Expression profiles of glutathione S-transferase genes in larval midgut of Bombyx mori exposed to insect hormones

Abstract

Glutathione S-transferases (GSTs) are believed to play a role in the detoxification of xenobiotics, resistance to insect viruses and pesticides, intracellular transport, biosynthesis of hormones and protection against oxidative stress. In this study, we used quantitative real time RT-PCR to examine expression profiles of the silkworm Bombyx mori GST-Sigma (BmGSTS2) and GST-Delta (BmGSTD2) genes in the larval midgut of the silkworm after exposure to 2-hydroxyecdysone (20E) and juvenile hormone analog (JHA). In concentration-course study, 20E at higher concentrations (1.0 and 2.0 μg/μl) caused significant upregulation of BmGSTD2, and all concentrations (0.5-2.0 μg/μl) of 20E caused significant upregulation of BmGSTS2. However, JHA in all concentrations downregulated the expression of BmGSTD2 and BmGSTS2. When exposed to either 20E (2.0 μg/μl) or JHA (2.0 μg/μl) on the third day of the fifth instar, the silkworm had higher BmGSTD2 at later time points: 15, 18, and 24 h for 20E and 24 h for JHA. BmGSTS2 expression was downregulated within 24 h after exposure to JHA and showed a time-dependent response after exposure to 20E. We also did a stage-dependent study, in which JHA downregulated BmGSTD2 expression and upregulated BmGSTS2 expression significantly at both day 1 and day 3 of the fifth instar. 20E upregulated the expression of BmGSTD2 and BmGSTS2 at the two stages. These findings imply that hormones have an important role in the regulation of basal GST expression. However, further validation and field trials should be carried out on the regulatory elements relevant to BmGSTD2 and BmGSTS2 gene expression.

OPDA isomerase GST16 is involved in phytohormone detoxification and insect development

“…Genetic, biochemical and physiological studies have established the importance of ecdysone signaling in the regulation of metabolic processes. There is an accumulating body of evidence that the expression of specific GSTs can be regulated by 20E and juvenile hormone titers and it has recently been suggested that there are ecdysone binding motifs in the promoter sequence of several GSTs in Bombyx mori [7]. Taken together, our data suggest that the GST16 protein might have an important but yet unknown function in insects with the isomerization (inactivation) of cis-OPDA being one of the catalytic functions attached to it.…”

Molecular impact of juvenile hormone agonists on neonatal Daphnia magna

“…Although JH‐responsive genes involving acute toxicity in daphnids have not been reported, a few JH‐responsive genes encoding serine protease and glutathione‐ S ‐transferase have already been identified in insects (Horst et al ., ; Zou et al ., ). Expression of most of glutathione‐ S ‐transferase gene was not fluctuated by JH analogs.…”

Genomic Insights into the Glutathione S-Transferase Gene Family of Two Rice Planthoppers, Nilaparvata lugens (Stål) and Sogatella furcifera (Horváth) (Hemiptera: Delphacidae)

“…In insects, the expression of GST genes is life-, stage-, sex- and tissue-specific and influenced by internal and external factors including physiological condition, diet and exposure to toxins [21]–[23]. In N. lugens , GST gene expression levels were generally highest in macropterous adults, but lower in eggs and lower still in nymphs.…”