Differences in the regulation of adipose tissue and liver lipogenesis by carbohydrates in humans

• Published in: Journal of lipid research Vol. 44; no. 4; pp. 846 - 853
• Main Authors: Diraison, Frédérique, Yankah, Vivienne, Letexier, Dominique, Dusserre, Eric, Jones, Peter, Beylot, Michel
• Format: Journal Article
• Language: English
• Published: United States Elsevier 01.04.2003
• Subjects: Acetyl-CoA Carboxylase; Acetyl-CoA Carboxylase - genetics; Adipose Tissue; Adipose Tissue - metabolism; administration & dosage; Adolescent; Adult; analysis; biosynthesis; carbohydrate metabolism; Carbohydrates; Carbohydrates - administration & dosage; Carbohydrates - pharmacology; CCAAT-Enhancer-Binding Proteins; CCAAT-Enhancer-Binding Proteins - genetics; DNA-Binding Proteins; DNA-Binding Proteins - genetics; Fatty Acid Synthases; Fatty Acid Synthases - genetics; fatty-acid synthase; Female; Gene Expression Regulation; genetics; Humans; lipid metabolism; Lipids; Lipids - biosynthesis; Liver; Liver - metabolism; Male; metabolism; Middle Aged; mRNA; obesity; pharmacology; RNA, Messenger; RNA, Messenger - analysis; stable isotopes; Sterol Regulatory Element Binding Protein 1; sterol-regulatory element-binding protein-1c; Transcription Factors; Transcription Factors - genetics
• DOI: 10.1194/jlr.M200461-JLR200
• ISSN: 0022-2275

We assessed the contributions of human liver and adipose tissue de novo lipogenesis (DNL) to triacylglycerol (TAG) synthesis. Volunteers were fed a high-energy, high-carbohydrate diet (HC, n = 5) or a normocaloric diet (NC, n = 10). NC subjects remained in the fasting state (Study 1, n = 5) or received oral glucose (Study 2, n = 5) throughout the test (12 h). HC subjects remained in the fasting state (Study 3). They ingested deuterated water and [U-13C]acetate to trace lipogenesis. Adipose tissue fatty-acid (FA) synthase (FAS), acetyl-CoA carboxylase 1 (ACC1), and SREBP-1c mRNA were measured. Plasma TAG-FA was labeled by 13C and deuterium showing active liver lipogenesis, which was stimulated (P < 0.05) by oral glucose and HC diet. Adipose tissue TAG had no detectable 13C enrichment in any test, showing no significant incorporation of TAG-FA provided by liver lipogenesis, but were labeled by deuterium in all tests, showing active DNL in situ; however, rough quantitative estimates showed that adipose DNL was minimal (<1 g), and poorly stimulated by oral glucose or HC diet. mRNA levels were not increased by the HC diet. Adipose DNL is active in humans, but contributes little to TAG stores and is less responsive than liver DNL to stimulation by carbohydrates.