In Vivo Glutathione S-Transferases Superfamily Proteome Analysis: An Insight into Aedes albopictus Mosquitoes upon Acute Xenobiotic Challenges.

In this study, the induction of glutathione S-transferase (GST) enzymatic activities in Aedes albopictus under 24 h of xenobiotic challenges was investigated. From LCMS analysis, 23 GST isoforms were identified under Delta, Epsilon, Sigma, Zeta, Omega, and Iota classes, together with one GSTX1-1 isoform, in both treated and untreated samples. Using STRING 11.5, the functional enrichment network of Gene Ontology (GO) analysis, the identified peptides were found to be involved in the glutathione metabolic biological process (GO:0006749, p-value: 1.93 × 10−29), and the molecular functions involved are due to glutathione transferase (GO:0016848, p-value: 2.92 × 10−8) aside from carbon-halide lyase activity (GO:004364, p-value: 1.21 × 10−31). The Protein-Protein Interaction (PPI) network (STRING 11.5) showed significant interactions within the GST superfamily and some of the GST classes interacted with other proteins among the input domain of the identified peptides (p-value < 1.0 × 10−16). In TMT labeling for the quantification of peptide abundance, isoforms from Delta (GSTD1-2, GSTD1-3, GSTD1-4) and Epsilon (GSTE3-1, GSTE4-2) were found to be overexpressed (between 1.5-fold and 2-fold changes). In the PPI analysis, 12 common enriched pathways of Kyoto Encyclopedia of Genes and Genomes (KEGG) were found to be intercorrelated with the identified GSTs at PPI enrichment p-value < 1.0 × 10−16. Overall, this study indicates that distinct GST enzymes, which were identified up to their specific protein isoforms, are involved in the metabolic mechanisms underlying xenobiotic stress.

Isoenzymes of Aedes albopictus (Diptera: Culicidae) Glutathione S-transferases: Isolation and expression after acute insecticide treatment.

Glutathione S-transferases (GSTs) from susceptible Aedes albopictus larvae were partially isolated using two different purification strategies (GSTrap™ HP and GSH-agarose affinity columns) and the effects of permethrin and DDT on expression of the GSTs were investigated. Distinct double bands on SDS-PAGE with molecular weights between 20 and 25 kDa were successfully purified using GSTrap™ HP while a single band of 24.5 kDa was purified using GSH-agarose. The isolated GSTs belonged to the Delta, Sigma and Theta GST classes. When exposed to permethrin, one isoform of Theta, four isoforms of Sigma and thirteen isoforms of Delta GSTs showed an increased expression between 1.4-fold and 2.5-fold while DDT treatment resulted in between 1.4-fold and 3.2-fold increased expression in one isoform of Theta, four isoforms of Sigma and eleven isoforms of Delta GSTs (p < .05). This study indicated that GSTrap™ HP was more competent in isolating Ae. albopictus GSTs compared to GSH-agarose and also variable expression of GST isoforms occur in response to different insecticides. This information may be useful for improving insecticide resistance management strategies in aspect of molecular resistant and evolutionary tolerant detoxification enzyme.