Abstract
The CUL4-ROC1 E3 ligase complex regulates genome stability, replication and cell cycle progression. A novel WD40 domain-containing protein, L2DTL/CDT2 and PCNA were identified as proteins associated with CUL4/DDB1 complexes. Inactivation of CUL4A, L2DTL, PCNA, DDB1 or ROC1 induced p53 stabilization and growth arrest. L2DTL, PCNA and DDB1/CUL4A complexes were found to physically interact with p53 tumor suppressor and its regulator MDM2/HDM2. The isolated CUL4A complexes display potent and robust polyubiquitination activity towards p53 and this activity is dependent on L2DTL, PCNA, DDB1, ROC1 and MDM2/HDM2. We also found that the interaction between p53 and CUL4 complex is regulated by DNA damage. Our data further showed that MDM2/HDM2 is rapidly proteolyzed in response to UV irradiation and this process is regulated by CUL4/DDB1 and PCNA. Our studies demonstrate that PCNA, L2DTL and the DDB1-CUL4A complex play critical and differential roles in regulating the protein stability of p53 and MDM2/HDM2 in unstressed and stressed cells.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Adaptor Proteins, Signal Transducing / deficiency
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Adaptor Proteins, Signal Transducing / metabolism*
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Animals
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Carrier Proteins / metabolism
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Cullin Proteins / isolation & purification
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Cullin Proteins / metabolism*
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DNA-Binding Proteins / deficiency
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DNA-Binding Proteins / metabolism*
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Gamma Rays
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HeLa Cells
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Heat-Shock Proteins / deficiency
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Heat-Shock Proteins / metabolism*
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Humans
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Mice
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Nuclear Proteins
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Polyubiquitin / metabolism*
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Proliferating Cell Nuclear Antigen / metabolism*
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Protein Binding / radiation effects
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Protein Processing, Post-Translational / radiation effects
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Proto-Oncogene Proteins c-mdm2 / metabolism*
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Thermodynamics
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Tumor Suppressor Protein p53 / metabolism*
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Ubiquitin-Protein Ligase Complexes / metabolism
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Ubiquitin-Protein Ligases
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Ultraviolet Rays
Substances
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Adaptor Proteins, Signal Transducing
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CUL4A protein, human
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Carrier Proteins
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Cullin Proteins
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DDB1 protein, human
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DNA-Binding Proteins
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DTL protein, human
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Heat-Shock Proteins
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Nuclear Proteins
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Proliferating Cell Nuclear Antigen
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RBX1 protein, human
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Tumor Suppressor Protein p53
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Polyubiquitin
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Ubiquitin-Protein Ligase Complexes
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MDM2 protein, human
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Proto-Oncogene Proteins c-mdm2
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Ubiquitin-Protein Ligases