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Published on: June 21, 2021
Thioredoxin reductase-1 knock down does not result in thioredoxin-1 oxidation
Walter H Watson1, Jacqueline M Heilman, Laura L Hughes
1Johns Hopkins Bloomberg School of Public Health, Department of Environmental Health Sciences, Division of Toxicology, 615 N. Wolfe Street, Room E7545, Baltimore, MD 21205, USA.
Inhibiting thioredoxin reductase-1 (TrxR1) alone does not oxidize thioredoxin-1 (Trx1). Only monomethylarsonous acid (MMA(III)) exposure oxidized Trx1 and increased reactive oxygen species (ROS), indicating Trx1-independent pathways are involved.
Area of Science:
- Biochemistry
- Cell Biology
- Toxicology
Background:
- Thioredoxin-1 (Trx1) is a key cellular antioxidant, with its active site oxidized by reactive oxygen species (ROS) and reduced by thioredoxin reductase-1 (TrxR1).
- Understanding the factors influencing Trx1 redox state is crucial for cellular redox homeostasis and understanding toxicological mechanisms.
Purpose of the Study:
- To investigate the sensitivity of Trx1 redox state to changes in opposing reactions involving ROS and TrxR1 activity.
- To determine if TrxR1 inhibition alone is sufficient to cause Trx1 oxidation.
Main Methods:
- Measuring Trx1 redox state and ROS generation in cells.
- Utilizing TrxR1 inhibitors: aurothioglucose (ATG) and monomethylarsonous acid (MMA(III)).
- Employing siRNA to deplete TrxR1 activity.
Main Results:
- All treatments (ATG, MMA(III), TrxR1 siRNA) inhibited TrxR1 activity by approximately 90%.
- Only MMA(III) exposure led to Trx1 oxidation and elevated ROS levels.
- ATG and TrxR1 siRNA treatments did not result in Trx1 oxidation or significant ROS increase.
Conclusions:
- TrxR1 inhibition alone is insufficient to oxidize Trx1.
- Trx1-independent pathways play a significant role in cellular responses to TrxR1 inhibition.
- These findings necessitate consideration of Trx1-independent mechanisms in evaluating pharmacological and toxicological effects of TrxR1 inhibition.
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