Clock mutation facilitates accumulation of cholesterol in the liver of mice fed a cholesterol and/or cholic acid diet

Takashi Kudo, Mihoko Kawashima, Toru Tamagawa, Shigenobu Shibata

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    Abstract

    Cholesterol (CH) homeostasis in the liver is regulated by enzymes of CH synthesis such as 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and catabolic enzymes such as cytochrome P-450, family 7, subfamily A, and polypeptide 1 (CYP7A1). Since a circadian clock controls the gene expression of these enzymes, these genes exhibit circadian rhythm in the liver. In this study, we examined the relationship between a diet containing CH and/or cholic acid (CA) and the circadian regulation of Hmgcr, low-density lipoprotein receptor (Ldlr), and Cyp7a1 gene expression in the mouse liver. A 4-wk CA diet lowered and eventually abolished the circadian expression of these genes. Not only clock genes such as period homolog 2 (Drosophila) (Per2) and brain and muscle arnt-like protein-1 (Bmal1) but also clock-controlled genes such as Hmgcr, Ldlr, and Cyp7a1 showed a reduced and arrhythmic expression pattern in the liver of Clock mutant mice. The reduced gene expression of Cyp7a1 in mice fed a diet containing CA or CH + CA was remarkable in the liver of Clock mutants compared with wild-type mice, and high liver CH accumulation was apparent in Clock mutant mice. In contrast, a CH diet without CA only elevated Cyp7a1 expression in both wild-type and Clock mutant mice. The present findings indicate that normal circadian clock function is important for the regulation of CH homeostasis in the mouse liver, especially in conjunction with a diet containing high CH and CA.

    Original languageEnglish
    JournalAmerican Journal of Physiology - Endocrinology and Metabolism
    Volume294
    Issue number1
    DOIs
    Publication statusPublished - 2008 Jan

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    Keywords

    • Cholesterol-7α-hydroxylase
    • Circadian
    • Clock mutant mice

    ASJC Scopus subject areas

    • Physiology
    • Endocrinology
    • Biochemistry

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