PMID:10859308

Citation	Antes, TJ, Goodart, SA, Huynh, C, Sullivan, M, Young, SG and Levy-Wilson, B (2000) Identification and characterization of a 315-base pair enhancer, located more than 55 kilobases 5' of the apolipoprotein B gene, that confers expression in the intestine. J. Biol. Chem. 275:26637-48
Abstract	We recently reported that an 8-kilobase (kb) region, spanning from -54 to -62 kb 5' of the human apolipoprotein B (apoB) gene, contains intestine-specific regulatory elements that control apoB expression in the intestines of transgenic mice. In this study, we further localized the apoB intestinal control region to a 3-kb segment (-54 to -57 kb). DNaseI hypersensitivity studies uncovered a prominent DNaseI hypersensitivity site, located within a 315-base pair (bp) fragment at the 5'-end of the 3-kb segment, in transcriptionally active CaCo-2 cells but not in transcriptionally inactive HeLa cells. Transient transfection experiments with CaCo-2 and HepG2 cells indicated that the 315-bp fragment contained an intestine-specific enhancer, and analysis of the DNA sequence revealed putative binding sites for the tissue-specific transcription factors hepatocyte nuclear factor 3beta, hepatocyte nuclear factor 4, and CAAT enhancer-binding protein beta. Binding of these factors to the 315-bp enhancer was demonstrated in gel retardation experiments. Transfection of deletion mutants of the 315-bp enhancer revealed the relative contributions of these transcription factors in the activity of the apoB intestinal enhancer. The corresponding segment of the mouse apoB gene (located -40 to -83 kb 5' of the structural gene) exhibited a high degree of sequence conservation in the binding sites for the key transcriptional activators and also exhibited enhancer activity in transient transfection assays with CaCo-2 cells. In transgenic mouse expression studies, the 315-bp enhancer conferred intestinal expression to human apoB transgenes.
Links	PubMed Online version:10.1074/jbc.M003025200
Keywords	Animals; Apolipoproteins B/genetics; Base Sequence; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; DNA-Binding Proteins/metabolism; Deoxyribonuclease EcoRI/metabolism; Deoxyribonuclease HindIII/metabolism; Deoxyribonuclease I/metabolism; Electrophoresis, Polyacrylamide Gel; Enhancer Elements, Genetic; Hepatocyte Nuclear Factor 3-beta; Hepatocyte Nuclear Factor 4; Humans; Intestines/metabolism; Mice; Mice, Transgenic; Molecular Sequence Data; Nuclear Proteins/metabolism; Phosphoproteins/metabolism; Restriction Mapping; Ribonucleases/metabolism; Sequence Alignment; Transcription Factors/metabolism; Transgenes
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