文章基本信息

标题：Biosynthesis of the regulatory oxysterol, 5-cholesten-3{beta},25-diol 3-sulfate, in hepatocytes
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作者：Li, Xiaobo ; Pandak, William M. ; Erickson, Sandra K. 等
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2007
卷号：48
期号：12
页码：2587-2596
DOI：10.1194/jlr.M700301-JLR200
出版社：American Society for Biochemistry and Molecular Biology
摘要：Cellular cholesterol homeostasis is maintained through coordinatedregulation of cholesterol synthesis, degradation, and secretion.Nuclear receptors for oxygenated cholesterol derivatives (oxysterols)are known to play key roles in the regulation of cholesterolhomeostasis. We recently identified a sulfated oxysterol, 5-cholesten-3ß,25-diol3-sulfate (25HC3S), that is localized to liver nuclei. The presentstudy reports a biosynthetic pathway for 25HC3S in hepatocytes.Assays using mitochondria isolated from rats and sterol 27-hydroxylase(Cyp27A1) gene knockout mice indicated that 25-hydroxycholesterol(25HC) is synthesized by CYP27A1. Incubation of cholesterolor 25HC with mitochondrial and cytosolic fractions in the presenceof 3'-phosphoadenosyl 5'-phosphosulfate resulted in the synthesisof 25HC3S. Real-time RT-PCR and Western blot analysis showedthe presence of insulin-regulated hydroxycholesterol sulfotransferase2B1b (SULT2B1b) in hepatocytes. 25HC3S, but not 25HC, decreasedSULT2B1b mRNA and protein levels. Specific small interferingRNA decreased SULT2B1b mRNA, protein, and activity levels. Thesefindings demonstrate that mitochondria synthesize 25HC, whichis subsequently 3ß-sulfated to form 25HC3S. Supplementary key words sterol 27-hydroxylase • mitochondria • 25-hydroxycholesterol • sulfated 25-hydroxycholesterol • hydroxysteroid sulfotransferase • sulfated oxysterols • cholesterol metabolism • oxysterol sulfation • oxysterol metabolism