# Cholesterol inhibits capsaicin activation of the TRPV1 channel

## TL;DR

Cholesterol can block the activation of the TRPV1 channel by capsaicin, suggesting a competitive interaction at the binding site.

## Contribution

The study demonstrates that cholesterol inhibits capsaicin activation of TRPV1 by occupying the vanilloid-binding pocket.

## Key findings

- Membrane cholesterol enrichment suppresses capsaicin-evoked currents at low concentrations.
- The G563S mutation reduces capsaicin sensitivity and alters deactivation dynamics.
- Elevated cholesterol further inhibits capsaicin-evoked activity in mutated TRPV1 channels.

## Abstract

TRPV1 is a polymodal ion channel activated by vanilloids, noxious heat, and pro-inflammatory signals. A recent cryo-EM structure of human TRPV1 bound to SAF312, a potent, selective, noncompetitive antagonist, revealed a cholesterol molecule occupying the vanilloid-binding pocket, a site well established as the activation locus for vanilloid agonists. This observation led us to test whether cholesterol functionally inhibits capsaicin-dependent TRPV1 activation. Using HEK293 cells heterologously expressing TRPV1, we found that membrane cholesterol enrichment markedly suppressed capsaicin-evoked currents at low agonist concentrations, whereas responses to saturating capsaicin were unaffected. The functional interaction between cholesterol and capsaicin was further supported by site-directed mutagenesis targeting the conserved Gly563, a residue within the S4-S5 linker of the vanilloid-binding pocket. The G563S mutation reduced the sensitivity to capsaicin and caused slow and incomplete deactivation; nevertheless, elevated cholesterol further suppressed capsaicin-evoked activity. Together, these findings support a model in which cholesterol competes with capsaicin at the vanilloid-binding pocket to inhibit activation of the TRPV1 channel.