title: DNase I- and micrococcal nuclease-hypersensitive sites in the human apolipoprotein B gene are tissue specific.
abstract: We have mapped the DNase I- and micrococcal nuclease-hypersensitive sites present in the 5' end of the human apolipoprotein B (apo-B) gene in nuclei from cells expressing or not expressing the gene. Four DNase I-hypersensitive sites were found in nuclei from liver-derived HepG2 cells and intestine-derived CaCo-2 cells, which express the apo-B gene, but not in HeLa cells, which do not. These sites are located near positions -120, -440, -700, and +760 base pairs relative to the transcriptional start site. Undifferentiated CaCo-2 cells exhibited another site, near position -540. Six micrococcal nuclease-hypersensitive sites were found in nuclei from HepG2 and CaCo-2 cells, but not in HeLa cells or free DNA. These sites are located near positions -120, -390, -530, -700, -850, and +210. HepG2 cells exhibited another site, near position +460. Comparison of the DNA sequence of the 5' flanking regions of the human and mouse apo-B genes revealed a high degree of evolutionary conservation of short stretches of sequences in the immediate vicinity of each of the DNase I- and most of the micrococcal nuclease-hypersensitive sites.
authors.affiliation: Gladstone Foundation Laboratories for Cardiovascular Disease, University of California, San Francisco 94140-0608.
authors.forename: B
authors.initials: B
authors.lastname: Levy-Wilson
authors.forename: C
authors.initials: C
authors.lastname: Fortier
authors.forename: B D
authors.initials: BD
authors.lastname: Blackhart
authors.forename: B J
authors.initials: BJ
authors.lastname: McCarthy
mesh_terms: D001055:Apolipoproteins B / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D002843:Chromatin / Q000648:ultrastructure*; D003850:Deoxyribonuclease I; D005786:Gene Expression Regulation; D006801:Humans; D008836:Micrococcal Nuclease; D009707:Nucleosomes / Q000648:ultrastructure; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid
chemical_list: D001055:Apolipoproteins B; D002843:Chromatin; D009707:Nucleosomes; D012333:RNA, Messenger; D003850:Deoxyribonuclease I; D008836:Micrococcal Nuclease