PDF(Pubmed)
Abstract：
Previous studies reported that a mild, non-protein-denaturing, fever-like temperature increase induced the unfolded protein response (UPR) in mammalian cells. Our dSTORM super-resolution microscopy experiments revealed that the master regulator of the UPR, the IRE1 (inositol-requiring enzyme 1) protein, is clustered as a result of UPR activation in a human osteosarcoma cell line (U2OS) upon mild heat stress. Using ER thermo yellow, a temperature-sensitive fluorescent probe targeted to the endoplasmic reticulum (ER), we detected significant intracellular thermogenesis in mouse embryonic fibroblast (MEF) cells. Temperatures reached at least 8 °C higher than the external environment (40 °C), resulting in exceptionally high ER temperatures similar to those previously described for mitochondria. Mild heat-induced thermogenesis in the ER of MEF cells was likely due to the uncoupling of the Ca2+/ATPase (SERCA) pump. The high ER temperatures initiated a pronounced cytosolic heat-shock response in MEF cells, which was significantly lower in U2OS cells in which both the ER thermogenesis and SERCA pump uncoupling were absent. Our results suggest that depending on intrinsic cellular properties, mild hyperthermia-induced intracellular thermogenesis defines the cellular response mechanism and determines the outcome of hyperthermic stress.
摘要：
以前的研究报告说，一个温和的，非蛋白质变性，发热样温度升高可诱导哺乳动物细胞的未折叠蛋白反应（UPR）。我们的dSTORM超分辨率显微镜实验表明，UPR的主调节器，IRE1（需要肌醇的酶1）蛋白，在轻度热应激下，由于人骨肉瘤细胞系（U2OS）中的UPR激活而成簇。使用ER热黄色，针对内质网（ER）的温度敏感荧光探针，我们在小鼠胚胎成纤维细胞（MEF）细胞中检测到显着的细胞内产热。温度至少比外部环境（40°C）高8°C，导致与先前描述的线粒体相似的异常高的ER温度。MEF细胞ER中轻度热诱导的产热可能是由于Ca2/ATPase（SERCA）泵的解偶联。高ER温度在MEF细胞中引发了明显的胞浆热休克反应，在不存在ER产热和SERCA泵解偶联的U2OS细胞中，这一比例显着降低。我们的结果表明，根据固有的细胞特性，轻度高热诱导的细胞内产热定义了细胞反应机制并决定了高热应激的结果。
