Figure 4.

Alpha-mangostin inhibited the activity of hyperactive TRPV3 mutant channels and rescued mutation-induced cell death. (A) Alpha-mangostin inhibited the channel current in representative TRPV3 (G573S)- and TRPV3 (G573C)-expressing HEK 293T cells. (B) The dose–response curve of alpha-mangostin in cells expressing the TRPV3 mutants (IC₅₀ = 2.04 ± 0.64 µM for G573S and IC₅₀ = 1.94 ± 0.40 µM for G573C). Currents were normalized to the response at −100 mV before adding alpha-mangostin. (C) Alpha-mangostin inhibited TRPV3-mediated intracellular calcium increase in TRPV3 (G573S)-expressing HEK 293T cells. The left panel shows a representative trace. The bar graph on the right summarizes the change in the intracellular calcium rise inhibited by alpha-mangostin. Cells were perfused with calcium-free solutions containing 0 or 1 µM alpha-mangostin or 10 µM 74a before changing to 1.3 mM Ca²⁺ solutions containing the same substance concentration. (D) Alpha-mangostin inhibited TRPV3-mediated intracellular calcium increase in TRPV3 (G573C)-expressing HEK 293T cells. The left panel shows a representative trace. The bar graph on the right summarizes the change in the intracellular calcium rise inhibited by alpha-mangostin. Cells were perfused with calcium-free solutions containing 0 or 1 µM alpha-mangostin or 10 µM 74a before changing to 1.3 mM Ca²⁺ solutions containing the same substance concentration. (E) Alpha-mangostin improved cell viability in TRPV3 (G573S)- and TRPV3 (G573C)-expressing HEK 293T cells. Transfected HEK 293T cells were plated onto a 96-well plate 6 h after transfection and treated with 300 µM carvacrol, 1 µM alpha-mangostin, 10 µM 74a, or a mixture of 300 µM carvacrol and either 1 µM alpha-mangostin or 10 µM 74a for 24 h before CCK-8 assays. The optical density (O.D.) values were normalized to the untreated HEK 293T cells. Data are presented as means ± SEM. * p < 0.05, ** p < 0.01, **** p < 0.0001.