Abstract
When mouse erythroleukemia (MEL) cells were incubated in the presence of chloramphenicol (a specific inhibitor for mitochondrial protein synthesis) during the early stage of in vitro erythroid differentiation, the number of induced erythroid cells was greatly reduced. By use of cell fusion between two genetically marked MEL cells, this finding was further investigated. We found that the drug, along with other agents which inhibit mitochondrial protein synthesis, blocked the induction and turnover of the DMSO-inducible intracellular-erythroid-inducing activity (differentiation-inducing factor II) in a manner similar to that of cycloheximide, an inhibitor for nuclear protein synthesis. The inhibitory effect was confirmed by directly assaying differentiation-inducing factor II in the cell extracts. These results strongly suggest that mitochondrial protein synthesis is closely associated with in vitro erythroid differentiation of MEL cells.