Interferon-induced synthesis of 2-5A-dependent RNase in mouse JLS-V9R cells

Interferon treatment of mouse JLS-V9R cells resulted in a 10- to 20-fold increase in the levels of the 2–5A (ppp(A2′p)nA)-dependent RNase. The nuclease was monitored in cell extracts by covalent and noncovalent binding of 32P-labeled 2–5A derivatives to the nuclease and by the appearance of 2–5A-mediated ribosomal RNA cleavage products. Untreated JLS-V9R cells contained very low levels of the nuclease (5–10% of that found in control Ehrlich ascites tumor cells). An increase in the nuclease was first detected between 3 and 6 hr after interferon treatment and was completely inhibited by actinomycin D. Control experiments indicated that the increase in the nuclease was not due to an intracellular redistribution of the enzyme. The results indicate that in JLS-V9R cells, interferon controls the activity of the 2–5A system at two levels: by inducing the synthesis of both the 2–5A-dependent RNase and the 2–5A-synthetase.