title: Metabolism of oxysterols derived from nonenzymatic oxidation of 7-dehydrocholesterol in cells.
abstract: Recent studies suggest that 7-dehydrocholesterol (7-DHC)-derived oxysterols play important roles in the pathophysiology of Smith-Lemli-Opitz syndrome (SLOS), a metabolic disorder that is caused by defective 3β-hydroxysterol-Δ(7)-reductase (DHCR7). Although 14 oxysterols have been identified as the primary products of 7-DHC autoxidation in organic solution, the metabolic fate of these oxysterols in a biological environment has not yet been elucidated. Therefore, we incubated these primary 7-DHC oxysterols in control Neuro2a and control human fibroblast cells and identified metabolites of these oxysterols by HPLC-MS. We also incubated Dhcr7-deficient Neuro2a cells and fibroblasts from SLOS patients with isotopically labeled 7-DHC (d(7)-7-DHC). The observation of matching d(0)- and d(7) peaks in HPLC-MS confirmed the presence of true metabolites of 7-DHC after excluding the possibility of ex vivo oxidation. The metabolites of primary 7-DHC oxysterols were found to contribute to the majority of the metabolic profile of 7-DHC in cells. Furthermore, based on this new data, we identified three new 7-DHC-derived metabolites in the brain of Dhcr7-KO mice. Our studies suggest that 7-DHC peroxidation is a major source of oxysterols observed in cells and in vivo and that the stable metabolites of primary 7-DHC oxysterols can be used as markers of 7-DHC peroxidation in these biological systems.
authors: Department of Chemistry and Vanderbilt Institute of Chemical Biology and, Vanderbilt University, Nashville, TN 37235, USA. libin.xu@vanderbilt.edu
authors: Libin
authors: L
authors: Xu
authors: Zeljka
authors: Z
authors: Korade
authors: Dale A
authors: DA
authors: Rosado
authors: Karoly
authors: K
authors: Mirnics
authors: Ned A
authors: NA
authors: Porter
mesh_terms: D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003684:Dehydrocholesterols / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D050356:Lipid Metabolism / Q000502:physiology; D013058:Mass Spectrometry; D051379:Mice; D018345:Mice, Knockout; D010084:Oxidation-Reduction; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000172:deficiency / Q000235:genetics; D053719:Tandem Mass Spectrometry
chemical_list: D003684:Dehydrocholesterols; C016705:7-dehydrocholesterol; D044925:Oxidoreductases Acting on CH-CH Group Donors; C019995:7-dehydrocholesterol reductase
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