Abstract
The cyclin-dependent kinase (CDK) inhibitor p21CDKN1A is known to induce cell cycle arrest by inhibiting CDK activity and by interfering with DNA replication through binding to proliferating cell nuclear antigen. Although the molecular mechanisms have been elucidated, the temporal dynamics, as well as the intracellular sites of the activity of p21 bound to cyclin/CDK complexes during cell cycle arrest, have not been fully investigated. In this study we have induced the expression of p21CDKN1A fused to green fluorescent protein (GFP) in HeLa cells, in order to visualize the intracellular localization of the inhibitor during the cell cycle arrest. We show that p21-GFP is preferentially expressed in association with cyclin E in cells arrested in G1 phase, and with cyclin A more than with cyclin B1 in cells arrested in the G2/M compartment. In addition, we show for the first time that p21-GFP colocalizes with cyclin E in the nucleolus of HeLa cells during the G1 phase arrest.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Cell Cycle / physiology*
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Cell Division / physiology
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Cell Nucleolus / chemistry
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Cell Nucleolus / metabolism
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Cell Nucleus / chemistry
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Cell Nucleus / metabolism
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Chromatin / chemistry
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Chromatin / metabolism
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Cyclin A / analysis
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Cyclin A / metabolism
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Cyclin B / analysis
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Cyclin B / metabolism
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Cyclin B1
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Cyclin E / analysis
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Cyclin E / metabolism
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Cyclin-Dependent Kinase Inhibitor p21
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Flow Cytometry
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G1 Phase / physiology
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G2 Phase / physiology
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Gene Expression
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Genetic Vectors / genetics
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Green Fluorescent Proteins / genetics
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Green Fluorescent Proteins / metabolism
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HeLa Cells
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Humans
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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S Phase / physiology
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Transfection
Substances
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CCNB1 protein, human
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CDKN1A protein, human
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Cell Cycle Proteins
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Chromatin
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Cyclin A
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Cyclin B
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Cyclin B1
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Cyclin E
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Cyclin-Dependent Kinase Inhibitor p21
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Recombinant Fusion Proteins
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Green Fluorescent Proteins