[Nucleo-cytoplasmic mRNA transport in liver rat and hepatoma cells following suppression of protein synthesis by cycloheximide].

Specific radioactivity of uridylic nucleotide pool was found to be 2-2.5-fold higher in rat liver cells treated with cycloheximide within 3 hrs as compared with the control liver cells. Cycloheximide did not affect the specific radioactivity of the nucleotide pool in cells of Zajhdel ascites hepatoma. Nuclear-cytoplasmic transport of mRNA was decreased by 40-60% in rat liver cells after inhibition of protein synthesis by cycloheximide within 3 hrs. In this case, synthesis of non-ribosomal RNA was also decreased by 20-30% in nuclei. Treatment with cycloheximide caused 2.5-3-fold increase in synthesis of non-ribosomal nuclear RNA in rat cells of Zajhdel ascites hepatoma; amount of mRNA, transported from nucleus into cytoplasm, was also 2-3-fold higher in the tumoral cells as compared with controls. Under conditions of cycloheximide action, mRNA, which is transported from nuclei, continued to enter the polyribosomes of Zajhdel ascites hepatoma cells at the normal rate, although the protein synthesis did not occur in these polyribosomes.