title: Role of DNA sequences outside the cores of DNase hypersensitive sites (HSs) in functions of the beta-globin locus control region. Domain opening and synergism between HS2 and HS3.
abstract: The roles of each DNase hypersensitive site (HS), and the DNA sequences between them, in the activity of the locus control region of the mammalian beta-globin gene domain were examined by placing human and rabbit restriction fragments containing the cores of HS2, HS3, HS4, and HS5, along with varying amounts of flanking DNA, upstream of a hybrid epsilon-globin-luciferase reporter gene and testing for effects on expression both prior to and after integration into the chromosomes of K562 cells, a human erythroid cell line. Prior to integration, fragments containing HS2 enhanced expression to the greatest extent, and the modest enhancement by some fragments containing HS3 correlated with the presence of a well-conserved binding site for AP1/NFE2. The stronger effects of larger locus control region DNA fragments in clones of stably transfected cells indicates a role for sequences outside the HS cores after integration into the genome. The strong effect of a 1.9-kilobase HindIII fragment containing HS3 after, but not prior to, integration argues for the presence of a chromatin domain-opening activity. Use of a rabbit DNA fragment containing both HS2 and HS3 demonstrated a synergistic interaction between the two HSs when their natural context and spacing are preserved.
authors.affiliation: Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park 16802, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Jackson
authors.forename: H
authors.initials: H
authors.lastname: Petrykowska
authors.forename: S
authors.initials: S
authors.lastname: Philipsen
authors.forename: W
authors.initials: W
authors.lastname: Miller
authors.forename: R
authors.initials: R
authors.lastname: Hardison
mesh_terms: D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D004247:DNA / Q000737:chemistry*; D003851:Deoxyribonucleases / Q000494:pharmacology*; D005914:Globins / Q000235:genetics*; D006801:Humans; D011817:Rabbits
chemical_list: D005914:Globins; D004247:DNA; D003851:Deoxyribonucleases