Dynamic changes in complexes of IRE1α, PERK, and ATF6α during endoplasmic reticulum stress.
Dynamic changes in complexes of IRE1α, PERK, and ATF6α during endoplasmic reticulum stress.
复制标题
内质网应激期间IRE1α，PERK和ATF6α复合物的动态变化。
DOI：
10.1091/mbc.e17-10-0594
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发表时间：
2018-06-01
影响因子：
3.3
通讯作者：
Mariappan M
中科院分区：
文献类型：
--
作者：
Sundaram A;Appathurai S;Plumb R;Mariappan M
内质网（ER）定位的未折叠蛋白反应（UPR）传感器IRE1α、PERK和ATF 6 α通过错误折叠蛋白在ER中的积累而被激活。目前还不清楚内源性UPR传感器如何受到ER应激和ER管腔伴侣BiP的调节，BiP是UPR传感器的负调节剂。在这里，我们同时研究了在未应激和应激细胞中通过蓝色非变性PAGE免疫印迹的UPR传感器的内源性复合物的变化。我们发现，所有三个UPR传感器存在的预制复合物，即使在未受应力的细胞。虽然PERK复合物转变为大复合物，但在ER应激下，ATF 6 α复合物减少为较小的复合物。相反，IRE1α复合物的大小在ER应激时没有显著增加，除非IRE1α过表达。令人惊讶的是，耗尽BiP对UPR传感器的内源性复合物几乎没有影响。此外，BiP过表达对UPR复合物没有显著影响，但抑制了ER应激介导的IRE1α、ATF6α的激活，并在较小程度上抑制了PERK。此外，我们捕获了IRE1α与细胞中错误折叠的分泌蛋白之间的相互作用，这表明未折叠蛋白与UPR传感器的预形成复合物的结合可能是激活的关键。
The endoplasmic reticulum (ER) localized unfolded protein response (UPR) sensors, IRE1α, PERK, and ATF6α, are activated by the accumulation of misfolded proteins in the ER. It is unclear how the endogenous UPR sensors are regulated by both ER stress and the ER luminal chaperone BiP, which is a negative regulator of UPR sensors. Here we simultaneously examined the changes in the endogenous complexes of UPR sensors by blue native PAGE immunoblotting in unstressed and stressed cells. We found that all three UPR sensors exist as preformed complexes even in unstressed cells. While PERK complexes shift to large complexes, ATF6α complexes are reduced to smaller complexes on ER stress. In contrast, IRE1α complexes were not significantly increased in size on ER stress, unless IRE1α is overexpressed. Surprisingly, depletion of BiP had little impact on the endogenous complexes of UPR sensors. In addition, overexpression of BiP did not significantly affect UPR complexes, but suppressed ER stress mediated activation of IRE1α, ATF6α and, to a lesser extent, PERK. Furthermore, we captured the interaction between IRE1α and misfolded secretory proteins in cells, which suggests that the binding of unfolded proteins to preformed complexes of UPR sensors may be crucial for activation.