REGULATION OF THE HUMAN SPERMIDINE SYNTHASE MESSENGER-RNA TRANSLATION BY ITS 5'-UNTRANSLATED REGION

An increased mRNA content of spermidine synthase ,vas found in phytohemagglutinin stimulated human peripheral lymphocytes and in cultured human myeloma (Sultan) cells stimulated to grow by change of the culture medium, The many-fold increase in the amount of the message mas accompanied by stimulation of the enzyme activity in activated lymphocytes, but not in stimulated myeloma cells, In the present study the effect of the 5'-untranslated region of spermidine synthase mRNA on the posttranscriptional control of its expression was studied both in vitro in rabbit reticulocyte system and in cultured mammalian cells, The results show that the GC-rich 5'-untranslated region of spermidine synthase mRNA has an inhibitory effect on its translation.