurrent challenge of finding an initial set of model parameters enabling effective convergence during data fitting procedures. We performed algebraic calculations to derive equations for all gating model parameters as functions of key features of thermoTRP channel data obtained from patch-clamp experiments. We used a minimal set of experimental data: the steady-state open probability and time constant of current relaxation as functions of the membrane potential determined at two temperatures. Specifically, we could express the electric distance of the gating charge and the enthalpy and entropy changes associated with the gating transitions, as functions of the voltages for half-maximal activation, the voltages for maximal time constant of current relaxation and the maximal time constant. Our results provide a method to analytically estimate an initial set thermoTRP thermodynamic parameters enabling robust subsequent nonlinear global data fitting. This approach facilitates quantitative analysis of channel thermodynamics, and has potential applications to more complex gating models, and to the study of permeation, block and other ion channel gating mechanisms.

biophysics↗

bioRxiv2026

Activation by statins unveils two putative agonist binding sites in the pore domain of TRPA1

TRPA1 is a non-selective cation channel that plays a crucial role in several pain and inflammatory conditions. Agents reducing membrane cholesterol decrease TRPA1 activation, but it remains unclear how cholesterol-lowering medications affect TRPA1 function. Given that TRPA1 is activated by a wide variety of chemicals, we explored whether statins have acute effects on this channel. We found that five commonly used statins activate human and mouse TRPA1 in a reversible and concentration-dependent manner. The effective concentrations were above the micromolar range, in the order: simvastatin {approx} lovastatin < fluvastatin < atorvastatin < pravastatin. Statin-induced activation was not correlated to changes in membrane order, nor mediated by N-terminal cysteine residues contributing to electrophilic compound agonism. Molecular docking calculations and the functional characterization of single-point mutants revealed two separate putative binding sites, one situated close to the kink of transmembrane segment 5 (TM5) and the other at the interface between TM4 and TM5. The mTRPA1 inhibitor A-967079 largely abrogated the response to the electrophilic agonist allyl isothiocyanate, but had weaker and varied effects across different statins and menthol. Mutation T877L strongly altered the effect of A-967079, also in an agonist-dependent manner, suggesting competitive binding between this antagonist and the non-electrophilic agonists. The identification of two distinct agonist binding sites may help explaining how TRPA1 is able to respond to a large variety of non-electrophilic compounds, while the finding of competitive interactions at one of these sites may help guide the development of agonist-specific antagonists of therapeutic relevance.

pharmacology and toxicology↗

bioRxiv2026

TRPA1 channel activation by synthetic lipid nanoparticles

TRPA1 is a polymodal ion channel receptor known for its role in nociception. TRPA1 can be activated by local mechanical perturbations in the surrounding plasma membrane (PM) by molecules that insert in the lipid bilayer. Here, we tested whether TRPA1 function can be modulated by lipid nanoparticles (LNPs) while interacting with the target cell plasma membrane. We found that LNP induce irregular Ca2+ transients in heterologous and native TRPA1-expressing cells, which may reflect stochastic LNP-PM interactions. By using different cell types and applying selective and non-selective TRPA1 inhibitors, we revealed that the cytosolic [Ca2+] is elevated transients arise as a result through multiple mechanisms: TRPA1-dependent Ca2+ influx, TRPA1-independent Ca2+ influx, and Ca2+ mobilization from the endoplasmic reticulum. Our results describe a novel, non-canonical TRPA1 activation mechanism by LNPs, that may be relevant in the context of the development of cancer and nasal vaccines.

pharmacology and toxicology↗

bioRxiv2026

Tactile and pain mechanical sensitivity of the human hand

The human hand has a refined mechanical sensitivity, allowing it to play crucial roles in tactile exploration and object manipulation. Despite its fundamental and clinical relevance, a comprehensive characterization of mechanical sensitivity across the human palm is still lacking. Here, we mapped the spatial distribution of innocuous and noxious mechanical sensitivity across the palmar surface of the human hand. We examined 66 hands from 33 healthy adults, dividing the palm into 27 areas, in each of which we measured the mechanical detection threshold, the mechanical pain threshold and the pain intensity evoked by a standard 300 g pinprick stimulus. We found distal areas (i.e., fingertips) to exhibit higher tactile sensitivity than proximal areas (i.e., the wrist). Notably, the sensitivity to innocuous and noxious mechanical stimuli were inversely correlated across areas, such that areas with higher tactile sensitivity displayed higher pain thresholds. In addition, the dominant hand was less sensitive than the non-dominant one, and women displayed higher sensitivity than men. Together, this work provides the first detailed spatial characterization of mechanical sensitivity across the human hand and introduces a systematic methodology for its assessment. These findings set the stage for future studies of the neurophysiological mechanisms of touch and pain in the human hand and for clinical research into pathological conditions involving the altered hand sensitivity.

physiology↗