Fukuda A, Osawa T, Oda H, Toyokuni S, Satoh K, Uchida K
Laboratory of Food and Biodynamics, Nagoya University School of Agriculture, Japan.
Arch Biochem Biophys. 1996 May 1;329(1):39-46. doi: 10.1006/abbi.1996.0189.
An iron chelate, ferric nitrilotriacetate (Fe-NTA), induces acute renal proximal tubular necrosis, a consequence of free radical-mediated oxidative tissue damage, that eventually leads to a high incidence of renal adenocarcinoma in rodents. In the present study, we investigated the free radical-induced oxidative stress response in this carcinogenesis model, focusing on the expression of glutathione S-transferases (GSTs) which catalyze the conjugation of reactive chemicals with glutathione and play an important role in protecting cells. A single intraperitoneal Fe-NTA treatment (15 mg Fe/kg body weight) induced a rapid oxidative stress, which was monitored by the accumulation of lipid peroxidation products and the loss of sulfhydryl contents in the kidneys, resulting in a 30% reduction of GST activity 1 h after an Fe-NTA treatment. The enzyme activity returned to the control level after 16 h. The immunoblot analysis of GST isozymes demonstrated that the level of alpha-class GSTs (GST-Ya and GST-Yc) and pi-class GST (GST-Yp), major GST isozymes constitutively produced in the kidney, decreased immediately within 1 h of the Fe-NTA treatment. The onset of the recovery of GST-Yp protein levels was detected 3 h after the Fe-NTA treatment. The enhanced production of GST-Yp in gene expression was evident in the drastic elevation of mRNA levels and these increases coincided with a substantial rise in the GST activity and protein levels. The alpha-class GSTs were not inducible by treatment with Fe-NTA. The immunohistochemical analysis demonstrated that the expression of GST-Yp was strongly induced in the regenerating proximal tubular cells. A steady accumulation of GST-Yp protein was observed in the subacute toxicity experiments with multiple injections of Fe-NTA. These results suggest that the enhanced expression of GST-Yp is important in mediating cell repairs or increasing the resistance to subsequent injury.
一种铁螯合物，次氮基三乙酸铁（Fe-NTA），可诱发急性肾近端小管坏死，这是自由基介导的氧化性组织损伤的结果，最终导致啮齿动物肾腺癌的高发病率。在本研究中，我们调查了这种致癌模型中自由基诱导的氧化应激反应，重点关注谷胱甘肽S-转移酶（GSTs）的表达，该酶催化反应性化学物质与谷胱甘肽的结合，并在保护细胞中发挥重要作用。单次腹腔注射Fe-NTA（15 mg铁/千克体重）可诱导快速氧化应激，通过肾脏中脂质过氧化产物的积累和巯基含量的损失进行监测，导致Fe-NTA处理1小时后GST活性降低30%。16小时后酶活性恢复到对照水平。GST同工酶的免疫印迹分析表明，肾脏中组成性产生的主要GST同工酶α类GSTs（GST-Ya和GST-Yc）和π类GST（GST-Yp）的水平在Fe-NTA处理后1小时内立即下降。Fe-NTA处理3小时后检测到GST-Yp蛋白水平开始恢复。GST-Yp基因表达的增强在mRNA水平的急剧升高方面很明显，这些增加与GST活性和蛋白水平的大幅上升一致。α类GSTs不能被Fe-NTA处理诱导。免疫组织化学分析表明，GST-Yp的表达在再生的近端小管细胞中被强烈诱导。在多次注射Fe-NTA的亚急性毒性实验中观察到GST-Yp蛋白的稳定积累。这些结果表明，GST-Yp的增强表达在介导细胞修复或增加对后续损伤的抵抗力方面很重要。
