Avart S J, Bernard D W, Jerome W G, Glick J M
Department of Molecular and Cellular Engineering, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
J Lipid Res. 1999 Mar;40(3):405-14.
The relationship of cholesteryl ester hydrolysis to the physical state of the cholesteryl ester in J774 murine macrophages was explored in cells induced to store cholesteryl esters either in anisotropic (ordered) inclusions or isotropic (liquid) inclusions. In contrast to other cell systems, the rate of cholesteryl ester hydrolysis was faster in cells containing anisotropic inclusions than in cells containing isotropic inclusions. Two contributing factors were identified. Kinetic analyses of the rates of hydrolysis are consistent with a substrate competition by co-deposited triglyceride in cells with isotropic inclusions. In addition, hydrolysis of cholesteryl esters in cells with anisotropic droplets is mediated by both cytoplasmic and lysosomal lipolytic enzymes, as shown by using the lysosomotropic agent, chloroquine, and an inhibitor of neutral cholesteryl ester hydrolase, umbelliferyl diethylphosphate. In cells containing anisotropic inclusions, hydrolysis was partially inhibited by incubation in media containing either chloroquine or umbelliferyl diethylphosphate. Together, chloroquine and umbelliferyl diethylphosphate completely inhibited hydrolysis. However, when cells containing isotropic inclusions were incubated with umbelliferyl diethylphosphate, cholesteryl ester hydrolysis was completely inhibited, but chloroquine had no effect. Transmission electron microscopy demonstrated a primarily lysosomal location for lipid droplets in cells with anisotropic droplets and both non-lysosomal and lysosomal populations of lipid droplets in cells with isotropic droplets. These results support the conclusion that there is a lysosomal component to the hydrolysis of stored cholesteryl esters in foam cells.
在诱导储存胆固醇酯于各向异性（有序）包涵体或各向同性（液态）包涵体中的J774小鼠巨噬细胞中，研究了胆固醇酯水解与胆固醇酯物理状态之间的关系。与其他细胞系统不同，含有各向异性包涵体的细胞中胆固醇酯水解速率比含有各向同性包涵体的细胞更快。确定了两个促成因素。水解速率的动力学分析与各向同性包涵体细胞中共沉积甘油三酯的底物竞争一致。此外，如使用溶酶体促渗剂氯喹和中性胆固醇酯水解酶抑制剂伞形酮基二乙基磷酸酯所示，各向异性液滴细胞中胆固醇酯的水解由细胞质和溶酶体脂解酶介导。在含有各向异性包涵体的细胞中，在含有氯喹或伞形酮基二乙基磷酸酯的培养基中孵育可部分抑制水解。氯喹和伞形酮基二乙基磷酸酯共同作用可完全抑制水解。然而，当含有各向同性包涵体的细胞与伞形酮基二乙基磷酸酯一起孵育时，胆固醇酯水解被完全抑制，但氯喹没有作用。透射电子显微镜显示，各向异性液滴细胞中脂滴主要位于溶酶体，而各向同性液滴细胞中脂滴存在非溶酶体和溶酶体群体。这些结果支持以下结论：泡沫细胞中储存的胆固醇酯水解存在溶酶体成分。
