Protein kinase CK2 phosphorylates and upregulates Akt/PKB.
Treatment of Jurkat cells with specific inhibitors of protein kinase CK2 induces apoptosis. Here we provide evidence that the anti-apoptotic effect of CK2 can be at least partially mediated by upregulation of the Akt/PKB pathway. Such a conclusion is based on the following observations: (1) inhibition of CK2 by cell ... treatment with two structurally unrelated CK2 inhibitors induces downregulation of Akt/PKB, as judged from decreased phosphorylation of its physiological targets, and immunoprecipitate kinase assay; (2) similar results are observed upon reduction of CK2 catalytic subunit by the RNA-interference technique; (3) Akt/PKB Ser129 is phosphorylated by CK2 in vitro and in vivo; (4) such a phosphorylation of activated Akt/PKB correlates with a further increase in catalytic activity. These data disclose an unanticipated mechanism by which constitutive phosphorylation by CK2 may be required for maximal activation of Akt/PKB.
Mesh Terms:
Amino Acid Sequence, Casein Kinase II, Catalytic Domain, Cell Line, Down-Regulation, Enzyme Induction, Humans, Molecular Sequence Data, Mutation, Phosphorylation, Phosphoserine, Protein Kinase Inhibitors, Protein-Serine-Threonine Kinases, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-akt, RNA Interference, Signal Transduction, Up-Regulation
Amino Acid Sequence, Casein Kinase II, Catalytic Domain, Cell Line, Down-Regulation, Enzyme Induction, Humans, Molecular Sequence Data, Mutation, Phosphorylation, Phosphoserine, Protein Kinase Inhibitors, Protein-Serine-Threonine Kinases, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-akt, RNA Interference, Signal Transduction, Up-Regulation
Cell Death Differ.
Date: Jun. 01, 2005
PubMed ID: 15818404
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