Murthy S, Albright E, Mathur S N, Field F J
Department of Internal Medicine, University of Iowa, Iowa City 52242.
J Lipid Res. 1988 Jun;29(6):773-80.
Membrane fatty acid composition of CaCo-2 cells was modified by incubating the cells for 8 days in medium containing 100 microM eicosapentaenoic acid or palmitic acid. The effect of membrane fatty acid changes on cholesterol metabolism was then studied. Cells incubated with eicosapentaenoic acid had significant changes in membrane fatty acid composition with an accumulation of 20:5 and 22:5 and a reduction in monoenoic fatty acids compared to cells grown in palmitic acid. Intracellular cholesteryl esters could not be detected in CaCo-2 cells grown in the presence of the n-3 polyunsaturated fatty acid. In contrast, cells incubated with the saturated fatty acid contained 2 micrograms/mg protein of cholesteryl esters. Cells grown in eicosapentaenoic acid, however, accumulated significantly more triglycerides compared to cells modified with palmitic acid. The rate of oleic acid incorporation into triglycerides was significantly increased in cells incubated with eicosapentaenoic acid. CaCo-2 cells modified by eicosapentaenoic acid had lower rates of HMG-CoA reductase and ACAT activities compared to cells modified with palmitic acid. The incorporation of the two fatty acids into cellular lipids also differed. Palmitic acid was predominantly incorporated into cellular triglycerides, whereas eicosapentaenoic acid was preferentially incorporated into phospholipids with 60% of it in the phosphatidylethanolamine fraction. The data indicate that membrane fatty acid composition is significantly altered by growing CaCo-2 cells in eicosapentaenoic acid. These modifications in membrane fatty acid saturation are accompanied by a decrease in the rates of cholesterol synthesis and cholesterol esterification.
通过在含有100微摩尔二十碳五烯酸或棕榈酸的培养基中培养CaCo-2细胞8天，对其膜脂肪酸组成进行了修饰。随后研究了膜脂肪酸变化对胆固醇代谢的影响。与在棕榈酸中生长的细胞相比，用二十碳五烯酸培养的细胞膜脂肪酸组成有显著变化，20:5和22:5积累，单烯脂肪酸减少。在n-3多不饱和脂肪酸存在下生长的CaCo-2细胞中未检测到细胞内胆固醇酯。相比之下，用饱和脂肪酸培养的细胞含有2微克/毫克蛋白质的胆固醇酯。然而，与用棕榈酸修饰的细胞相比，在二十碳五烯酸中生长的细胞积累的甘油三酯显著更多。在用二十碳五烯酸培养的细胞中，油酸掺入甘油三酯的速率显著增加。与用棕榈酸修饰的细胞相比，用二十碳五烯酸修饰的CaCo-2细胞的HMG-CoA还原酶和ACAT活性较低。两种脂肪酸掺入细胞脂质的情况也有所不同。棕榈酸主要掺入细胞甘油三酯，而二十碳五烯酸优先掺入磷脂，其中60%在磷脂酰乙醇胺部分。数据表明，通过在二十碳五烯酸中培养CaCo-2细胞，膜脂肪酸组成发生了显著改变。膜脂肪酸饱和度的这些改变伴随着胆固醇合成和胆固醇酯化速率的降低。
