Disturbances in endothelial cell (EC) barrier regulation are a hallmark of lung inflammation, angiogenesis and cancer. EC permeability is regulated by a balance between contractile and tethering forces and critically depends upon the coordinate rearrangement of actin and microtubule cytoskeleton. Growing evidence indicates that inflammatory cytokines like TGF-B increase EC permeability in vitro and are involved in the increase in lung permeability in vivo. TGF-B elicits cellular effects on endothelium by engagement of TGF-B type I receptors, ALK1 and ALK5, following by activation of specific SMAD proteins that control the transcription of target genes. However, the involvement of ALK/SMAD signaling in TGF-B-induced cytoskeletal rearrangement and permeability are virtually unexplored. Our novel preliminary data indicated that specific depletion or inhibition of ALK5 and SMAD4 proteins significantly attenuated TGF-B decrease in transendothelial electrical resistance (TER) indicating the involvement of ALK/SMAD signaling in TGF-B-induced EC barrier compromise. Our recent data also indicate that TGF-B-induced decrease in TER and formation of paracellular gaps is tightly linked to F-actin stress fiber formation and increases in myosin light chain (MLC) phosphorylation indicating the involvement of contractile mechanisms in TGF-B-induced EC permeability. TGF-B-induced changes in EC cytoskeleton are critically dependent upon Rho GTPase activity and microtubule remodeling, but not Ca2+ signaling or MLC kinase activation. cAMP activation attenuates both TGF-B-induced decreases in TER and increases in MLC phosphorylation supporting the involvement of cAMP/PKA in barrier protection against TGF-B-induced EC permeability. In addition, TGF-B-induced EC stimulation activates p38 MAP kinase pathway, which also potentially can be involved in Rho-independent EC contractility via phosphorylation of key cytoskeletal proteins, like caldesmon and HSP-27. However, the link between activation of ALK/SMAD signaling and activation of EC contractility is unknown. In this proposal, we will explore the role of SMAD dependent and independent pathways involved in TGF-B-induced EC barrier dysfunction. Engagement of ALK1 and ALK5 receptors will be temporally linked with regulatory SMAD proteins phosphorylation and activation of Rho- and p38 MAPK-mediated EC cytoskeletal rearrangement and permeability.
In Specific Aim 1, we will examine the link between TGF-B-induced Rho activation, ALK/SMAD signaling and EC permeability.
In Specific Aim 2, we will examine the link between p38 MAPK-dependent pathways involved in TGF-B-induced EC barrier dysfunction and ALK/SMAD signaling.
In Specific Aim 3, we will explore the molecular mechanisms by which cAMP/PKA protects against TGF-B-induced EC barrier failure focusing on the SMADs, Rho, p38 and cytoskeletal proteins as potential PKA targets. These studies will provide an understanding of novel signaling pathways involved in cytokine-mediated lung EC barrier regulation and promise new directions and targets for treatment of lung disorders.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL080675-04
Application #
7446642
Study Section
Lung Injury, Repair, and Remodeling Study Section (LIRR)
Program Officer
Moore, Timothy M
Project Start
2005-06-15
Project End
2010-05-31
Budget Start
2008-06-01
Budget End
2010-05-31
Support Year
4
Fiscal Year
2008
Total Cost
$348,456
Indirect Cost
Name
Georgia Regents University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
966668691
City
Augusta
State
GA
Country
United States
Zip Code
30912
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Jezierska, Agnieszka; Kolosova, Irina A; Verin, Alexander D (2011) Toll Like Receptors Signaling Pathways as a Target for Therapeutic Interventions. Curr Signal Transduct Ther 6:428-440
Zemskov, Evgeny; Lucas, Rudolf; Verin, Alexander D et al. (2011) P2Y receptors as regulators of lung endothelial barrier integrity. J Cardiovasc Dis Res 2:14-22

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