Cytosol-modulated transport of messenger RNA from isolated nuclei.

SUMMARY The influence of cytoplasmic factors on the energy-dc pendent release from nuclei of messenger-like RNA in ribonucleoprotein particles (i.e., informosomes) has been investigated in a cell-free system that precludes detectable nuclear lysis. Maximum release of rapidly labeled RNA from the prelabeled nuclei of normal, regenerating, or neo plastic rat liver was observed only when the latter were in cubated in autologous cytosol. Comparative studies in volving RNA-DNA hybridization and density gradient centrifugation of the presumptive messenger RNA released in autologous and heterologous systems indicated that the RNA transported is both qualitatively and quantitatively dependent not only upon the source of the nuclei but also upon the source of the dialyzed cytosol. The results suggest that the cytosol contains nondialyzable compo nents that act posttranscriptionally to regulate the nuclear processing and/or transport of messenger RNA and fur ther that there are differences in these factors in normal, re generating, and neoplastic liver.