Francis V N, Dwarki V I, Padmanaban G
Nucleic Acids Res. 1986 Mar 25;14(6):2497-510. doi: 10.1093/nar/14.6.2497.
A cDNA clone for the Ya subunit of glutathione transferase from rat liver was constructed in E. coli. The clone hybridized to Ya and Yc subunit messenger RNAs. On the basis of experiments involving cell-free translation and hybridization to the cloned probe, it was shown that prototype inducers of cytochrome P-450 such as phenobarbitone and 3-methylcholanthrene as well as inhibitors such as CoCl2 and 3-amino-1,2,4-triazole enhanced the glutathione transferase (Ya+Yc) messenger RNA contents in rat liver. A comparative study with the induction of cytochrome P-450 (b+e) by phenobarbitone revealed that the drug manifested a striking increase in the nuclear pre-messenger RNAs for the cytochrome at 12 hr, but did not significantly affect the same in the case of glutathione transferase (Ya+Yc). 3-Amino-1,2,4-triazole and CoCl2 blocked the phenobarbitone mediated increase in cytochrome P-450 (b+e) nuclear pre-messenger RNAs. These compounds did not significantly affect the glutathione transferase (Ya+Yc) nuclear pre-messenger RNA levels. The polysomal, poly (A)- containing messenger RNAs for cytochrome P-450 (b+e) increased by 12-15 fold after phenobarbitone administration, reached a maximum around 16 hr and then decreased sharply. In comparison, the increase in the case a glutathione transferase (Ya+Yc) messenger RNAs was sluggish and steady and a value of 3-4 fold was reached around 24 hr. Run-off transcription rates for cytochrome P-450 (b+e) increased by nearly 15 fold in 4 hr after phenobarbitone administration, whereas the increase for glutathione transferase (Ya+Yc) was only 2.0 fold. At 12 hr after the drug administration, the glutathione transferase (Ya+Yc) transcription rates were near normal. Administration of 3-amino-1,2,4-triazole and CoCl2 blocked the phenobarbitone-mediated increase in the transcription of cytochrome P-450 (b+e) messenger RNAs. These compounds at best had only marginal effects on the transcription of glutathione transferase (Ya+Yc) messenger RNAs. The half-life of cytochrome P-450 (b+e) messenger RNA was estimated to be 3-4 hr, whereas that for glutathione transferase (Ya+Yc) was found to be 8-9 hr. Administration of phenobarbitone enhanced the half-life of glutathione transferase (Ya+Yc) messenger RNA by nearly two fold. It is suggested that while transcription activation may play a primary role in the induction of cytochrome P-450 (b+e), the induction of glutathione transferase (Ya+Yc) may essentially involve stabilization of the messenger RNAs.
在大肠杆菌中构建了大鼠肝脏谷胱甘肽转移酶 Ya 亚基的 cDNA 克隆。该克隆与 Ya 和 Yc 亚基信使 RNA 杂交。基于无细胞翻译和与克隆探针杂交的实验表明，细胞色素 P - 450 的原型诱导剂如苯巴比妥和 3 - 甲基胆蒽以及抑制剂如 CoCl2 和 3 - 氨基 - 1,2,4 - 三唑可提高大鼠肝脏中谷胱甘肽转移酶（Ya + Yc）信使 RNA 的含量。对苯巴比妥诱导细胞色素 P - 450（b + e）的比较研究表明，该药物在 12 小时时细胞色素的核前体信使 RNA 显著增加，但对谷胱甘肽转移酶（Ya + Yc）的情况没有显著影响。3 - 氨基 - 1,2,4 - 三唑和 CoCl2 阻断了苯巴比妥介导的细胞色素 P - 450（b + e）核前体信使 RNA 的增加。这些化合物对谷胱甘肽转移酶（Ya + Yc）核前体信使 RNA 水平没有显著影响。苯巴比妥给药后，细胞色素 P - 450（b + e）的多聚核糖体、含 poly（A）的信使 RNA 增加了 12 - 15 倍，在约 16 小时达到最大值，然后急剧下降。相比之下，谷胱甘肽转移酶（Ya + Yc）信使 RNA 的增加缓慢且稳定，在约 24 小时达到 3 - 4 倍的值。苯巴比妥给药后 4 小时，细胞色素 P - 450（b + e）的转录速率增加了近 15 倍，而谷胱甘肽转移酶（Ya + Yc）仅增加了 2.0 倍。给药后 12 小时，谷胱甘肽转移酶（Ya + Yc）的转录速率接近正常。3 - 氨基 - 1,2,4 - 三唑和 CoCl2 的给药阻断了苯巴比妥介导的细胞色素 P - 450（b + e）信使 RNA 转录的增加。这些化合物对谷胱甘肽转移酶（Ya + Yc）信使 RNA 的转录充其量只有轻微影响。细胞色素 P - 450（b + e）信使 RNA 的半衰期估计为 3 - 4 小时，而谷胱甘肽转移酶（Ya + Yc）的半衰期为 8 - 9 小时。苯巴比妥给药使谷胱甘肽转移酶（Ya + Yc）信使 RNA 的半衰期增加了近两倍。有人提出，虽然转录激活可能在细胞色素 P - 450（b + e）的诱导中起主要作用，但谷胱甘肽转移酶（Ya + Yc）的诱导可能主要涉及信使 RNA 的稳定。
