1. The 5' boundary of the human apolipoprotein B chromatin domain in intestinal cells.
- Author
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Antes TJ, Namciu SJ, Fournier RE, and Levy-Wilson B
- Subjects
- 5' Untranslated Regions genetics, Animals, Apolipoproteins B chemistry, Base Composition, Binding Sites genetics, CCCTC-Binding Factor, COS Cells, Caco-2 Cells chemistry, Chromatin chemistry, DNA-Binding Proteins genetics, DNA-Binding Proteins metabolism, Deoxyribonuclease EcoRI genetics, Drosophila melanogaster genetics, Enhancer Elements, Genetic, Female, Humans, Nuclear Matrix genetics, Nuclear Matrix metabolism, Protein Structure, Tertiary genetics, RNA-Binding Proteins genetics, Repressor Proteins antagonists & inhibitors, Repressor Proteins genetics, Repressor Proteins metabolism, Transcription Factors genetics, Transcription Factors metabolism, 5' Untranslated Regions chemistry, Apolipoproteins B genetics, Caco-2 Cells metabolism, Chromatin genetics, Drosophila Proteins, Nuclear Proteins
- Abstract
The 5' boundary of the chromosomal domain of the human apolipoprotein B (apoB) gene in intestinal cells has been localized and characterized. It is composed of two kinds of boundary elements; the first, functional boundary is an insulator activity exhibited by a 1.8 kb DNA fragment located between -58 and -56 kb upstream of the human apoB promoter. In this region, an enhancer-blocking activity has been mapped to a CTCF binding site that is located upstream of two apoB intestinal enhancers (IEs), the 315 IE and the 485 IE. The CTCF site represents a boundary between two types of chromatin structure: an open, DNaseI-sensitive region 3' of the CTCF site containing the intestinal regulatory elements and a closed, DNaseI-resistant region 5' of the CTCF site. The 1.8 kb fragment harboring the CTCF site also insulated mini-white transgenes against position effects in Drosophila melanogaster. The second, structural boundary is represented by a nuclear matrix attachment region (MAR), situated about 3 kb 5' of the CTCF site. This MAR may represent the 5' anchorage site for a chromosomal loop that functions to bring the intestinal regulatory elements closer to the apoB promoter.
- Published
- 2001
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