Vasconcelos M H, Tam S C, Beattie J H, Hesketh J E
Division of Biochemical Sciences, Rowett Research Institute, Aberdeen, Scotland, U.K.
Biochem J. 1996 Apr 15;315 ( Pt 2)(Pt 2):665-71. doi: 10.1042/bj3150665.
The expression of metallothionein (MT)-1 and -2 mRNAs in rat liver following administration of Cd or Cu was investigated using specific oligonucleotides. The specificity was confirmed using a competitive prehybridization assay. Cd injection caused a biphasic induction of both isoform mRNAs, whereas Cu induced a sustained, monophasic response. Analysis of polyribosomal RNA showed that, after both Cd and Cu treatments, the recruitment of MT-1 mRNA into polyribosomes paralleled the increase in transcription, but the increase of polyribosomal MT-2 mRNA was less than that of total MT-2 mRNA. This indicates that not all the MT-2 mRNA induced was translated, suggesting that there is translational control of MT-2 mRNA expression, but not of MT-1 mRNA. This hypothesis was supported by the observation that, after Cu treatment, the induction of MT-1 protein was induced to the same extent as MT-1 mRNA, whereas the total MT protein (MT-1 + MT-2) was increased far less (7-fold) than MT-2 mRNA (30-fold).
使用特异性寡核苷酸研究了给予镉（Cd）或铜（Cu）后大鼠肝脏中金属硫蛋白（MT）-1和-2 mRNA的表达。通过竞争性预杂交试验确认了特异性。注射Cd导致两种异构体mRNA的双相诱导，而Cu诱导持续的单相反应。多核糖体RNA分析表明，在Cd和Cu处理后，MT-1 mRNA进入多核糖体的过程与转录增加平行，但多核糖体MT-2 mRNA的增加小于总MT-2 mRNA的增加。这表明并非所有诱导的MT-2 mRNA都被翻译，提示存在MT-2 mRNA表达的翻译控制，但MT-1 mRNA不存在这种情况。这一假设得到以下观察结果的支持：Cu处理后，MT-1蛋白的诱导程度与MT-1 mRNA相同，而总MT蛋白（MT-1 + MT-2）的增加远低于MT-2 mRNA（30倍）的增加（7倍）。
