Identification of Pannexins in Rat Nasal Mucosa

Pannexins are a second family of gap-junction proteins in vertebrates, classified as pannexin-1, pannexin-2, and pannexin-3. Pannexin-1 is one of the candidates for channel-mediated ATP release into the extracellular space. In airway epithelia, ATP signaling modulates multiple cellular functions such as mucus/ion secretion and mucociliary clearance systems. However, the expression of pannexins in the upper airway has not been investigated. Nasal septal mucosae were collected from adult male Wistar rats aged 20-24 weeks. The expression of pannexin-1, pannexin-2, and pannexin-3 was examined by reverse transcription polymerase chain reaction (RT-PCR) and by whole-mount fluorescence immunohistochemistry. Transcripts for pannexin-1, pannexin-2, and pannexin-3 were detected in nasal septal mucosae of adult rats by RT-PCR. Distinct immunohistochemical fluorescence for pannexin-1 was observed in the epithelial layer, whereas there was no immunoreactivity for pannexin-2 or pannexin-3. This is the first article establishing the existence of pannexins (predominantly pannexin-1) in the upper airway, suggesting their possible participation in the physiological functions of ATP release and signaling in this tissue.