Expression of ABC7, MTABC3, and ABC-me during the differentiation of MEL cells.

(A) Northern blots. MEL cells were cultured for the period indicated in the presence of 2% Me₂SO. Total RNA was collected, separated by electrophoresis, transferred onto a membrane, and hybridized with radiolabeled probes specific for ABC7, MTABC3, ABC-me, ferrochelatase, and β-actin. (B) Effect of antisense phosphorothioate oligonucleotides to mouse ABC7, MTABC3, and ABC-me mRNAs on induction of heme biosynthesis in MEL cells. Cells treated with or without 2% Me₂SO were incubated for 30 hours. They were then transfected with sense oligonucleotide (10 μM) to ABC7 mRNA or antisense oligonucleotide (10 μM) to ABC7, MTABC3, or ABC-me mRNA. The cells were further incubated with 2% Me₂SO for 18 hours, after which they were collected and the amount of heme was estimated by fluorescence spectrophotometry. Bars represent SD (n = 4).