title: Modulation of human Niemann-Pick C1-like 1 gene expression by sterol: Role of sterol regulatory element binding protein 2.
abstract: Niemann-Pick C1-like 1 (NPC1L1) is an essential intestinal component of cholesterol absorption. However, little is known about the molecular regulation of intestinal NPC1L1 expression and promoter activity. We demonstrated that human NPC1L1 mRNA expression was significantly decreased by 25-hydroxycholesterol but increased in response to cellular cholesterol depletion achieved by incubation with Mevinolin (an inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase) in human intestinal Caco-2 cells. We also showed that a -1741/+56 fragment of the NPC1L1 gene demonstrated high promoter activity in Caco-2 cells that was reduced by 25-hydroxycholesterol and stimulated by cholesterol depletion. Interestingly, we showed that the NPC1L1 promoter is remarkably transactivated by the overexpression of sterol regulatory element (SRE) binding protein (SREBP)-2, suggesting its involvement in the sterol-induced alteration in NPC1L1 promoter activity. Finally, we identified two putative SREs in the human NPC1L1 promoter and established their essential roles in mediating the effects of cholesterol on promoter activity. Our study demonstrated the modulation of human NPC1L1 expression and promoter activity by cholesterol in a SREBP-2-dependent mechanism.
authors.affiliation: Section of Digestive Diseases and Nutrition, Department of Medicine, University of Illinois, and Jesse Brown Veterans Affairs Medical Center, Chicago, IL 60612, USA. walrefai@uic.edu
authors.forename: Waddah A
authors.initials: WA
authors.lastname: Alrefai
authors.forename: Fadi
authors.initials: F
authors.lastname: Annaba
authors.forename: Zaheer
authors.initials: Z
authors.lastname: Sarwar
authors.forename: Alka
authors.initials: A
authors.lastname: Dwivedi
authors.forename: Seema
authors.initials: S
authors.lastname: Saksena
authors.forename: Amika
authors.initials: A
authors.lastname: Singla
authors.forename: Pradeep K
authors.initials: PK
authors.lastname: Dudeja
authors.forename: Ravinder K
authors.initials: RK
authors.lastname: Gill
mesh_terms: D001483:Base Sequence; D018938:Caco-2 Cells; D002467:Cell Nucleus / Q000235:genetics; D002784:Cholesterol / Q000172:deficiency; D017931:DNA Primers; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D006888:Hydroxycholesterols / Q000494:pharmacology*; D008565:Membrane Proteins / Q000235:genetics*; D026901:Membrane Transport Proteins; D009542:Niemann-Pick Diseases / Q000235:genetics*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051782:Sterol Regulatory Element Binding Protein 2 / Q000502:physiology*; D014162:Transfection
chemical_list: D017931:DNA Primers; D006888:Hydroxycholesterols; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C410800:NPC1L1 protein, human; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011994:Recombinant Proteins; D051782:Sterol Regulatory Element Binding Protein 2; C007997:25-hydroxycholesterol; D002784:Cholesterol