The airway epithelium expresses a considerable H+ conductance localized in the apical membrane where it contributes to acid release into the airway surface liquid. In April 2006 a H+ channel gene (HVCN1) was identified. Our preliminary data suggest that HVCN1 is the H+ channel found in the airways. This application explores the contribution of HVCN1 to the airway H+ conductance and its physiological function. Both our preliminary data and the described function of the H+ channel in phagocytes suggest that the H+ channel in the airways supports the NADPH oxidase DUOX1, and is thus part of airway defenses. Our general hypothesis is that HVCN1 codes for the airway epithelial H+ channel and HVCN1 supports the NADPH oxidase DUOX1.
Our specific aims are to 1) molecularly identify, express, and functionally characterize the HVCN1 H+ channel of the human airway epithelium, and 2) determine the role of the HVCN1 H+ channel in DUOX1 function.
These aims test a model in which HVCN1 is necessary for the DUOX1-based airway defenses. The proposed studies will be done by a combination of molecular biology approaches, cell culture techniques, and electrophysiological and fluorescence microscopy methods. This study will result in information about the identity of the airway H+ channel, its function, and its proposed role in airway defense. The results of this study will have public health relevance because ineffective bacterial defenses are commonly found in airway diseases.

Public Health Relevance

. The innate defenses of the airways are crucial to prevent infection of the lungs with airborne pathogens, which is an important area of public health. This project will investigate a novel mechanism of airway defenses focused on the function of the proton channel of the airways, which may in the long-term lead to therapeutic applications in inflammatory airway diseases, such as cystic fibrosis or asthma. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21HL089196-01A2
Application #
7531075
Study Section
Lung Cellular, Molecular, and Immunobiology Study Section (LCMI)
Program Officer
Banks-Schlegel, Susan P
Project Start
2008-07-08
Project End
2010-05-31
Budget Start
2008-07-08
Budget End
2009-05-31
Support Year
1
Fiscal Year
2008
Total Cost
$234,000
Indirect Cost
Name
Children's Hospital & Res Ctr at Oakland
Department
Type
DUNS #
076536184
City
Oakland
State
CA
Country
United States
Zip Code
94609
Fischer, Horst (2012) Function of Proton Channels in Lung Epithelia. Wiley Interdiscip Rev Membr Transp Signal 1:247-258
Cho, Do-Yeon; Hwang, Peter H; Illek, Beate et al. (2011) Acid and base secretion in freshly excised nasal tissue from cystic fibrosis patients with ?F508 mutation. Int Forum Allergy Rhinol 1:123-7
Iovannisci, David; Illek, Beate; Fischer, Horst (2010) Function of the HVCN1 proton channel in airway epithelia and a naturally occurring mutation, M91T. J Gen Physiol 136:35-46
Fischer, Horst (2009) Mechanisms and function of DUOX in epithelia of the lung. Antioxid Redox Signal 11:2453-65
Cho, D-Y; Hajighasemi, M; Hwang, P H et al. (2009) Proton secretion in freshly excised sinonasal mucosa from asthma and sinusitis patients. Am J Rhinol Allergy :
Fischer, Horst; Illek, Beate (2008) Activation of the CFTR Cl- channel by trimethoxyflavone in vitro and in vivo. Cell Physiol Biochem 22:685-92