Abstract
Mammalian cells have a remarkable capacity to compensate for heterozygous gene loss or extra gene copies. One exception is Down syndrome (DS), where a third copy of chromosome 21 mediates neurogenesis defects and lowers the frequency of solid tumors. Here we combine live-cell imaging and single-cell analysis to show that increased dosage of chromosome 21-localized Dyrk1a steeply increases G1 cell cycle duration through direct phosphorylation and degradation of cyclin D1 (CycD1). DS-derived fibroblasts showed analogous cell cycle changes that were reversed by Dyrk1a inhibition. Furthermore, reducing Dyrk1a activity increased CycD1 expression to force a bifurcation, with one subpopulation of cells accelerating proliferation and the other arresting proliferation by costabilizing CycD1 and the CDK inhibitor p21. Thus, dosage of Dyrk1a repositions cells within a p21-CycD1 signaling map, directing each cell to either proliferate or to follow two distinct cell cycle exit pathways characterized by high or low CycD1 and p21 levels.
Copyright © 2013 Elsevier Inc. All rights reserved.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Cell Line, Tumor
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Cell Proliferation*
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Cell Tracking / methods
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Chromosomes, Human, Pair 21
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Cyclin D1 / genetics
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Cyclin D1 / metabolism*
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Cyclin-Dependent Kinase Inhibitor p21 / genetics
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Cyclin-Dependent Kinase Inhibitor p21 / metabolism*
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Down Syndrome / genetics
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Down Syndrome / metabolism
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Down Syndrome / pathology
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Dyrk Kinases
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Fibroblasts / metabolism
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Fibroblasts / pathology
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G1 Phase*
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Gene Expression Regulation
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Gene Knockdown Techniques
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Humans
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Microscopy, Fluorescence
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Microscopy, Video
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Phosphorylation
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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Protein Stability
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Protein-Tyrosine Kinases / genetics
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Protein-Tyrosine Kinases / metabolism*
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RNA Interference
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Signal Transduction
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Time Factors
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Time-Lapse Imaging
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Transfection
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ras Proteins / metabolism
Substances
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CCND1 protein, human
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CDKN1A protein, human
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Cyclin-Dependent Kinase Inhibitor p21
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Cyclin D1
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Protein-Tyrosine Kinases
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Protein Serine-Threonine Kinases
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ras Proteins