DIMETHYL-SULFOXIDE AND HEMIN INDUCE FERROCHELATASE MESSENGER-RNA BY DIFFERENT MECHANISMS IN MURINE ERYTHROLEUKEMIA-CELLS

The level of mRNA encoding ferrochelatase (FeC), the terminal enzyme of the haem biosynthetic pathway, was examined in murine erythroleukaemia (MEL) cells when they were induced to undergo erythroid cell differentiation by treatment with dimethyl sulphoxide (DMSO), or haemin. FeC mRNA increased within 12 h after DMSO or haemin treatment of MEL cells, and its level continued to increase for 48 h. Treatment of cells with succinylacetone (SA), a potent inhibitor of haem synthesis, suppressed a DMSO-mediated increase in FeC mRNA, and haemin treatment reversed a SA-mediated decrease in FeC mRNA. Nuclear runoff analyses showed that, while DMSO increased the rate of transcription of FeC mRNA, haemin did not. These results indicate that the induction of FeC mRNA by DMSO is largely transcriptional, while that by haemin is post-transcriptional.