Human endothelial cells in primary culture incorporation of acetate and mevalonate into lipids

Abstract

Incorporation of [2- 14C]mevalonate and [2- 14C]acetate into lipids was measured in primary cultures of human endothelial cells isolated from the intima of umbilical veins. (1) In culture medium supplemented with 20% (v/v) serum, the removal of lipid or lipoproteins stimulated the conversion of acetate into sterols, while incorporation into the fatty acid and esterified sterol fractions decreased. (2) Mevalonate incorporation into sterols also increased significantly, indicating feedback inhibition at postmevalonate steps. (3) A labeled fatty acid fraction obtained after incubation with labeled mevalonate confirms that mevalonate also can serve as a substrate for fatty acids. (4) When incorporation into sterols was stimulated by lipoprotein removal, labeled sterols accumulated mainly intracellularly when either acetate or mevalonate was used as precursor. Thus endothelial cells are sensitive to the same negative feedback control mechanisms previously demonstrated in skin fibroblasts and smooth muscle cells.