Cholesterol Ester and Triglyceride Metabolism in Intact Fibroblasts from Patients with Wolman's Disease and Cholesterol Ester Storage Disease

Abstract

ABSTRACT. Cholesterol ester and triglyceride metabolism was examined in intact fibroblast monolayers from normal individuals and patients with Wolman's disease and cholesterol ester storage disease. Cholesterol esters were introduced into cells by incubation in medium containing [3H]cholesteryl linoleate (CL) bound to human low density lipoprotein. Triglycerides were introduced by incubation with glycerol tri[l-'4CJoleate (trjolein) bound to hunian very low-density lipoprotein. Both types of mutant cell lines accumulated the unhydrolyzed substrates to a greater extent than did normal cells with the greatest accumulation observed in Wolman's disease cells. Wolman's disease cells hydrolyzed CL at 10-22% and triolein at 11-19% the rate of normal cells; cholesterol ester storage disease cells hydrolyzed these substrates at 28-49 and 3047% the normal rate, respectively. In contrast, assays of acid lipase activity in cell lysates revealed less than 1% of control activity in both disorders. The data suggest that the mutant acid lipase present in Wolman's disease and cholesterol ester storage disease is more active in the intact cell than assays of cell lysates would indicate. In addition, the differences observed between the two disorders provide a biochemical explanation for the different phenotypes associated with the two disorders. (Pediatr Res 18:1242-1245,1984

Independence of triacylglycerol‐containing compartments in cultured fibroblasts from Wolman disease and multisystemic lipid storage myopathy

“…This low level of residual catabolic activity is in agreement with the very low value for the acid lipase determined in vitro (c 5% of control) ( fig.2). It is also consistent with the values reported by Brown et al [24] and Goldstein and coworkers [25] for degradation of cholesteryl esters, but significantly lower than that determined by Burton et al [26] who probably overestimated the apparent residual activity because of the retroendocytosis process [5] occurring at the beginning of the chase. Therefore, the severe catabolic block in Wolman fibroblasts demonstrates that triacylglycerols stored in lysosomes cannot reach, to an appreciable extent, the cytoplasmic compartment where endogenously biosynthesized triacylglycer01s are degraded at the normal rate (as shown by studying endogenous triacylglycerol catabolism).…”

Accumulated lipids, aberrant fatty acid composition and defective cholesterol ester hydrolase activity in cholesterol ester storage disease

“…20 In addition, Burton et al 21 reported the existence of a non-lysosomal hydrolysis pathway for cholesterol esters or triglycerides, in which neutral cholesterol ester hydrolase participates. Hence, two forms of hydrolysis of cholesterol esters from LDL in the liver have been identi®ed and attention has been paid to the relationship between the fatty acid composition of accumulated cholesterol esters and other lipids in the liver and the fatty acid composition of serum LDL.…”

Regulation of Lipid Droplet Cholesterol Efflux From Macrophage Foam Cells

“…CESD is a milder, later onset disorder, characterized by CE accumulation in visceral tissues; higher residual LAL activity in patients affected by CESD as compared with Wolman disease may be the basis for the milder phenotype of CESD. 28 Because efforts were concentrated on measuring candidate CEH enzymatic activity in cell-free assays, potential endocytic pathways that contribute to this process-requiring cytoskeletal integrity to transpire-were not discovered. An effective way to characterize the hydrolytic arm of the CE cycle is to incubate cells in the presence of an extracellular cholesterol acceptor and an ACAT inhibitor (to prevent cholesterol reesterification following hydrolysis), and to measure the amount of CE remaining as compared with the initial amount of cellular CE; in this way, dissipation of CE can be expressed as percentage of hydrolysis and the contribution of various enzymes/pathways to this process can be measured in a biologically relevant context, using LDs as substrate.…”