Transcriptomic and Proteomic Profiling Revealed High Proportions of Odorant Binding and Antimicrobial Defense Proteins in Olfactory Tissues of the House Mouse

Abstract

Mammalian olfaction depends on chemosensory neurons of the main olfactory epithelia (MOE), and/or of the accessory olfactory epithelia in the vomeronasal organ (VNO). Thus, we have generated the VNO and MOE transcriptomes and the nasal cavity proteome of the house mouse, Mus musculus musculus. Both transcriptomes had low levels of sexual dimorphisms, while the soluble proteome of the nasal cavity revealed high levels of sexual dimorphism similar to that previously reported in tears and saliva. Due to low levels of sexual dimorphism in the olfactory receptors in MOE and VNO, the sex-specific sensing seems less likely to be dependent on receptor repertoires. However, olfaction may also depend on a continuous removal of background compounds from the sites of detection. Odorant binding proteins (OBPs) are thought to be involved in this process and in our study Obp transcripts were most expressed along other lipocalins (e.g., Lcn13, Lcn14) and antimicrobial proteins. At the level of proteome, OBPs were highly abundant with only few being sexually dimorphic. We have, however, detected the major urinary proteins MUP4 and MUP5 in males and females and the male-biased central/group-B MUPs that were thought to be abundant mainly in the urine. The exocrine gland-secreted peptides ESP1 and ESP22 were male-biased but not male-specific in the nose. For the first time, we demonstrate that the expression of nasal lipocalins correlates with antimicrobial proteins thus suggesting that their individual variation may be linked to evolvable mechanisms that regulate natural microbiota and pathogens that regularly enter the body along the ‘eyes-nose-oral cavity’ axis.

Expression and function of murine WFDC2 in the respiratory tract

“…These observations are consistent with those seen in man, where the protein has been reported in nasal secretions, bronchioalveolar lavage fluid, saliva, tears and endocervical mucus [36][37][38][39][40]. It has been identified in murine nasal secretions [41] and saliva [35]. The protein appears as multiple bands in mouse BAL fluid samples and contains multiple potential O-glycosylation sites.…”

Characterization of rat glutathione transferases in olfactory epithelium and mucus

“…For example, tubulin, keratin and clathrin, which shape rounded vesicles in the cytoplasm, were in this group. As previously observed in mice and human mucus proteomes, many proteins involved in bacterial resistance were identified [1,2]. These proteins can be involved in this resistance directly, such as proteases or ribonucleases (4.2%), or indirectly, such as the group of proteins consisting of protease inhibitors (5.2%).…”

“…To reach the olfactory receptors, odorants cross through an aqueous layer of mucus lining the epithelium. The proteins contained in the olfactory mucus have been previously characterized in humans and mice [1,2]. These proteins, which are involved in many functions, such as antimicrobial resistance and protein folding, also include odorant transporters and enzymes involved in odorant transport and metabolism, respectively.…”

Kidney Response to Heart Failure: Proteomic Analysis of Cardiorenal Syndrome

“…However, major urinary proteins serve as carriers of small molecules, including odorants and pheromones. In rodents (but not in humans) these lipocalins are secreted by the kidneys into urine in large quantities and play role in social behavior, mating and response to xenobiotics [50]; significance of these changes for kidney function in HF are not known.…”