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RB18A regulates p53-dependent apoptosis
Raymond Frade1, Michelle Balbo, Monique Barel
1Immunochimie des Régulations Cellulaires et des Interactions Virales, INSERM U.354, Centre INSERM, Hôpital Saint-Antoine, 75012, Paris, France. frade354@easynet.fr
Oncogene
|February 13, 2002
Summary
RB18A, a transcription cofactor, reduces p53wt-dependent apoptosis by decreasing p53wt protein levels via proteasome degradation, upregulating MDM2 expression.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Research
Background:
- RB18A is a transcription cofactor regulating p53wt activity.
- p53wt is a tumor suppressor protein crucial for apoptosis and cell cycle arrest.
Purpose of the Study:
- To investigate the mechanism by which RB18A regulates p53wt-dependent apoptosis.
- To elucidate the role of RB18A in p53wt protein degradation.
Main Methods:
- Transfection of p53-negative cells with RB18A constructs.
- Assessment of p53wt, p53mut, and GAPDH protein levels.
- Inhibition of proteasome activity using MG-132.
- Analysis of MDM2 expression and promoter activity.
Main Results:
- RB18A down-regulated p53wt-dependent apoptosis.
- RB18A specifically decreased p53wt protein levels, not p53mut or GAPDH.
- p53wt degradation was proteasome-dependent and correlated with increased MDM2 expression.
- RB18A upregulated MDM2 promoter activity, independent of p53wt.
Conclusions:
- RB18A regulates p53wt function through direct interaction and by upregulating MDM2.
- RB18A promotes p53wt degradation via the proteasome pathway by increasing MDM2 levels.