title: Alternative sets of DNase I-hypersensitive sites characterize the various functional states of the chicken lysozyme gene.
abstract: The structural organization of chromatin is thought to determine the state of differentiation and activity of eukaryotic genes. Local interruptions of the regular nucleosomal array, the so-called DNase-hypersensitive sites, may indicate regions of the genome which play a critical part in regulation of differential gene activity. We present here two new observations on the chromatin structure of the chicken lysozyme gene, which strongly support a regulatory function for these sites. First, different sets of DNase I-hypersensitive sites have been found upstream from the promoter, depending on whether the gene is constitutively expressed (cultured macrophages) or in the steroid hormone-controlled state (oviduct). It seems, therefore, that diverse modes of regulation of the same gene are associated with discrete patterns of DNase I hypersensitivity. Second, one of the DNase I-hypersensitive sites in the oviduct chromatin disappears and reappears on steroid hormone withdrawal and secondary induction. These reversible changes in a narrow chromatin region reflect the transition from the potentially active to the active state of the lysozyme gene.
mesh_terms: D000818:Animals; D002645:Chickens / Q000235:genetics; D002843:Chromatin / Q000648:ultrastructure*; D003850:Deoxyribonuclease I; D004706:Endodeoxyribonucleases; D005786:Gene Expression Regulation; D005796:Genes; D009113:Muramidase / Q000235:genetics*
chemical_list: D002843:Chromatin; D004706:Endodeoxyribonucleases; D003850:Deoxyribonuclease I; D009113:Muramidase