The influence of chylomicron remnants on cholesteryl ester metabolism in cultured rat hepatocytes: comparison of the effects of particles enriched in n-3 or n-6 polyunsaturated fatty acids. 2001

K M Botham, and E N Maldonado, and Y Chico, and X Zheng, and M Avella, and B Ochoa
Department of Physiology, University of the Basque Country, Medical School, Bilbao, Spain.

The effect of chylomicron remnants derived from fish oil (rich in n-3 polyunsaturated fatty acids) or corn oil (rich in n-6 polyunsaturated fatty acids) on the formation and hydrolysis of cholesteryl esters in cultured rat hepatocytes was investigated. Hepatocytes were incubated with or without fish or corn oil chylomicron remnants (0.25-0.75 mM triacylglycerol), and the activity of acyl-CoA:cholesterol acyltranferase (ACAT) and cholesteryl ester hydrolases in the cytosol (cCEH) and endoplasmic reticulum (erCEH), and the expression of mRNA for ACAT1, ACAT2 and cCEH, and of enzyme protein for erCEH was determined. Addition of either type of remnants to hepatocyte cultures resulted in a decreased activity of erCEH, cCEH (after 6 and 19 h incubation), and of ACAT (after 6 h only). Hepatocyte levels of mRNA encoding ACAT1 and ACAT2 were not affected by either type of chylomicron remnants after 6 h of incubation, while ACAT2 mRNA levels were down-regulated by fish oil remnants as compared with corn oil remnants, and also with control cells in the long term (19 h). In contrast, cCEH mRNA levels were down-regulated by chylomicron remnants derived from corn oil but not fish oil. The expression of erCEH protein was induced in response to the inhibitory effect of both types of remnants on the activity of the enzyme, with corn oil remnants having a significantly greater effect. These findings demonstrate that dietary polyunsaturated fatty acids when delivered to hepatocytes in chylomicron remnants regulate the activity of the enzymes governing the intracellular cholesteryl ester balance, and suggest that dietary n-3 and n-6 polyunsaturated fatty acids or a metabolite thereof have differential effects on the expression of their genes at the mRNA and post-transcriptional levels.

UI MeSH Term Description Entries
D008297 Male Males
D002478 Cells, Cultured Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others. Cultured Cells,Cell, Cultured,Cultured Cell
D002785 Sterol O-Acyltransferase An enzyme that catalyzes the formation of cholesterol esters by the direct transfer of the fatty acid group from a fatty acyl CoA derivative. This enzyme has been found in the adrenal gland, gonads, liver, intestinal mucosa, and aorta of many mammalian species. EC 2.3.1.26. Acyl-CoA-Cholesterol Acyltransferase,Cholesterol Acyltransferase,Cholesterol Esterifying Enzyme,Acyl CoA Cholesterol Acyltransferase,Acyltransferase, Acyl-CoA-Cholesterol,Acyltransferase, Cholesterol,Enzyme, Cholesterol Esterifying,Esterifying Enzyme, Cholesterol,O-Acyltransferase, Sterol,Sterol O Acyltransferase
D002788 Cholesterol Esters Fatty acid esters of cholesterol which constitute about two-thirds of the cholesterol in the plasma. The accumulation of cholesterol esters in the arterial intima is a characteristic feature of atherosclerosis. Cholesterol Ester,Cholesteryl Ester,Cholesteryl Esters,Ester, Cholesterol,Ester, Cholesteryl,Esters, Cholesterol,Esters, Cholesteryl
D002914 Chylomicrons A class of lipoproteins that carry dietary CHOLESTEROL and TRIGLYCERIDES from the SMALL INTESTINE to the tissues. Their density (0.93-1.006 g/ml) is the same as that of VERY-LOW-DENSITY LIPOPROTEINS. Chylomicron
D003314 Corn Oil Oil from ZEA MAYS or corn plant. Maize Oil,Lipomul,Corn Oils,Lipomuls,Maize Oils,Oil, Corn,Oil, Maize,Oils, Corn,Oils, Maize
D004042 Dietary Fats, Unsaturated Unsaturated fats or oils used in foods or as a food. Dietary Oils,Unsaturated Dietary Fats,Dietary Fat, Unsaturated,Dietary Oil,Fat, Unsaturated Dietary,Fats, Unsaturated Dietary,Oil, Dietary,Oils, Dietary,Unsaturated Dietary Fat
D005231 Fatty Acids, Unsaturated FATTY ACIDS in which the carbon chain contains one or more double or triple carbon-carbon bonds. Fatty Acids, Polyunsaturated,Polyunsaturated Fatty Acid,Unsaturated Fatty Acid,Polyunsaturated Fatty Acids,Acid, Polyunsaturated Fatty,Acid, Unsaturated Fatty,Acids, Polyunsaturated Fatty,Acids, Unsaturated Fatty,Fatty Acid, Polyunsaturated,Fatty Acid, Unsaturated,Unsaturated Fatty Acids
D005395 Fish Oils Oils high in unsaturated fats extracted from the bodies of fish or fish parts, especially the LIVER. Those from the liver are usually high in VITAMIN A. The oils are used as DIETARY SUPPLEMENTS. They are also used in soaps and detergents and as protective coatings. Fish Liver Oils,Fish Oil,Liver Oils, Fish,Oil, Fish,Oils, Fish,Oils, Fish Liver
D000097587 Sterol O-Acyltransferase 2 A sterol O-acyltransferase that catalyzes reaction of Acyl-CoA and cholesterol into CoA and cholesterol ester. It is a distinct enzyme from Acetyl-CoA C-Acetyltransferase 2, which is also referred to as ACAT2. Acyl-CoA Cholesterol Acyltransferase-2,Acyl-Coenzyme A:Cholesterol Acyltransferase 2 (ACAT-2),Acyl-Coenzyme A:Cholesterol Acyltransferase 2 (ACAT2),SOAT-2 Protein,SOAT2 Protein

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