Transient Receptor Potential Melastatin-3 (TRPM3)–Induced Activation of AP-1 Requires Ca²⁺Ions and the Transcription Factors c-Jun, ATF2, and Ternary Complex Factor

Abstract

The steroid pregnenolone sulfate activates the transcription factor activator protein-1 (AP-1) via stimulation of transient receptor potential melastatin-3 (TRPM3) channels. Here, we show that the signaling pathway requires an influx of Ca 21 ions into the cells and a rise in the intracellular Ca 21 levels. The upregulation of AP-1 was attenuated in cells that overexpressed mitogen activated protein kinase phosphatase-1, indicating that Ca 21 ions prolong the signaling cascade via activation of mitogen activated protein kinases. On the transcriptional level, expression of a dominant-negative mutant of the basic region leucine zipper protein c-Jun, a major constituent of the AP-1 transcription factor complex, or expression of a c-Jun-specific short hairpin RNA attenuated pregnenolone sulfate-induced AP-1 activation. In addition, stimulation of TRPM3 channels increased the transcriptional activation potential of the basic region leucine zipper protein ATF2. Inhibition of ATF2 target gene expression via expression of a dominant-negative mutant of ATF2 or expression of an ATF2-specific short hairpin RNA interfered with TRPM3-mediated stimulation of AP-1. Moreover, we show that a dominant-negative mutant of the ternary complex factor (TCF) Elk-1 attenuated the upregulation of AP-1 following stimulation of TRPM3 channels. Thus, c-Jun, ATF2, and TCFs are required to connect the intracellular signaling cascade elicited by activation of TRPM3 channels with enhanced transcription of AP-1-regulated genes. We conclude that pregnenolone sulfateinduced TRPM3 channel activation changes the gene expression pattern of the cells by activating transcription of c-Jun-, ATF2-, and TCF-controlled genes.

Extracellular Signal-Regulated Protein Kinase, c-Jun N-Terminal Protein Kinase, and Calcineurin Regulate Transient Receptor Potential M3 (TRPM3) Induced Activation of AP-1

“…Stimulation of HEK293 cells expressing TRPM3 channels with pregnenolone sulfate increases the activity of the transcription factor AP‐1. Previous experiments showed that TRPM3 expression is essential for connecting pregnenolone sulfate stimulation with enhanced transcription of AP‐1‐responsive genes [Lesch et al, , ]. Recently, we showed that the TRPM3‐induced signaling pathway requires an influx of Ca 2+ ions into the cells and a rise in the intracellular Ca 2+ concentration [Lesch et al, ].…”

“…Previous experiments showed that TRPM3 expression is essential for connecting pregnenolone sulfate stimulation with enhanced transcription of AP‐1‐responsive genes [Lesch et al, , ]. Recently, we showed that the TRPM3‐induced signaling pathway requires an influx of Ca 2+ ions into the cells and a rise in the intracellular Ca 2+ concentration [Lesch et al, ]. A rise in cytosolic Ca 2+ activates calcineurin, a serine/threonine phosphatase that is regulated by Ca 2+ and calmodulin [Rusnak and Mertz, ].…”

“…Stimulation of TRPM3 channels with pregnenolone sulfate upregulates AP‐1 regulated gene transcription in insulinoma cells and in HEK293 cells engineered to express TRPM3 channels [Müller et al, ; Lesch et al, , ]. AP‐1 is a group of several distinct homodimers or heterodimers composed of various members of the Fos, Jun, and ATF basic region leucine zipper (bZIP) transcription factor families that function as a convergence point for many intracellular signaling cascades.…”

Activation of gene transcription via CIM0216, a synthetic ligand of transient receptor potential melastatin-3 (TRPM3) channels

“…We discovered that TRPM3 stimulation induces a intracellular signaling cascade that results in the activation of the stimulus-responsive transcription factors AP-1, c-Fos, cJun, CREB, Egr-1, and Elk-1. [1][2][3][4][5] The natural ligands for TRPM3 channels are still unknown, but several compounds have been suggested to function as TRPM3-specific agonists. In most of these studies, the influx of Ca 2C ions into the cells and the subsequent rise in the intracellular Ca 2C concentration was used as an indication of activated TRPM3 channels.…”

“…The lentiviral transfer vectors pLL.TRPM3, encoding a TRPM3-specific shRNA, has been described. 1,4 The viral particles were produced as previously described 13,14 by triple transfection of 293T/17 cells with the gag-pol-rev packaging plasmid, the env plasmid encoding VSV glycoprotein, and the transfer vector.…”