O-GlcNAcylation alters the selection of mRNAs for translation and promotes 4E-BP1-dependent mitochondrial dysfunction in the retina
O-GlcNAcylation alters the selection of mRNAs for translation and promotes 4E-BP1-dependent mitochondrial dysfunction in the retina
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DOI：
10.1074/jbc.ra119.007494
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发表时间：
2019-04-05
影响因子：
4.8
通讯作者：
Dennis, Michael D.
中科院分区：
文献类型：
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作者：
Dierschke, Sadie K.;Miller, William P.;Dennis, Michael D.
糖尿病通过在蛋白质的 Ser/Thr 残基上 O 连接添加 GlcNAc (O-GlcNAcylation) 来促进蛋白质的翻译后修饰，从而导致糖尿病并发症。在糖尿病小鼠的视网膜中，mRNA 翻译的抑制因子 eIF4E 结合蛋白 1 (4E-BP1) 被 O-GlcNA 酰化，并且帽结合蛋白真核翻译起始因子 (eIF4E) 的隔离作用增强。在几种真核翻译起始因子和核糖体蛋白上也检测到了 O-GlcNAc 酰化。然而，这种修改的功能后果尚不清楚。在这里，我们使用核糖体分析评估了增强的 O-GlcNAcNAc 化对视网膜基因表达的影响。接受 O-GlcNAc 水解酶 O-GlcNAcase 抑制剂硫美美特 G (TMG) 治疗的小鼠表现出视网膜蛋白 O-GlcNAc 酰化增强。 TMG 对视网膜基因表达的主要影响是在核糖体相关 mRNA（即正在进行翻译的 mRNA）中观察到的，因为只有不到 1% 的 mRNA 表现出丰度变化。值得注意的是，大约 19% 的转录组表现出 TMG 诱导的核糖体占据变化，其中 1912 个 mRNA 翻译率降低，1683 个 mRNA 翻译率增加。在视网膜中，O-GlcNAcase 抑制对特定线粒体蛋白（包括超氧化物歧化酶 2 (SOD2)）翻译的影响取决于 4E-BP1/2。 O-GlcNAcylation 增强了 WT 细胞中的细胞呼吸并提高了线粒体超氧化物水平，而 4E-BP1/2 缺失则阻止了培养细胞和视网膜细胞中 O-GlcNAcylation 诱导的线粒体超氧化物。糖尿病 WT 小鼠的视网膜表现出活性氧水平升高，而在 4E-BP1/2 缺陷型糖尿病小鼠中未观察到这种效应。这些发现为糖尿病诱导的 O-GlcNAcylation 通过改变翻译 mRNA 的选择来促进视网膜氧化应激的机制提供了证据。
Diabetes promotes the posttranslational modification of proteins by O-linked addition of GlcNAc (O-GlcNAcylation) to Ser/Thr residues of proteins and thereby contributes to diabetic complications. In the retina of diabetic mice, the repressor of mRNA translation, eIF4E-binding protein 1 (4E-BP1), is O-GlcNAcylated, and sequestration of the cap-binding protein eukaryotic translation initiation factor (eIF4E) is enhanced. O-GlcNAcylation has also been detected on several eukaryotic translation initiation factors and ribosomal proteins. However, the functional consequence of this modification is unknown. Here, using ribosome profiling, we evaluated the effect of enhanced O-GlcNAcylation on retinal gene expression. Mice receiving thiamet G (TMG), an inhibitor of the O-GlcNAc hydrolase O-GlcNAcase, exhibited enhanced retinal protein O-GlcNAcylation. The principal effect of TMG on retinal gene expression was observed in ribosome-associated mRNAs (i.e. mRNAs undergoing translation), as less than 1% of mRNAs exhibited changes in abundance. Remarkably, approximate to 19% of the transcriptome exhibited TMG-induced changes in ribosome occupancy, with 1912 mRNAs having reduced and 1683 mRNAs having increased translational rates. In the retina, the effect of O-GlcNAcase inhibition on translation of specific mitochondrial proteins, including superoxide dismutase 2 (SOD2), depended on 4E-BP1/2. O-GlcNAcylation enhanced cellular respiration and promoted mitochondrial superoxide levels in WT cells, and 4E-BP1/2 deletion prevented O-GlcNAcylation-induced mitochondrial superoxide in cells in culture and in the retina. The retina of diabetic WT mice exhibited increased reactive oxygen species levels, an effect not observed in diabetic 4E-BP1/2-deficient mice. These findings provide evidence for a mechanism whereby diabetes-induced O-GlcNAcylation promotes oxidative stress in the retina by altering the selection of mRNAs for translation.