Mechanisms of Calmodulin-dependent EC Barrier Regulation

Project: Research project

Project Details


DESCRIPTION (provided by applicant): Disturbances in endothelial cell (EC)
barrier regulation is a hallmark of lung inflammation, angiogenesis and cancer.
Maintaining of EC barrier is under close regulation by competing contractile
and tethering forces whose effects are critically dependent upon EC
cytoskelatal rearrangement and is under control of intracellular messengers
including free Ca2+ and its major intracellular receptor, calmodulin (CaM).
Substantial work, including our own, has verified that Ca2+/calmodulin complex
triggered permeability induced by edemagenic agents such as the serine protease
thrombin. Thrombin receptor proteolysis is sequentially coupled to
intracellular Ca2+ increases, activation of Ca2+/CaM-dependen myosin light
chain kinase (MLCK), increases in myosin light chain (MLC) phosphorylation,
initiation of actomyosin contraction and finally gap formation and barrier
dysfunction. However, the role of Ca2+/CaM targets (other than MLCK) in EC
barrier regulation is not completely understood. Our preliminary data indicate
that thrombin-mediated endothelial cell permeability is dependent (in part)
upon activation of the Ca2+/CaM dependent protein kinase II (CaMKII) as
specific CaMKII inhibition significantly attenuates thrombin-induced stress
fiber formation and permeability. Paradoxically, thrombin also activates the
Ca2+/CaM-dependent phosphatase 2B (PPase 2B or calcineurin) which decreases
thrombin-induced MLC phosphorylation providing a regulatory mechanism to
potentially reverse or limit thrombin-induced cytoskeletal rearrangement and
permeability. In addition, thrombin-induced EC barrier dysfunction is
correlated with increased phosphorylation of several cytoskeletal proteins
including Ca2+/CaM-dependent regulatory protein caldesmon and CaMKII targets,
filamin, tau and vimentin. Together, these data clearly convey the complex
involvement of Ca2+/CaM-dependent signaling pathways in the regulation of
endothelial permeability. In this proposal, we will explore the role of
Ca2+/CaM targets (other than MLCK) in thrombin-mediated EC regulation. In SA 1
we will examine the role of CaMKII activity in agonist-induced cytoskeletal
protein phosphorylation, cytoskeletal rearrangement and barrier dysfunction. In
SA 2 we will examine the role of PPase 2B activity in EC barrier regulation. In
SA 3 we will examine the role of caldesmon in agonist-mediated cytoskeletal
rearrangement and barrier regulation. These studies will provide an
understanding of novel signaling pathways involved in lung EC barrier
regulation and promise new directions and targets for treatment of lung
Effective start/end date7/1/015/31/05


  • National Heart, Lung, and Blood Institute: $367,875.00
  • National Heart, Lung, and Blood Institute: $367,875.00
  • National Heart, Lung, and Blood Institute: $367,875.00
  • National Heart, Lung, and Blood Institute: $367,875.00


  • Medicine(all)


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