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Updated: Oct 26, 2025
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In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
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Cullin 2-RBX1 E3 ligase and USP2 regulate antithrombin ubiquitination and stability
Dacai Xu1, Jiawen Wu1, Jinghong Chen1
1Guangzhou Municipal and Guangdong Provincial Key Lab of Protein Modification and Degradation Lab, State Key Lab of Respiratory Disease, School of Basic Medical Sciences, Affiliated Cancer Hospital of Guangzhou Medical University, Guangzhou, China.
Summary
Novel regulators Cullin 2 and USP2 (ubiquitin-specific peptidase-2) modulate antithrombin ubiquitination and degradation. Targeting these may offer new hemophilia treatments by controlling antithrombin levels.
Area of Science:
- Biochemistry
- Molecular Biology
- Hematology
Background:
- Hemophilia A and B are genetic bleeding disorders linked to deficiencies in factors VIII or IX.
- Current treatments aim to downregulate antithrombin, but its expression regulation is unclear.
Purpose of the Study:
- To identify novel molecular regulators of antithrombin expression.
- To investigate the role of Cullin 2 and USP2 in antithrombin ubiquitination and degradation.
Main Methods:
- Cellular assays using HepG2 and SMMC7721 cell lines.
- Inhibition of proteasome and neddylation pathways (MLN4924).
- RNA interference (siRNA) to silence NAE1, UBA3, UBE2M, Cullin 2, and USP2.
- Co-immunoprecipitation to identify protein interactions.
Main Results:
- Proteasome inhibition led to antithrombin and its ubiquitinated forms accumulation.
- Neddylation inhibition and silencing of neddylation enzymes suppressed antithrombin ubiquitination and degradation.
- Cullin 2 knockdown reduced antithrombin ubiquitination and increased protein levels.
- USP2 regulated antithrombin expression by inhibiting its ubiquitination and proteasomal degradation.
Conclusions:
- Cullin 2 E3 ubiquitin ligase and USP2 are novel, coordinated regulators of antithrombin ubiquitination and degradation.
- Targeting Cullin 2 and USP2 presents a potential therapeutic strategy for hemophilia treatment.
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