DNase I hypersensitive sites and histone acetylation status in the chicken Ig-β locus

Abstract

DNase I hypersensitive sites (DHSs) and histone acetylation status were examined in the Ig-β locus of chicken B lymphocyte-derived DT40 cells and liver-derived LMH cells. Twelve DT40-specific DHSs were identified: one in the Ig-β promoter, one in the first intron of the Ig-β gene, three in the sodium channel gene located upstream of the Ig-β gene, two between the sodium channel gene and the Ig-β gene, four between the Ig-β gene and a downstream growth hormone ( GH) gene, and one in the downstream region of the GH gene. Transient transfection studies show that the DHS in the intron of Ig-β gene enhances the activity of the Ig-β promoter fourfold. A 1.6 kb DNA fragment, which includes two DHSs, from the sodium channel gene enhanced promoter activity threefold. The transcription enhancing ability of the intron DHS was dependent on orientation, but was not promoter specific. Electrophoretic mobility shift assays (EMSA) demonstrated that an Ets protein family member binds to the intron DHS. In DT40 cells, a distinguished acetylation of H3 and H4 histones was found at the Ig-β promoter, in addition to the enhanced acetylation of both histones at DT40-specific DHSs.