Exaggerated airway narrowing and inflammation are hallmarks of clinically-important diseases such as asthma. Airway tone, largely determined by intracellular Ca2+ ([Ca2+]i) (mediated by Ca2+ influx and sarcoplasmic (SR) Ca2+ release) and Ca2+ sensitivity for force generation of airway smooth muscle (ASM), is enhanced by pro-inflammatory cytokines such as TNFa. In this regard, the role of caveolae and caveolins in the lung is an exciting and emerging area of research. Caveolae are small, uncoated flask-shaped invaginations of the plasma membrane (PM) of most cell types, and contain structural proteins called caveolins (caveolin-1, -2 and/or -3). Recent studies including our own have demonstrated that normal human ASM expresses caveolae and caveolin-1, with specific proteins involved in [Ca2+]i and force regulation co-localizing with caveolin-1. Preliminary studies show that airway inflammation (either in vitro following TNFa exposure or in vivo in a mouse model) increases caveolin-1 expression and enhances caveolar regulation of ASM contractility, suggesting that overall, caveolin-1 is associated with or promotes ASM contractility. The long term goal of the proposed studies is to understand the mechanisms by which caveolae and caveolins regulate ASM contractility under normal conditions and with airway disease. Ca2+ The overall hypothesis is that caveolae facilitate PM- SR interactions, thus influencing [Ca2+]i and force in ASM. In addition, we hypothesize that airway inflammation increases caveolae and caveolin-1 expression, and thus enhances PM-SR interactions, leading to increased [Ca2+]i and force in ASM. The novelty of our studies lies in linking previous anatomical and biochemical evidence for caveolin-1 in ASM to a physiological role in regulation of ASM contractility. Overall Approach: In vitro studies with human ASM cells and tissues in Aim 1 will examine mechanisms that can be modulated by caveolin-1 with agonist (ACh) stimulation under normal conditions, focusing on agonist receptors, second messengers (PLC/IP3, cADPR), regulation of store-operated Ca2+ entry (SOCE) by (STIM1/Orai1), and RhoA (Ca2+ sensitization). Mechanisms underlying altered caveolin-1 expression (Aim 2) and caveolin-1 contribution to enhanced ASM contractility (Aim 3) with inflammation (induced by TNFa) will then be examined, focusing on specific mechanisms (TNFR1, PTRF, MAPK, NF-?B). Finally in Aim 4, in vitro data will be integrated at the in vivo level using an ovalbumin (OVA) model of airway hyperresponsiveness in wildtype (WT) and caveolin-1 knockout (KO) mice.
The Specific Aims of this proposal are: 1) To determine mechanisms by which caveolae/caveolin-1 regulate [Ca2+]i and force responses of human ASM to agonist 2 ) To determine mechanisms by which cytokine (TNFa) stimulation alters caveolin-1 expression in human ASM 3) To determine the mechanisms by which caveolin-1 contributes to TNFa-induced enhancement of [Ca2+]i and force in human ASM;4) To determine the role of caveolin-1 in airway hyperresponsiveness in vivo.

Public Health Relevance

There is increasing recognition that abnormalities in airway smooth muscle contractility (exacerbated by inflammation) contribute to exaggerated airway narrowing and accompanying shortness of breath in clinically- important diseases such as asthma and chronic bronchitis. In this regard, the potential role of cellular structures called caveolae and their constituent caveolin proteins in regulation of airway contractility is an exciting and emerging area of research. By establishing the role of caveolae and caveolins in airway narrowing with or without inflammation, the proposed studies will the foundation for better understanding of airway diseases, and potential development of new therapeutic targets.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL090595-05
Application #
8431776
Study Section
Lung Cellular, Molecular, and Immunobiology Study Section (LCMI)
Program Officer
Banks-Schlegel, Susan P
Project Start
2009-04-01
Project End
2014-03-31
Budget Start
2013-04-01
Budget End
2014-03-31
Support Year
5
Fiscal Year
2013
Total Cost
$320,420
Indirect Cost
$108,362
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
006471700
City
Rochester
State
MN
Country
United States
Zip Code
55905
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Sathish, Venkatachalem; Thompson, Michael A; Sinha, Sutapa et al. (2014) Inflammation, caveolae and CD38-mediated calcium regulation in human airway smooth muscle. Biochim Biophys Acta 1843:346-51
Martin, Yvette N; Pabelick, Christina M (2014) Sex differences in the pulmonary circulation: implications for pulmonary hypertension. Am J Physiol Heart Circ Physiol 306:H1253-64
Aravamudan, Bharathi; Kiel, Alexander; Freeman, Michelle et al. (2014) Cigarette smoke-induced mitochondrial fragmentation and dysfunction in human airway smooth muscle. Am J Physiol Lung Cell Mol Physiol 306:L840-54
Thompson, Michael A; Prakash, Y S; Pabelick, Christina M (2014) The role of caveolae in the pathophysiology of lung diseases. Expert Rev Respir Med 8:111-22
Sathish, Venkatachalem; Vanoosten, Sarah Kay; Miller, Brent S et al. (2013) Brain-derived neurotrophic factor in cigarette smoke-induced airway hyperreactivity. Am J Respir Cell Mol Biol 48:431-8
Aravamudan, Bharathi; Thompson, Michael A; Pabelick, Christina M et al. (2013) Mitochondria in lung diseases. Expert Rev Respir Med 7:631-46
Vohra, Pawan K; Thompson, Michael A; Sathish, Venkatachalem et al. (2013) TRPC3 regulates release of brain-derived neurotrophic factor from human airway smooth muscle. Biochim Biophys Acta 1833:2953-60
Sathish, Venkatachalem; Abcejo, Amard J; Thompson, Michael A et al. (2012) Caveolin-1 regulation of store-operated Ca(2+) influx in human airway smooth muscle. Eur Respir J 40:470-8
Grim, K J; Abcejo, A J; Barnes, A et al. (2012) Caveolae and propofol effects on airway smooth muscle. Br J Anaesth 109:444-53

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