Markedly reduced bile acid synthesis but maintained levels of cholesterol and vitamin D metabolites in mice with disrupted sterol 27-hydroxylase gene

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Item Type:	Article
Title:	Markedly reduced bile acid synthesis but maintained levels of cholesterol and vitamin D metabolites in mice with disrupted sterol 27-hydroxylase gene
Creators Name:	Rosen, H., Reshef, A., Maeda, N., Lippoldt, A., Shpizen, S., Triger, L., Eggertsen, G., Bjorkhem, I. and Leitersdorf, E.
Abstract:	Sterol 27-hydroxylase is important for the degradation of the steroid side chain in conversion of cholesterol into bile acids and has been ascribed a regulatory role in cholesterol homeostasis. Its deficiency causes the autosomal recessive disease cerebrotendinous xanthomatosis (CTX), characterized by progressive dementia, xanthomatosis, and accelerated atherosclerosis. Mice with a disrupted cyp27 (cyp27(-/-)) had normal plasma levels of cholesterol, retinol, tocopherol, and 1,25-dihydroxyvitamin D. Excretion of fecal bile acids was decreased (<20% of normal), and formation of bile acids from tritium-labeled 7alpha-hydroxycholesterol was less than 15% of normal. Compensatory up-regulation of hepatic cholesterol 7alpha-hydroxylase and hydroxymethylglutaryl-CoA reductase (9- and 2-3-fold increases in mRNA levels, respectively) was found. No CTX-related pathological abnormalities were observed. In CTX, there is an increased formation of 25-hydroxylated bile alcohols and cholestanol. In bile and feces of the cyp27(-/-) mice only traces of bile alcohols were found, and there was no cholestanol accumulation. It is evident that sterol 27-hydroxylase is more important for bile acid synthesis in mice than in humans. The results do not support the contention that 27-hydroxylated steroids are critical for maintenance of cholesterol homeostasis or levels of vitamin D metabolites in the circulation.
Keywords:	Bile, Bile Acids and Salts, Carotenoids, Cerebrotendinous Xanthomatosis, Cholestanetriol 26-Monooxygenase, Cholesterol, Cytochrome P-450 Enzyme System, Feces, Gas Chromatography-Mass Spectrometry, Gene Targeting, Hydroxycholesterols, Steroid Hydroxylases, Sterols, Vitamin D, Vitamins, Animals, Mice
Source:	Journal of Biological Chemistry
ISSN:	0021-9258
Publisher:	American Society for Biochemistry and Molecular Biology
Volume:	273
Number:	24
Page Range:	14805-14812
Date:	June 1998
Official Publication:	https://doi.org/10.1074/jbc.273.24.14805
PubMed:	View item in PubMed

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