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Regulation of Nrf2-an update
Suryakant K Niture1, Raju Khatri1, Anil K Jaiswal1
1Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Free Radical Biology & Medicine
|February 26, 2013
Summary
Nuclear factor erythroid 2-related factor 2 (Nrf2) and its inhibitor INrf2 (Keap1) sense cellular stress. Their interaction regulates protective gene expression, but mutations can drive cancer.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Biology
Background:
- Nuclear factor erythroid 2-related factor 2 (Nrf2) and its inhibitor INrf2 (Keap1) are key regulators of cellular responses to oxidative and electrophilic stress.
- Nrf2 controls the expression of genes involved in detoxification, antioxidant defense, and cell survival.
- Under basal conditions, Nrf2 is targeted for degradation by INrf2 via the Cul3/Rbx1 E3 ubiquitin ligase complex.
Purpose of the Study:
- To elucidate the intricate signaling pathways governing the activation and repression of Nrf2.
- To understand how external stimuli like antioxidants and radiation modulate the Nrf2:INrf2 interaction.
- To explore the consequences of Nrf2 pathway dysregulation in diseases such as cancer.
Main Methods:
- The study describes the molecular mechanisms of Nrf2 regulation, including phosphorylation events and protein-protein interactions.
- It details the roles of specific kinases (tyrosine kinases, PKC, GSK3β) and phosphatases in controlling Nrf2 stability and localization.
- The research examines the impact of oxidative/electrophilic modifications on INrf2 and Nrf2.
Main Results:
- Antagonists of the Nrf2:INrf2 interaction, such as antioxidants and phytochemicals, stabilize and activate Nrf2.
- Oxidative stress triggers a preinduction response involving tyrosine kinase activation and nuclear export of negative regulators.
- Further induction involves INrf2 modification and PKC-mediated Nrf2 phosphorylation, leading to Nrf2 nuclear translocation and gene activation. A postinduction response involving Fyn kinase mediates Nrf2 degradation.
- Mutations in INrf2 or Nrf2 can lead to aberrant Nrf2 accumulation, promoting oncogenesis and drug resistance.
Conclusions:
- The Nrf2 pathway is tightly regulated through sequential preinduction, induction, and postinduction signaling events.
- Proper activation and repression of Nrf2 are crucial for cellular protection against stress and associated diseases.
- Dysregulation of the Nrf2 pathway, particularly due to mutations, contributes to cancer development and treatment resistance.
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