Thallium(I) induces a prolonged inhibition of (6-4)photoproduct binding and UV damage excision repair activities in zebrafish (Danio rerio) embryos via protein inactivation

Chem Biol Interact. 2023 Dec 15:110837. doi: 10.1016/j.cbi.2023.110837. Online ahead of print.ABSTRACTCyclobutane pyrimidine dimer (CPD) and (6-4)photoproduct (6-4PP) are two major types of UV-induced DNA lesion and 6-4PP is more mutagenic than CPD. Activated by lesion detection, nucleotide excision repair (NER) eliminates CPDs and 6-4PPs. Thallium (Tl) is a toxic metal existing primarily as Tl+ in the aquatic environment. Ingestion of Tl+-contaminated foods and water is a major route of human poisoning. As Tl+ may inhibit enzyme activities via binding to sulfhydryl groups, this study explored if Tl+ could intensify UV mutagenicity by inactivating NER-linked damage recognition factors using zebrafish (Danio rerio) embryo as a model system. Incubation of Tl+ (as thallium nitrate) at 0.1-0.4μg/mL with zebrafish extracts for 20 min caused a concentration-dependent inhibition of 6-4PP binding activities as shown by a photolesion-specific band shift assay, while CPD binding activities were insensitive to Tl+. The ability of Tl+ to suppress 6-4PP detection was stronger than that of Hg2+. Exposure of zebrafish embryos at 1 h post fertilization (hpf) to Tl+ at 0.4-1μg/mL for 9 or 71 h also specifically inhibited 6-4PP detection, indicating that Tl+ induced a prolonged inhibition of 6-4PP sensing ability primarily via its direct interaction with damage recognition molecules. Tl+-mediated inhibition of 6-4PP binding in embryos at distinct stages resulted in a suppression of NER capac...
Source: Chemico-Biological Interactions - Category: Molecular Biology Authors: Source Type: research