Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Southern California Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine USC, Los Angeles, CA 90033, USA.
Hepatology. 2010 Apr;51(4):1291-301. doi: 10.1002/hep.23471.
UNLABELLED: We previously showed that hepatic expression of glutathione (GSH) synthetic enzymes and GSH levels fell 2 weeks after bile duct ligation (BDL) in mice. This correlated with a switch in nuclear anti-oxidant response element (ARE) binding activity from nuclear factor erythroid 2-related factor 2 (Nrf2) to c-avian musculoaponeurotic fibrosarcoma (c-Maf)/V-maf musculoaponeurotic fibrosarcoma oncogene homolog G (MafG). Our current aims were to examine whether the switch in ARE binding activity from Nrf2 to Mafs is responsible for decreased expression of GSH synthetic enzymes and the outcome of blocking this switch. Huh7 cells treated with lithocholic acid (LCA) exhibited a similar pattern of change in GSH synthetic enzyme expression as BDL mice. Nuclear protein levels of Nrf2 fell at 20 hours after LCA treatment, whereas c-Maf and MafG remained persistently induced. These changes translated to ARE nuclear binding activity. Knockdown of c-Maf or MafG individually blunted the LCA-induced decrease in Nrf2 ARE binding and increased ARE-dependent promoter activity, whereas combined knockdown was more effective. Knockdown of c-Maf or MafG individually increased the expression of GSH synthetic enzymes and raised GSH levels, and combined knockdown exerted an additive effect. Ursodeoxycholic acid (UDCA) or S-adenosylmethionine (SAMe) prevented the LCA-induced decrease in expression of GSH synthetic enzymes and promoter activity and prevented the increase in MafG and c-Maf levels. In vivo knockdown of the Maf genes protected against the decrease in GSH enzyme expression, GSH level, and liver injury after BDL. CONCLUSION: Toxic bile acid induces a switch from Nrf2 to c-Maf/MafG ARE nuclear binding, which leads to decreased expression of GSH synthetic enzymes and GSH levels and contributes to liver injury during BDL. UDCA and SAMe treatment targets this switch.
未加标签:我们之前表明,在小鼠胆管结扎(BDL)后两周,肝内谷胱甘肽(GSH)合成酶的表达和 GSH 水平下降。这与核抗氧化反应元件(ARE)结合活性从核因子红细胞 2 相关因子 2(Nrf2)向 c-禽 Musculoaponeurotic Fibrosarcoma(c-Maf)/V-maf Musculoaponeurotic Fibrosarcoma Oncogene Homolog G(MafG)的转换相关。我们目前的目的是研究从 Nrf2 到 Mafs 的 ARE 结合活性的转换是否是 GSH 合成酶表达减少和阻断这种转换的结果。用石胆酸(LCA)处理的 Huh7 细胞表现出与 BDL 小鼠相似的 GSH 合成酶表达变化模式。LCA 处理 20 小时后,核蛋白水平的 Nrf2 下降,而 c-Maf 和 MafG 持续诱导。这些变化转化为 ARE 核结合活性。单独敲低 c-Maf 或 MafG 减弱了 LCA 诱导的 Nrf2 ARE 结合减少和增加的 ARE 依赖性启动子活性,而联合敲低更有效。单独敲低 c-Maf 或 MafG 增加了 GSH 合成酶的表达并提高了 GSH 水平,联合敲低则具有相加作用。熊去氧胆酸(UDCA)或 S-腺苷甲硫氨酸(SAMe)可预防 LCA 诱导的 GSH 合成酶表达和启动子活性下降,并可防止 MafG 和 c-Maf 水平升高。体内敲低 Maf 基因可防止 BDL 后 GSH 酶表达、GSH 水平和肝损伤的下降。 结论:有毒胆酸诱导 Nrf2 向 c-Maf/MafG ARE 核结合的转换,导致 GSH 合成酶和 GSH 水平的表达降低,并导致 BDL 期间的肝损伤。UDCA 和 SAMe 治疗针对这种转换。
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