Abstract
The cyclin dependent kinase 2 (Cdk2) is required for initiation and progression of DNA replication. Activation of Cdk2 involves binding to cyclin E or cyclin A and dephosphorylation of Tyr15. The present studies demonstrate that treatment of U-937 cells with 1-beta-D-arabinofuranosylcytosine (ara-C) is associated with tyrosine phosphorylation of Cdk2 and inhibition of Cdk2 activity. The results also demonstrate that Cdk2 directly associates with the Src-like tyrosine kinase Lyn as a consequence of ara-C-treatment. Confocal microscopy studies show that Lyn is detectable in the nucleus and that it colocalises with Cdk2. Subcellular fractionation and coimmunoprecipitation studies further demonstrate nuclear binding of Lyn and Cdk2. We also show that Lyn phosphorylates Tyr15 of Cdk2 and that incubation of Lyn with Cdk2 results in inhibition of Cdk2 activity. These findings suggest that the association of Lyn and Cdk2 in ara-C-treated cells may contribute to regulation of Cdk2-dependent cell cycle checkpoints.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Antimetabolites, Antineoplastic / pharmacology
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CDC2-CDC28 Kinases*
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Cyclin-Dependent Kinase 2
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Cyclin-Dependent Kinases / drug effects
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Cyclin-Dependent Kinases / immunology
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Cyclin-Dependent Kinases / metabolism*
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Cyclins / metabolism
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Cytarabine / pharmacology*
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Enzyme Activation
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Humans
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Immunoblotting
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Leukemia / drug therapy
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Leukemia / metabolism
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Leukemia / pathology
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Membrane Proteins / metabolism
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Nuclear Proteins / metabolism
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Phosphorylation
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Platelet-Derived Growth Factor / immunology
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Precipitin Tests
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Protein Serine-Threonine Kinases / drug effects
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Protein Serine-Threonine Kinases / immunology
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Protein Serine-Threonine Kinases / metabolism*
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Recombinant Fusion Proteins / drug effects
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Recombinant Fusion Proteins / metabolism
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Subcellular Fractions
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Tumor Cells, Cultured
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Tyrosine / metabolism
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src-Family Kinases / drug effects
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src-Family Kinases / immunology
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src-Family Kinases / metabolism*
Substances
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Antimetabolites, Antineoplastic
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Cyclins
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Membrane Proteins
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Nuclear Proteins
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Platelet-Derived Growth Factor
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Recombinant Fusion Proteins
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Cytarabine
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Tyrosine
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lyn protein-tyrosine kinase
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src-Family Kinases
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Protein Serine-Threonine Kinases
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CDC2-CDC28 Kinases
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CDK2 protein, human
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Cyclin-Dependent Kinase 2
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Cyclin-Dependent Kinases