Related Experiment Video
Updated: Jun 4, 2025
In Vivo Alkaline Comet Assay and Enzyme-modified Alkaline Comet Assay for Measuring DNA Strand Breaks and Oxidative DNA Damage in Rat Liver
Published on: May 4, 2016
Repair of Retrorsine-Induced DNA Damage in Rat Livers: Insights Gained from Transcriptomic and Proteomic Studies
Yun Long1, Yiwei Wang1, Zijing Song1
1School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China.
Abstract:
Pyrrolizidine alkaloids (PAs) are common phytotoxins that are found worldwide. Upon hepatic metabolic activation, the reactive PA metabolites covalently bind to DNAs and form DNA adducts, causing mutagenicity and tumorigenicity in the liver. However, the molecular basis of the formation and removal of PA-derived DNA adducts remains largely unexplored. In the present study, Sprague Dawley (SD) rats were exposed to retrorsine (RTS), a representative PA, at a human-relevant dose of 3.3 mg/kg/day for 28 days. The rats were divided into three groups: control, RTS-28 (sacrificed after continuous RTS exposure), and RTS-161 (sacrificed at 133 days post-RTS-exposure). The multi-omics analyses demonstrated the involvement of homologous recombination (HR) and non-homologous end joining (NHEJ) repair pathways as a response to PA-induced DNA damage. Additionally, the characteristic guanine adducts induced by RTS exposure were in accordance with the higher expression of XPA and XPC, indicating that nucleotide excision repair (NER) and base excision repair (BER) also contributed to repairing RTS-induced DNA damage. Furthermore, we also showed that DNA damage persisted after PA exposure, and mutagenically related repair errors might occur due to the prolonged genotoxic effects. The present study lays the foundation for bridging PA-derived DNA adducts, DNA damage, DNA repair, and the follow-up mutagenesis and carcinogenesis associated with PA exposure.
Insights
Pyrrolizidine alkaloids (PAs) cause DNA damage and adducts. DNA repair pathways like HR, NHEJ, NER, and BER are activated, but damage may persist, potentially leading to mutations and cancer.
Area of Science:
- Toxicology
- Molecular Biology
- Genetics
Background:
- Pyrrolizidine alkaloids (PAs) are widespread phytotoxins.
- PA metabolites form DNA adducts after hepatic activation, leading to liver mutagenicity and tumorigenicity.
- The molecular mechanisms of PA-DNA adduct formation and removal are not well understood.
Purpose of the Study:
- To investigate the DNA damage and repair responses to retrorsine (RTS), a representative PA, in Sprague Dawley rats.
- To elucidate the molecular basis of PA-derived DNA adduct formation, removal, and potential long-term genotoxic effects.
Main Methods:
- Sprague Dawley rats were exposed to retrorsine (RTS) at a human-relevant dose (3.3 mg/kg/day) for 28 days.
- Rats were analyzed immediately after exposure (RTS-28) and after a recovery period (RTS-161).
- Multi-omics analyses were employed to assess DNA damage and repair pathway involvement.
Main Results:
- PA exposure induced DNA damage, activating homologous recombination (HR) and non-homologous end joining (NHEJ) repair pathways.
- Increased expression of XPA and XPC indicated the involvement of nucleotide excision repair (NER) and base excision repair (BER) in repairing RTS-induced guanine adducts.
- DNA damage persisted post-exposure, suggesting potential mutagenic repair errors due to prolonged genotoxic effects.
Conclusions:
- This study reveals the involvement of multiple DNA repair pathways in response to PA-induced DNA damage.
- Persistent DNA damage and potential repair errors highlight the long-term risks associated with PA exposure.
- The findings provide a foundation for understanding the link between PA-DNA adducts, DNA repair, and carcinogenesis.
