Non-cardiac pulmonary edema is a frequent affliction in pulmonary medicine and is caused by endothelial barrier dysfunction. It is now recognized that this dysfunction may be initiated by programmed cell signaling as opposed to non-specific disruption of the vascular barrier. Since the endothelial barrier is known to be altered by exposure to hypoxia leading to pulmonary edema, we have utilized a rat pulmonary artery microvascular endothelial cell (EC) monolayer culture model to study the effects of hypoxia on EC barrier function. Preliminary studies have led to the hypothesis that exposure to hypoxia initiates cell signaling through the p38 MAP kinase pathway involving MK2 and HSP27 activation that leads to actin cytoskeleton and hic-5 redistribution. These signaling events are associated with an alteration in biomechanical """"""""tethering"""""""" and """"""""stiffness"""""""" and enhanced permeability of the EC monolayer. """"""""Tethering"""""""" may be regulated by the p38 MAP kinase pathway while """"""""stiffness"""""""" is regulated by Rho/Rho kinase and myosin light chain phosphorylation. We plan in the present proposal to study these responses more thoroughly in the rat pulmonary artery microvascular EC monolayer and to perform confirmatory studies in similar cells from human pulmonary microvasculature. In addition, we will investigate these signaling pathways in mice in vivo using pharmacological inhibitors, as well as mice in which the expression of MK2, a key kinase in the p38 pathway, has been """"""""knocked-out"""""""". Specifically, we plan to:
Aim 1 : Define signaling pathways important for mediating cytoskeletal changes in endothelial cell monolayers exposed to hypoxia;
Aim 2 : Determine the relevance of the biomechanical endpoints """"""""stiffness"""""""" and """"""""tethering"""""""", which increase with exposure to hypoxia, to physiological determinants of endothelial barrier function;
and Aim 3 : Evaluate the signaling events that lead to increased pulmonary endothelial permeability in hypoxia in vivo. The findings of this study are expected to further our understanding of mechanisms involved in the development of endothelial barrier dysfunction, in general, and to suggest targets for treatment of pulmonary edema.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
3R01HL079320-05S1
Application #
7822427
Study Section
Respiratory Integrative Biology and Translational Research Study Section (RIBT)
Program Officer
Moore, Timothy M
Project Start
2009-06-01
Project End
2011-08-31
Budget Start
2009-06-01
Budget End
2011-08-31
Support Year
5
Fiscal Year
2009
Total Cost
$65,190
Indirect Cost
Name
Tufts University
Department
Type
DUNS #
079532263
City
Boston
State
MA
Country
United States
Zip Code
02111
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Liu, Tiegang; Guevara, Oscar E; Warburton, Rod R et al. (2010) Regulation of vimentin intermediate filaments in endothelial cells by hypoxia. Am J Physiol Cell Physiol 299:C363-73
Liu, Tiegang; Guevara, Oscar E; Warburton, Rod R et al. (2009) Modulation of HSP27 alters hypoxia-induced endothelial permeability and related signaling pathways. J Cell Physiol 220:600-10
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