title: Short communication: Identification of the bovine sterol regulatory element binding protein-1c promoter and its activation by liver X receptor.
abstract: Sterol regulatory element binding proteins (SREBP) are a family of transcription factors that regulate cholesterogenesis and lipogenesis. Sterol regulatory element binding proteins-1a and -1c are transcribed from the same gene by the use of alternate promoters, and only differ at their first exon. Sterol regulatory element binding protein-1c is hypothesized to be an important regulator of genes involved in milk fat synthesis in the lactating dairy cow. However, the bovine SREBP-1c promoter has not been previously characterized, and studies to date that have investigated the role of SREBP-1 in the bovine mammary gland have not distinguished between isoforms 1a and 1c. The purpose of this study was to characterize the bovine SREBP-1c promoter and to investigate the DNA elements involved in the regulation of SREBP-1c expression by the liver X receptor agonist T0901317 in 2 different bovine mammary epithelial cell lines. Luciferase reporter constructs containing the wild-type SREBP-1c promoter or constructs with mutated liver X receptor response elements or sterol response element were transfected into MacT cells and bovine mammary epithelial (BME-UV) cells. We have demonstrated that the liver X receptor response elements sites in the SREBP-1c promoter are necessary for mediating the T0901317 response, and that stimulation through the sterol response element site plays only a minor role in this pathway. This report describes the bovine SREBP-1c promoter and its regulation by liver X receptor in bovine mammary epithelial cells.
authors.affiliation: Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061-0315, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Lengi
authors.forename: B A
authors.initials: BA
authors.lastname: Corl
mesh_terms: D000818:Animals; D002417:Cattle; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D004041:Dietary Fats / Q000032:analysis; D004847:Epithelial Cells / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D000071518:Liver X Receptors; D008156:Luciferases / Q000235:genetics; D008321:Mammary Glands, Animal / Q000378:metabolism*; D008892:Milk / Q000737:chemistry; D057093:Orphan Nuclear Receptors / Q000819:agonists / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D051780:Sterol Regulatory Element Binding Protein 1 / Q000235:genetics* / Q000378:metabolism; D014162:Transfection / Q000662:veterinary
chemical_list: D004268:DNA-Binding Proteins; D004041:Dietary Fats; D000071518:Liver X Receptors; D057093:Orphan Nuclear Receptors; D051780:Sterol Regulatory Element Binding Protein 1; D008156:Luciferases