Basal and benzo[a]pyrene-induced expression profile of phase I and II enzymes and ABC transporter mRNA in the early life stage of Chinese rare minnows (Gobiocypris rarus)

Abstract

a b s t r a c t ATP-binding cassette (ABC) transporters together with phase I and II detoxification enzymes have been considered as included in a cellular detoxification system. Previous studies have highlighted the involvement of aryl hydrocarbon receptor (AHR) and Cyp1a in PAH-induced embryo toxicity. However, the response of other xenobiotic enzymes/transporters in PAH-mediated embryo toxicity is not fully characterized. In the present study, rare minnow embryos were exposed to 10 and 100 mg/L BaP within 4 h post-fertilization (hpf) up to 168 hpf. RNA was extracted at 24, 48, 96, and 168 hpf. The basal and BaP-induced expression of phase I enzyme genes (cyp1a, 1b1, and 1c1), phase II enzyme gene (gstm and ugt1a), and ABC transporter genes (abcb1, abcc1, abcc2, and abcg2) mRNA was determined using realtime PCR. Severe developmental defects (e.g., spinal deformities, pericardial and yolk-sac edema) were observed in the BaP treated groups. The basal expression showed that gstm was most strongly expressed, followed by abcb1, ugt1a, and abcc2, whereas cyp1a, 1b1, 1c1, and abcg2 showed weak expression. BaP significantly induced the mRNA expression of three CYP1s (cyp1a, 1b1, and 1c1) (p o0.05) and the ABC transporters (abcc1, abcc2, and abcg2) in a dose-dependent manner. However, the mRNA expression of Phase II enzymes (gstm, ugt1a) for the BaP treatments showed no significant difference with that of the controls. Furthermore, distinct induced patterns of these genes were observed during different exposure periods. Simultaneous up-regulation of the cyp and ABC transporter gene transcripts suggests that a possible involvement and cooperation in the detoxification process could provide protection against the BaP toxicity of rare minnows at the early life stage.

Novel ABCB1 and ABCC Transporters Are Involved in the Detoxification of Benzo(α)pyrene in Thick Shell Mussel, Mytilus coruscus

“…Unfortunately, there are only a few available studies on the role of ABCC in PAHs detoxification in mollusks for establishing comparisons. In the present study, a significant induction of McoABCC was also observed, suggesting that it possibly takes part in Bap scavenging, as ABCB1 does (Costa et al, 2012;Yuan et al, 2014;Kim et al, 2017). Notably, in 100 µg/L Bap group, the mRNA expression levels of McoABCB1 and McoABCC were significantly induced at 1 dpe, sharply decreased over time, and ultimately reached a lower level compared to control group.…”

“…However, the mRNA levels of ABCB1b and ABCC1 were not significantly changed after exposed to a BAP-containing diet and water (Costa et al, 2012). In the fish Gobiocypris rarus, Bap significantly induced the transcriptional expression levels of three ABC transporters (i.e., ABCC1, ABCC2, and ABCG2) in a dosedependent manner, while demonstrated no apparent effect on ABCB1 mRNA expression (Yuan et al, 2014). Collectively, ABC transporters have a highly complex detoxifying response to Bap exposure, and the available data are still confusing, especially in mollusks, where the relevant information is very scarce and requires further investigation.…”

Modulatory Effects of Silymarin on Benzo[a]pyrene-Induced Hepatotoxicity

“…These defense systems are modulated by phase detoxification enzymes such as GSTs, SULTs, uridine 5 -diphospho-glucuronosyltransferases (UGTs), and ABCCs that induce the excretion of toxicants through urine [58]. Previous studies showed that B[a]P-induced genotoxicity was reduced by the modulation of phase detoxifying enzymes before BPDE-DNA adduct formation [17,47]. GSTs are typical phase II detoxifying enzymes and are important in reducing B[a]P-induced DNA damage by inhibiting the formation of DNA adducts and 8-oxo-G [59].…”

“…Nrf2 and PXR are well-known as inducers of phase II detoxification enzyme and phase III transporter expression [17,33,[38][39][40]. To elucidate the pathways involved in the silymarin-mediated suppression of BPDE metabolites, the effects of Nrf2 and PXR translocation were evaluated using immunofluorescence staining.…”

“…In the body, defense systems against xenobiotics such as BPDE include the activation of detoxifying phase II and III enzymes to prevent further cellular damage; specifically, glutathione S-transferases (GSTs) [14], nicotinamide adenine dinucleotide phosphate (NAD(P)H): quinone oxidoreductase 1 (NQO1), sulfotransferases (SULTs), and multidrug resistance-associated proteins (ABCCs) [15][16][17]. Previous studies showed that the genotoxicity of B[a]P was reduced by phase II enzymes conjugated with B[a]P metabolites and that B[a]P was excreted by ABCCs before BPDE-DNA adducts could form [18][19][20].…”