Inducible transcription of five globin genes in K562 human leukemia cells.

Abstract

Abundance and structure were studied of globin mRNA present in K562 cells before and after induction of Hb synthesis by hemin. In-vitro translation of poly(A)+ RNA from K562 cells generated protein products corresponding to .alpha., A.gamma.-, G.gamma.-, .epsilon. and .zeta.-globin mRNA. Individual globin mRNA increased 1.5- to 3-fold after induction. Similar results were obtained by measuring steady-state mRNA concentrations of induced and uninduced cells by using S1 nuclease mapping. Globin gene transcripts were correctly initiated and processed. S1 nuclease analysis revealed the presence of .delta.-globin mRNA in control and induced cells. A small percentage of .delta.-globin transcripts appeared to be initiated upstream from the normal initiation site. .beta.-Globin mRNA was not detected in any of the studies. Hemin induction of K562 cells is mediated at a transcriptional level. Dissociation of .delta.- and .beta.-globin gene expression occurs in K562 cells, compared with normal erythroid cells.