title: Induction of interferon in HeLa cells of a protein kinase activated by double-stranded RNA.
abstract: Treatment of HeLa cells with human fibroblast interferon results in increased levels of latent protein kinase activity that can be activated by double-stranded RNA (dsRNA). The protein kinase activity in extracts of interferon-treated cells is assayed by two methods: (a) inhibition of protein synthesis in rabbit reticulocyte lysates and (b) phosphorylation of two polypeptides of Mr 72000 (P1) and 38000 (the eIF-2 alpha subunit of initiation factor 2). When extracts of interferon-treated cells are fractionated by centrifugation at 150000 x g, the protein kinase activity is found in the pellet fraction. The kinase is maximally activated by 0.1 micrograms/ml poly(I) . poly(C). An increase in protein kinase activity is detected after 8 h of treatment with 100 units interferon/ml or after a 17-h treatment with 12.5 units/ml or greater interferon concentrations. Therefore, the kinase activity increases as a function of both time of treatment and interferon concentration. Addition of actinomycin D to cells during interferon treatment prevents this increase. The protein kinase activity decreases gradually over three days when interferon-treated cells are subsequently grown in the absence of interferon.
mesh_terms: D000818:Animals; D004789:Enzyme Activation; D004790:Enzyme Induction; D006367:HeLa Cells / Q000187:drug effects / Q000201:enzymology*; D006801:Humans; D007372:Interferons / Q000494:pharmacology*; D007700:Kinetics; D008970:Molecular Weight; D010448:Peptide Initiation Factors / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000096:biosynthesis*; D012313:RNA / Q000494:pharmacology*; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism
chemical_list: D010448:Peptide Initiation Factors; D012313:RNA; D007372:Interferons; D011494:Protein Kinases