Wainfan E, Dizik M, Hluboky M, Balis M E
Carcinogenesis. 1986 Mar;7(3):473-6. doi: 10.1093/carcin/7.3.473.
A diet that is deficient in methionine, choline, folic acid and vitamin B12 has been found to induce alterations rapidly in liver tRNA methylation in male Fischer rats. In vitro assays indicated that activity of N2-guanine tRNA methyltransferase II (NMG2) was increased to 150% of controls levels in 1 week and 300% of control levels after 2 weeks or longer on this diet. Incompletely methylated tRNA was isolated from livers of these same animals, indicating that there was impairment of methylation in vivo. The effects on liver tRNA methylation of this methyl-deficient diet were thus seen to mimic those of the liver carcinogen, ethionine, which also causes production of hypomethylated tRNA and increased activity of NMG2. The effect of the same diet on liver tRNA methyltransferase activity of C57BL/6J and C3H/HeJ inbred mice were also studied. Intake of the lipotrope-deficient diet induced elevation in activity of liver N2-guanine tRNA methyltransferase II activity in C57BL/6J mice, similar to that seen in rats. In contrast, the methyl-deficient diet had very little effect on the same enzyme activity in C3H/HeJ animals.
已发现，缺乏蛋氨酸、胆碱、叶酸和维生素B12的饮食会使雄性Fischer大鼠肝脏tRNA甲基化迅速发生改变。体外试验表明，在这种饮食喂养1周后，N2-鸟嘌呤tRNA甲基转移酶II（NMG2）的活性增加到对照水平的150%，2周或更长时间后增加到对照水平的300%。从不完全甲基化的tRNA是从这些相同动物的肝脏中分离出来的，这表明体内甲基化存在缺陷。因此，可以看出这种甲基缺乏饮食对肝脏tRNA甲基化的影响与肝脏致癌物乙硫氨酸的影响相似，乙硫氨酸也会导致低甲基化tRNA的产生和NMG2活性的增加。还研究了相同饮食对C57BL/6J和C3H/HeJ近交系小鼠肝脏tRNA甲基转移酶活性的影响。摄入缺乏促脂物质的饮食会导致C57BL/6J小鼠肝脏N2-鸟嘌呤tRNA甲基转移酶II活性升高，与在大鼠中观察到的情况相似。相比之下，甲基缺乏饮食对C3H/HeJ动物的相同酶活性影响很小。
