Muc5b is mainly expressed and sialylated in the nasal olfactory epithelium whereas Muc5ac is exclusively expressed and fucosylated in the nasal respiratory epithelium

• Published in: Histochemistry and cell biology Vol. 152; no. 2; pp. 167 - 174
• Main Authors: Amini, Salah-Eddine, Gouyer, Valérie, Portal, Céline, Gottrand, Frédéric, Desseyn, Jean-Luc
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2019; Springer Nature B.V; Springer Verlag
• Series: Histochemistry and cell biology
• Subjects: Animals; Biochemistry; Biomedical and Life Sciences; Biomedicine; Cell Biology; Cell surface; Developmental Biology; Glands; Glycosylation; Goblet cells; Green fluorescent protein; Immunohistochemistry; Lamina propria; Lectins; Life Sciences; Localization; Mice; Mice, Inbred C57BL; Mice, Knockout; Microbiota; Mucin; Mucin 5AC/analysis; Mucin 5AC/genetics; Mucin 5AC/metabolism; Mucin-5B/analysis; Mucin-5B/deficiency; Mucin-5B/metabolism; Mucous membrane; Mucus; Nasal Mucosa/chemistry; Nasal Mucosa/cytology; Nasal Mucosa/metabolism; Nose; Odor; Olfactory epithelium; Respiratory Mucosa/chemistry; Respiratory Mucosa/cytology; Respiratory Mucosa/metabolism; Respiratory tract; Short Communication; Bowman’s gland; Lectin; Mucin; Muc5b; Mouse nose; Muc5ac
• ISSN: 0948-6143; 1432-119X
• DOI: 10.1007/s00418-019-01785-5

The nose is a complex organ that filters and warms breathing airflow. The nasal epithelium is the first barrier between the host and the external environment and is covered by a mucus gel that is poorly documented. Mucins are large, heavily O-glycosylated polymeric molecules secreted in the nose lumen by specialized cells, and they are responsible for the biochemical properties of the mucus gel. The mucus traps particles and clears them, and it also bathes microbiota, host molecules, and receptors that are all essential for odor perception in the olfactory epithelium. We used histology and immunohistochemistry to study the expression of the two main airway polymeric mucins, Muc5ac and Muc5b, in wild-type, green fluorescent protein-reporter Muc5b, and in genetically Muc5b-deficient mice. We report that Muc5ac is produced by goblet cells at the cell surface in the respiratory epithelium but is not expressed in the olfactory epithelium, whereas Muc5b is secreted by Bowman’s glands situated in the lamina propria beneath the olfactory epithelium and also by goblet cells in the distal part of the respiratory epithelium. We also observed that Muc5b-deficient mice exhibited depletion of Bowman’s glands. Using lectins, we found that terminally O-glycosylated chains of Muc5b were sialylated but not fucosylated, whereas Muc5ac was fucosylated but not sialylated. Specific localization and specific terminal glycosylation of the two mucins suggest different functions of the mucins.