Yang Huan, Niemeijer Marije, van de Water Bob, Beltman Joost B
Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
iScience. 2020 Feb 21;23(2):100860. doi: 10.1016/j.isci.2020.100860. Epub 2020 Jan 23.
The unfolded protein response (UPR) pathway senses unfolded proteins and regulates proteostasis and cell fate through activity of the transcription factors ATF4, ATF6, and XBP1 within a complex network of three main branches. Here, we investigated contributions of the three branches to UPR activity in single cells using microscopy-based quantification and dynamic modeling. BAC-GFP HepG2 reporter cell lines were exposed to tunicamycin, and activation of various UPR components was monitored for 24 h. We constructed a dynamic model to describe the adaptive UPR signaling network, for which incorporation of all three branches was required to match the data. Our calibrated model suggested that ATF6 shapes the early dynamics of pro-apoptotic CHOP. We confirmed this hypothesis by measurements beyond 24 h, by perturbing single siRNA knockdowns and by ATF6 measurements. Overall, our work indicates that ATF6 is an important regulator of CHOP, which in turn regulates cell fate decisions.
未折叠蛋白反应（UPR）通路可感知未折叠蛋白，并通过转录因子ATF4、ATF6和XBP1在由三个主要分支构成的复杂网络中的活性来调节蛋白质稳态和细胞命运。在此，我们使用基于显微镜的定量分析和动态建模方法，研究了这三个分支对单细胞中UPR活性的贡献。将携带BAC-GFP的HepG2报告细胞系暴露于衣霉素中，并对各种UPR组分的激活情况进行了24小时监测。我们构建了一个动态模型来描述适应性UPR信号网络，该模型需要纳入所有三个分支才能与数据匹配。我们校准后的模型表明，ATF6塑造了促凋亡蛋白CHOP的早期动态变化。我们通过24小时以上的测量、干扰单个基因的siRNA敲低以及对ATF6的测量，证实了这一假设。总体而言，我们的研究表明，ATF6是CHOP的重要调节因子，而CHOP反过来又调节细胞命运的决定。
