Abstract
TSG101 was discovered in a screen for tumor susceptibility genes and has since been shown to have a multiplicity of biological effects. However, the basis for TSG101's ability to regulate cell growth has not been elucidated. We report here that the TSG101 protein binds to the cyclin/cyclin-dependent kinase (CDK) inhibitor (CKI) p21(Cip1/WAF1) and increases stability of the p21 protein in HEK293F cells and differentiating primary keratinocytes, suppressing differentiation in a p21-dependent manner. In proliferating keratinocytes where the p21 protein is relatively stable, TSG101 does not affect the stability or expression of p21 but shows p21-dependent recruitment to cyclin/CDK complexes, inhibits cyclin/CDK activity, and causes strong growth suppression to a much greater extent in p21+/+ than in p21-/- cells. Conversely, suppression of endogenous TSG101 expression by an antisense TSG101 cDNA causes doubling of the fraction of keratinocytes in the S phase of the cell cycle as occurs during p21 deficiency. Our results indicate that TSG101 has a direct role in the control of growth and differentiation in primary epithelial cells, and that p21 is an important mediator of these TSG101 functions.
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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Animals
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CDC2-CDC28 Kinases*
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Cell Differentiation
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Cell Division
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Cell Line
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Cyclin-Dependent Kinase 2
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Cyclin-Dependent Kinase Inhibitor p21
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Cyclin-Dependent Kinases / metabolism
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Cyclins / chemistry
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Cyclins / physiology*
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DNA, Complementary / metabolism
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / physiology*
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Down-Regulation
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Endosomal Sorting Complexes Required for Transport
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Green Fluorescent Proteins
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Humans
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Keratinocytes / metabolism
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Luminescent Proteins / metabolism
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Mice
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Oligonucleotides, Antisense / chemistry
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Phosphorylation
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Precipitin Tests
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Protein Binding
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Protein Serine-Threonine Kinases / metabolism
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Recombinant Fusion Proteins / metabolism
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Retinoblastoma Protein / metabolism
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S Phase
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Time Factors
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Transcription Factors / chemistry
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Transcription Factors / physiology*
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Transfection
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Two-Hybrid System Techniques
Substances
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CDKN1A protein, human
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Cdkn1a protein, mouse
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Cyclin-Dependent Kinase Inhibitor p21
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Cyclins
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DNA, Complementary
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DNA-Binding Proteins
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Endosomal Sorting Complexes Required for Transport
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Luminescent Proteins
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Oligonucleotides, Antisense
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Recombinant Fusion Proteins
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Retinoblastoma Protein
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Transcription Factors
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Tsg101 protein
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Green Fluorescent Proteins
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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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Cdk2 protein, mouse
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Cyclin-Dependent Kinase 2
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Cyclin-Dependent Kinases