title: Cholesterol supply and SREBPs modulate transcription of the Niemann-Pick C-1 gene in steroidogenic tissues.
abstract: We tested whether sterol-regulatory element binding proteins (SREBPs) mediate sterol-regulated transactivation of the Niemann-Pick C-1 (NPC-1) gene. Loading granulosa cells with 22- or 25-hydroxycholesterol decreased NPC-1 mRNA, whereas culturing in cholesterol-depleted medium or inhibition of cholesterol biosynthesis increased NPC-1 promoter activity and NPC-1 mRNA abundance. Cotransfection of SREBP1a, SREBP1c, and SREBP2 and the NPC-1 promoter-luciferase reporter into granulosa cell lines increased the transcriptional activity of porcine, human, and mouse NPC-1 promoters. Deletion analysis of the 5' flanking region of the pig NPC-1 gene demonstrated significant promoter activity between fragments -934 and -636 bp upstream from the transcription initiation site. Sequence analysis revealed three sterol-regulatory elements (SREs) clustered between -558 and -650 bp. Each site, along with E-box sequences, bound recombinant SREBP in electromobility shift assays. Mutation of all three sites attenuated the SREBP induction of promoter activity. Chromatin immunoprecipitation (ChIP) assays revealed that cholesterol depletion enriched the association of both SREBP and acetylated histone H3 with the NPC-1 promoter fragment containing the three SREs. ChIP analysis confirmed that SREBP's association with SRE and the E-box was enriched in cells cultured in cholesterol-depleted medium. We conclude that NPC-1 is sterol-regulated, achieved by SREBP acting via SRE and the E-box sequences.
authors.affiliation: Centre de Recherche en Reproduction Animale, Faculté de Médecine Vétérinaire, Université de Montréal, St. Hyacinthe, Quebec, Canada J2S 7C6.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Gévry
authors.forename: Kristina
authors.initials: K
authors.lastname: Schoonjans
authors.forename: Fréderic
authors.initials: F
authors.lastname: Guay
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Murphy
mesh_terms: D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D002784:Cholesterol / Q000494:pharmacology*; D002843:Chromatin / Q000648:ultrastructure; D017931:DNA Primers; D005260:Female; D006107:Granulosa Cells / Q000187:drug effects / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins / Q000235:genetics*; D000077296:Niemann-Pick C1 Protein; D020033:Protein Isoforms / Q000235:genetics; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D051779:Sterol Regulatory Element Binding Proteins / Q000494:pharmacology*; D013552:Swine; D014158:Transcription, Genetic / Q000187:drug effects*; D014162:Transfection
chemical_list: D002352:Carrier Proteins; D002843:Chromatin; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; C106881:NPC1 protein, human; D000077296:Niemann-Pick C1 Protein; D020033:Protein Isoforms; D051779:Sterol Regulatory Element Binding Proteins; D012313:RNA; D002784:Cholesterol