Different Munc18 proteins mediate baseline and stimulated airway mucin secretion.

JCI Insight
Ana M JaramilloBurton F Dickey

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.

Citations

Jan 31, 2019·The Journal of Biological Chemistry·Eduardo I CardenasRoberto Adachi
Apr 17, 2021·Science·Elisabeth E L NyströmMalin E V Johansson
Jun 24, 2021·Scientific Reports·J M SweeterJ D Dickinson

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Methods Mentioned

BETA
reverse transcription PCR
lavage
PCR
electron microscopy
protein assay
sedation

Software Mentioned

ImageJ
USEARCH
ImagePro
GraphPad Prism

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