Interferon action: transcriptional control of a gene specifying a 56,000-Da protein in Ehrlich ascites tumor cells.

The exposure of cells to interferons enhances the accumulation of particular mRNAs and of the corresponding proteins. A cDNA clone (clone 202) complementary to an mRNA (202 mRNA) whose level is enhanced over 12-fold in mouse Ehrlich ascites tumor cells upon exposure to beta-interferon for 10 hr has previously been isolated. The level of this mRNA was also increased in other beta-interferon-responsive mouse cell lines (i.e., L929, L1210S) but not in a line (L1210R) which is not responsive to beta-interferon. The extent of induction in Ehrlich ascites tumor cells depended on the beta-interferon concentration and reached its maximal level between 300 and 1000 units of interferon/ml. Nuclei isolated from Ehrlich ascites tumor cells which had been exposed to beta-interferon produced in vitro more 202 specific RNA than nuclei from control Ehrlich ascites tumor cells: an increase in this production was detectable 2 hr after beginning the exposure of the cells to 1000 units/ml of beta-interferon and the increase reached its maximal level, around 18-fold, after 18 hr exposure. Much, if not all of this increase, appeared to be due to an increase in the rate of synthesis of the RNA and not to a decrease in its rate of turnover. The 202 mRNA was translated in a reticulocyte lysate into a 56,000-Da protein.