title: Demonstration of diet-induced decoupling of fatty acid and cholesterol synthesis by combining gene expression array and 2H2O quantification.
abstract: The liver is a crossroad for metabolism of lipid and carbohydrates, with acetyl-CoA serving as an important metabolic intermediate and a precursor for fatty acid and cholesterol biosynthesis pathways. A better understanding of the regulation of these pathways requires an experimental approach that provides both quantitative metabolic flux measurements and mechanistic insight. Under conditions of high carbohydrate availability, excess carbon is converted into free fatty acids and triglyceride for storage, but it is not clear how excessive carbohydrate availability affects cholesterol biosynthesis. To address this, C57BL/6J mice were fed either a low-fat, high-carbohydrate diet or a high-fat, carbohydrate-free diet. At the end of the dietary intervention, the two groups received (2)H(2)O to trace de novo fatty acid and cholesterol synthesis, and livers were collected for gene expression analysis. Expression of lipid and glucose metabolism genes was determined using a custom-designed pathway focused PCR-based gene expression array. The expression analysis showed downregulation of cholesterol biosynthesis genes and upregulation of fatty acid synthesis genes in mice receiving the high-carbohydrate diet compared with the carbohydrate-free diet. In support of these findings, (2)H(2)O tracer data showed that fatty acid synthesis was increased 10-fold and cholesterol synthesis was reduced by 1.6-fold in mice fed the respective diets. In conclusion, by applying gene expression analysis and tracer methodology, we show that fatty acid and cholesterol synthesis are differentially regulated when the carbohydrate intake in mice is altered.
authors: Department of Atherosclerosis, Merck Research Labs., Merck & Co., Inc., 126 E. Lincoln Ave., Rahway, NJ 07065, USA. kristian_jensen@merck.com
authors: Kristian K
authors: KK
authors: Jensen
authors: Stephen F
authors: SF
authors: Previs
authors: Lei
authors: L
authors: Zhu
authors: Kithsiri
authors: K
authors: Herath
authors: Sheng-Ping
authors: SP
authors: Wang
authors: Gowri
authors: G
authors: Bhat
authors: Guanghui
authors: G
authors: Hu
authors: Paul L
authors: PL
authors: Miller
authors: David G
authors: DG
authors: McLaren
authors: Myung K
authors: MK
authors: Shin
authors: Thomas F
authors: TF
authors: Vogt
authors: Liangsu
authors: L
authors: Wang
authors: Kenny K
authors: KK
authors: Wong
authors: Thomas P
authors: TP
authors: Roddy
authors: Douglas G
authors: DG
authors: Johns
authors: Brian K
authors: BK
authors: Hubbard
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000096:biosynthesis* / Q000235:genetics; D050528:Diet, Carbohydrate-Restricted; D059305:Diet, High-Fat; D004040:Dietary Carbohydrates / Q000378:metabolism; D004041:Dietary Fats / Q000378:metabolism; D005227:Fatty Acids / Q000096:biosynthesis* / Q000235:genetics; D015870:Gene Expression; D020869:Gene Expression Profiling; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005227:Fatty Acids; D002784:Cholesterol