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Keap1 modification and nuclear accumulation in response to S-nitrosocysteine
Barbara J Buckley1, Sheng Li, A Richard Whorton
1Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
Free Radical Biology & Medicine
|December 8, 2007
Summary
Nitric oxide and S-nitrosocysteine modify Keap1, stabilizing the Nrf2 (Nuclear factor erythroid 2-related factor 2) protein. This leads to Nrf2 accumulation in the nucleus, enhancing antioxidant defenses.
Area of Science:
- Molecular Biology
- Cellular Signaling
- Oxidative Stress Response
Background:
- Keap1 regulates the Nrf2 (Nuclear factor erythroid 2-related factor 2) transcription factor, controlling antioxidant defense proteins.
- Under normal conditions, Keap1 targets Nrf2 for degradation, ensuring rapid Nrf2 turnover.
- Oxidative or electrophilic stress stabilizes Nrf2, promoting its nuclear accumulation.
Purpose of the Study:
- To investigate the mechanism by which nitric oxide and S-nitrosocysteine affect Keap1 and Nrf2.
- To determine if Keap1 thiol modification mediates the stabilization of Nrf2.
Main Methods:
- Utilized HEK293 cells and HEK293 cells overexpressing hemagglutinin-tagged Keap1.
- Administered nitric oxide and S-nitrosocysteine (CSNO) to cells.
- Assessed Keap1 thiol modification, Nrf2 nuclear accumulation, and Keap1 nuclear translocation.
Main Results:
- Nitric oxide and CSNO induced time- and dose-dependent Keap1 thiol modification.
- CSNO treatment resulted in Keap1 accumulation in the nucleus.
- The time course of Keap1 nuclear accumulation mirrored that of Nrf2.
Conclusions:
- Thiol modification of Keap1 by nitric oxide and CSNO is a key event in Nrf2 stabilization.
- Nitric oxide signaling pathways influence Keap1 activity and Nrf2 regulation.
- These findings elucidate a novel mechanism for controlling the antioxidant response.
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