Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
Department of Kinesiology, Exercise Physiology Research Group, KU Leuven, Belgium.
Biochem Biophys Res Commun. 2014 Jul 18;450(1):459-63. doi: 10.1016/j.bbrc.2014.05.143. Epub 2014 Jun 8.
The purpose of this study was to examine the link between oxidative stress and endoplasmic reticulum (ER) stress in myogenic cells. C2C12 myotubes were incubated with hydrogen peroxide (H2O2, 200 μM) and harvested 4h or 17 h after the induction of this oxidative stress. A massive upregulation of binding immunoglobulin protein (BiP) was found, indicating the presence of ER stress. Nevertheless, the three branches of the unfolded protein response (UPR) were not activated to the same extent. The double-stranded RNA-dependent protein kinase (PKR)-like ER kinase (PERK) branch was the most activated as shown by the increase of phospho-eukaryotic translation-initiation factor 2α (eIF2α, Ser51) and the mRNA levels of activating transcription factor 4 (ATF4), C/EBP homologous (CHOP) and tribbles homolog 3 (TRB3). The slight increase in the spliced form of X-box binding protein 1 (XBP1s) together with the decrease of the unspliced form (XBP1u) indicated a higher endoribonuclease activity of inositol-requiring 1α (IRE1α). The transcriptional activity of activating transcription factor 6 (ATF6) remained unchanged after incubation with H2O2. The mechanisms by which the three branches of UPR can be specifically regulated by oxidative stress are currently unresolved and need further investigations.
本研究旨在探讨肌细胞中氧化应激与内质网（ER）应激之间的联系。将 C2C12 肌管用过氧化氢（H2O2，200 μM）孵育，并在诱导氧化应激后 4h 或 17h 收获。发现结合免疫球蛋白蛋白（BiP）大量上调，表明存在 ER 应激。然而，未折叠蛋白反应（UPR）的三个分支并未被同等程度地激活。双链 RNA 依赖性蛋白激酶（PKR）样 ER 激酶（PERK）分支被激活最多，表现为磷酸化真核翻译起始因子 2α（eIF2α，Ser51）增加和激活转录因子 4（ATF4）、C/EBP 同源（CHOP）和 tribbles 同源 3（TRB3）的 mRNA 水平增加。X 盒结合蛋白 1（XBP1）的剪接形式略有增加，而未剪接形式（XBP1u）减少，表明肌醇需求酶 1α（IRE1α）的内切核酸酶活性更高。用 H2O2 孵育后，激活转录因子 6（ATF6）的转录活性保持不变。UPR 的三个分支如何被氧化应激特异性调节的机制目前尚未解决，需要进一步研究。
