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

SIMPLE SUMMARY: Glutathione S-transferases (GSTs) are a superfamily of enzymes that play a crucial part in phase II detoxification reactions. In many cases, GSTs have been implicated in toxicological challenges by association only (i.e., detected using model substrates or due to an increase in GST activity) and not through the identification of the individual peptides involved. In this study, the aim was to identify the GSTs induced by acute insecticide challenges up to the isoform or peptide level and the detoxification mechanisms involved in Aedes albopictus larvae. Upon permethrin and malathion inductions, the GST-based peptides were identified, and the functional characteristics as well as protein-protein interactions were analyzed along with the quantification of the abundance. Twenty-four GST peptide isoforms were identified under seven different classes with a highly significant protein-protein interaction between GST groups and within other detoxification metabolism-related peptides (p-value < 1.0 × 10(−16)). Overall, our findings indicate that out of seven GST classes, only Delta and Epsilon GSTs were mainly involved in the detoxification mechanism via the direct glutathione metabolism or the sequestration of the insecticides, as well as providing the protection of sulfhydryl groups in enzymes against oxidative stress induced by insecticide exposure. ABSTRACT: 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.