Activation of protein kinase A inhibits interferon induction of the Jak/Stat pathway in U266 cells.
Activation of early response genes by interferons (IFNs) requires tyrosine phosphorylation of the Stat transcription factors and is mediated by the Jak family of tyrosine kinases. Recent evidence suggests that ERK2 serine/threonine kinase modulates the IFN-stimulated Jak/Stat pathway. In this report we show that in the myeloma cell line U266 protein kinase A specifically interacts with the cytoplasmic domain of the IFNalpha/beta receptor. Treatment of cells with the adenylate cyclase activator forskolin inhibits IFNbeta-, IFNgamma-, and hydrogen peroxide/vanadate-induced formation of complexes that bind to enhancers known to stimulate the expression of IFN-regulated genes. Immunoprecipitations followed by anti-phosphotyrosine immunoblots indicate that tyrosine phosphorylation of the alpha chain of the IFNalpha/beta receptor, Jak1, Tyk2, as well as Stat1 and Stat2 is reduced as a consequence of incubation of cells with forskolin. In contrast, dideoxyforskolin, which fails to activate adenylate cyclase, has no effect on IFN induction of the Jak/Stat pathway. These results indicate a novel regulatory mechanism by which protein kinase A can modulate the Jak/Stat signaling cascade.
David
M
M
Division of Cytokine Biology, Center for Biologics Evaluation and Research, National Institutes of Health, Bethesda, Maryland 20892, USA.
Petricoin
E
E
Larner
A C
AC
D000262:Adenylyl Cyclases / Q000378:metabolism; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004742:Enhancer Elements, Genetic; D004789:Enzyme Activation; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D016899:Interferon-beta / Q000494:pharmacology*; D007371:Interferon-gamma / Q000494:pharmacology*; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis*; D053633:Receptor, Interferon alpha-beta; D017471:Receptors, Interferon / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology*
D000911:Antibodies, Monoclonal; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D017471:Receptors, Interferon; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D053633:Receptor, Interferon alpha-beta; D005576:Colforsin; D014638:Vanadates; D016899:Interferon-beta; D007371:Interferon-gamma; D006861:Hydrogen Peroxide; D011505:Protein-Tyrosine Kinases; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases