This project seeks to understand the mechanisms by which the contractility of airway smooth muscle (ASM) is controlled and regulated. The present proposal focuses on the highly localized and short-lived Ca2+ events (Ca2+ sparks), resulting from the opening of ryanodine receptors (RyRs) in the sarcoplasmic reticulum membrane, and their interactions with nearby Ca2+-activated ion channels in the plasma membrane. As in vascular smooth muscle, Ca2+ sparks activate a small number of large-conductance K+ (BK) channels in the spark microdomain to generate spontaneous transient outward currents (STOCs) which hyperpolarize the membrane in ASM. Recently we have identified another important target of Ca2+ sparks in ASM, i.e. Ca2+-activated CI- (CIca) channels which cause spontaneous transient inward currents (STICs) and thus depolarize the membrane. Accordingly, the central hypothesis of this proposal is that Ca2+ sparks coordinate the activation of membrane channels to regulate airway contractility. An integrated approach using high-speed digital Ca2+ imaging with simultaneous patch-clamping, and also 2D and 3D protein localization, will be applied using normal and transgenic mouse models. Furthermore, a physiological airway preparation, i.e., lung slices, will be employed to investigate the role of Ca2+ sparks in regulating contractility of airways themselves. Our specific objectives are to uncover the biophysics of RyRs underlying Ca2+ sparks using our newly developed signal mass approach (Aim 1); to determine the functional and spatial relationships of RyRs to BK channels and CIca channels (Aims 2 and 3); and to determine the physiological role of Ca2+ sparks in airways (Aim 4). We expect that these studies will provide new knowledge which could lead to development of novel therapeutic approaches for asthma and other bronchospasitc disorders.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL073875-03
Application #
7061288
Study Section
Lung Biology and Pathology Study Section (LBPA)
Program Officer
Noel, Patricia
Project Start
2004-06-10
Project End
2008-04-30
Budget Start
2006-05-31
Budget End
2007-04-30
Support Year
3
Fiscal Year
2006
Total Cost
$310,527
Indirect Cost
Name
University of Massachusetts Medical School Worcester
Department
Physiology
Type
Schools of Medicine
DUNS #
603847393
City
Worcester
State
MA
Country
United States
Zip Code
01655
Wu, Lichang; Sun, Yu; Ma, Liqiao et al. (2016) A C-terminally truncated mouse Best3 splice variant targets and alters the ion balance in lysosome-endosome hybrids and the endoplasmic reticulum. Sci Rep 6:27332
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Zhang, Cheng-Hai; Chen, Chen; Lifshitz, Lawrence M et al. (2012) Activation of BK channels may not be required for bitter tastant-induced bronchodilation. Nat Med 18:648-50; author reply 650-1
Lifshitz, Lawrence M; Carmichael, Jeffrey D; Lai, F Anthony et al. (2011) Spatial organization of RYRs and BK channels underlying the activation of STOCs by Ca(2+) sparks in airway myocytes. J Gen Physiol 138:195-209
Zhuge, Ronghua; Bao, Rongfeng; Fogarty, Kevin E et al. (2010) Ca2+ sparks act as potent regulators of excitation-contraction coupling in airway smooth muscle. J Biol Chem 285:2203-10
Lefkowitz, Jason J; Fogarty, Kevin E; Lifshitz, Lawrence M et al. (2009) Suppression of Ca2+ syntillas increases spontaneous exocytosis in mouse adrenal chromaffin cells. J Gen Physiol 134:267-80
Bao, Rongfeng; Lifshitz, Lawrence M; Tuft, Richard A et al. (2008) A close association of RyRs with highly dense clusters of Ca2+-activated Cl- channels underlies the activation of STICs by Ca2+ sparks in mouse airway smooth muscle. J Gen Physiol 132:145-60
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