The olfactory epithelium is continuously exposed to exogenous chemicals, including odorants. During the past decade, the enzymes surrounding the olfactory receptors have been shown to make an important contribution to the process of olfaction. Mammalian xenobiotic metabolising enzymes, such as cytochrome P450, esterases and glutathione transferases (GSTs), have been shown to participate in odorant clearance from the olfactory receptor environment, consequently contributing to the maintenance of sensitivity toward odorants. GSTs have previously been shown to be involved in numerous physiological processes, including detoxification, steroid hormone biosynthesis, and amino acid catabolism. These enzymes ensure either the capture or the glutathione conjugation of a large number of ligands. Using a multi-technique approach (proteomic, immunocytochemistry and activity assays), the results indicate that GSTs play an important role in the rat olfactory process. First, proteomic analysis demonstrated the presence of different putative odorant metabolising enzymes, including different GSTs, in the rat nasal mucus. Second, GST expression was investigated in situ in rat olfactory tissues using immunohistochemical methods. Third, the activity of the main GST (GSTM2) odorant was studied with in vitro experiments. Recombinant GSTM2 was used to screen a set of odorants and characterise the nature of its interaction with the odorants. These results support a significant role of GSTs in the modulation of odorant availability for receptors in the peripheral olfactory process.
Authors: Heydel JM, Menetrier F, Belloir C, Canon F, Faure P, Lirussi F, Chavanne E, Saliou JM, Artur Y, Canivenc-Lavier MC, Briand L, Neiers F.
; Full Source: PLoS One. 2019 Jul 24;14(7): e0220259. doi: 10.1371/journal.pone.0220259. eCollection 2019.