Valproic acid increases conservative homologous recombination frequency and reactive oxygen species formation: A potential mechanism for valproic acid-induced neural tube defects
Valproic acid increases conservative homologous recombination frequency and reactive oxygen species formation: A potential mechanism for valproic acid-induced neural tube defects
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DOI：
10.1124/mol.105.017855
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发表时间：
2006-04-01
影响因子：
3.6
通讯作者：
Winn, LM
中科院分区：
文献类型：
--
作者：
Defoort, EN;Kim, PM;Winn, LM
丙戊酸是一种常用的抗癫痫药，在妊娠期间服用时与1 - 2%的神经管缺陷发生率相关;然而，发生这种情况的分子机制尚未阐明。先前的研究表明，丙戊酸暴露导致活性氧（ROS）增加。由于ROS导致的DNA损伤可导致DNA双链断裂，其可通过同源重组（HR）修复，这是一个并非无错误的过程，可导致有害的遗传变化。由于发育中的胚胎需要严格调控基因表达才能正常发育，因此我们认为，通过异常HR参与胚胎发育的基因的丢失或功能障碍可能最终导致神经管缺陷。为了确定丙戊酸是否诱导HR，将含有新霉素直接重复重组底物的中国仓鼠卵巢3-6细胞暴露于丙戊酸4小时，或在暴露于丙戊酸（5和10 mM）24小时后观察到HR显著性，这似乎是通过保守HR机制发生的。我们还证明，暴露于丙戊酸（5和10 mM）显着增加细胞内的ROS水平，这是衰减与聚乙二醇结合（PEG）-过氧化氢酶预孵育。丙戊酸暴露后，8-羟基-2 '-脱氧鸟苷/2'-脱氧鸟苷（DNA氧化的测量）的比例未发生显著变化;然而，用PEG-过氧化氢酶预孵育可显著阻断HR的增加。这些数据表明，丙戊酸可增加HR频率，并为丙戊酸诱导的神经管缺陷提供了一种可能的机制。
Valproic acid, a commonly used antiepileptic agent, is associated with a 1 to 2% incidence of neural tube defects when taken during pregnancy; however, the molecular mechanism by which this occurs has not been elucidated. Previous research suggests that valproic acid exposure leads to an increase in reactive oxygen species (ROS). DNA damage due to ROS can result in DNA double-strand breaks, which can be repaired through homologous recombination (HR), a process that is not error-free and can result in detrimental genetic changes. Because the developing embryo requires tight regulation of gene expression to develop properly, we propose that the loss or dysfunction of genes involved in embryonic development through aberrant HR may ultimately cause neural tube defects. To determine whether valproic acid induces HR, Chinese hamster ovary 3-6 cells, containing a neomycin direct repeat recombination substrate, were exposed to valproic acid for 4 or significant in HR after exposure to valproic acid (5 and 10 mM) for 24 h was observed, which seems to occur through a conservative HR mechanism. We also demonstrated that exposure to valproic acid (5 and 10 mM) significantly increased intracellular ROS levels, which were attenuated by preincubation with polyethylene glycol-conjugated (PEG)-catalase. A significant change in the ratio of 8-hydroxy-2'-deoxyguanosine/2'-de-oxyguanosine, a measure of DNA oxidation, was not observed after valproic acid exposure; however, preincubation with PEG-catalase significantly blocked the increase in HR. These data demonstrate that valproic acid increases HR frequency and provides a possible mechanism for valproic acid-induced neural tube defects.