Conversion of 7-ketocholesterol to oxysterol metabolites by recombinant CYP27A1 and retinal pigment epithelial cells

Journal of Lipid Research
2011.0

Abstract

Of the different oxygenated cholesterol metabolites, 7-ketocholesterol (7KCh) is considered a noxious oxy-sterol 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, 3β,27-dihydroxy-5-cholesten-7-one (7KCh-27OH) and 3β-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.

Knowledge Graph

Similar Paper

Conversion of 7-ketocholesterol to oxysterol metabolites by recombinant CYP27A1 and retinal pigment epithelial cells
Journal of Lipid Research 2011.0
Induction of CYP26A1 by Metabolites of Retinoic Acid: Evidence That CYP26A1 Is an Important Enzyme in the Elimination of Active Retinoids
Molecular Pharmacology 2015.0
Metabolism of 4β-Hydroxycholesterol in Humans
Journal of Biological Chemistry 2002.0
Metabolism of vitamin D by human microsomal CYP2R1
Biochemical and Biophysical Research Communications 2004.0
Inhibition of Human Sterol Δ7-Reductase and Other Postlanosterol Enzymes by LK-980, a Novel Inhibitor of Cholesterol Synthesis
Drug Metabolism and Disposition 2011.0
Measurement of oxysterols and α-tocopherol in plasma and tissue samples as indices of oxidant stress status
Analytical Biochemistry 2003.0
Exploration of Long-Chain Vitamin E Metabolites for the Discovery of a Highly Potent, Orally Effective, and Metabolically Stable 5-LOX Inhibitor that Limits Inflammation
Journal of Medicinal Chemistry 2021.0
Identification of Human Hepatic Cytochrome P450 Enzymes Involved in the Biotransformation of Cholic and Chenodeoxycholic Acid
Drug Metabolism and Disposition 2008.0
CYP4F Enzymes Are Responsible for the Elimination of Fingolimod (FTY720), a Novel Treatment of Relapsing Multiple Sclerosis
Drug Metabolism and Disposition 2011.0
The Effect of Small Molecules on Sterol Homeostasis: Measuring 7-Dehydrocholesterol in Dhcr7-Deficient Neuro2a Cells and Human Fibroblasts
Journal of Medicinal Chemistry 2016.0