Aoki Hisa, Kimura Kumi, Igarashi Kiharu, Takenaka Asako
Course of the Science of Bioresources, The United Graduate School of Agricultural Sciences, Iwate University, Iwate, Japan.
Biosci Biotechnol Biochem. 2006 Apr;70(4):843-9. doi: 10.1271/bbb.70.843.
Dietary soy protein isolate (SPI) reduces hepatic lipogenesis by suppressing gene expression of lipogenic enzymes, including acetyl-CoA carboxylase (ACC). In order to elucidate the mechanism of this regulation, the effect of dietary SPI on promoter (PI and PII) specific gene expression of ACC alpha was investigated. Rats were fed experimental diets containing SPI or casein as a nitrogen source. SPI feeding decreased the hepatic contents of total ACC mRNA as well as triglyceride (TG) content, but dietary SPI affected the amount of sterol-regulatory element binding protein (SREBP)-1 mRNA and protein very little. The amount of ACC mRNA transcribed from PII promoter containing SRE was not significantly affected by dietary protein, while a significant decrease in PI-generated ACC mRNA content was observed in rats fed the SPI diet. These data suggest that SPI feeding decreased the hepatic contents of ACC alpha mRNA mainly by regulating PI promoter via a nuclear factor(s) other than SREBP-1.
膳食大豆分离蛋白（SPI）通过抑制包括乙酰辅酶A羧化酶（ACC）在内的生脂酶的基因表达来减少肝脏脂肪生成。为了阐明这种调节机制，研究了膳食SPI对ACCα启动子（PI和PII）特异性基因表达的影响。给大鼠喂食以SPI或酪蛋白作为氮源的实验性饮食。喂食SPI可降低肝脏中总ACC mRNA的含量以及甘油三酯（TG）含量，但膳食SPI对固醇调节元件结合蛋白（SREBP）-1 mRNA和蛋白质的量影响很小。含有固醇调节元件（SRE）的PII启动子转录的ACC mRNA量不受膳食蛋白质的显著影响，而在喂食SPI饮食的大鼠中观察到PI产生的ACC mRNA含量显著降低。这些数据表明，喂食SPI主要通过SREBP-1以外的核因子调节PI启动子，从而降低肝脏中ACCα mRNA的含量。
