Dataset Information

Characterization of rat glutathione transferases in olfactory epithelium and mucus.

ABSTRACT: 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 metabolizing 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), our results indicate that GSTs play an important role in the rat olfactory process. First, proteomic analysis demonstrated the presence of different putative odorant metabolizing 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 characterize the nature of its interaction with the odorants. Our results support a significant role of GSTs in the modulation of odorant availability for receptors in the peripheral olfactory process.

SUBMITTER: Heydel JM

PROVIDER: S-EPMC6656353 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Characterization of rat glutathione transferases in olfactory epithelium and mucus.

Heydel Jean-Marie JM Menetrier Franck F Belloir Christine C Canon Francis F Faure Philippe P Lirussi Frederic F Chavanne Evelyne E Saliou Jean-Michel JM Artur Yves Y Canivenc-Lavier Marie-Chantal MC Briand Loïc L Neiers Fabrice F

PloS one 20190724 7

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 metabolizing 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 ...[more]

PMID: 31339957

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Project description:BackgroundGlutathione transferases (GSTs) represent an extended family of multifunctional proteins involved in detoxification processes and tolerance to oxidative stress. We thus anticipated that some GSTs could play an essential role in the protection of fungal necrotrophs against plant-derived toxic metabolites and reactive oxygen species that accumulate at the host-pathogen interface during infection.ResultsMining the genome of the necrotrophic Brassica pathogen Alternaria brassicicola for glutathione transferase revealed 23 sequences, 17 of which could be clustered into the main classes previously defined for fungal GSTs and six were 'orphans'. Five isothiocyanate-inducible GSTs from five different classes were more thoroughly investigated. Analysis of their catalytic properties revealed that two GSTs, belonging to the GSTFuA and GTT1 classes, exhibited GSH transferase activity with isothiocyanates (ITC) and peroxidase activity with cumene hydroperoxide, respectively. Mutant deficient for these two GSTs were however neither more susceptible to ITC nor less aggressive than the wild-type parental strain. By contrast mutants deficient for two other GSTs, belonging to the Ure2pB and GSTO classes, were distinguished by their hyper-susceptibility to ITC and low aggressiveness against Brassica oleracea. In particular AbGSTO1 could participate in cell tolerance to ITC due to its glutathione-dependent thioltransferase activity. The fifth ITC-inducible GST belonged to the MAPEG class and although it was not possible to produce the soluble active form of this protein in a bacterial expression system, the corresponding deficient mutant failed to develop normal symptoms on host plant tissues.ConclusionsAmong the five ITC-inducible GSTs analyzed in this study, three were found essential for full aggressiveness of A. brassicicola on host plant. This, to our knowledge is the first evidence that GSTs might be essential virulence factors for fungal necrotrophs.

Project description:The glutathione S-transferases (GSTs) are a family of phase II detoxification enzymes which protect against chemical injury. In contrast to mammals, GST expression in fish has not been extensively characterized, especially in the context of detoxifying waterborne pollutants. In the Northwestern United States, coho salmon (Oncorhynchus kisutch) are an important species of Pacific salmon with complex life histories that can include exposure to a variety of compounds including GST substrates. In the present study we characterized the expression of coho hepatic GST to better understand the ability of coho to detoxify chemicals of environmental relevance. Western blotting of coho hepatic GST revealed the presence of multiple GST-like proteins of approximately 24-26kDa. Reverse phase HPLC subunit analysis of GSH affinity-purified hepatic GST demonstrated six major and at least two minor potential GST isoforms which were characterized by liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI MS-MS) and Fourier transform-ion cyclotron resonance (FT-ICR) MS analyses. The major hepatic coho GST isoforms consisted of a pi and a rho-class GST, whereas GSTs representing the alpha and mu classes constituted minor isoforms. Catalytic studies demonstrated that coho cytosolic GSTs were active towards the prototypical GST substrate 1-chloro-2,4-dinitrobenzene, as well as towards ethacrynic acid and nitrobutyl chloride. However, there was no observable cytosolic GST activity towards the pesticides methyl parathion or atrazine, or products of oxidative stress, such as cumene hydroperoxide and 4-hydroxynonenal. Interestingly, coho hepatic cytosolic fractions had a limited ability to bind bilirubin, reflecting a potential role in the sequestering of metabolic by-products. In summary, coho salmon exhibit a complex hepatic GST isoform expression profile consisting of several GST classes, but may have a limited a capacity to conjugate substrates of toxicological significance such as pesticides and endogenous compounds associated with cellular oxidative stress.

Dataset Information

Characterization of rat glutathione transferases in olfactory epithelium and mucus.

Publications

Characterization of rat glutathione transferases in olfactory epithelium and mucus.

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