PT - JOURNAL ARTICLE AU - Ryuichi Takezawa AU - Henrique Cheng AU - Andreas Beck AU - Jun Ishikawa AU - Pierre Launay AU - Hirokazu Kubota AU - Jean-Pierre Kinet AU - Andrea Fleig AU - Toshimitsu Yamada AU - Reinhold Penner TI - A Pyrazole Derivative Potently Inhibits Lymphocyte Ca<sup>2+</sup> Influx and Cytokine Production by Facilitating Transient Receptor Potential Melastatin 4 Channel Activity AID - 10.1124/mol.105.021154 DP - 2006 Apr 01 TA - Molecular Pharmacology PG - 1413--1420 VI - 69 IP - 4 4099 - http://molpharm.aspetjournals.org/content/69/4/1413.short 4100 - http://molpharm.aspetjournals.org/content/69/4/1413.full SO - Mol Pharmacol2006 Apr 01; 69 AB - 3,5-Bis(trifluoromethyl)pyrazole derivative (BTP2) or N-[4-3, 5-bis(trifluromethyl)pyrazol-1-yl]-4-methyl-1,2,3-thiadiazole-5-carboxamide (YM-58483) is an immunosuppressive compound that potently inhibits both Ca2+ influx and interleukin-2 (IL-2) production in lymphocytes. We report here that BTP2 dosedependently enhances transient receptor potential melastatin 4 (TRPM4), a Ca2+-activated nonselective (CAN) cation channel that decreases Ca2+ influx by depolarizing lymphocytes. The effect of BTP2 on TRPM4 occurs at low nanomolar concentrations and is highly specific, because other ion channels in T lymphocytes are not significantly affected, and the major Ca2+ influx pathway in lymphocytes, ICRAC, is blocked only at 100-fold higher concentrations. The efficacy of BTP2 in blocking IL-2 production is reduced approximately 100-fold when preventing TRPM4-mediated membrane depolarization, suggesting that the BTP2-mediated facilitation of TRPM4 channels represents the major mechanism for its immunosuppressive effect. Our results demonstrate that TRPM4 channels represent a previously unrecognized key element in lymphocyte Ca2+ signaling and that their facilitation by BTP2 supports cell membrane depolarization, which reduces the driving force for Ca2+ entry and ultimately causes the potent suppression of cytokine release.