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Journal of Lipid Research, Vol. 48, 1167-1174, May 2007
Copyright © 2007 by American Society for Biochemistry and Molecular Biology





* Institute of Pathophysiology, Center of Molecular Medicine, Medical University of Graz, Graz, Austria
Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Graz, Austria
Division of Clinical Chemistry, Karolinska University Hospital, Karolinska Institutet, Huddinge, Sweden
Published, JLR Papers in Press, February 26, 2007.
1 To whom correspondence should be addressed. e-mail: ingemar.bjorkhem{at}karolinska.se
The most serious consequence of sterol 27-hydroxylase deficiency in humans [cerebrotendinous xanthomatosis (CTX)] is the development of cholestanol-containing brain xanthomas. The cholestanol in the brain may be derived from the circulation or from 7
-hydroxylated intermediates in bile acid synthesis, present at 50- to 250-fold increased levels in plasma. Here, we demonstrate a transfer of 7
-hydroxy-4-cholesten-3-one across cultured porcine brain endothelial cells (a model for the blood-brain barrier) that is
100-fold more efficient than the transfer of cholestanol. Furthermore, there was an efficient conversion of 7
-hydroxy-4-cholesten-3-one to cholestanol in cultured neuronal and glial cells as well as in monocyte-derived macrophages of human origin. It is concluded that the continuous intracellular production of cholestanol from a bile acid precursor capable of rapidly passing biomembranes, including the blood-brain barrier, is likely to be of major importance for the accumulation of cholestanol in patients with CTX. Such a mechanism also fits well with the observation that treatment with chenodeoxycholic acid, which normalizes the level of the bile acid precursor, results in a reduction of cholestanol-containing xanthomas even in the brain.
Supplementary key words blood-brain barrier brain xanthomas brain endothelial cells
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