MODULATION OF GAMMA-GLUTAMYLCYSTEINE SYNTHETASE LARGE SUBUNIT MESSENGER-RNA EXPRESSION BY BUTYLATED HYDROXYANISOLE
MODULATION OF GAMMA-GLUTAMYLCYSTEINE SYNTHETASE LARGE SUBUNIT MESSENGER-RNA EXPRESSION BY BUTYLATED HYDROXYANISOLE
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DOI：
10.1006/taap.1994.1101
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发表时间：
1994-05-01
影响因子：
3.8
通讯作者：
EATON, DL
中科院分区：
文献类型：
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作者：
BORROZ, KI;BUETLER, TM;EATON, DL
膳食中2(3)-叔丁基-4-羟基茴香醚（BHA）处理已被证明可增加大鼠和小鼠肝脏谷胱甘肽（GSH）含量。我们实验室的后续研究表明，在饮食中添加BHA的小鼠中，肝脏γ -谷氨酰半胱氨酸合成酶（GCS）活性增加。为了测试GCS活性的增加是否与GCS大亚基（GCS- ls mRNA）的肝脏信使RNA的增加有关，我们使用PCR反应扩增了大鼠GCS- ls cDNA序列5'端附近区域对应的390碱基对片段，并用于在Northern blots上检测GCS- ls mRNA。研究人员分别测定各组小鼠的肝脏GSH、GCS活性和GCS- ls mRNA水平。各组小鼠分别在饲粮中注射BHA 12天，或在24小时内注射马来酸二乙酯（DEM）、佛洛酮和/或dl -丁硫氨酸-[S，R]-亚砜亚胺（BSO）。到第12天，BHA使GSH水平增加1.5倍，肝脏GCS活性增加1.7倍，肝脏GCS mRNA水平迅速增加5倍，在2-3天后达到最高水平。手机素（70%）或DEM（50%）部分消耗GSH导致肝脏GCS- ls mRNA水平在9小时内增加4至5倍，肝脏GSH和GCS活性在24小时内增加1.5至2倍。用GCS酶抑制剂BSO去除GSH对GCS mRNA表达没有影响，即使GSH被去除到30%。当BSO与电话酮联合处理时，GSH水平下降至< 10%，但电话酮单独处理时GCS-LS mRNA的大幅增加大大减弱。这些数据表明，GSH本身的消耗并不足以诱导GCS-LS mRNA水平的升高，但GSH偶联物的形成可能需要触发GCS-LS mRNA的诱导。GCS- ls mRNA水平的增加可能解释了BHA处理后GCS活性的增加和GSH的升高，以及其他化学物质消耗GSH 18-24小时后GSH高于对照水平的“反弹”。这些结果与Talalay的Michael受体假说是一致的。(C) 1994学术出版社，Inc.
Dietary 2(3)-tert-butyl-4-hydroxyanisole (BHA) treatment has been shown to increase hepatic glutathione (GSH) content in rats and mice. Subsequent studies in our laboratory have demonstrated that hepatic gamma-glutamylcysteine synthetase (GCS) activity is increased in mice treated with dietary BHA. To test whether this increase in GCS activity follows an increase in hepatic messenger RNA for the large subunit of GCS (GCS-LS mRNA), a 390-base pair fragment corresponding to a region near the 5' end of the rat GCS-LS cDNA sequence was amplified using the PCR reaction and used to detect GCS-LS mRNA on Northern blots. Hepatic GSH, GCS activity, and GCS-LS mRNA levels were determined either in mice treated with BHA in the diet for 12 days or mice injected with diethyl maleate (DEM), phorone, and/or DL-buthionine-[S,R]-sulfoximine (BSO) over a 24 hr period. BHA caused a 1.5-fold increase in GSH levels, a 1.7-fold increase in hepatic GCS activity by Day 12, and a rapid 5-fold increase in hepatic GCS mRNA levels reaching maximal levels after 2-3 days. Partial depletion of GSH with either phorone (70%) or DEM (50%) resulted in a 4- to 5-fold increase in hepatic GCS-LS mRNA levels by 9 hr and a 1.5- to 2-fold increase in hepatic GSH and GCS activity by 24 hr. Depletion of GSH with the GCS enzyme inhibitor BSO had no effect on GCS mRNA expression, even though GSH was depleted to 30%. When BSO was combined with the phorone treatment GSH levels were depleted to < 10%, but the large increase in GCS-LS mRNA seen with phorone alone was greatly attenuated. These data suggest that depletion of GSH per se, is not sufficient to induce elevation of GCS-LS mRNA levels, but that the formation of GSH conjugates may be required to trigger GCS-LS mRNA induction. The increase in GCS-LS mRNA levels may account for the increase in GCS activity and elevation of GSH observed following BHA treatment, as well as the ''rebound'' of GSH above control levels observed 18-24 hr following depletion of GSH by other chemicals. These results are consistent with the Michael acceptor hypothesis by Talalay. (C) 1994 Academic Press, Inc.