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Published on: February 7, 2018
Increased susceptibility to oxidative stress-induced toxicological evaluation by genetically modified nrf2a-deficient
Akihito Yamashita1, Jiro Deguchi2, Yayoi Honda2
1Department of Systems Pharmacology, Mie University Graduate School of Medicine, Mie, Japan; Preclinical Research Unit, Sumitomo Dainippon Pharma Co., Ltd., Osaka, Japan.
Introduction:
Oxidative stress plays an important role in drug-induced toxicity. Oxidative stress-mediated toxicities can be detected using conventional animal models but their sensitivity is insufficient, and novel models to improve susceptibility to oxidative stress have been researched. In recent years, gene targeting methods in zebrafish have been developed, making it possible to generate homozygous null mutants. In this study, we established zebrafish deficient in the nuclear factor erythroid 2-related factor 2a (nrf2a), a key antioxidant-responsive gene, and its potential to detect oxidative stress-mediated toxicity was examined.
Methods:
Nrf2a-deficient zebrafish were generated using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 technique. The loss of nrf2a function was confirmed by the tolerability to hydrogen peroxide and hydrogen peroxide-induced gene expression profiles being related to antioxidant response element (ARE)-dependent signaling. Subsequently, vulnerability of nrf2a-deficient zebrafish to acetaminophen (APAP)- or doxorubicin (DOX)-induced toxicity was investigated.
Results:
Nrf2a-deficient zebrafish showed higher mortality than wild type accompanied by less induction of ARE-dependent genes with hydrogen peroxide treatment. Subsequently, this model showed increased severity and incidence of APAP-induced hepatotoxicity or DOX-induced cardiotoxicity than wild type.
Discussion:
Our results demonstrated that anti-oxidative response might not fully function in this model, and resulted in higher sensitivity to drug-induced oxidative stress. Our data support the usefulness of nrf2a-deficient model as a tool for evaluation of oxidative stress-related toxicity in drug discovery research.
Insights
Zebrafish lacking the nuclear factor erythroid 2-related factor 2a (nrf2a) gene show increased sensitivity to drug-induced oxidative stress. This nrf2a-deficient model enhances the detection of drug toxicities, proving useful in drug discovery.
Area of Science:
- Toxicology
- Genetics
- Zebrafish Models
Background:
- Oxidative stress is a key factor in drug-induced toxicity.
- Conventional animal models lack sensitivity for detecting oxidative stress-mediated toxicities.
- Zebrafish offer a promising platform for developing novel toxicity detection models due to advancements in gene targeting.
Purpose of the Study:
- To establish and evaluate zebrafish deficient in nuclear factor erythroid 2-related factor 2a (nrf2a) for detecting oxidative stress-mediated drug toxicity.
- To assess the utility of this nrf2a-deficient model in drug discovery research.
Main Methods:
- Generated nrf2a-deficient zebrafish using CRISPR/Cas9 gene editing.
- Confirmed loss of nrf2a function through hydrogen peroxide (H2O2) tolerance and gene expression analysis.
- Investigated the vulnerability of nrf2a-deficient zebrafish to acetaminophen (APAP) and doxorubicin (DOX) toxicity.
Main Results:
- Nrf2a-deficient zebrafish exhibited higher mortality and reduced induction of antioxidant response element (ARE)-dependent genes upon H2O2 treatment compared to wild-type.
- The model demonstrated increased severity and incidence of APAP-induced hepatotoxicity and DOX-induced cardiotoxicity.
- These findings indicate a compromised anti-oxidative response in the nrf2a-deficient model.
Conclusions:
- The nrf2a-deficient zebrafish model displays heightened sensitivity to drug-induced oxidative stress.
- This model is a valuable tool for evaluating oxidative stress-related toxicity in the context of drug discovery.
- The study supports the use of genetically modified zebrafish for improved toxicity screening.
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