Effects of glucocorticoids and cycloheximide upon transcription of ribosomal RNA gene in rat liver: application of quantitative S1 nuclease mapping analysis.

The change in the amount of pre-rRNA synthesized in rat liver was examined by S1 nuclease mapping analysis using the probe containing the 5' end of the rat 45S rRNA gene. It was found that the amount of pre-rRNA of adrenalectomized rats, which was about half of the normal level, was increased after administration of dexamethasone attaining to the normal level at 12 h, and that the hormone-induced pre-rRNA synthesis was completely abolished within 1 h after injection of cycloheximide. These results indicate that the glucocorticoids-stimulated initiation of rRNA transcription is mediated by the hormone-dependent short-lived protein(s).