Ozolins T R, Hales B F
Department of Pharmacology and Therapeutics, McGill University, Montreal, Québec, Canada.
J Pharmacol Exp Ther. 1997 Feb;280(2):1085-93.
The transcription factor activator protein-1 (AP-1), composed of the Fos and Jun families of proto-oncogenes, is induced in response to extracellular signals as part of an immediate-early gene response. We hypothesize that teratogens such as oxidative stress induce AP-1 activity in the rat conceptus and that this AP-1 response may either trigger abnormal development or protect the embryo against insult. To test this hypothesis, the AP-1 response was assessed in whole embryos in culture. There was a significant elevation in the oxidized to reduced glutathione ratio in the embryo and yolk sac within 0.25 hr of the initiation of culture, peaking at 0.5 hr; this is indicative of heightened oxidative stress. At 0.5 hr protein oxidation was also enhanced, as demonstrated by increased protein reactivity with 2,4-dinitrophenylhydrazine. In the conceptus, the steady-state concentrations of c-fos, c-jun, junB and junD mRNAs were induced, peaking at 0.5 hr and returning to base line by 1 to 2 hr in the embryo and by 1 to 6 hr in the yolk sac. Electrophoretic mobility shift assays showed enhanced AP-1 DNA-binding activity in both the embryo (elevated by 0.5 hr and persisting for 1 hr) and the yolk sac (persisting for 3 hr). Thus, there are tissue-specific differences in the duration of the AP-1 response in the conceptus. Addition of the antioxidants catalase and superoxide dismutase, but not vitamin E, prevented the rise in the oxidized to reduced glutathione ratio and also inhibited the induction of AP-1 mRNAs and DNA-binding activity. The AP-1 response to oxidative stress may determine how the conceptus responds to insult.
转录因子激活蛋白1（AP-1）由原癌基因的Fos和Jun家族组成，作为即时早期基因反应的一部分，它会在细胞外信号的刺激下被诱导产生。我们推测，诸如氧化应激等致畸剂会在大鼠孕体中诱导AP-1活性，并且这种AP-1反应可能会引发异常发育，或者保护胚胎免受损伤。为了验证这一假设，我们对培养的完整胚胎中的AP-1反应进行了评估。培养开始后0.25小时内，胚胎和卵黄囊中氧化型谷胱甘肽与还原型谷胱甘肽的比率显著升高，在0.5小时达到峰值；这表明氧化应激增强。0.5小时时蛋白质氧化也增强，这通过蛋白质与2,4-二硝基苯肼反应性增加得以证明。在孕体中，c-fos、c-jun、junB和junD mRNA的稳态浓度被诱导，在胚胎中于0.5小时达到峰值，并在1至2小时恢复至基线水平，在卵黄囊中则在1至6小时恢复至基线水平。电泳迁移率变动分析显示，胚胎（在0.5小时升高并持续1小时）和卵黄囊（持续3小时）中的AP-1 DNA结合活性均增强。因此，孕体中AP-1反应的持续时间存在组织特异性差异。添加抗氧化剂过氧化氢酶和超氧化物歧化酶，但不添加维生素E，可防止氧化型谷胱甘肽与还原型谷胱甘肽比率升高，还能抑制AP-1 mRNA的诱导和DNA结合活性。AP-1对氧化应激的反应可能决定了孕体对损伤的反应方式。
