Regulated expression of K+ channel genes in electrically silent mammalian cells by linkage to beta-globin gene-activation elements.

Fundamental studies of the mechanism of human beta-like globin gene-expression have identified DNA sequences (locus control regions or LCRs) which directly influence the specific activation of beta-globin genes in erythroid cells. Here we report the first applications of LCR-mediated gene-activation to stable electrophysiological expression of several homomultimeric ion channel proteins. We describe expression driven from a native K+ channel gene promoter region, contiguous to an intronless coding sequence, within a single excised human genomic DNA fragment. In addition, cDNAs encoding both inactivating and non-inactivating mammalian K+ currents have been expressed by insertion between the promoter and second intron of the human beta-globin gene. Expression levels are characteristically independent of integration position and are proportional to LCR-gene copy number, a parameter specific for each clonal cell line. K+ channel expression is inducible by erythroid differentiation and has been demonstrated by electrophysiological recordings of cells taken directly from culture.