? This translational research proposal seeks to apply recent novel insights into the mechanisms of cell signaling at the level of the plasma membrane (the caveola/raft signaling hypothesis and the interleukin-6-raft-STAT3 signaling model) to an understanding of the pathogenesis of PH. Caveolin-1-containing detergent-resistant plasma membrane rafts are now recognized as specialized signaling organelles, including cytokine signaling. There is now growing evidence for a role of cytokines in the pathogenesis of lung diseases. As examples, elevated serum levels of IL-6 have been observed in primary pulmonary hypertension (PH) and in PH associated with autoimmune diseases and AIDS. In a rat model, a single injection of the plant alkaloid monocrotaline (MCI) results within 48 hrs in endothelial cell damage, membrane leakage, upregulation of IL-6 mRNA and bioactivity but a marked downregulation of caveolin-1 in the lung, followed by development of PH 10-14 days later. ? ? The focus of the proposed studies is two-pronged: (a) to evaluate the hypothesis that pulmonary endothelial-cell raft/caveolar disruption by MCT is an initiating event in the pathogenesis of PH (Specific Aim I), and (b) to investigate the function of membrane rafts and of the newly discovered cytosolic caveolin-containing Palade complexes in IL-6-induced STAT3 signaling in lung-specific cells (Specific Aims II and III).
Aim I will include investigations of the time-course, histologic location, and cellular and molecular mechanisms for the downregulation of caveolin proteins and gene expression, and of the integrity of caveolar/raft function in pulmonary vascular and parenehymal tissues of MCT-treated rats.
Aim II includes molecular studies of the mechanisms of association of STAT3 with caveolin-1 and of STAT3 activation in plasma membrane rafts in pulmonary endothelial cells, alveolar type II-like epithelial cells and lung fibroblasts.
Aim I ll includes studies of the protein components of STAT3-containing cytosolic Palade complexes and their function in ferrying signaling molecules from the plasma membrane rafts to the cell interior. ? ? Mechanistic insights derived from this project are likely to suggest novel therapeutic approaches in the management of pulmonary hypertension. Moreover, the proposed studies are of particularly broad significance in that insights into the molecular mechanisms involved in raft-STAT signaling are likely to be applicable to cytokine-mediated activation of STAT transcription factors in perhaps all cell types, as well as to other signaling pathways localized in raft microdomains (eNOS and angiotensin II signaling). ? ?

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL073301-02
Application #
6718421
Study Section
Lung Biology and Pathology Study Section (LBPA)
Program Officer
Denholm, Elizabeth M
Project Start
2003-04-01
Project End
2008-03-31
Budget Start
2004-04-01
Budget End
2005-03-31
Support Year
2
Fiscal Year
2004
Total Cost
$350,719
Indirect Cost
Name
New York Medical College
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
041907486
City
Valhalla
State
NY
Country
United States
Zip Code
10595
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Sehgal, Pravin B (2008) Paradigm shifts in the cell biology of STAT signaling. Semin Cell Dev Biol 19:329-40
Sehgal, Pravin B; Mukhopadhyay, Somshuvra; Xu, Fang et al. (2007) Dysfunction of Golgi tethers, SNAREs, and SNAPs in monocrotaline-induced pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol 292:L1526-42
Mukhopadhyay, Somshuvra; Sehgal, Pravin B (2006) Discordant regulatory changes in monocrotaline-induced megalocytosis of lung arterial endothelial and alveolar epithelial cells. Am J Physiol Lung Cell Mol Physiol 290:L1216-26
Jain, Sudhir; Shah, Mehul; Li, Yanna et al. (2006) Upregulation of human angiotensinogen (AGT) gene transcription by interferon-gamma: involvement of the STAT1-binding motif in the AGT promoter. Biochim Biophys Acta 1759:340-7
Mukhopadhyay, Somshuvra; Shah, Mehul; Patel, Kirit et al. (2006) Monocrotaline pyrrole-induced megalocytosis of lung and breast epithelial cells: Disruption of plasma membrane and Golgi dynamics and an enhanced unfolded protein response. Toxicol Appl Pharmacol 211:209-20
Shah, Mehul; Patel, Kirit; Mukhopadhyay, Somshuvra et al. (2006) Membrane-associated STAT3 and PY-STAT3 in the cytoplasm. J Biol Chem 281:7302-8
Shah, Mehul; Patel, Kirit; Sehgal, Pravin B (2005) Monocrotaline pyrrole-induced endothelial cell megalocytosis involves a Golgi blockade mechanism. Am J Physiol Cell Physiol 288:C850-62
Mathew, Rajamma; Huang, Jing; Shah, Mehul et al. (2004) Disruption of endothelial-cell caveolin-1alpha/raft scaffolding during development of monocrotaline-induced pulmonary hypertension. Circulation 110:1499-506
Sehgal, Pravin B (2003) Plasma membrane rafts and chaperones in cytokine/STAT signaling. Acta Biochim Pol 50:583-94