Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong 250100, China.
Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong 250100, China.
Cell Calcium. 2017 Dec;68:24-33. doi: 10.1016/j.ceca.2017.10.004. Epub 2017 Oct 20.
Animal steroid hormones stimulate extracellular Ca influx into cells; however, the mechanism remains unclear. In this study, we determined that the Ca influx induced by steroid hormone 20-hydroxyecdysone (20E) is mediated by the calcium release-activated calcium channel modulator 1 (CRACM1/Orai1). The Orai1 mRNA is highly expressed during midgut programmed cell death in the lepidopteran insect Helicoverpa armigera. 20E upregulated the expression of Orai1 in H. armigera larvae and in an epidermal cell line (HaEpi). Knockdown of Orai1 in HaEpi cells blocked 20E-induced Ca influx, and the inhibitor of inositol 1, 4, 5-trisphosphate receptor (IPR) Xestospongin (XeC) blocked 20E-induced Ca influx, suggesting that 20E, via Orai1, induces stored-operated Ca influx. Orai1 interacts with stromal interaction molecule 1(Stim1) to exert its function in 20E-induced Ca influx. 20E promotes Orai1 aggregation through G-protein-coupled receptors, phospholipase C gamma 1, and Stim1. Knockdown of Orai1 in the HaEpi cell line repressed apoptosis and maintained autophagy under 20E regulation. Knockdown of Orai1 in larvae delayed pupation, repressed midgut apoptosis, maintained the midgut in an autophagic state, and repressed 20E-pathway gene expression. These results revealed that steroid hormone 20E, via Orai1, induces Ca influx to promote the transition of midgut from autophagy to apoptosis.
动物甾体激素刺激细胞外 Ca 内流；然而，其机制尚不清楚。在本研究中，我们确定甾体激素 20-羟基蜕皮甾酮（20E）诱导的 Ca 内流是由钙释放激活钙通道调节剂 1（CRACM1/Orai1）介导的。Orai1mRNA 在鳞翅目昆虫棉铃虫的中肠程序性细胞死亡过程中高度表达。20E 上调了棉铃虫幼虫和表皮细胞系（HaEpi）中 Orai1 的表达。在 HaEpi 细胞中敲低 Orai1 可阻断 20E 诱导的 Ca 内流，而肌醇 1,4,5-三磷酸受体（IPR）Xestospongin（XeC）抑制剂可阻断 20E 诱导的 Ca 内流，表明 20E 通过 Orai1 诱导储存操纵的 Ca 内流。Orai1 与基质相互作用分子 1（Stim1）相互作用以发挥其在 20E 诱导的 Ca 内流中的作用。20E 通过 G 蛋白偶联受体、磷脂酶 Cγ1 和 Stim1 促进 Orai1 聚集。在 HaEpi 细胞系中敲低 Orai1 可抑制凋亡并维持自噬在 20E 调节下。幼虫中敲低 Orai1 会延迟化蛹，抑制中肠细胞凋亡，使中肠保持自噬状态，并抑制 20E 通路基因表达。这些结果表明，甾体激素 20E 通过 Orai1 诱导 Ca 内流，促进中肠从自噬向凋亡的转变。
