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In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
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MDM2-C Functions as an E3 Ubiquitin Ligase.
Jun Yeob Kim1, Rusia Lee1,2, Gu Xiao1
1The Department of Biological Sciences, Hunter College, City University of New York, New York, NY, USA.
Cancer Management and Research
|September 9, 2020
Summary
The MDM2-C protein isoform exhibits E3 ubiquitin ligase activity, promoting ubiquitination of both wild-type and mutant p53. This finding clarifies MDM2-C
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Mouse double minute 2 (MDM2) is an over-expressed E3 ubiquitin ligase in many cancers.
- While full-length MDM2 (MDM2-FL) targets wild-type p53 for degradation, functions of MDM2 splice variants are underexplored.
- MDM2-C is over-expressed in breast cancer and linked to poorer survival with mutant p53.
Purpose of the Study:
- To investigate the biochemical function of the MDM2-C isoform.
- To determine if MDM2-C possesses E3 ubiquitin ligase activity, similar to MDM2-FL.
Main Methods:
- In vitro ubiquitination assay.
- Glutaraldehyde cross-linking assay.
Main Results:
- MDM2-C demonstrates E3 auto-ubiquitin ligase activity.
- MDM2-C promotes ubiquitination of wild-type p53 and mutant p53 R273H.
- MDM2-C forms protein-protein interactions with p53.
Conclusions:
- MDM2-C exhibits biochemical activities, including p53 ubiquitination.
- These activities may explain varied patient outcomes based on MDM2-C and p53 status (wild-type vs. mutant).
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