Abstract
The Myc oncoprotein represses initiator-dependent transcription through the POZ domain transcription factor Miz-1. We now show that transactivation by Miz-1 is negatively regulated by association with topoisomerase II binding protein (TopBP1); UV irradiation downregulates expression of TopBP1 and releases Miz-1. Miz-1 binds to the p21Cip1 core promoter in vivo and is required for upregulation of p21Cip1 upon UV irradiation. Using both c-myc(-/-) cells and a point mutant of Myc that is deficient in Miz-1 dependent repression, we show that Myc negatively regulates transcription of p21Cip1 upon UV irradiation and facilitates recovery from UV-induced cell cycle arrest through binding to Miz-1. Our data implicate Miz-1 in a pathway that regulates cell proliferation in response to UV irradiation.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Cell Cycle Proteins / metabolism
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Cell Division / physiology
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Cell Division / radiation effects
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Cells, Cultured
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Cyclin-Dependent Kinase Inhibitor p15
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Cyclin-Dependent Kinase Inhibitor p16 / metabolism
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Cyclin-Dependent Kinase Inhibitor p21
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Cyclins / genetics
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Cyclins / metabolism
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DNA-Binding Proteins / metabolism*
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Genes, Reporter
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Humans
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Keratinocytes / cytology
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Keratinocytes / physiology
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Keratinocytes / radiation effects
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Kruppel-Like Transcription Factors
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Models, Molecular
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Molecular Sequence Data
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Nuclear Proteins
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Protein Structure, Tertiary
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Proto-Oncogene Proteins c-myc / genetics
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Proto-Oncogene Proteins c-myc / metabolism*
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Sequence Alignment
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Transcription Factors
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Transcription, Genetic / radiation effects*
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Transcriptional Activation*
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Tumor Suppressor Proteins*
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Two-Hybrid System Techniques
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Ultraviolet Rays*
Substances
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CDKN1A protein, human
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CDKN2B protein, human
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Carrier Proteins
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Cell Cycle Proteins
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Cyclin-Dependent Kinase Inhibitor p15
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Cyclin-Dependent Kinase Inhibitor p16
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Cyclin-Dependent Kinase Inhibitor p21
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Cyclins
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DNA-Binding Proteins
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Kruppel-Like Transcription Factors
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Nuclear Proteins
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Proto-Oncogene Proteins c-myc
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Recombinant Fusion Proteins
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TOPBP1 protein, human
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Transcription Factors
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Tumor Suppressor Proteins
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ZBTB17 protein, human