Decreased ER-associated degradation of α-TCR induced by Grp78 depletion with the SubAB cytotoxin
Decreased ER-associated degradation of α-TCR induced by Grp78 depletion with the SubAB cytotoxin
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DOI：
10.1016/j.biocel.2008.06.003
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发表时间：
2008-01-01
影响因子：
4
通讯作者：
Wojcik, Cezary
中科院分区：
文献类型：
--
作者：
Lass, Agnieszka;Kujawa, Marek;Wojcik, Cezary
使用稳定表达T细胞受体α链（α TCR）（ER相关降解（ERAD）的模型底物）的HeLa细胞来分析SubAB细胞毒素对BiP/Grp 78消耗的影响。SubAB诱导XBP 1剪接，随后是JNK磷酸化、eIF 2 α磷酸化、ATF 3/4上调和部分ATF 6切割。ER应激的其他标志物，包括ERAD途径的元件，以及细胞质应激的标志物，未被诱导。SubAB处理降低了α TCR的绝对水平，这是由蛋白质合成的抑制引起的。与此同时，OeTCR的半衰期从70分钟延长到210分钟，几乎延长了四倍，表明BiP通常促进ERAD。p97/VCP的消耗部分地挽救了SubAB诱导的aTCR的消耗，证实了VCP在aTCR的ERAD中的作用。因此，α TCR的ERAD似乎由位于ER膜两侧的至少两种不同的ATP酶系统驱动，BiP位于内腔侧，而p97/VCP位于细胞质侧。虽然SubAB通过诱导细胞质空泡化和脂滴积累改变细胞形态，但caspase活化是部分的，并且在长时间孵育后消退。CHOP/GADD 153的表达仅在长时间孵育后发生，并且与凋亡无关。(c)2008爱思唯尔有限公司保留所有权利。
HeLa cells stably expressing the a chain of T-cell receptor (alpha TCR), a model substrate of ER-associated degradation (ERAD), were used to analyze the effects of BiP/Grp78 depletion by the SubAB cytotoxin. SubAB induced XBP1 splicing, followed by JNK phosphorylation, eIF2 alpha phosphorylation, upregulation of ATF3/4 and partial ATF6 cleavage. Other markers of ER stress, including elements of ERAD pathway, as well as markers of cytoplasmic stress, were not induced. SubAB treatment decreased absolute levels of alpha TCR, which was caused by inhibition of protein synthesis. At the same time, the half-life of OeTCR was extended almost fourfold from 70 min to 210 min, suggesting that BiP normally facilitates ERAD. Depletion of p97/VCP partially rescued SubAB-induced depletion of alpha TCR, confirming the role of VCP in ERAD of aTCR. It therefore appears that ERAD of alpha TCR is driven by at least two different ATP-ase systems located at two sides of the ER membrane, BiP located on the lumenal side, while p97/VCP on the cytoplasmic side. While SubAB altered cell morphology by inducing cytoplasm vacuolization and accumulation of lipid droplets, caspase activation was partial and subsided after prolonged incubation. Expression of CHOP/GADD153 occurred only after prolonged incubation and was not associated with apoptosis. (c) 2008 Elsevier Ltd. All rights reserved.