Lesch Andrea, Rubil Sandra, Thiel Gerald
Br J Pharmacol. 2014 May;171(10):2645-58. doi: 10.1111/bph.12524.
Transient receptor potential-3 (TRPM3) channels function as Ca2+ permeable cation channels. While the natural ligands for these channels are still unknown, several compounds have been described that either activate or inhibit TRPM3 channel activity. experimental approach: We assessed TRPM3-mediated gene transcription, which relies on the induction of intracellular signalling to the nucleus following activation of TRPM3 channels. Activator protein-1 (AP-1) and Egr-1-responsive reporter genes were integrated into the chromatin of the cells. This strategy enabled us to analyse gene transcription of the AP-1 and Egr-1-responsive reporter genes that were packed into an ordered chromatin structure.
The neurosteroid pregnenolone sulfate strikingly up-regulated AP-1 and Egr-1 transcriptional activity, while nifedipine and D-erythro-sphingosine, also putative activators of TRPM3 channels, exhibited either no or TRPM3-independent effects on gene transcription. In addition, pregnenolone sulfate robustly enhanced the transcriptional activation potential of the ternary complex factor Elk-1. Pregnenolone sulfate-induced activation of gene transcription was blocked by treatment with mefenamic acid and, to a lesser extent, by the polyphenol naringenin. In contrast, progesterone, pregnenolone and rosiglitazone reduced AP-1 activity in the cells, but had no inhibitory effect on Egr-1 activity in pregnenolone sulfate-stimulated cells.
Pregnenolone sulfate is a powerful activator of TRPM3-mediated gene transcription, while transcription is completely inhibited by mefenamic acid in cells expressing activated TRPM3 channels. Both compounds are valuable tools for further investigating the biological functions of TRPM3 channels.
瞬时受体电位3（TRPM3）通道作为Ca2+通透阳离子通道发挥作用。虽然这些通道的天然配体仍不明确，但已描述了几种可激活或抑制TRPM3通道活性的化合物。实验方法：我们评估了TRPM3介导的基因转录，其依赖于TRPM3通道激活后向细胞核内的细胞内信号传导诱导。将活化蛋白-1（AP-1）和早期生长反应蛋白-1（Egr-1）反应性报告基因整合到细胞染色质中。该策略使我们能够分析包装成有序染色质结构的AP-1和Egr-1反应性报告基因的基因转录。
神经甾体硫酸孕烯醇酮显著上调AP-1和Egr-1转录活性，而硝苯地平和D-赤藓糖神经鞘氨醇（也是TRPM3通道的假定激活剂）对基因转录要么无影响，要么具有不依赖于TRPM3的效应。此外硫酸孕烯醇酮强烈增强三元复合因子Elk-1的转录激活潜能。硫酸孕烯醇酮诱导的基因转录激活被甲芬那酸处理阻断，在较小程度上被多酚柚皮素阻断。相比之下，孕酮、孕烯醇酮和罗格列酮降低细胞中的AP-1活性，但对硫酸孕烯醇酮刺激的细胞中的Egr-1活性无抑制作用。
硫酸孕烯醇酮是TRPM3介导的基因转录的强力激活剂，而在表达活化TRPM3通道的细胞中甲芬那酸完全抑制转录。这两种化合物都是进一步研究TRPM3通道生物学功能的有价值工具。
