Idiopathic pulmonary arterial hypertension (IPAH) is a lethal disorder characterized by pulmonary vasoconstriction and remodeling, leading to progressively worsening right ventricular hypertrophy, and eventually right heart failure. The familial form of IPAH is usually due to mutations in the type 2 receptor for the bone morphogenic protein pathway, BMPR2. BMPR2 can signal through several different pathways, including SMAD 1/5/8 and both p38 and p42/44 MAPK. The BMPR2 mutations in human IPAH patients frequently appear to leave SMAD signaling intact, whereas mutations leading to constitutive activation of both p38 and p42/44 MAPK are common. This strongly suggests that, in vivo in human patients, it is loss of BMPR2-mediated suppression of MAPK, rather than loss of SMAD signaling, that leads to the pulmonary hypertensive phenotype. We therefore hypothesize that it is dysregulation of p38 and p42/44 MAPK signaling through BMPR2 which leads to defects both in vasoreactivity and in pulmonary vascular structure, the central hallmarks of PAH. The purpose of this proposal is to directly test this hypothesis in transgenic models of PAH. To do this, we have developed inducible smooth muscle-specific mouse models of PAH which have defects primarily in vasoreactivity (BMPR2-delx4+) or in pulmonary vascular structure (BMPR2-R899X). We intend to (aim 1) determine whether either or both of the phenotypes can be prevented or treated with pharmacologic p38 or p42/44 MAPK inhibitors, (aim 2) determine the molecular pathways that link BMPR2 to elevated p38 and p42/44 MAPK, and (aim 3) determine the molecular consequences of aberrant MAPK signaling through BMPR2, using smooth muscle cells cultured from these animals. Relevance: Evidence from human pulmonary arterial hypertension patients suggests that defective MAPK signaling through BMPR2 causes disease. This study will determine how and whether defective MAPK signaling results in these problems, and will attempt interventions to effect prevention or treatment. We will do this using new mouse models which replicate both the mutations and the central characteristics of human disease, as well as cells cultured from these animals, with the goal of developing more effective therapies.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL082694-05
Application #
8133025
Study Section
Respiratory Integrative Biology and Translational Research Study Section (RIBT)
Program Officer
Moore, Timothy M
Project Start
2007-09-01
Project End
2012-08-31
Budget Start
2011-09-01
Budget End
2012-08-31
Support Year
5
Fiscal Year
2011
Total Cost
$383,750
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
004413456
City
Nashville
State
TN
Country
United States
Zip Code
37212
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Chen, Wen-Chi; Park, Sung-Hyun; Hoffman, Carol et al. (2013) Right ventricular systolic pressure measurements in combination with harvest of lung and immune tissue samples in mice. J Vis Exp :e50023
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Park, Sung-Hyun; Chen, Wen-Chi; Hoffman, Carol et al. (2013) Modification of hemodynamic and immune responses to exposure with a weak antigen by the expression of a hypomorphic BMPR2 gene. PLoS One 8:e55180
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Nagayoshi, Masaru; Tada, Yuji; West, James et al. (2011) Inhalation of Stachybotrys chartarum evokes pulmonary arterial remodeling in mice, attenuated by Rho-kinase inhibitor. Mycopathologia 172:5-15

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