[Interrelation between protein synthesis and nucleo-cytoplasmic transport of messenger RNA in cells of rat livers in different stages of regeneration].

Synthesis of nonribosomal RNA was increased 2-2.5-fold in nuclei of rat liver cells at early steps of regeneration /2 days after partial hepatectomy/under conditions of protein synthesis inhibition by means of cycloheximide within 3 hrs. Amount of mRNA, transferred from nuclei into cytoplasm, was also 2-fold higher under these conditions as compared with control cells. The mRNA, transferred from nuclei into cytoplasm under the conditions of cycloheximide treatment of liver cells at early steps of regeneration, did penetrate the polyribosomes although the protein synthesis did not occur on the polyribosomes formed. At the later steps of regeneration /within 5 days after partial hepatectomy/ under the conditions of protein synthesis inhibition by cycloheximide within 3 hrs, formation of nonribosomal RNA was decreased by 40% in liver cell nuclei; amount of mRNA, transferred into cytoplasm, was also decreased by 40%. When the cycloheximide treatment was carried out during 1 hr, synthesis of nonribosomal RNA was increased 1.5-fold in liver cell nuclei at the later steps of regeneration although the amount of mRNA, transferred from nuclei into cytoplasm, was decreased by 30% as compared with the control cells. The data obtained suggest that during rat liver tissue regeneration a change occurred in the molecular mechanisms linking translation, biosynthesis and nuclear-cytoplasmic transport of mRNA of "tumoral" type/at early steps of regeneration/ or "normal type"/ at later steps of regeneration.