Suppression of uracil-DNA glycosylase induces neuronal apoptosis
Suppression of uracil-DNA glycosylase induces neuronal apoptosis
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DOI：
10.1074/jbc.m408025200
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发表时间：
2004-10-15
影响因子：
4.8
通讯作者：
Mattson, MP
中科院分区：
文献类型：
--
作者：
Kruman, II;Schwartz, E;Mattson, MP
由一碳代谢损伤引起的 DNA 前体的慢性失衡可能导致 DNA 修复缺陷和 DNA 损伤增加。尽管间接证据表明 DNA 损伤在神经元凋亡和神经退行性疾病的发病机制中发挥作用，但其潜在机制尚不清楚。特别是，对于错误掺入的尿嘧啶的碱基切除修复在神经元存活中的作用知之甚少。为了检验与尿嘧啶错误掺入相关的 DNA 损伤修复对于神经元存活至关重要的假设，我们采用了针对 UNG 基因编码的尿嘧啶 DNA 糖基化酶的反义 (AS) 寡核苷酸，以消耗培养的大鼠海马神经元中的 UNG。 AS（而非乱序对照寡核苷酸）诱导细胞凋亡，通过彗星测定分析，细胞凋亡与 DNA 损伤和 p53 上调有关。 UNG mRNA 和蛋白质水平在暴露于 UNG AS 寡核苷酸后 30 分钟内下降，并且在 6-9 小时内检测不到。尽管与非增殖细胞（如神经元）相比，增殖细胞中的 UNG 表达显着较高，但在胱硫醚β-合酶敲除小鼠（高同型半胱氨酸血症模型）的大脑中，UNG mRNA 水平升高，表明一碳代谢损伤和尿嘧啶错误掺入可诱导 UNG 表达上调。
A chronic imbalance in DNA precursors, caused by one-carbon metabolism impairment, can result in a deficiency of DNA repair and increased DNA damage. Although indirect evidence suggests that DNA damage plays a role in neuronal apoptosis and in the pathogenesis of neurodegenerative disorders, the underlying mechanisms are poorly understood. In particular, very little is known about the role of base excision repair of misincorporated uracil in neuronal survival. To test the hypothesis that repair of DNA damage associated with uracil misincorporation is critical for neuronal survival, we employed an antisense (AS) oligonucleotide directed against uracil-DNA glycosylase encoded by the UNG gene to deplete UNG in cultured rat hippocampal neurons. AS, but not a scrambled control oligonucleotide, induced apoptosis, which was associated with DNA damage analyzed by comet assay and up-regulation of p53. UNG mRNA and protein levels were decreased within 30 min and were undetectable within 6-9 h of exposure to the UNG AS oligonucleotide. Whereas UNG expression is significantly higher in proliferating as compared with nonproliferating cells, such as neurons, the levels of UNG mRNA were increased in brains of cystathionine beta-synthase knockout mice, a model for hyperhomocysteinemia, suggesting that one-carbon metabolism impairment and uracil misincorporation can induce the up-regulation of UNG expression.