Department of Medical Biochemistry and Molecular Biology, Saarland University Medical Faculty, D-66421 Homburg, Germany.
Department of Medical Biochemistry and Molecular Biology, Saarland University Medical Faculty, D-66421 Homburg, Germany.
Biochem Pharmacol. 2017 Apr 1;129:96-107. doi: 10.1016/j.bcp.2017.01.007. Epub 2017 Jan 19.
Hypericum perforatum is one of the most prominent medical plants. Hyperforin, a main ingredient of H. perforatum, has been shown to activate transient receptor potential canonical C6 (TRPC6) channels. Alternatively, it has been proposed that hyperforin functions as a protonophore in a TRPC6-independent manner. Here, we show that hyperforin stimulation activates the transcription factor AP-1 in HEK293 cells expressing TRPC6 (T6.11 cells), but did not substantially change the AP-1 activity in HEK293 cells lacking TRPC6. We identified the AP-1 binding site as a hyperforin-responsive element. AP-1 is composed of the transcription factors c-Jun and c-Fos, or other members of the c-Jun and c-Fos families of proteins. Hyperforin stimulation increased c-Jun and c-Fos promoter activities in T6.11 cells and induced an upregulation of c-Jun and c-Fos biosynthesis. The analysis of the c-Fos promoter revealed that the cAMP-response element also functions as a hyperforin-responsive element. Hyperforin-induced upregulation of AP-1 in T6.11 cells was attenuated by preincubation of the cells with either pregnenolone or progesterone, indicating that gene regulation via TRPC6 is under control of hormones or hormonal precursors. The signal transduction of hyperforin-induced AP-1 gene transcription required an influx of Ca ions into the cells, the activation of MAP kinases, and the activation of the transcription factors c-Jun and ternary complex factor. We conclude that hyperforin regulates gene transcription via activation of TRPC6 channels, involving stimulus-regulated protein kinases and stimulus-responsive transcription factors. The fact that hyperforin regulates gene transcription may explain many of the intracellular alterations induced by this compound.
贯叶金丝桃是一种最突出的药用植物。贯叶金丝桃中的有效成分金丝桃素被证实可以激活瞬时受体电位经典型 C6（TRPC6）通道。另一种假说认为金丝桃素以非 TRPC6 依赖的方式作为质子载体起作用。在这里，我们发现金丝桃素刺激能够激活表达 TRPC6（T6.11 细胞）的 HEK293 细胞中的转录因子 AP-1，但在缺乏 TRPC6 的 HEK293 细胞中，AP-1 的活性没有明显改变。我们确定了 AP-1 结合位点是金丝桃素反应元件。AP-1 由转录因子 c-Jun 和 c-Fos 或 c-Jun 和 c-Fos 蛋白家族的其他成员组成。金丝桃素刺激能够增加 T6.11 细胞中 c-Jun 和 c-Fos 启动子的活性，并诱导 c-Jun 和 c-Fos 的生物合成上调。对 c-Fos 启动子的分析表明，cAMP 反应元件也作为金丝桃素反应元件起作用。在 T6.11 细胞中，金丝桃素诱导的 AP-1 上调可以通过细胞的预孵育被孕烯醇酮或孕酮所抑制，表明通过 TRPC6 的基因调控受到激素或激素前体的控制。金丝桃素诱导的 AP-1 基因转录的信号转导需要 Ca2+ 流入细胞，MAP 激酶的激活以及转录因子 c-Jun 和三元复合物因子的激活。我们的结论是，金丝桃素通过激活 TRPC6 通道调节基因转录，涉及刺激调节蛋白激酶和刺激反应性转录因子。金丝桃素调节基因转录的事实可能解释了该化合物引起的许多细胞内改变。
