CD38过表达降低细胞 NAD 水平并改变能量代谢相关蛋白的表达和抗氧化防御

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Overexpression of CD38 Decreases Cellular NAD Levels and Alters the Expression of Proteins Involved in Energy Metabolism and Antioxidant Defense 

Abstract

摘要

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Nicotinamide adenine dinucleotide (NAD) is a coenzyme found in all living cells and mediates multiple cellular signaling pathways. In the present study, a 35% decrease of cellular NAD level is achieved by stable expression of the N-terminal truncated CD38, a NAD hydrolase. CD38-expressing (CD38(+)) cells have the lower growth rate and are more susceptive to oxidative stress than the wild type cells and empty vector-transfected (CD38(−)) cells. Quantitative proteomic analysis shows that 178 proteins are down-regulated in CD38(+) cells, which involve in diverse cellular processes including glycolysis, RNA processing and protein synthesis, antioxidant, and DNA repair. Down regulation of six selected proteins is confirmed by Western blotting. However, down-regulation of mRNA expressions of genes associated with glycolysis, antioxidant, and DNA repair is less significant than the corresponding change in protein expression, suggesting the low NAD level impairs the protein translational machinery in CD38(+) cells. Down-regulation of antioxidant protein and DNA-repair protein expression contributes to the susceptibility of CD38(+) cells to oxidative stress. Taken together, these results demonstrate that CD38(+) cells are a useful model to study effects of the cellular NAD levels on cellular processes and establish a new linker between cellular NAD levels and oxidative stress.

烟酰胺腺嘌呤二核苷酸是一种存在于所有活细胞中的辅酶,介导多种细胞信号通路。在本研究中,通过稳定表达 n 端截短型 CD38,即 NAD 水解酶,可使细胞 NAD 水平降低35% 。CD38表达细胞的生长速度低于野生型细胞和空载体转染的 CD38(-)细胞,对氧化应激的敏感性高于野生型细胞。定量蛋白质组学分析表明,CD38(+)细胞中有178种蛋白质表达下调,涉及糖酵解、 RNA 加工和蛋白质合成、抗氧化和 DNA 修复等多种细胞过程。下调6个选定的蛋白质已被西方墨点法证实。然而,与糖酵解、抗氧化和 DNA 修复相关基因 mRNA 表达的下调不如蛋白质表达的下调显著,这表明低 NAD 水平损害了 CD38(+)细胞中的蛋白质翻译机制。抗氧化蛋白和 dna 修复蛋白表达的下调有助于 CD38(+)细胞对氧化应激的敏感性。总之,这些结果表明,CD38(+)细胞是一个有用的模型,研究细胞 NAD 水平对细胞过程的影响,并建立一个新的连接细胞 NAD 水平和氧化应激之间的关系。KEYWORDS: 关键词:

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