1. Different Munc18 proteins mediate baseline and stimulated airway mucin secretion.
- Author
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Jaramillo AM, Piccotti L, Velasco WV, Delgado ASH, Azzegagh Z, Chung F, Nazeer U, Farooq J, Brenner J, Parker-Thornburg J, Scott BL, Evans CM, Adachi R, Burns AR, Kreda SM, Tuvim MJ, and Dickey BF
- Subjects
- Animals, Cystic Fibrosis metabolism, Disease Models, Animal, Epithelial Cells metabolism, Exocytosis, Lung metabolism, Lung pathology, Mice, Mice, Inbred C57BL, Munc18 Proteins genetics, Respiratory Mucosa pathology, Transcriptome, Asthma metabolism, Mucins metabolism, Munc18 Proteins metabolism, Respiratory Mucosa metabolism
- Abstract
Airway mucin secretion is necessary for ciliary clearance of inhaled particles and pathogens but can be detrimental in pathologies such as asthma and cystic fibrosis. Exocytosis in mammals requires a Munc18 scaffolding protein, and airway secretory cells express all 3 Munc18 isoforms. Using conditional airway epithelial cell-deletant mice, we found that Munc18a has the major role in baseline mucin secretion, Munc18b has the major role in stimulated mucin secretion, and Munc18c does not function in mucin secretion. In an allergic asthma model, Munc18b deletion reduced airway mucus occlusion and airflow resistance. In a cystic fibrosis model, Munc18b deletion reduced airway mucus occlusion and emphysema. Munc18b deficiency in the airway epithelium did not result in any abnormalities of lung structure, particle clearance, inflammation, or bacterial infection. Our results show that regulated secretion in a polarized epithelial cell may involve more than one exocytic machine at the apical plasma membrane and that the protective roles of mucin secretion can be preserved while therapeutically targeting its pathologic roles.
- Published
- 2019
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