Nucleotides and nucleosides in the ainway surface liquid (ASL) activate cell surface purinergic receptors that critically regulate ainway epithelial fluid secretion and mucociliary clearance (l /!CC) functions. Nucleotide release rates and nucleotide/nucleoside levels in ASL are finely tuned to sustain MCC activities without promoting excessive fluid secretion or inflammation. However, the mechanisms of ainway epithelial nucleotide release are incompletely understood. Studies in our lab have revealed that goblet and ciliated cells release nucleotides via exocytotic and conductive pathways, but there are important gaps in identifying/characterizing key components of these pathways. Our recent results provide insights into ATP uptake, storage, and release from goblet cell mucin granules. Our data suggest that the vesicular nucleotide transporter (VNUT) SLC17A9 regulates the uptake of ATP into mucin granules, and therefore contributes to mucin granule secretion-associated ATP release. Our results also suggest that the plasma membrane channel pannexin 1 mediates ATP release from ciliated cells, and that pannexin 1 activity is controlled by TRPV4 and Rho/ROCK activation. A plan to define the contribution of VNUT and pannexin 1 to nucleotide release from ainway epithelia is outlined in this project by pursuing the following Specific Aims: (1) to test the hypothesis that VNUT contributes to mucin granule secretion-associated nucleotide release, and (2) to test the hypothesis that pannexin 1 channels mediate ATP release from ciliated cell-rich ainway epithelia. We will utilize RNA interference techniques and gene targeting approaches in in vitro and in vivo models of airway epithelia, respectively, to assess (a) the extent to which VNUT contributes to nucleotide transport into mucin granules and to nucleotide release from mucin secreting epithelia, and (b) to define the role of pannexin 1 and upstream effectors in nucleotide release in the ASL. We will further explore the effect of VNUT and pannexin 1 gene deletions in the mucociliary and alveolar liquid clearance defects that have been attributed to unbalanced nucleotide release in asthma and viral infected lungs. Completion of these studies will establish molecular mechanism(s) for the physiologically important process of nucleotide release, and may delineate novel pharmacological strategies aimed to treat lung diseases associated with abnormal mucus clearance and inflammatory lung diseases.
This project proposes to study two novel regulatory pathways of nucleotide release and their involvement in lung diseases and identify new therapeutic approaches to treat abnormal liquid clearance and inflammatory lung diseases. Nucleotides and adenosine in the ASL are critical regulators of ainway mucociliary and liquid clearance. Imbalance of these activities is at the pathogenesis core of obstructive and inflammatory lung diseases, which are responsible for high morbidity and lethality in the United States.
|He, Lihua; Aleksandrov, Andrei A; An, Jianli et al. (2015) Restoration of NBD1 thermal stability is necessary and sufficient to correct ?F508 CFTR folding and assembly. J Mol Biol 427:106-20|
|Roy, Michelle G; Livraghi-Butrico, Alessandra; Fletcher, Ashley A et al. (2014) Muc5b is required for airway defence. Nature 505:412-6|
|Henderson, Ashley G; Ehre, Camille; Button, Brian et al. (2014) Cystic fibrosis airway secretions exhibit mucin hyperconcentration and increased osmotic pressure. J Clin Invest 124:3047-60|
|Esther Jr, Charles R; Boucher, Richard C; Johnson, M Ross et al. (2014) Airway drug pharmacokinetics via analysis of exhaled breath condensate. Pulm Pharmacol Ther 27:76-82|
|Donnelley, Martin; Morgan, Kaye S; Siu, Karen K W et al. (2014) Non-invasive airway health assessment: synchrotron imaging reveals effects of rehydrating treatments on mucociliary transit in-vivo. Sci Rep 4:3689|
|Cholon, Deborah M; Quinney, Nancy L; Fulcher, M Leslie et al. (2014) Potentiator ivacaftor abrogates pharmacological correction of ?F508 CFTR in cystic fibrosis. Sci Transl Med 6:246ra96|
|Bove, Peter F; Dang, Hong; Cheluvaraju, Chaitra et al. (2014) Breaking the in vitro alveolar type II cell proliferation barrier while retaining ion transport properties. Am J Respir Cell Mol Biol 50:767-76|
|Guo, Xueliang; Zheng, Shuo; Dang, Hong et al. (2014) Genome reference and sequence variation in the large repetitive central exon of human MUC5AC. Am J Respir Cell Mol Biol 50:223-32|
|Yang, Zhengrong; Wang, Chi; Zhou, Qingxian et al. (2014) Membrane protein stability can be compromised by detergent interactions with the extramembranous soluble domains. Protein Sci 23:769-89|
|Hill, David B; Vasquez, Paula A; Mellnik, John et al. (2014) A biophysical basis for mucus solids concentration as a candidate biomarker for airways disease. PLoS One 9:e87681|
Showing the most recent 10 out of 12 publications