Role of NAD(P)H:quinone oxidoreductase 1 in clofibrate-mediated hepatoprotection from acetaminophen
Role of NAD(P)H:quinone oxidoreductase 1 in clofibrate-mediated hepatoprotection from acetaminophen
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DOI：
10.1016/j.tox.2006.11.052
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发表时间：
2007-02-12
期刊：
影响因子：
4.5
通讯作者：
Manautou, Jose E.
中科院分区：
文献类型：
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作者：
Moffit, Jeffrey S.;Aleksunes, Lauren M.;Manautou, Jose E.
用过氧化物酶体增殖剂氯贝丁酯 (CFB) 预处理的小鼠对对乙酰氨基酚 (APAP) 肝毒性具有抵抗力。虽然保护机制尚不完全清楚，但 CFB 可以减少 APAP 反应性代谢物 N-乙酰基对苯醌亚胺 (NAPQI) 形成的蛋白质加合物。 NAD(P)H：醌氧化还原酶 1 (NQO1) 是一种具有抗氧化特性的酶，负责细胞醌的还原。我们假设 CFB 会增加 NQO1 活性，从而增强 NAPQI 向母体 APAP 的转换。这可以解释 CFB 产生的 APAP 共价结合和谷胱甘肽消耗的减少，而不影响 APAP 对 NAPQI 的生物激活。对雄性 CD-1 小鼠施用 CFB（500 mg/kg，腹腔注射）5 或 10 天可增加 NQO1 蛋白和活性水平。为了评估 NQO1 将 NAPQI 还原为 APAP 的能力，我们利用了微粒体激活系统。微粒体中存在的细胞色素 P450 酶将 APAP 生物激活为 NAPQI，后者与亲电子捕获剂 N-乙酰半胱氨酸 (NAC) 结合。我们分析了人重组 NQO1 存在下 APAP-NAC 代谢物的形成。结果表明 NQO1 能够降低 NAPQI。然后在原代肝细胞中评估 NQO1 改善 APAP 毒性的能力。从接受 CFB 给药的小鼠中分离出的原代肝细胞对 APAP 毒性具有抵抗力。在 APAP 存在的情况下，这些肝细胞还暴露于 ES936，这是一种高亲和力、不可逆的 NQO1 抑制剂。 ES936 的浓度导致 NQO1 活性抑制超过 94%，但并没有增加 CFB 处理小鼠的肝细胞对 APAP 的敏感性。虽然 NQO1 在机制上能够降低 NAPQI，但 CFB 介导的肝脏保护似乎并不依赖于 NQO1 表达的增强。 (c) 2006 Elsevier Ireland Ltd. 保留所有权利。
Mice pretreated with the peroxisome proliferator clofibrate (CFB) are resistant to acetaminophen (APAP) hepatotoxicity. Whereas the mechanism of protection is not entirely known, CFB decreases protein adducts formed by the reactive metabolite of APAP, N-acetyl-p-benzoquinone imine (NAPQI). NAD(P)H:quinone oxidoreductase 1 (NQO1) is an enzyme with antioxidant properties that is responsible for the reduction of cellular quinones. We hypothesized that CFB increases NQO1 activity, which in turn enhances the conversion of NAPQI back to the parent APAP. This could explain the decreases in APAP covalent binding and glutathione depletion produced by CFB without affecting APAP bioactivation to NAPQI. Administration of CFB (500 mg/kg, i.p.) to male CD-1 mice for 5 or 10 days increased NQO1 protein and activity levels. To evaluate the capacity of NQO1 to reduce NAPQI back to APAP, we utilized a microsomal activating system. Cytochrome P450 enzymes present in microsomes bioactivate APAP to NAPQI, which binds the electrophile trapping agent, N-acetyl cysteine (NAC). We analyzed the formation of APAP-NAC metabolite in the presence of human recombinant NQO1. Results indicate that NQO1 is capable of reducing NAPQI. The capacity of NQO1 to amelioriate APAP toxicity was then evaluated in primary hepatocytes. Primary hepatocytes isolated from mice dosed with CFB are resistant to APAP toxicity. These hepatocytes were also exposed to ES936, a high affinity, and irreversible inhibitor of NQO1 in the presence of APAP. Concentrations of ES936 that resulted in over 94% inhibition of NQO1 activity did not increase the susceptibility of hepatocytes from CFB treated mice to APAP. Whereas NQO1 is mechanistically capable of reducing NAPQI, CFB-mediated hepatoprotection does not appear to be dependent upon enhanced expression of NQO1. (c) 2006 Elsevier Ireland Ltd. All rights reserved.