Abstract
24-Hydroxycholesterol (24-OHChol) is a major cholesterol metabolite and the form in which cholesterol is secreted from the brain. 24-OHChol is transported by apolipoprotein E to the liver and converted into bile acids or excreted. In both brain and liver, 24-OHChol is a liver X receptor (LXR) agonist and has an important role in cholesterol homeostasis. 24-OHChol sulfation was examined to understand its role in 24-OHChol metabolism and its effect on LXR activation. 24-OHChol was conjugated by three isoforms of human cytosolic sulfotransferase (SULT). SULT2A1 and SULT1E1 sulfated both the 3- and 24-hydroxyls to form the 24-OHChol-3, 24-disulfate. SULT2B1b formed only 24-OHChol-3-sulfate. The 3-sulfate as a monosulfate or as the disulfate was hydrolyzed by human placental steroid sulfatase, whereas the 24-sulfate was resistant. At physiological 24-OHChol concentrations, SULT2A1 formed the 3-monosulfate and the 3, 24-disulfate as a result of a high affinity for sulfation of the 3-OH in 24-OHChol-24-sulfate. Molecular docking simulations indicate that 24-OHChol-24-sulfate binds in an active configuration in the SULT2A1 substrate binding site with high affinity only when the SULT2A1 homodimer structure was used. 24-OHChol is an LXR activator. In contrast, the 24-OHChol monosulfates were not LXR agonists in a fluorescence resonance energy transfer coactivator recruitment assay. However, both the 24-OHChol-3-sulfate and 24-sulfate were antagonists of LXR activation by N-(2,2,2-trifluoroethyl)-N-[4-[2,2,2-trif-luoro-1-hydroxy-1-(trifluoromethyl)ethyl]phenyl]-benzenesulfonamide (T0901317) with an IC50 of 0.15 and 0.31 μM, respectively. Inhibition of LXR activation by the 24-OHChol monosulfates at low nanomolar concentrations indicates that sulfation has a role in LXR regulation by oxysterols.
- 24-OHChol, 24(S)-hydroxycholesterol
- OAT, organic anion transporter
- ApoE, apolipoprotein E
- LXR, liver X receptor
- SULT, sulfotransferase
- PAPS, 3′-phosphoadenosine-5′-phosphosulfate
- STS, steroid sulfatase C
- DHEA, dehydroepiandrosterone
- E2, β-estradiol
- TLC, thin-layer chromatography
- T0901317, N-(2,2,2-trifluoroethyl)-N-[4-[2,2,2-trifluoro-1-hydroxy-1-(trifluoromethyl)ethyl]phenyl]-benzenesulfonamide
- TR-FRET, time-resolved fluorescence resonance energy transfer
- BFE, binding free energy
- MS/MS, tandem mass spectrometry
- DMSO, dimethyl sulfoxide
- LC, liquid chromatography.
Footnotes
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This work was supported in part by the National Institutes of Health National Institute of General Medical Sciences [Grant GM38953]; the National Institutes of Health National Institute of Environmental Health Sciences [Grant ES05823]; the National Institutes of Health National Heart, Lung, and Blood Institute [Grant HL050710]; and the Environmental Health Sciences Center [Grant ES06636].
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Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
↵ The online version of this article (available at http://dmd.aspetjournals.org) contains supplemental material.
- Received March 13, 2009.
- Accepted July 6, 2009.
- Copyright © 2009 by The American Society for Pharmacology and Experimental Therapeutics
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