Katsurada A, Iritani N, Fukuda H, Matsumura Y, Nishimoto N, Noguchi T, Tanaka T
Tezukayama Gakuin College, Osaka, Japan.
Eur J Biochem. 1990 Jun 20;190(2):427-33. doi: 10.1111/j.1432-1033.1990.tb15592.x.
The effects of nutrients and hormones on transcriptional and post-transcriptional regulation of fatty acid synthase in rat liver were investigated following cDNA cloning. When fasted rats were fed a carbohydrate/protein diet, the transcriptional rate was greatly increased even in 1 h. The transcriptional rate, mRNA concentration and enzyme induction reached maximum levels in 4 h, 8-16 h and 48 h, respectively. Although dietary carbohydrate increased each level more than protein did, both carbohydrate and protein were required to reach a high level. Corn oil feeding markedly decreased the transcriptional rate. In diabetic rats, the transcriptional rate, mRNA concentration and enzyme induction were very low in comparison with the normal. By treating the diabetic rats with insulin, however, the transcriptional rate was increased 5-fold in 1 h and 15-fold in 6 h, preceding a great increase in the mRNA and enzyme levels. On the other hand, fructose feeding or triiodothyronine treatment of diabetic rats abundantly increased the mRNA concentration and somewhat increased the transcriptional rate. Thus, it is suggested that insulin mainly stimulates the transcription of the fatty acid synthase gene, whereas triiodothyronine and fructose mainly increase the mRNA stability.
在克隆大鼠肝脏脂肪酸合酶cDNA后，研究了营养物质和激素对其转录及转录后调控的影响。饥饿大鼠喂食碳水化合物/蛋白质饮食后，即使在1小时内转录速率也大幅增加。转录速率、mRNA浓度和酶诱导分别在4小时、8 - 16小时和48小时达到最高水平。尽管饮食中的碳水化合物比蛋白质更能提高各水平，但碳水化合物和蛋白质都需要才能达到高水平。喂食玉米油显著降低了转录速率。与正常大鼠相比，糖尿病大鼠的转录速率、mRNA浓度和酶诱导水平非常低。然而，用胰岛素治疗糖尿病大鼠，转录速率在1小时内增加5倍，在6小时内增加15倍，随后mRNA和酶水平大幅增加。另一方面，给糖尿病大鼠喂食果糖或用三碘甲状腺原氨酸治疗，可大量增加mRNA浓度，并在一定程度上增加转录速率。因此，提示胰岛素主要刺激脂肪酸合酶基因的转录，而三碘甲状腺原氨酸和果糖主要增加mRNA的稳定性。
