Landau J M, Sekowski A, Hamm M W
Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ 08903, USA.
Biochim Biophys Acta. 1997 Apr 21;1345(3):349-57. doi: 10.1016/s0005-2760(97)00010-6.
The effect of cholesterol on stearoyl CoA desaturase (SCD) was investigated. Previous work had shown that the addition of cholesterol to the diet of rats produced higher liver SCD activity compared to non-cholesterol-fed controls. We have confirmed this result and investigated the mechanism responsible for this cholesterol-induced higher SCD activity. Rats were fed either a 10% corn oil (CO) or a 10% corn oil/1% cholesterol (CO/CH) diet for 1, 3, or 7 days. SCD mRNA abundance was 3.3, 1.9, and 2.4 times greater in livers from CO/CH-fed animals after 1, 3, and 7 days, respectively. Northern hybridization of RNA from kidney, intestinal mucosa, heart, adipose, and liver demonstrated that cholesterol feeding specifically altered liver SCD mRNA. Liver esterified cholesterol content increased 27-fold with cholesterol feeding. This esterified cholesterol increase was accompanied by a proportionately greater increase in oleic acid compared to other fatty acids. These studies indicate that cholesterol does influence the expression of SCD specifically in the liver and suggest that the product, oleic acid, is preferentially esterified to cholesterol in the liver. Preliminary liver nuclear run-on assays from rats fed CO or CO/CH diets for 1 and 3 days indicate that transcription regulation is not a factor.
研究了胆固醇对硬脂酰辅酶A去饱和酶（SCD）的影响。先前的研究表明，与未喂食胆固醇的对照组相比，给大鼠喂食含胆固醇的饮食会使肝脏SCD活性更高。我们证实了这一结果，并研究了导致胆固醇诱导的SCD活性升高的机制。将大鼠分别喂食10%玉米油（CO）或10%玉米油/1%胆固醇（CO/CH）饮食1天、3天或7天。在喂食CO/CH的动物肝脏中，SCD mRNA丰度在1天、3天和7天后分别比对照组高3.3倍、1.9倍和2.4倍。对来自肾脏、肠黏膜、心脏、脂肪和肝脏的RNA进行Northern杂交表明，喂食胆固醇特异性地改变了肝脏SCD mRNA。喂食胆固醇后，肝脏酯化胆固醇含量增加了27倍。与其他脂肪酸相比，这种酯化胆固醇的增加伴随着油酸的更大比例增加。这些研究表明，胆固醇确实特异性地影响肝脏中SCD的表达，并表明产物油酸在肝脏中优先与胆固醇酯化。对喂食CO或CO/CH饮食1天和3天的大鼠进行的初步肝脏细胞核连续转录分析表明，转录调控不是一个因素。
