The cholesterol storage disorder of the mutant BALB/c mouse. A primary genetic lesion closely linked to defective esterification of exogenously derived cholesterol and its relationship to human type C Niemann-Pick disease

Abstract

An inborn murine cholesterol storage disorder exists which is characterized by a lesion in intracellular cholesterol esterification not accounted for by any discernible abnormality in acyl-CoA: cholesterol acyltransferase (Pentchev, P.G., Boothe, A.D., Kruth, H.S., Weintroub, H., Stivers, J., and Brady, R.O. (1984) J. Biol. Chem. 259, 5784-5791). Current studies have shown that the level of esterification of nonlipoprotein-derived [3H]cholesterol in cultured fibroblasts from heterozygous mutant mice was intermediary between the level found in normal fibroblasts and the deficient level found in fibroblasts from homozygous mutant mice. Homozygous-affected fibroblasts took up and converted [3H]desmosterol to [3H]cholesterol at a normal rate indicating that the murine mutation does not compromise the transport of exogenous sterol to microsomes. In contrast to the defect in esterification of exogenously derived cholesterol, synthesis of cholesteryl ester from [3H]mevalonic acid and [3H]squalene was normal in affected fibroblasts as was the stimulation of cholesteryl ester synthesis from endogenous cholesterol induced by 25-hydroxycholesterol. In surveying a number of mutant cell lines from human metabolic disorders with phenotypic manifestations similar in part to the mutant cholesterol storage mouse, Niemann-Pick C fibroblasts displayed a similar defect in esterification of exogenously derived cholesterol.