Hyperactivity of the Ero1α Oxidase Elicits Endoplasmic Reticulum Stress but No Broad Antioxidant Response
Hyperactivity of the Ero1α Oxidase Elicits Endoplasmic Reticulum Stress but No Broad Antioxidant Response
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DOI：
10.1074/jbc.m112.405050
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发表时间：
2012-11-16
影响因子：
4.8
通讯作者：
Ellgaard, Lars
中科院分区：
文献类型：
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作者：
Hansen, Henning Gram;Schmidt, Jonas Damgard;Ellgaard, Lars
哺乳动物细胞内质网（ER）中氧化蛋白折叠过程的氧化等价物主要由Ero 1 α氧化酶提供。调节Ero 1 α活性以利用其氧化能力的分子机制已经相当清楚。然而，对哺乳动物ER内腔中Ero 1 α产生的氧化应激的总体细胞反应的特征很差。在这里，我们调查的影响，过度表达一个过度活跃的突变体（C104 A/C131 A）的Ero 1 α。我们发现Ero 1 alpha过度活跃会导致ER氧化还原酶ERp 57过度氧化，并诱导两个已确定的未折叠蛋白反应（UPR）靶点BiP（免疫球蛋白结合蛋白）和HERP（高半胱氨酸诱导的ER蛋白）的表达。N-乙酰半胱氨酸和丁硫克百威亚砜亚胺可分别逆转或加重上述作用。由于这两种药物都能操纵细胞谷胱甘肽氧化还原缓冲液，因此我们得出结论，观察到的Ero 1 α-C104 A/C131 A过表达的影响可能是由ER谷胱甘肽氧化还原缓冲液的氧化扰动引起的。根据，我们表明，雌激素1 α过度活跃影响细胞活力时，细胞谷胱甘肽水平受到损害。使用微阵列分析，我们表明，细胞反应Ero 1 α过度活跃引起的氧化挑战，打开UPR。此外，该分析允许鉴定哺乳动物UPR的两个新靶标，CRELD 1和c18 orf 45。有趣的是，没有诱导广泛的抗氧化反应。我们的研究结果表明，Ero 1 α-C104 A/C131 A产生的过氧化作用是在ER腔中解决的，不太可能在整个细胞中产生氧化损伤。
Oxidizing equivalents for the process of oxidative protein folding in the endoplasmic reticulum (ER) of mammalian cells are mainly provided by the Ero1 alpha oxidase. The molecular mechanisms that regulate Ero1 alpha activity in order to harness its oxidative power are quite well understood. However, the overall cellular response to oxidative stress generated by Ero1 alpha in the lumen of the mammalian ER is poorly characterized. Here we investigate the effects of overexpressing a hyperactive mutant (C104A/C131A) of Ero1 alpha. We show that Ero1 alpha hyperactivity leads to hyperoxidation of the ER oxidoreductase ERp57 and induces expression of two established unfolded protein response (UPR) targets, BiP (immunoglobulin-binding protein) and HERP (homocysteine-induced ER protein). These effects could be reverted or aggravated by N-acetylcysteine and buthionine sulfoximine, respectively. Because both agents manipulate the cellular glutathione redox buffer, we conclude that the observed effects of Ero1 alpha-C104A/C131A overexpression are likely caused by an oxidative perturbation of the ER glutathione redox buffer. In accordance, we show that Ero1 alpha hyperactivity affects cell viability when cellular glutathione levels are compromised. Using microarray analysis, we demonstrate that the cell reacts to the oxidative challenge caused by Ero1 alpha hyperactivity by turning on the UPR. Moreover, this analysis allowed the identification of two new targets of the mammalian UPR, CRELD1 and c18orf45. Interestingly, a broad antioxidant response was not induced. Our findings suggest that the hyperoxidation generated by Ero1 alpha-C104A/C131A is addressed in the ER lumen and is unlikely to exert oxidative injury throughout the cell.