TRPA1 channels play a fundamental role in chemonociception, as molecular transducers of reactive irritants, stress and tissue damage. Their role in cold and mechanical nociception has also being described. Sigma-1 receptor (σ-1R) is a molecular chaperone that modulates both trafficking and function of various ion channels. In mice, the σ-1R antagonist, S1RA, is able to reduce the symptoms of neuropathic pain. Since the molecular determinants of this antinociceptive effect remain unknown, we studied a possible modulation of TRPA1 by σ-1R. We performed calcium imaging and patch-clamp experiments in HEK293 cells transfected with hTRPA1 tagged with tGFP (hTRPA1-tGFP). Incubation of these cells with S1RA decreased the amplitude of [Ca2+]i responses and of the membrane currents evoked by AITC. Similar results were obtained with BD1086, another σ-1R antagonist. FRET experiments in cells transfected with hTRPA1-tGFP and mCherry- σ-1R revealed that both proteins are localized at a distance compatible with a physical interaction that was supported by co-immunoprecipitation experiments. Treatment of these cells with S1RA decreased FRET levels, suggesting an impairment or conformational change of this putative interaction. Finally, TIRF-FRAP experiments indicate that S1RA reduces the trafficking of TRPA1 towards the plasma membrane, resulting in a reduction of TRPA1 expression at the plasma membrane which was confirmed by cell surface biotinylation assays. These results suggest a role TRPA1 in the anti-nociceptive effects of σ-1R antagonists.

Funding source: SAF2016-77233-R, PID2019-108194RB-100, co-financed by ERDF, Severo Ochoa Program SEV-2017-0723 and GRISOLIA/2015/034.

Resumen del póster presentado al 4th International TRP Meeting, celebrado virtualmente del 15 al 17 de septiembre de 2021.

Peer reviewed