Conversion of 7-ketocholesterol to oxysterol metabolites by recombinant CYP27A1 and retinal pigment epithelial cells
Conversion of 7-ketocholesterol to oxysterol metabolites by recombinant CYP27A1 and retinal pigment epithelial cells
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DOI：
10.1194/jlr.m014217
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发表时间：
2011-06-01
影响因子：
6.5
通讯作者：
Pikuleva, Irina A.
中科院分区：
文献类型：
--
作者：
Heo, Gun-Young;Bederman, Ilya;Pikuleva, Irina A.
在不同的含氧胆固醇代谢物中，7-酮胆固醇 (7KCh) 被认为是一种有毒的氧甾醇，与某些病理学的发展有关，包括在眼睛中发现的病理学。在这里，我们阐明了甾醇 27-羟化酶细胞色素 P450 27A1 (CYP27A1) 是否参与从眼睛后部：神经视网膜和下面的视网膜色素上皮 (RPE) 消除 7KCh。我们首先确定纯化的重组 CYP27A1 对 7KCh 及其内源底物胆固醇的亲和力相似，但在体外重组系统中 7KCh 的代谢速率比胆固醇高 4 倍。然后通过同位素稀释 GC-MS 分析牛神经视网膜和 RPE 的脂质提取物中是否存在 7KCh 衍生的氧化甾醇。在 RPE 中检测到两种代谢物，3β,27-二羟基-5-胆甾烯-7-酮 (7KCh-27OH) 和 3β-羟基-5-胆甾烯-7-一-26-油酸 (7KCh-27COOH)，但在神经视网膜中未检测到。当 RPE 匀浆补充 NADPH 和线粒体氧化还原系统时，也会形成 7KCh-27OH。人类 RPE 的定量表明，CYP27A1 在 RPE 中的表达水平确实比神经视网膜中高 2-4 倍。获得的数据代表了 CYP27A1 在 7KCh 视网膜代谢中作用的证据，并表明，除了去除胆固醇之外，该酶的功能还可能包括消除有毒的内源性化合物。-Heo，G-Y.，I. Bederman，N. Mast，W-L。廖、I.V. Turko 和 I.A. Pikuleva。重组 CYP27A1 和视网膜色素上皮细胞将 7-酮胆固醇转化为氧甾醇代谢物。 J.脂质研究。 2011。52：1117-1127。
Of the different oxygenated cholesterol metabolites, 7-ketocholesterol (7KCh) is considered a noxious oxysterol implicated in the development of certain pathologies, including those found in the eye. Here we elucidated whether sterol 27-hydroxylase cytochrome P450 27A1 (CYP27A1) is involved in elimination of 7KCh from the posterior part of the eye: the neural retina and underlying retinal pigment epithelium (RPE). We first established that the affinities of purified recombinant CYP27A1 for 7KCh and its endogenous substrate cholesterol are similar, yet 7KCh is metabolized at a 4-fold higher rate than cholesterol in the reconstituted system in vitro. Lipid extracts from bovine neural retina and RPE were then analyzed by isotope dilution GC-MS for the presence of the 7KCh-derived oxysterols. Two metabolites, 3 beta,27-dihydroxy-5-cholesten-7-one (7KCh-27OH) and 3 beta-hydroxy-5-cholesten-7-one-26-oic acid (7KCh-27COOH), were detected in the RPE but not in the neural retina. 7KCh-27OH was also formed when RPE homogenates were supplemented with NADPH and the mitochondrial redox system. Quantifications in human RPE showed that CYP27A1 is indeed expressed in the RPE at 2-4-fold higher levels than in the neural retina. The data obtained represent evidence for the role of CYP27A1 in retinal metabolism of 7KCh and suggest that, in addition to cholesterol removal, the functions of this enzyme could also include elimination of toxic endogenous compounds.-Heo, G-Y., I. Bederman, N. Mast, W-L. Liao, I. V. Turko, and I. A. Pikuleva. Conversion of 7-ketocholesterol to oxysterol metabolites by recombinant CYP27A1 and retinal pigment epithelial cells. J. Lipid Res. 2011. 52: 1117-1127.