title: Inhibitory effect of cholesterol oxides on low density lipoprotein receptor gene expression.
abstract: The effects of the cholesterol oxides on low density lipoprotein receptor (LDLR) gene expression were investigated. Cultured rabbit aortic smooth muscle cells were incubated with 1, 2, and 5 micrograms/ml culture medium concentrations of pure cholesterol, 25-hydroxycholesterol (25-OH), 7-ketocholesterol (7-keto), cholestane-3 beta, 5 alpha, 6 beta-triol (triol) and cholesterol-5 alpha, 6 alpha-epoxide (epoxide) for 12 hours and with vehicle only as control. Total mRNAs were extracted and electrophoresed. Northern blot hybridization analyses were performed. The results showed mRNA expressions of LDLR gene were inhibited to 16.1 +/- 4.4%, 33.8 +/- 0.6%, 42.8 +/- 1.8% and 46.9 +/- 3.9% of control by 25-OH, 7-keto, epoxide and triol respectively. Pure cholesterol showed only minimal inhibition. The inhibitions were time dependent. Although cholesterol oxides have been shown to alter many membrane-related functions and the LDLR domain are located in the cell membrane. The findings of this study suggested that the cholesterol oxides exerted their repressive actions on LDLR function primarily by down-regulating LDLR gene expression rather than directly upon cell membrane.
authors.affiliation: Department of Pathology and Laboratory Medicine, UCLA School of Medicine, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Peng
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: N N
authors.initials: NN
authors.lastname: Chai
authors.forename: Y
authors.initials: Y
authors.lastname: Wan
authors.forename: R J
authors.initials: RJ
authors.lastname: Morin
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D002478:Cells, Cultured; D002777:Cholestanols / Q000494:pharmacology; D002784:Cholesterol / Q000031:analogs & derivatives / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006888:Hydroxycholesterols / Q000494:pharmacology*; D007653:Ketocholesterols / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D018110:Receptors, Lipoprotein / Q000235:genetics* / Q000378:metabolism
chemical_list: D002777:Cholestanols; D006888:Hydroxycholesterols; D007653:Ketocholesterols; D012333:RNA, Messenger; D018110:Receptors, Lipoprotein; C000474:cholestane-3,5,6-triol; C002415:cholesterol alpha-oxide; C007997:25-hydroxycholesterol; D002784:Cholesterol; C003001:7-ketocholesterol