MRC Toxicology Unit, University of Leicester, Leicester, United Kingdom.
PLoS One. 2013;8(2):e56603. doi: 10.1371/journal.pone.0056603. Epub 2013 Feb 15.
Recently we described a new, evolutionarily conserved cellular stress response characterized by a reversible reorganization of endoplasmic reticulum (ER) membranes that is distinct from canonical ER stress and the unfolded protein response (UPR). Apogossypol, a putative broad spectrum BCL-2 family antagonist, was the prototype compound used to induce this ER membrane reorganization. Following microarray analysis of cells treated with apogossypol, we used connectivity mapping to identify a wide range of structurally diverse chemicals from different pharmacological classes and established their ability to induce ER membrane reorganization. Such structural diversity suggests that the mechanisms initiating ER membrane reorganization are also diverse and a major objective of the present study was to identify potentially common features of these mechanisms. In order to explore this, we used hierarchical clustering of transcription profiles for a number of chemicals that induce membrane reorganization and discovered two distinct clusters. One cluster contained chemicals with known effects on Ca(2+) homeostasis. Support for this was provided by the findings that ER membrane reorganization was induced by agents that either deplete ER Ca(2+) (thapsigargin) or cause an alteration in cellular Ca(2+) handling (calmodulin antagonists). Furthermore, overexpression of the ER luminal Ca(2+) sensor, STIM1, also evoked ER membrane reorganization. Although perturbation of Ca(2+) homeostasis was clearly one mechanism by which some agents induced ER membrane reorganization, influx of extracellular Na(+) but not Ca(2+) was required for ER membrane reorganization induced by apogossypol and the related BCL-2 family antagonist, TW37, in both human and yeast cells. Not only is this novel, non-canonical ER stress response evolutionary conserved but so also are aspects of the mechanism of formation of ER membrane aggregates. Thus perturbation of ionic homeostasis is important in the regulation of ER membrane reorganization.
最近，我们描述了一种新的、进化上保守的细胞应激反应，其特征是内质网（ER）膜的可逆重排，与经典的 ER 应激和未折叠蛋白反应（UPR）不同。阿朴戈斯泊醇，一种假定的广谱 BCL-2 家族拮抗剂，是用于诱导这种 ER 膜重排的原型化合物。在用阿朴戈斯泊醇处理的细胞进行微阵列分析后，我们使用连接性映射从不同药理学类别中识别出广泛的结构多样的化学物质，并确定了它们诱导 ER 膜重排的能力。这种结构多样性表明，启动 ER 膜重排的机制也多种多样，本研究的主要目标之一是确定这些机制的潜在共同特征。为了探索这一点，我们对许多诱导膜重排的化学物质的转录谱进行了层次聚类，并发现了两个不同的簇。一个簇包含已知对 Ca(2+)稳态有影响的化学物质。这一发现提供了支持，即 ER 膜重排是由耗尽 ER Ca(2+)的试剂（他普西醇）或引起细胞内 Ca(2+)处理改变的试剂（钙调蛋白拮抗剂）诱导的。此外，内质网腔 Ca(2+)传感器 STIM1 的过表达也引发了 ER 膜重排。虽然 Ca(2+)稳态的扰动显然是一些试剂诱导 ER 膜重排的一种机制，但阿朴戈斯泊醇和相关的 BCL-2 家族拮抗剂 TW37 诱导的 ER 膜重排需要细胞外 Na(+)而不是 Ca(2+)的流入，这在人和酵母细胞中都是如此。这种非经典的 ER 应激反应不仅在进化上是保守的，而且 ER 膜聚集形成的机制的某些方面也是如此。因此，离子稳态的扰动在 ER 膜重排的调节中很重要。
