Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421 Homburg, Germany.
School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK.
Cell Chem Biol. 2019 Apr 18;26(4):571-583.e6. doi: 10.1016/j.chembiol.2019.01.010. Epub 2019 Feb 21.
Eeyarestatin 1 (ES1) inhibits p97-dependent protein degradation, Sec61-dependent protein translocation into the endoplasmic reticulum (ER), and vesicular transport within the endomembrane system. Here, we show that ES1 impairs Ca homeostasis by enhancing the Ca leakage from mammalian ER. A comparison of various ES1 analogs suggested that the 5-nitrofuran (5-NF) ring of ES1 is crucial for this effect. Accordingly, the analog ES24, which conserves the 5-NF domain of ES1, selectively inhibited protein translocation into the ER, displayed the highest potency on ER Ca leakage of ES1 analogs studied and induced Ca-dependent cell death. Using small interfering RNA-mediated knockdown of Sec61α, we identified Sec61 complexes as the targets that mediate the gain of Ca leakage induced by ES1 and ES24. By interacting with the lateral gate of Sec61α, ES1 and ES24 likely capture Sec61 complexes in a Ca-permeable, open state, in which Sec61 complexes allow Ca leakage but are translocation incompetent.
依维莫司 1（ES1）抑制 p97 依赖性蛋白降解、Sec61 依赖性蛋白向内质网（ER）易位以及细胞内膜系统内的囊泡运输。在此，我们表明 ES1 通过增强哺乳动物 ER 中的 Ca 渗漏来损害 Ca 稳态。对各种 ES1 类似物的比较表明 ES1 的 5-硝呋咱（5-NF）环对于该作用至关重要。相应地，类似物 ES24 保留了 ES1 的 5-NF 结构域，选择性地抑制蛋白向 ER 的易位，对所研究的 ES1 类似物的 ER Ca 渗漏显示出最高的效力，并诱导 Ca 依赖性细胞死亡。通过使用小干扰 RNA 介导的 Sec61α 敲低，我们确定 Sec61 复合物是介导 ES1 和 ES24 诱导的 Ca 渗漏增加的靶标。通过与 Sec61α 的侧门相互作用，ES1 和 ES24 可能将 Sec61 复合物捕获在可渗透 Ca 的开放状态中，其中 Sec61 复合物允许 Ca 渗漏但易位无能力。
