Transcriptomic analyses uncover emerging roles of mucins, lysosome/secretory addressing and detoxification pathways in insect midguts

• Published in: Current opinion in insect science Vol. 29; pp. 34 - 40
• Main Authors: Terra, Walter R, Dias, Renata O, Oliveira, Pedro L, Ferreira, Clélia, Venancio, Thiago M
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-10-2018
• ISSN: 2214-5745; 2214-5745
• DOI: 10.1016/j.cois.2018.05.015

•Genes for mucus-forming mucins are widespread in insect midguts.•Insects lack the mannose 6-phosphate-depending lysosomal targeting mechanism.•Xenobiotic detoxification pathways can play roles in host–microbiota interactions.
The study of insect midgut features has been made possible by the recent availability of transcriptome datasets. These data uncovered the preferential expression of mucus-forming mucins at midgut regions that require protection (e.g. the acidic middle midgut of Musca domestica) or at sites of enzyme immobilization, particularly around the peritrophic membrane of Spodoptera frugiperda. Coleoptera lysosomal peptidases are directed to midgut lumen when over-expressed and targeted to lysosomes by a mechanism other than the mannose 6-phosphate-dependent pathway. We show that this second trend is likely conserved across Annelida, Mollusca, Nematoda, and Arthropoda. Furthermore, midgut transcriptomes of distantly related species reveal a general overexpression of xenobiotic detoxification pathways. In addition to attenuating toxicity of plant-derived compounds and insecticides, we also discuss a role for these detoxification pathways in regulating host–microbiota interactions by metabolizing bacterial secondary metabolites.