title: Characterization and functional analysis of the 5'-flanking promoter region of the mouse Tcf3 gene.
abstract: Tcf3 is a nuclear mediator of canonical Wnt signaling which functions in many systems as a repressor of target gene transcription. In this study, we have cloned and characterized a 6.7 kb fragment of the 5'-flanking promoter region of the mouse Tcf3 gene. In silico analysis of the promoter sequence identified the existence of GC boxes and CpG islands, but failed to identify any TATA box. In addition, the promoter sequence contained putative binding sites for multiple transcription factors, including a few known to regulate the function of mTcf3. Of those, we confirmed functional binding sites for NFκB and Oct1 using a luciferase assay and ChIP. In vitro analysis revealed five potential transcription start sites which resulted in a 298 base pair 5'-untranslated region upstream of the mTcf3 translation start site ATG. Using a luciferase assay, we analyzed the activity of the cloned promoter fragment in embryonically derived neural stem cells. The luciferase activity of a 3.5 kb core promoter fragment (-3243/+211) showed up to 40-fold increased activity compared to the empty vector. Addition of sequences 5' to the 3.5 kb core promoter fragment resulted in a 20-fold drop in luciferase activity, indicating the presence of further upstream repressive elements. In vivo analysis of a 4.5 kb promoter fragment (-4303/+211) driving, the expression of EGFP in mouse embryos highly resembled endogenous expression of mTcf3.
authors.affiliation: Department of Microbiology, Oslo University Hospital, Rikshospitalet, Forskningsparken, Oslo, Norway. Nina.Therese.Solberg@rr-research.no
authors.forename: Nina
authors.initials: N
authors.lastname: Solberg
authors.forename: Ondrej
authors.initials: O
authors.lastname: Machon
authors.forename: Stefan
authors.initials: S
authors.lastname: Krauss
mesh_terms: D024506:5' Flanking Region; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics*; D001665:Binding Sites; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018387:Codon, Initiator; D017124:Conserved Sequence; D004622:Embryo, Mammalian / Q000378:metabolism; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D049410:Luciferases, Renilla / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000235:genetics; D050811:Octamer Transcription Factor-1 / Q000235:genetics; D011401:Promoter Regions, Genetic
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D018387:Codon, Initiator; D049452:Green Fluorescent Proteins; D049410:Luciferases, Renilla; D016328:NF-kappa B; D050811:Octamer Transcription Factor-1; C494166:Pou2f1 protein, mouse; C075668:Tcf3 protein, mouse; C485184:enhanced green fluorescent protein