Glucocorticoids repress ribosome biosynthesis in lymphosarcoma cells by affecting gene expression at the level of transcription, posttranscription and translation.

Growth arrest of P1798 murine lymphosarcoma cells by glucocorticoids is accompanied by a remarkable decrease in transcription of rRNA and translation of mRNAs encoding basic ribosomal proteins (rps). Here we report that the expression of other genes involved in ribosome biogenesis is repressed in dexamethasone-treated P1798 cells. These include posttranscriptionally regulated decline in the abundance of the mRNA and primary transcript of nucleolin; abrupt drop in the transcription rate of U3 small nucleolar RNA; and inhibition of translation of mRNAs coding for P2 and L5, acidic and basic rps, respectively. Normal expression of these genes is resumed upon hormonal withdrawal.