Cytochrome P450 2E1-dependent oxidant stress and upregulation of anti-oxidant defense in liver cells
Cytochrome P450 2E1-dependent oxidant stress and upregulation of anti-oxidant defense in liver cells
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DOI：
10.1111/j.1440-1746.2006.04595.x
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发表时间：
2006-10-01
影响因子：
4.1
通讯作者：
Cederbaum, Arthur I.
中科院分区：
文献类型：
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作者：
Cederbaum, Arthur I.
细胞色素P450 2E1（CYP2E1）的诱导是乙醇产生氧化应激的中心途径。细胞色素P450 2E1代谢许多其他毒性化合物。由于诱导CYP2E1，乙醇可增强这些药物的毒性。细胞色素P450 2E1在多种生理和病理生理条件下被诱导。西奈山医学院的实验室建立了组成型表达人CYP2E1的HepG2细胞系。乙醇、多不饱和脂肪酸和铁对表达CYP2E1的HepG2细胞（E47细胞）有毒性，但对对照HepG2细胞无毒性。由于编码γ谷氨酰半胱氨酸合成酶的重亚基和轻亚基（GCLC和GCLM）的基因的激活，E47细胞具有比对照HepG2细胞更高的谷胱甘肽水平。在E47细胞中，过氧化氢酶、胞质和微粒体谷胱甘肽转移酶和血红素加氧酶-1（HO-1）也因各自基因的激活而增加了两倍。这些激活被抗氧化剂阻止，这表明这些抗氧化剂基因的上调可能反映了清除CYP2E1衍生氧化剂的适应性机制。在慢性酒精喂养和吡唑治疗的大鼠或小鼠的肝细胞肝脏中观察到核因子红细胞2相关因子2（Nrf2）蛋白和mRNA增加，已知这些条件会升高CYP2E1。E47细胞Nrf2 mRNA和蛋白表达增加。E47细胞中GCLC和HO-1的上调依赖于Nrf2。这些结果表明，当CYP2E1升高时，Nrf2被激活，其水平升高。这表明，Nrf2在对CYP2E1引起的氧化应激增加的适应性反应中起着关键作用。
Induction of cytochrome P450 2E1 (CYP2E1) is a central pathway by which ethanol generates oxidative stress. Cytochrome P450 2E1 metabolizes many other toxicologic compounds. Toxicity of these agents is enhanced by ethanol, due to induction of CYP2E1. Cytochrome P450 2E1 is induced under a variety of physiological and pathophysiological conditions. The laboratory at Mount Sinai School of Medicine established HepG2 cell lines that constitutively express human CYP2E1. Ethanol, polyunsaturated fatty acids and iron were toxic to the HepG2 cells that express CYP2E1 (E47 cells) but not control HepG2 cells. The E47 cells had higher glutathione levels than control HepG2 cells due to activation of the genes encoding the heavy and light subunits of gamma glutamyl cysteine synthetase (GCLC and GCLM). There was also a twofold increase in catalase, cytosolic and microsomal glutathione transferase, and heme oxygenase-1 (HO-1) in the E47 cells due to activation of their respective genes. These activations were prevented by anti-oxidants, suggesting that the upregulation of these anti-oxidant genes may reflect an adaptive mechanism to remove CYP2E1-derived oxidants. Increases in nuclear factor erythroid 2-related factor 2 (Nrf2) protein and mRNA were observed in livers of hepatocytes of chronic alcohol-fed and of pyrazole-treated rats or mice, conditions known to elevate CYP2E1. E47 cells showed increased Nrf2 mRNA and protein expression. Upregulation of GCLC and HO-1 in E47 cells is dependent on Nrf2. These results suggest that Nrf2 is activated and its levels are increased when CYP2E1 is elevated. It is suggested that Nrf2 plays a key role in the adaptive response against increased oxidative stress caused by CYP2E1.