Airway mucus forms a protective layer against inhaled particles and pathogens. However, excessive mucus secretion in response to inflammatory stimuli can lead to airflow obstruction. Mucus hypersecretion can be divided into two distinct stages: metaplasia of an epithelial layer that consists predominantly of ciliated and Clara cells into a layer that consists predominantly of mucus-secreting goblet cells; this is followed by regulated secretion of mucus from the metaplastic epithelium. At a molecular level, secretory metaplasia involves expression of genes encoding three sets of proteins: secretory products; components of an exocytic machinery; and signal transduction pathways connecting extracellular secretory signals to exocytic membrane fusion. Secreted macromolecules and signal transduction pathways are subjects of intensive study, but little is known about the exocytic machinery. Munc18 proteins are ubiquitous components of the exocytic machinery of secretory cells. Their absence leads to a complete failure of secretion, and their overexpression also impairs secretion. Together, these data indicate the critical role played by Munc18 proteins and suggest that their expression is tightly regulated. We have found that Munc18B is highly upregulated in metaplastic airway epithelium of mice, and that its promoter region contains elements known to respond to inflammatory stimuli. We propose to suppress expression of Munc18B to test the protective and pathophysiologic roles of mucus secretion in models of allergic and infectious lung inflammation in mice, and to analyze the control of Munc18B expression in mice and humans to gain insight into the molecular pathogenesis of mucus metaplasia.
Aim 1 : Further characterize the cellular biology of Munc18 proteins in the regulation of airway mucus secretion in murine and human cells.
Aim 2 : Analyze the protective and pathophysiologic roles of mucus hypersecretion in murine models of allergic asthma and bacterial pneumonia by reducing the capability of airway goblet cells to secrete mucus through reduction of Munc18B expression.
Aim 3 : Identify critical cis-acting DNA elements and transcription factors that control expression of the Munc18B gene in metaplastic airway epithelium of mice.
Aim 4 : Confirm the importance of cis-acting DNA elements and transcription factors that control expression of the Munc18B gene in airway secretory metaplasia of humans.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL072984-01
Application #
6600822
Study Section
Special Emphasis Panel (ZHL1-CSR-P (F1))
Program Officer
Croxton, Thomas
Project Start
2003-04-01
Project End
2007-03-31
Budget Start
2003-04-01
Budget End
2004-03-31
Support Year
1
Fiscal Year
2003
Total Cost
$376,250
Indirect Cost
Name
Baylor College of Medicine
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
051113330
City
Houston
State
TX
Country
United States
Zip Code
77030
Kim, Kyubo; Petrova, Youlia M; Scott, Brenton L et al. (2012) Munc18b is an essential gene in mice whose expression is limiting for secretion by airway epithelial and mast cells. Biochem J 446:383-94
Evans, Scott E; Xu, Yi; Tuvim, Michael J et al. (2010) Inducible innate resistance of lung epithelium to infection. Annu Rev Physiol 72:413-35
Evans, Scott E; Scott, Brenton L; Clement, Cecilia G et al. (2010) Stimulated innate resistance of lung epithelium protects mice broadly against bacteria and fungi. Am J Respir Cell Mol Biol 42:40-50
Nguyen, Long P; Lin, Rui; Parra, Sergio et al. (2009) Beta2-adrenoceptor signaling is required for the development of an asthma phenotype in a murine model. Proc Natl Acad Sci U S A 106:2435-40
Clement, Cecilia G; Tuvim, Michael J; Evans, Christopher M et al. (2009) Allergic lung inflammation alters neither susceptibility to Streptococcus pneumoniae infection nor inducibility of innate resistance in mice. Respir Res 10:70
Evans, Christopher M; Kim, Kyubo; Tuvim, Michael J et al. (2009) Mucus hypersecretion in asthma: causes and effects. Curr Opin Pulm Med 15:4-11
Tuvim, Michael J; Mospan, Andrea Rossi; Burns, Kimberlie A et al. (2009) Synaptotagmin 2 couples mucin granule exocytosis to Ca2+ signaling from endoplasmic reticulum. J Biol Chem 284:9781-7
Moghaddam, Seyed Javad; Clement, Cecilia G; De la Garza, M Miguelina et al. (2008) Haemophilus influenzae lysate induces aspects of the chronic obstructive pulmonary disease phenotype. Am J Respir Cell Mol Biol 38:629-38
Clement, Cecilia G; Evans, Scott E; Evans, Christopher M et al. (2008) Stimulation of lung innate immunity protects against lethal pneumococcal pneumonia in mice. Am J Respir Crit Care Med 177:1322-30
Zhu, Yunxiang; Ehre, Camille; Abdullah, Lubna H et al. (2008) Munc13-2-/- baseline secretion defect reveals source of oligomeric mucins in mouse airways. J Physiol 586:1977-92

Showing the most recent 10 out of 19 publications