Related Experiment Video
Updated: Mar 3, 2026
Comprehensive Assessment of Germline Chemical Toxicity Using the Nematode Caenorhabditis elegans
Published on: February 22, 2015
A Genetic Analysis of the Caenorhabditis elegans Detoxification Response
Tetsunari Fukushige1, Harold E Smith2, Johji Miwa3
1Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Abstract:
Oxidative damage contributes to human diseases of aging including diabetes, cancer, and cardiovascular disorders. Reactive oxygen species resulting from xenobiotic and endogenous metabolites are sensed by a poorly understood process, triggering a cascade of regulatory factors and leading to the activation of the transcription factor Nrf2 (Nuclear factor-erythroid-related factor 2, SKN-1 in Caenorhabditis elegans). Nrf2/SKN-1 activation promotes the induction of the phase II detoxification system that serves to limit oxidative stress. We have extended a previous C. elegans genetic approach to explore the mechanisms by which a phase II enzyme is induced by endogenous and exogenous oxidants. The xrep (xenobiotics response pathway) mutants were isolated as defective in their ability to properly regulate the induction of a glutathione S-transferase (GST) reporter. The xrep-1 gene was previously identified as wdr-23, which encodes a C. elegans homolog of the mammalian β-propeller repeat-containing protein WDR-23 Here, we identify and confirm the mutations in xrep-2, xrep-3, and xrep-4 The xrep-2 gene is alh-6, an ortholog of a human gene mutated in familial hyperprolinemia. The xrep-3 mutation is a gain-of-function allele of skn-1 The xrep-4 gene is F46F11.6, which encodes a F-box-containing protein. We demonstrate that xrep-4 alters the stability of WDR-23 (xrep-1), a key regulator of SKN-1 (xrep-3). Epistatic relationships among the xrep mutants and their interacting partners allow us to propose an ordered genetic pathway by which endogenous and exogenous stressors induce the phase II detoxification response.
Insights
Researchers identified key genes in the xenobiotic response pathway (xrep) that regulate the detoxification system. This pathway activation is crucial for managing oxidative stress and preventing age-related diseases.
Area of Science:
- Molecular Biology
- Genetics
- Toxicology
Background:
- Oxidative damage is implicated in aging-related diseases like cancer and diabetes.
- Reactive oxygen species trigger the Nuclear factor-erythroid-related factor 2 (Nrf2) pathway, activating detoxification systems.
- The precise mechanisms sensing oxidative stress and activating Nrf2 remain incompletely understood.
Purpose of the Study:
- To elucidate the genetic pathway controlling the induction of phase II detoxification enzymes in response to oxidants.
- To identify novel genes involved in the xenobiotic response pathway (xrep) in *C. elegans*.
Main Methods:
- Utilized a *C. elegans* genetic screen to isolate mutants defective in glutathione S-transferase (GST) reporter induction.
- Identified and confirmed mutations in *xrep-2*, *xrep-3*, and *xrep-4* genes.
- Analyzed epistatic relationships between identified *xrep* mutants and their interacting partners.
Main Results:
- Identified *alh-6* (*xrep-2*), a gain-of-function allele of *skn-1* (*xrep-3*), and *F46F11.6* (*xrep-4*) as critical components of the xenobiotic response pathway.
- Demonstrated that *xrep-4* (F-box protein) affects the stability of WDR-23 (*xrep-1*), a regulator of SKN-1 (*xrep-3*).
- Established an ordered genetic pathway for phase II detoxification induction by stressors.
Conclusions:
- The identified *xrep* genes and their interactions provide a framework for understanding how organisms respond to oxidative stress.
- This research deepens our knowledge of the Nrf2/SKN-1 pathway's role in cellular defense against endogenous and exogenous oxidants.
- Findings contribute to understanding the molecular basis of diseases linked to oxidative damage.
