Regulation of Human Fetal and Adult Globin Genes in Mouse Erythroleukemia Cells

Abstract

AbstractWe have examined whether transfected mouse erythroleukaemia (MEL) cells can be used to examine differential expression of human γ and 0-globin genes. These cells, which express only their adult globin genes, will transcribe the human adult β gene but not the fetal γ genes when they are introduced on an intact human chromosome 11 by cell fusion. However, MEL cells stably transfected with the human Aγ gene attached to one of the active elements (HS2) of the β-globin locus control region (LCR) readily produce γ-globin mRNA in amounts equivalent to those seen with a comparable β gene insert. When both β and γ genes are attached to HS2, equal amounts of β and Aγ mRNAs are produced, irrespective of the gene order. Furthermore, when HS2 is inserted into the 5' end of a 40-kb cosmid containing the GγA βγ-117δβ genes in their normal chromosomal organization (but with the Greek HPFH -117 Aγ gene mutation), it directs expression of readily detectable amounts of GγAγ and 0-globin mRNAs in MEL cells. Therefore, under these circumstances we have observed no competition between β and γ genes for expression in MEL cells. These findings suggest that MEL cells are capable of perpetuating regulatory information involved in developmental control when it is provided by an intact chromosome, but are incapable of reconstructing such information on transfected DNA.