Effect of arylamine acetyltransferase Nat3 gene knockout on N-acetylation in the mouse
Effect of arylamine acetyltransferase Nat3 gene knockout on N-acetylation in the mouse
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DOI：
10.1124/dmd.107.015396
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发表时间：
2007-07-01
影响因子：
3.9
通讯作者：
Grant, D. M.
中科院分区：
文献类型：
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作者：
Sugamori, K. S.;Brenneman, D.;Grant, D. M.
芳胺 N-乙酰转移酶 (NAT) 催化许多重要的芳胺药物和致癌物的生物转化。 NAT 可以解毒或激活原致癌物，使这些酶参与增强或防止对特定药物的毒性反应的方式复杂化。小鼠拥有三种 NAT 同工酶：Nat1、Nat2 和 Nat3。尽管 Nat1 和 Nat2 可以有效乙酰化许多芳胺，但 Nat3 似乎能明显代谢很少的底物。我们生成了 Nat3 敲除小鼠品系，并将其与双 Nat1/2(-/-) 敲除品系一起使用，以进一步研究 Nat3 的功能作用。 Nat3(-/-)小鼠表现出正常的生存能力和生殖能力。 Nat3 表达在野生型动物中非常低，在 Nat3(-/-) 小鼠中完全检测不到。相反，在 Nat1/2(-/-) 小鼠中观察到 Nat3 转录物的表达大大升高。我们使用转录标记多态性方法来确定 Nat1/2(-/-) 小鼠中 Nat3 表达的增加是磷酸甘油酸激酶新霉素抗性盒插入代替 Nat1/Nat2 基因区域和完整 Nat3 基因上游的位置伪影，而不是生物补偿机制。尽管 Nat3 转录物增加，但在 Nat1/2(-/-) 动物中，对氨基水杨酸盐、磺胺二甲嗪、2-氨基芴和 4-氨基联苯的 N-乙酰化在体内或体外均检测不到。同时，野生型和 Nat3(-/-) 小鼠之间这些底物的体内清除率或体外代谢没有观察到差异。因此，无论是在野生型小鼠中还是在缺乏 Nat1 和 Nat2 活性的小鼠中，Nat3 不太可能在芳胺的 N-乙酰化中发挥重要作用。
Arylamine N-acetyltransferases (NAT) catalyze the biotransformation of many important arylamine drugs and procarcinogens. NAT can either detoxify or activate procarcinogens, complicating the manner in which these enzymes may participate in enhancing or preventing toxic responses to particular agents. Mice possess three NAT isoenzymes: Nat1, Nat2, and Nat3. Whereas Nat1 and Nat2 can efficiently acetylate many arylamines, few substrates appear to be appreciably metabolized by Nat3. We generated a Nat3 knockout mouse strain and used it along with our double Nat1/2(-/-)knockout strain to further investigate the functional role of Nat3. Nat3(-/-) mice showed normal viability and reproductive capacity. Nat3 expression was very low in wild-type animals and completely undetectable in Nat3(-/-) mice. In contrast, greatly elevated expression of Nat3 transcript was observed in Nat1/2(-/-) mice. We used a transcribed marker polymorphism approach to establish that the increased expression of Nat3 in Nat1/2(-/-) mice is a positional artifact of insertion of the phosphoglycerate kinase-neomycin resistance cassette in place of the Nat1/Nat2 gene region and upstream of the intact Nat3 gene, rather than a biological compensatory mechanism. Despite the increase in Nat3 transcript, the N-acetylation of p-aminosalicylate, sulfamethazine, 2-aminofluorene, and 4-aminobiphenyl was undetectable either in vivo or in vitro in Nat1/2(-/-) animals. In parallel, no difference was observed in the in vivo clearance or in vitro metabolism of any of these substrates between wild-type and Nat3(-/-) mice. Thus, Nat3 is unlikely to play a significant role in the N-acetylation of arylamines either in wild-type mice or in mice lacking Nat1 and Nat2 activities.