Epithelial membrane transporters expression in the developing to adult mouse vomeronasal organ and olfactory mucosa

Abstract

To contribute clarifying mechanisms operating in nose chemosensory epithelia and their developmental patterns, we analyzed the expression of different epithelial membrane transporters as well as the Clara cell secretory protein, CC26 in the olfactory, vomeronasal organ (VNO), and respiratory epithelia of embryonic (E13-E19) and postnatal (P1-P60) mice by means of immunohistochemistry and reverse transcriptase-polymerase chain reaction. Results showed that CC26, cAMP-activated chloride channel (CFTR), and the water channel protein aquaporin 2, 3, 4, and 5 (AQP2, AQP3, AQP4, and AQP5) are expressed in developing to adult chemosensory epithelia with differential timing; moreover, their pattern of expression is not identical in VNO and olfactory epithelia as well as the corresponding associated glands; co-localization experiments using olfactory marker protein showed that CFTR, CC26, and AQP4 are not expressed in olfactory neurones. CFTR is expressed in sustentacular cells of the VNO and olfactory epithelium as well as blood vessels of the underlying mucosa, and VNO (but not Bowman's) glands; a similar pattern (excluding blood vessels) is present for AQP2; AQP4 is found in the two chemosensory epithelia and in Bowman's glands. AQP3 is expressed in the olfactory epithelium and the associated Bowman's glands, but not in the VNO chemosensory epithelium and glands. AQP5 is expressed in the olfactory epithelium and both Bowman's and VNO glands. These results indicate that water/ions handling as well as antioxidant mechanisms operating at the surface and/or inside the nose chemosensory epithelia start developing in utero and are maintained up to sexual maturity.

Novel role of cystic fibrosis transmembrane conductance regulator in maintaining adult mouse olfactory neuronal homeostasis

“…To this end, we first performed in situ hybridization and immunohistochemistry analysis to locate CFTR in mouse OE. Unlike published results, which tentatively localized CFTR mRNA in sustentacular cells (Merigo et al, ), we observed that CFTR is selectively expressed by CD73‐positive microvillar cells. Therefore, we systematically assessed the role of CFTR in microvillar cells for the regulation of olfactory homeostasis, using CFTR‐knockout mice and their wildtype littermates for comparison.…”

“…A previous study reported possible CFTR expression by sustentacular cells in the murine OE (Merigo et al, ). Here, we used the microvillar cell‐specific marker CD73 (Pfister et al, ) to prove CFTR expression and localization in microvillar cells.…”

Expression patterns of anoctamin 1 and anoctamin 2 chloride channels in the mammalian nose

“…CFTR plays a crucial role in maintaining the salt and water balance of mucosal secretions and is widely expressed in the nasal epithelia (Grubb et al 2007;Rochelle et al 2000). A notable exception is the Bowman's gland (Merigo et al 2011). In the absence of CFTR, Ca 2+ -activated Cl − channels can act as a substitute in mucosal secretion (Kidd and Thorn 2000).…”

Expression of aquaporins in inner ear disease

“…Expression of AQP4 was identified in the animal's olfactory, visual, and auditory organs. Expression of AQP4 was observed in olfactory epithelium, retina, and the optic nerve in rats . AQP4 was expressed in sensory organs and in the mammalian brain.…”