Increases in pericellular transport due to changes in endothelial cell shape and the formation of intercellular gaps has been implicated as the major pathway for increased solute flux in a number of disease states including vascular remodeling found during pulmonary hypertension. Endothelial cell shape and gap formation is believed to be controlled by signal transduction pathways that alter the balance of competing adhesive and contractile forces. The experiments outlined in this grant will investigate if decreases in cell-cell adhesion, which tethers endothelial cells to one another, contributes to the formation of intercellular gaps following the addition of the Cytokine transforming growth factor beta, (TGF-beta). TGF-beta is a cytokine which is known alter endothelial cell shape in confluent monolayers and concomitantly increases the permeability. I hypothesize the following mechanism to explain the TGF- beta induced shape change and the formation of intercellular gaps. TGF- beta will promote cell separation by decreasing Ca++ dependent cell-cell adhesion. This decrease in Ca++ dependent cell-cell adhesion, which is believed to mediated by cadherins, will be the result of a decrease in the affinity of cadherin homophilic binding and not the result of a decrease in cadherin surface expression. Then, after cell separation has occurred, the adherens junction disassembles. Moreover, while the TGF-beta induced change in cell shape is dependent on basal centripetal tension, TGF-beta will not increase endothelial cell contractile activity as has been demonstrated for mediators such as thrombin. This hypothesis will be tested by completing the following specific aims: 1) To determine if Ca++ dependent or Ca++ independent cell-cell adhesion is decreased in endothelial cells by TGF-beta. Changes in the expression of cadherins, which are believed to mediate Ca++ dependent cell adhesion will also be determined following treatment with TGF-beta. 2) To determine the kinetics of adherens junction disassembly following exposure of endothelial cell monolayers to TGF-beta. 3) To determine if phosphorylation of proteins in the adherens junction by tyrosine kinases are part of the signal transduction pathway in TGF-beta induced increases in endothelial monolayer permeability. 4) To determine the contribution of both changes in endothelial cell contractile state as well as reorganization of the actin cytoskeleton to TGF-beta mediated changes in cell shape.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29HL054206-05
Application #
6184407
Study Section
Lung Biology and Pathology Study Section (LBPA)
Project Start
1996-07-01
Project End
2002-06-30
Budget Start
2000-07-01
Budget End
2002-06-30
Support Year
5
Fiscal Year
2000
Total Cost
$117,766
Indirect Cost
Name
Albany Medical College
Department
Physiology
Type
Schools of Medicine
DUNS #
190592162
City
Albany
State
NY
Country
United States
Zip Code
12208
Iyer, Seema; Ferreri, Deana M; DeCocco, Nina C et al. (2004) VE-cadherin-p120 interaction is required for maintenance of endothelial barrier function. Am J Physiol Lung Cell Mol Physiol 286:L1143-53
Venkiteswaran, Kala; Xiao, Kanyan; Summers, Susan et al. (2002) Regulation of endothelial barrier function and growth by VE-cadherin, plakoglobin, and beta-catenin. Am J Physiol Cell Physiol 283:C811-21