title: A novel SREBP-1 splice variant: tissue abundance and transactivation potency.
abstract: Sterol regulatory element binding proteins (SREBPs) belong to the family of basic helix-loop-helix-leucine zipper transcription factors. The SREBP-1 gene encodes two different isoforms, SREBP-1a and -1c, that are expressed at varying levels in different tissues and cultured cells and exhibit common and distinct functions. We identified an additional SREBP-1 isoform, termed SREBP-1ac, and determined its mRNA abundance in different human tissues and cell lines. SREBP-1ac mRNA was detectable in all tissues studied, although at lower levels than the major SREBP-1a and -1c isoforms. Transcription of the novel SREBP isoform was not induced by insulin or cholesterol depletion. SREBP-1ac did not transactivate the human LDLR and UCP2 promoters but robustly attenuated the transactivation capacity of SREBP-1a, -1c and -2 in cotransfection experiments.
authors.affiliation: Department of Laboratory Medicine, Salzburger Landeskliniken and Paracelsus Private Medical University, Muellner Hauptstrasse 48, A-5020 Salzburg, Austria.
authors.forename: Thomas Klaus
authors.initials: TK
authors.lastname: Felder
authors.forename: Kerstin
authors.initials: K
authors.lastname: Klein
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Patsch
authors.forename: Hannes
authors.initials: H
authors.lastname: Oberkofler
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D006801:Humans; D008099:Liver / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D051780:Sterol Regulatory Element Binding Protein 1 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D013737:Testis / Q000378:metabolism; D014018:Tissue Distribution; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D020033:Protein Isoforms; C497387:SREBF1 protein, human; D051780:Sterol Regulatory Element Binding Protein 1