Wellinger R, Guigoz Y
Mech Ageing Dev. 1986 Apr;34(2):203-17. doi: 10.1016/0047-6374(86)90035-7.
Expression of the genes coding for tyrosine aminotransferase and tryptophan oxygenase in rats is induced in response to cold stress. We have studied the effect of ageing on this induction. The induction of tyrosine aminotransferase activity in young adult rats (10 months) was about twice that observed with old rats (25 months). This difference between the two age groups was also observed when the steady-state level of tyrosine aminotransferase mRNA was measured by hybridization with a specific DNA probe. However, when the transcription rate of the gene was measured by in vitro elongation of nascent RNA in isolated nuclei, no difference was detected. In contrast to the results with tyrosine aminotransferase, induced tryptophan oxygenase enzyme and mRNA levels did not show an age-dependent difference. These results suggest that there is, with ageing, an impairment in post-transcriptional regulation of the synthesis of tyrosine aminotransferase. The regulation of tryptophan oxygenase, on the other hand, is similar in the two age groups.
大鼠体内编码酪氨酸转氨酶和色氨酸加氧酶的基因表达会因冷应激而被诱导。我们研究了衰老对这种诱导作用的影响。年轻成年大鼠（10个月）中酪氨酸转氨酶活性的诱导程度约为老年大鼠（25个月）的两倍。当用特异性DNA探针杂交法测定酪氨酸转氨酶mRNA的稳态水平时，也观察到了这两个年龄组之间的这种差异。然而，当通过分离细胞核中新生RNA的体外延伸来测定基因的转录速率时，未检测到差异。与酪氨酸转氨酶的结果相反，诱导的色氨酸加氧酶活性和mRNA水平未表现出年龄依赖性差异。这些结果表明，随着衰老，酪氨酸转氨酶合成的转录后调控出现了损伤。另一方面，色氨酸加氧酶的调控在两个年龄组中是相似的。
