Trpm4-induced gene expression changes in Th1 and Th2 cells

T helper cell subsets have unique calcium (Ca2+) signals when activated with identical stimuli. The regulation of these Ca2+ signals and their correlation to the biological function of each T cell subset remains unclear. Trpm4 is a Ca2+-activated cation channel that we found is expressed at higher levels in Th2 cells compared to Th1 cells. Inhibition of Trpm4 expression increased Ca2+ influx and oscillatory levels in Th2 cells and decreased influx and oscillations in Th1 cells. This inhibition of Trpm4 expression also significantly altered T cell cytokine production and motility. Our experiments revealed that decreasing Trpm4 levels divergently regulates nuclear localization of NFAT. Consistent with this, gene profiling did not show Trpm4 dependent transcriptional regulation and T-bet and GATA-3 levels remain identical. Thus, Trpm4 is expressed at different levels on T helper cells and plays a distinctive role in T cell function by differentially regulating Ca2+ signaling and NFAT localization. T helper cell gene expression levels when Trpm4 is inhibited by siRNA or dominant negative Trpm4 construct. The ion channel Trpm4 was inhibited in Th1 or Th2 cells using either siRNA or a dominant negative Trpm4 retrovirus and changes in gene profiles were analyzed.