title: Transcription factor AP-4 is a ligand for immunoglobulin-kappa promoter E-box elements.
abstract: Immunoglobulin (Ig)-kappa promoters from humans and mice share conserved sequences. The octamer element is common to all Ig promoters and pivotal for their function. However, other conserved sequence motifs, that differ between Ig variable gene families, are required for normal promoter function. These conserved motifs do not stimulate transcription in the absence of an octamer. One example is an E-box of the E47/E12 type (5'-CAGCTG-3'), which is found in all promoters of the human and murine Ig-kappa gene subgroups/families, with the exception of subgroups II and VI and their related murine families. In the present study we show that the ubiquitously expressed transcription factor AP-4, and not E47, interacts specifically with the kappa promoter E-boxes when tested in electrophoretic mobility-shift assays using nuclear extracts derived from human and murine B-cell lines. Furthermore, AP-4, unlike E47, did not act as a transactivator, which is in agreement with previous studies on intact kappa promoters, showing that transcription is absent when the octamer element has been mutated. Based on these data, and the conservation of the 5'-CAGCTG-3' motif among human and murine kappa promoters, we propose that AP-4 is the major ligand for Ig-kappa promoter E-boxes.
authors.affiliation: Section for Immunology, Department of Cell and Molecular Biology, Lund University, BMC I13, S-22184 Lund, Sweden. Alaitz.Aranburu@immuno.lu.se
authors.forename: A
authors.initials: A
authors.lastname: Aranburu
authors.forename: R
authors.initials: R
authors.lastname: Carlsson
authors.forename: C
authors.initials: C
authors.lastname: Persson
authors.forename: T
authors.initials: T
authors.lastname: Leanderson
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism; D015153:Blotting, Western; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation; D006367:HeLa Cells; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000235:genetics*; D008024:Ligands; D051379:Mice; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D011817:Rabbits; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D007145:Immunoglobulin kappa-Chains; D008024:Ligands; D051820:TCF Transcription Factors; C544912:TCF7L1 protein, human; C544913:Tcf7l1 protein, mouse; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors; C055473:enhancer-binding protein AP-4; D004247:DNA