Lipogenesis hepatic

Biological actions Adipocyte differentiation fatty acid uptake lipogenesis glucose uptake other effects on nutrient metabolism which lower hepatic glucose production... 

The citric acid cycle is the final common pathway for the aerobic oxidation of carbohydrate, lipid, and protein because glucose, fatty acids, and most amino acids are metabolized to acetyl-CoA or intermediates of the cycle. It also has a central role in gluconeogenesis, lipogenesis, and interconversion of amino acids. Many of these processes occur in most tissues, but the hver is the only tissue in which all occur to a significant extent. The repercussions are therefore profound when, for example, large numbers of hepatic cells are damaged as in acute hepatitis or replaced by connective tissue (as in cirrhosis). Very few, if any, genetic abnormalities of citric acid cycle enzymes have been reported such ab-normahties would be incompatible with life or normal development. 

Increased activity of the hexose monophosphate pathway (HMP) The increased availability of glucose 6-phosphate in the well-fed state, combined with the active use of NADPH in hepatic lipogenesis, stimulate the HMP (see Chapter 12, p. 143). This pathway typically accounts for five to ten percent of the glucose metabolized by the liver (see Figure 24.3, ). 

Letexier, D., Diraison, F., and Beylot, M., Addition of inulin to a moderately high-carbohydrates diet reduces hepatic lipogenesis and plasma triacylglycerol concentrations in humans, Am. J. Clin. Nutr., 77, 559-564, 2003. 

Takahashi et al. (2003) previously demonstrated that CLA increases the activity and mRNA levels of hepatic lipogenic enzymes they suggested that enhanced lipogenesis is a principal mechanism of CLA-induced hepatic steatosis in mice. In this study, suppression of the activity and mRNA expression... 

Ikeda, I., Cha, J. Y., Yanagita, T., Nakatani, N., Oogami, K., Imaizumi, K., and Yazawa, K. 1998. Effects of dietary a-linoleic, eicosapentaenoic and docosahexaenoic acids on hepatic lipogenesis and P-oxidation in rats. Biosci. Biotech. Biochem., 62, 675-680. 

Lipogenesis, the synthesis of lipids from carbohydrate via acetyl-CoA, occurs almost exclusively in the liver cells and the fatty tissue, (s. fig. 3.9) According to lipid topogenesis (4), the enzymes involved in triglyceride and phospholipid synthesis are localized on the cytoplasmic surface of the endoplasmic reticulum. The level of hepatic synthesis is regulated primarily by the insulin-glucagon quotient, as described by R.H. Unger in 1971. 

Cha, J. Y., and Repa, J. J. The liver X receptor (LXR) and hepatic lipogenesis. The carbohydrate-response element-binding protein is a target gene of LXR. J Biol Chem 282(2007) 743-751. 

Foretz, M., Guichard, C., Ferre, P., and Foufelle, F. Sterol regulatory element binding protein-Ic is a major mediator of insulin action on the hepatic expression of glucokinase and lipogenesis-related genes. Proc Natl Acad Sci U S A 96 (1999) 12737-12742. 

Harada, N., Oda, Z., Hara, Y., Fujinami, K., Okawa, M., Ohbuchi, K., Yonemoto, M., Ikeda, Y., Ohwaki, K., Aragane, K., Tamai, Y. and Kusunoki, J., Hepatic de novo lipogenesis is present in liver-specific ACCl-deficient mice, Mol Cell Biol 27 (2007) 1881-1888. 

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