Abstract
It is believed that Mdm2 suppresses p53 in two ways: transcriptional inhibition by direct binding, and degradation via its E3 ligase activity. To study these functions physiologically, we generated mice bearing a single-residue substitution (C462A) abolishing the E3 function without affecting p53 binding. Unexpectedly, homozygous mutant mice died before E7.5, and deletion of p53 rescued the lethality. Furthermore, reintroducing a switchable p53 by crossing with p53ER(TAM) mice surprisingly demonstrated that the mutant Mdm2(C462A) was rapidly degraded in a manner indistinguishable from that of the wild-type Mdm2. Hence, our data indicate that (1) the Mdm2-p53 physical interaction, without Mdm2-mediated p53 ubiquitination, cannot control p53 activity sufficiently to allow early mouse embryonic development, and (2) Mdm2's E3 function is not required for Mdm2 degradation.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Substitution
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Animals
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Cells, Cultured
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DNA Damage
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Down-Regulation
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Embryo, Mammalian
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Fibroblasts / enzymology
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Fibroblasts / metabolism
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Fibroblasts / radiation effects
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Gamma Rays
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Gene Expression Regulation, Developmental* / radiation effects
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Genotype
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Gestational Age
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Homozygote
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Mice
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Mice, Inbred C57BL
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Mice, Knockout
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Mutagenesis, Site-Directed*
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Mutation
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Phenotype
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Proteasome Endopeptidase Complex / metabolism
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Protein Structure, Tertiary
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Proto-Oncogene Proteins c-mdm2 / chemistry
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Proto-Oncogene Proteins c-mdm2 / deficiency
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Proto-Oncogene Proteins c-mdm2 / genetics
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Proto-Oncogene Proteins c-mdm2 / metabolism*
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Transcription, Genetic* / radiation effects
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Tumor Suppressor Protein p53 / deficiency
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Tumor Suppressor Protein p53 / genetics
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Tumor Suppressor Protein p53 / metabolism*
Substances
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Tumor Suppressor Protein p53
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Mdm2 protein, mouse
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Proto-Oncogene Proteins c-mdm2
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Proteasome Endopeptidase Complex