Cytosolic thioredoxin reductase 1 is required for correct disulfide formation in the ER.
Cytosolic thioredoxin reductase 1 is required for correct disulfide formation in the ER.
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DOI：
10.15252/embj.201695336
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发表时间：
2017-03-01
期刊：
影响因子：
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通讯作者：
Bulleid NJ
中科院分区：
文献类型：
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作者：
Poet GJ;Oka OB;van Lith M;Cao Z;Robinson PJ;Pringle MA;Arnér ES;Bulleid NJ
在哺乳动物细胞中，进入分泌途径的蛋白质的折叠通常需要插入二硫键。二硫键插入可以导致在天然结构中发现的共价键以及那些不存在的共价键，即所谓的非天然二硫化物。二硫化物的形成途径已经有了很好的描述，但我们对非天然二硫化物是如何被还原从而形成正确的或天然的二硫化物的理解很差。在这里，我们使用一种新的方法来证明非天然二硫化物的还原需要NADPH作为最终的电子供体，并且需要一个强大的细胞质硫氧还蛋白系统，由硫氧还蛋白还原酶1(TrxR1或TXNRD1)驱动。抑制这一还原途径会阻止蛋白质的正确折叠和分泌，这些蛋白质在折叠过程中会形成非天然的二硫化物。因此，我们首次证明了哺乳动物细胞有一条将还原等价物从胞浆转移到内质网的途径，这是确保进入分泌途径的蛋白质正确形成二硫键所必需的。
Folding of proteins entering the secretory pathway in mammalian cells frequently requires the insertion of disulfide bonds. Disulfide insertion can result in covalent linkages found in the native structure as well as those that are not, so‐called non‐native disulfides. The pathways for disulfide formation are well characterized, but our understanding of how non‐native disulfides are reduced so that the correct or native disulfides can form is poor. Here, we use a novel assay to demonstrate that the reduction in non‐native disulfides requires NADPH as the ultimate electron donor, and a robust cytosolic thioredoxin system, driven by thioredoxin reductase 1 (TrxR1 or TXNRD1). Inhibition of this reductive pathway prevents the correct folding and secretion of proteins that are known to form non‐native disulfides during their folding. Hence, we have shown for the first time that mammalian cells have a pathway for transferring reducing equivalents from the cytosol to the ER, which is required to ensure correct disulfide formation in proteins entering the secretory pathway.