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The human immunodeficiency virus Vpr protein binds Cdc25C: implications for G2 arrest
Wei Chun Goh1, Nicolas Manel, Michael Emerman
1Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
Virology
|February 20, 2004
Summary
The human immunodeficiency virus (HIV) Vpr protein inhibits Cdc25C phosphatase, causing cell cycle arrest. This mechanism highlights a novel target for antiviral therapies.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- The human immunodeficiency virus (HIV) Vpr protein is known to induce G2 phase cell cycle arrest in infected cells.
- This arrest is associated with reduced Cyclin B1-p34Cdc2 activity and increased inhibitory phosphorylation of p34Cdc2.
Purpose of the Study:
- To investigate the molecular mechanism by which HIV Vpr induces G2 cell cycle arrest.
- To determine the role of Cdc25C phosphatase in Vpr-mediated cell cycle regulation.
Main Methods:
- In vitro phosphatase inhibition assays.
- Co-immunoprecipitation to assess Vpr-Cdc25C binding.
- Cell cycle analysis in mammalian cells expressing Vpr and Cdc25C mutants.
- Cdc25C depletion experiments.
Main Results:
- HIV Vpr directly inhibits the phosphatase activity of Cdc25C in vitro.
- Vpr binds to Cdc25C both in vitro and within mammalian cells at a site distinct from the catalytic domain.
- Expression of Vpr-resistant or catalytically inactive Cdc25C mutants partially rescues cells from Vpr-induced G2 arrest.
- Depletion of Cdc25C confers partial resistance to Vpr's effects.
Conclusions:
- HIV Vpr disrupts normal cell cycle progression by inhibiting the essential phosphatase Cdc25C.
- Vpr's interaction with Cdc25C, independent of its catalytic activity, is crucial for G2 arrest.
- Targeting the Vpr-Cdc25C interaction may offer a therapeutic strategy against HIV infection.