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Generation and characterization of keap1a- and keap1b-knockout zebrafish
Vu Thanh Nguyen1, Lixuan Bian2, Junya Tamaoki2
1Department of Molecular and Developmental Biology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan; Division of Aquaculture Biotechnology, Biotechnology Center of Ho Chi Minh City, Ho Chi Minh City, Viet Nam.
Redox Biology
|August 23, 2020
Summary
Zebrafish have two Keap1 proteins, Keap1a and Keap1b, that regulate the protective Keap1-Nrf2 pathway. Both inhibit Nrf2, but only Keap1a senses chemical stressors, revealing functional divergence.
Area of Science:
- Cellular Biology
- Molecular Biology
- Toxicology
Background:
- The Keap1-Nrf2 pathway is crucial for cellular defense against oxidative stress and electrophiles.
- Keap1 acts as a sensor and inhibitor of Nrf2, regulating its degradation.
- Vertebrates exhibit variations in Keap1 gene duplication, with fish and amphibians possessing two Keap1s (Keap1a, Keap1b) unlike mammals.
Purpose of the Study:
- To investigate the functional differences and similarities between Keap1a and Keap1b in zebrafish.
- To understand the distinct roles of Keap1a and Keap1b in regulating the Keap1-Nrf2 pathway.
- To explore the stress-sensing capabilities of Keap1a and Keap1b.
Main Methods:
- Generation of zebrafish knockout lines for keap1a and keap1b using zebrafish genetics.
- Analysis of basal expression of Nrf2 target genes and antioxidant activity in mutant larvae.
- Assessment of the response to the Nrf2 activator sulforaphane in keap1a and keap1b knockout zebrafish.
Main Results:
- Homozygous keap1a and keap1b knockout zebrafish mutants were viable and fertile.
- Both keap1a and keap1b knockout larvae showed up-regulated basal expression of Nrf2 target genes and antioxidant activity in an Nrf2-dependent manner.
- Only keap1a knockout larvae, not keap1b knockout larvae, responded to sulforaphane treatment, indicating differential chemical-sensing abilities.
Conclusions:
- Both Keap1a and Keap1b function as inhibitors of Nrf2 in zebrafish.
- Keap1a and Keap1b possess distinct stress/chemical-sensing capabilities, with Keap1a being responsive to sulforaphane while Keap1b is not.
- This study highlights the functional divergence of duplicated Keap1 genes in vertebrates, impacting cellular stress response.
