Distribution of the globin gene in active and inactive chromatin fractions from friend erythroleukemia cells

Abstract

Stimulation of the T3C12 clone of Friend erythroleukemia cells with 1.2% dimethyl sulfoxide (DMSO) results in progressive increase in the concentration of globin mRNA sequences in the total cellular RNA of treated cells, as measured by nucleic acid hybridization employing a globin cDNA probe. The greatest increment in the content of globin RNA occurs between 30 and 40 h after addition of DMSO. Globin cDNA was also used to measure the concentration of globin-specific sequences in the DNA and RNA of transcriptionally active and inactive chromatin fractions prepared from these cells by the DNase II-MgCl2 procedure of Gottesfeld et al. [16]. Essentially equal concentrations of globin sequences are present in the DNA isolated from active and inactive chromatin fractions of cells grown in the presence of 1.2% DMSO for 50 h (the time of initiation of hemoglobin synthesis). Furthermore, there are no significant differences in the globin gene concentrations between the active chromatin fractions from DMSO-treated and control cultures at either 50 or 120 h after initiation of DMSO treatment. However, chromatin-associated RNA isolated from the active chromatin of cells synthesizing maximum amounts of hemoglobin (120 h) contains a higher concentration of globin sequences than RNA from the active chromatin of control cells. Chromatin fractions from untreated cells also contain a significant amount of RNA which hybridizes to the globin cDNA probe. These observations suggest that both transcriptional and post-transcriptional control mechanisms are involved in hemoglobin gene expression in T3C12 erythroleukemia cells.