On the mechanism of accumulation of cholestanol in the brain of mice with a disruption of sterol 27-hydroxylase |
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Authors: | Ann B?vner Marjan Shafaati Magnus Hansson Maria Olin Shoshi Shpitzen Vardiella Meiner Eran Leitersdorf Ingemar Bj?rkhem |
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Affiliation: | *Department of Laboratory Medicine, Division of Clincial Chemistry, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden;†Department of Medicine B, Hadassah-Hebrew University Hospital, Israel;§Department of Human Genetics, Hadassah-Hebrew University Hospital, Israel |
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Abstract: | The rare disease cerebrotendinous xanthomatosis (CTX) is due to a lack of sterol 27-hydroxylase (CYP27A1) and is characterized by cholestanol-containing xanthomas in brain and tendons. Mice with the same defect do not develop xanthomas. The driving force in the development of the xanthomas is likely to be conversion of a bile acid precursor into cholestanol. The mechanism behind the xanthomas in the brain has not been clarified. We demonstrate here that female cyp27a1−/− mice have an increase of cholestanol of about 2.5- fold in plasma, 6-fold in tendons, and 12-fold in brain. Treatment of cyp27a1−/− mice with 0.05% cholic acid normalized the cholestanol levels in tendons and plasma and reduced the content in the brain. The above changes occurred in parallel with changes in plasma levels of 7α-hydroxy-4-cholesten-3-one, a precursor both to bile acids and cholestanol. Injection of a cyp27a1−/− mouse with 2H7-labeled 7α-hydroxy-4-cholesten-3-one resulted in a significant incorporation of 2H7-cholestanol in the brain. The results are consistent with a concentration-dependent flux of 7α-hydroxy-4-cholesten-3-one across the blood-brain barrier in cyp27a1−/− mice and subsequent formation of cholestanol. It is suggested that the same mechanism is responsible for accumulation of cholestanol in the brain of patients with CTX. |
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Keywords: | CYP27A1, 7α -hydroxy-4-cholesten-3-one, blood-brain barrier, tendon xanthomas |
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