Lysosomal acid lipase in cultivated fibroblasts: Characterization of enzyme activity in normal and enzymatically deficient cell lines

Burton, Barbara K.; Emery, David C.; Mueller, Howard W.

doi:10.1016/0009-8981(80)90052-2

Cited by 33 publications

(12 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These findings are in agreement with those by other investigators (Cortner et al, 1976;Burton et al, 1980;Hoeg et a!., 1982), although one group reported that neutral lipase activity was depressed in Wolman disease fibroblasts (Messiah et al, 1983). A large fraction of the 4-MeUmb oleate hydrolase activity in Wolman disease fibroblast extracts is attributable to an acid phospholipase A, which is separable from the acid lipase/cholesteryl ester hydrolase by hydrophobic chromatography (Sando and Rosenbaum, 1985), is not reactive with anti-lipase antibodies, and is inactivated by treatment with high thiol concentrations (Sando and Schlom, unpublished).…”

Section: Resultssupporting

confidence: 83%

Intercellular transport of lysosomal acid lipase mediates lipoprotein cholesteryl ester metabolism in a human vascular endothelial cell-fibroblast coculture system.

et al. 1990

View full text Add to dashboard Cite

We present results from studies of human cell culture models to support the premise that the extracellular transport of lysosomal acid lipase has a function in lipoprotein cholesteryl ester metabolism in vascular tissue. Vascular endothelial cells secreted a higher fraction of cellular acid lipase than did smooth muscle cells and fibroblasts. Acid lipase and lysosomal jl-hexosaminidase were secreted at approximately the same rate from the apical and basolateral surface of an endothelial cell monolayer. Stimulation of secretion with NH4CI did not affect the polarity. We tested for the ability of secreted endothelial lipase to interact with connective tissue cells and influence lipoprotein cholesterol metabolism in a coculture system in which endothelial cells on a micropore filter were suspended above a monolayer of acid lipase-deficient (Wolman disease) fibroblasts. After 5-7 d, acid lipase activity in the fibroblasts reached 10 %-20% of the level in normal cells; cholesteryl esters that had accumulated from growth in serum were cleared. Addition of mannose 6-phosphate to the coculture medium blocked acid lipase uptake and cholesterol clearance, indicating that lipase released from endothelial cells was packaged into fibroblast lysosomes by a phosphomannosyl receptor-mediated pathway. Supplementation of the coculture medium with serum was not required for lipase uptake and cholesteryl ester hydrolysis by the fibroblasts, but was necessary for cholesterol clearance.Results from our coculture model suggest that acid lipase may be transported from intact endothelium to cells in the lumen or the wall of a blood vessel. We postulate that delivery of acid hydrolases and lipoproteins to a common endocytic compartment may occur and have an impact on cellular lipoprotein processing. IntroductionWe are studying the extracellular transport of lysosomal acid lipase in human cell culture models of vascular tissue to determine its role in lipoprotein cholesteryl ester metabolism and to learn how it relates to the abnormal lysosomal hydrolase activity and lipid accumulation that are characteristic of atherogenesis. Lysosomal acid lipase, also termed acid cholesteryl ester hydrolase, or cholesterol esterase (3.1.1.13), is critical for the hydrolysis of triglycerides and cholesteryl esters that cells acquire by receptormediated endocytosis of lipoproteins (Goldstein and Brown, 1977). A hereditary deficiency of acid lipase activity, in patients with Wolman disease-or the clinically less severe condition, cholesteryl ester storage disease-is characterized by accumulation of esterified cholesterol

show abstract

Section: Resultssupporting

confidence: 83%

Intercellular transport of lysosomal acid lipase mediates lipoprotein cholesteryl ester metabolism in a human vascular endothelial cell-fibroblast coculture system.

et al. 1990

View full text Add to dashboard Cite

show abstract

“…Since the original reports of hepatic acid hydrolase deficiency in WD (20) and of acid lipase deficiency in CESD (2,22), several laboratories have reported very low acid hydrolase activities in cultured fibroblasts from WD or CESD subjects using either natural or artificial substrates (1,3,6,10). Neutral lipase activity has rarely been examined.…”

Section: Discussionmentioning

confidence: 99%

“…Wolman's disease Several investigators have described lipase activity with an acid pH optimum (3.5-4.5) in homogenates or subcellular fractions of cultured mammalian fibroblasts (1,3,(12)(13)(14)19). Tri-and diacylglycerols, cholesterol ester, and pnitrophenyl or Cmethylumbelliferyl-linked fatty acids are substrates.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Abnormal Neutral Lipase Activity in Acid-Lipase-Deficient Cultured Human Fibroblasts

et al. 1983

View full text Add to dashboard Cite

Acid and neutral lipase activities of homogenized or sonicated cultured fibroblasts were examined using [taHjglycerol triolein, glycerol tri[1-14CJoleate or cholesterol [l-14Clokate as substrates.In normal fibroblasts, optimal conditions for acid lipase activity were pH 4.5-5.0,0.15-0.2 m M triacylglycerol, and 0.25% Triton X-100. Fatty acid release was b a r to 2 h and between 0.2-2.0 mg fibroblast protein/ml. For the neutral lipase, activity was optimal at pH 6.0-7.0, >1.5 m M triacylglycerol or cholesterol oleate (suspended in 8 mg albumin/ml), and 160 pg pbosphatidylserine/ml. The reaction was b e a r to 60-120 min, and up to 1.0 mg protein/ml. In contrast to the situation at neutral pH, very little ["] and was less than 25% of controls when cholesterol oleate was the substrate. Neutral lipase activity in mixtures of conbol and WD fibroblast homogenates was similar to that predicted from individual activities. The triacylglycerol content of the control and mutant cells was within normal limits, and cbdesterol content was only slightly elevated, indicating that endogenous dilution of substrate was not the reason for the low activity in mutant cells. Hydrolysis of labeled endogenous triacylglyced was reduced by >75-80R, in the WD cells, indicating that low levels of activity measured with the exogenous substrate were not due solely to lack of accessibiUty to the neutral lipase. These results suggest a close relathmship between the acid and neutral activities of the normal cell in that mutations which affect one apparently affect the activity of the other.Abbreviations CESD, cholesterol ester storage disease FCS, fetal calf serum MEM, minimal essential medium WD. Wolman's disease Several investigators have described lipase activity with an acid pH optimum (3.5-4.5) in homogenates or subcellular fractions of cultured mammalian fibroblasts (1,3,(12)(13)(14)19). Tri-and diacylglycerols, cholesterol ester, and pnitrophenyl or Cmethylumbelliferyl-linked fatty acids are substrates. The acid lipase activity is probably localized in lysosomes (16) and is deficient in two human inherited diseases of neutral lipid metabolism, WD, and CESD (2,20). Although the clinical phenotype is quite different, both diseases are characterized by the intralysosomal accumulation of triacylglycerol and cholesterol esters (8).There is less certainty about the presence and relative amounts of other fibroblast lipases active with triacylglycerol and/or cholesterol esters. Several studies of acid lipase activity, in which the effects of pH on activity included the neutral range, have found very little or no detectable neutral activity (1, 3, 9). On the other hand, at least three studies have clearly demonstrated fibroblast l i p activities with pH optima in the neutral range. Lengle and Geyer (14) reported three pH optima (pH 4.5, 6.5, and 8.5) for lipase activities in mouse fibroblasts; 80% of the activity was at pH 6.5 and was localized in the cytosol. Oram et al. (19) also reported three pH optima (pH 4, 6, and 8) for lipase activities ...

show abstract

“…In most studies, less than 5% of control activity has been observed (4,6). Differences in residual activity that might account for the differing phenotypes in the two disorders have not been consistently demonstrated.…”

mentioning

confidence: 99%

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

1984

View full text Add to dashboard Cite

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

show abstract

Lysosomal acid lipase in cultivated fibroblasts: Characterization of enzyme activity in normal and enzymatically deficient cell lines

Cited by 33 publications

References 10 publications

Intercellular transport of lysosomal acid lipase mediates lipoprotein cholesteryl ester metabolism in a human vascular endothelial cell-fibroblast coculture system.

Intercellular transport of lysosomal acid lipase mediates lipoprotein cholesteryl ester metabolism in a human vascular endothelial cell-fibroblast coculture system.

Abnormal Neutral Lipase Activity in Acid-Lipase-Deficient Cultured Human Fibroblasts

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

Contact Info

Product

Resources

About