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mdmx is a negative regulator of p53 activity in vivo
Rick A Finch1, Dorit B Donoviel, David Potter
1Lexicon Genetics, Inc., 4000 Research Forest Drive, The Woodlands, TX 77381, USA.
Abstract:
Regulation of p53 protein activity is required for normal embryogenesis, tumor suppression, and cellular response to DNA damage. Here we report that loss of mdmx, a p53-binding protein, results in midgestational embryo lethality, a phenotype that is completely rescued by the absence of p53. Mice homozygous for both mdmx and p53 null mutations are viable and appear developmentally normal. Fibroblasts derived from embryos with reduced mdmx expression demonstrate a decreased growth rate and increased UV-induced apoptosis compared with wild-type cells and contain elevated levels of p53 and several p53 target proteins including the proapoptotic bax protein. These observations demonstrate that mdmx functions as a critical negative regulator of p53 in vivo.
Insights
Loss of MDMX, a p53-binding protein, causes embryonic lethality rescued by p53 absence. MDMX negatively regulates p53 protein activity in vivo, impacting embryogenesis and DNA damage response.
Area of Science:
- Molecular Biology
- Genetics
- Developmental Biology
Background:
- p53 protein activity is crucial for embryogenesis, tumor suppression, and DNA damage response.
- MDMX is a known p53-binding protein, but its in vivo function remains incompletely understood.
Purpose of the Study:
- To investigate the in vivo role of MDMX in regulating p53 activity.
- To determine the consequences of MDMX loss on embryonic development and cellular responses.
Main Methods:
- Generation and analysis of mdmx and p53 double knockout mice.
- Phenotypic characterization of embryos and fibroblasts from knockout mice.
- Assessment of p53 protein levels and target gene expression.
Main Results:
- Loss of mdmx leads to midgestational embryonic lethality, which is rescued by the absence of p53.
- Mice lacking both mdmx and p53 are viable and developmentally normal.
- Fibroblasts with reduced mdmx show decreased growth, increased UV-induced apoptosis, and elevated p53 levels.
Conclusions:
- MDMX functions as a critical negative regulator of p53 in vivo.
- The p53-MDMX interaction is essential for normal embryonic development and cellular homeostasis.