Effect of hemin on poly (A)-containing RNA synthesis and transport from nucleus into cytoplasm in Friend cells of the Fw line.

The effect of hemin on the transcription and post-transcriptional events (processing and transport of globin mRNA and other poly(A)-containing RNAs to the cytoplasm) was investigated in murine erythroleukemia Friend cells (MELC) of the Fw line. Uninduced Fw cells or Fw cells induced to differentiation by butyric acid were incubated in vitro without or with exogenous hemin. Short labelling periods (5-20 min) with (3H) uridine were used. The synthesis of globin mRNA and other poly(A)-containing RNAs at the level of their precursors in the nucleus and at the level of mature forms in the cytoplasm was measured. Our results indicate that hemin mainly affects the processing or transport of globin mRNA and other poly(A)-containing RNAs from the nucleus to the cytoplasm. The effect of exogenous hemin is quite different in uninduced and induced Fw cells. Exogenous hemin stimulates accumulation of poly(A)-containing RNA in nuclei of uninduced Fw cells. On the other hand exogenous hemin causes an increase in cytoplasmic globin mRNA and other cytoplasmic poly(A)-containing RNA in Fw cells induced by sodium butyrate.