title: LDL downregulates CYP51 in porcine vascular endothelial cells and in the arterial wall through a sterol regulatory element binding protein-2-dependent mechanism.
abstract: Hypercholesterolemia is associated with endothelial dysfunction and atherosclerotic lesion formation. By mRNA-differential display analysis, we have identified lanosterol 14alpha-demethylase (CYP51) as a gene highly regulated by native LDLs (nLDLs) in endothelial cells. CYP51 is a cytochrome P-450 enzyme involved in the postsqualene phases of cholesterol biosynthesis. CYP51 mRNA levels decrease in nLDL-treated cells in a dose- and time-dependent manner (9-fold after 24 hours with 180 mg of LDL cholesterol per deciliter), an effect that is blocked by cycloheximide. In parallel, sterol regulatory element (SRE) binding protein-2 (SREBP-2) expression falls (10-fold), without alteration in SREBP-1 level. N:-Acetyl-leucyl-leucyl-norleucinal, which inhibits catabolism of the active form of SREBPs, abolished the effect of high concentrations of nLDL on CYP51 expression. Gel-shift assays performed with the SRE of the cyp51 gene (cyp51-SRE) revealed a diminished SREBP-SRE interaction in LDL-treated cells. Moreover, nLDLs downregulate CYP51 promoter activity in transfection assays. Thus, atherogenic levels of nLDL downregulate endothelial CYP51 mRNA levels through a reduction in SRE-SREBP-2 interaction. Additionally, SREBP-2 and CYP51 mRNA levels are decreased in the arterial wall of hypercholesterolemic pigs. In summary, we have described for the first time, both in in vivo and in vitro systems, that CYP51 is expressed in the vascular wall and that it is downregulated together with SREBP-2 by high levels of nLDL. Because this transcription factor controls multiple cell lipid metabolism pathways, its regulation by nLDL could play a key role in lipid-mediated endothelial dysfunction.
authors.affiliation: Cardiovascular Research Center, Instituto de Investigaciones Biomédicas de Barcelona/Consejo Superior de Investigaciones Cientificas-Institut de Recerca Hospital de la Santa Creu i Sant Pau-UAB, Barcelona, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Rodríguez
authors.forename: J
authors.initials: J
authors.lastname: Martínez-González
authors.forename: S
authors.initials: S
authors.lastname: Sánchez-Gómez
authors.forename: L
authors.initials: L
authors.lastname: Badimon
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D001665:Binding Sites; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006937:Hypercholesterolemia / Q000097:blood / Q000235:genetics; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008055:Lipids / Q000097:blood; D008077:Lipoproteins, LDL / Q000378:metabolism / Q000494:pharmacology*; D008156:Luciferases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D058886:Sterol 14-Demethylase; D051782:Sterol Regulatory Element Binding Protein 2; D013552:Swine; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D008055:Lipids; D008077:Lipoproteins, LDL; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D051782:Sterol Regulatory Element Binding Protein 2; D014157:Transcription Factors; D005576:Colforsin; D003577:Cytochrome P-450 Enzyme System; D003513:Cycloheximide; D010088:Oxidoreductases; D008156:Luciferases; D058886:Sterol 14-Demethylase; D007930:Leucine