Inflammatory edema is mediated by cytoskeletal-based mechanical forces, which induce endothelial-cell retraction. Agents that increase intracellular cAMP protect the endothelium from inflammatory mediators. Understanding the mechanisms by which edemagenic agents and cAMP agonists remodel the endothelial cytoskeleton, which, in turn, regulates barrier function, is critical to precisely develop treatments. We previously reported that edemagenic agents disrupt barrier function independent of expression of actin-myosin contraction. Expression of actin-myosin contraction increases inflammatory edema by impacting the restoration of barrier function. Increased intracellular cAMP does not protect barrier function through inhibition of actin-myosin tension development, but does so by uncoupling this contractile load from disrupting cell adhesion. The PI, a new investigator, will test the hypothesis in human endothelial cells that microtubules modulate endothelial-cell adhesion through a counterbalance force with actin-myosin filaments. By modulating microtubule assembly, the expression of centripetal actin-myosin tension can have differential effects on cell adhesion. To test this hypothesis we have taken an interdisciplinary approach that uses cell biology and engineering to address this fundamental question.
In Aim 1, we will test whether changes in microtubule assembly remodel mechanical forces through shifts in load-bearing forces between microtubules and actin-myosin elements.
In Aim 2, we will localize whether microtubules and actin-myosin forces are directed at cell-cell or cell-matrix sites.
In Aim 3, we will then test whether changes in microtubule assembly alter cell adhesion based on shifts in load-bearing forces, and whether physiological stimuli utilize this basic mechanism.
In Aim 4, we will test an alternative hypothesis that changes in microtubule assembly alter cell adhesion through crosstalk communication through integrin-ligand interactions. We have assembled an interdisciplinary group of biologists, a physician, a physicist and engineers. We will use a mathematical model of transendothelial impedance to localize changes in cell adhesion. We will directly measure centripetal tension and cell stiffness. We will measure biochemical changes in myosin, actin and microtubules. We will utilize molecular approaches and quantitative dynamic imaging approaches in living cells to further validate our hypothesis. We believe that the results of these studies will greatly advance vascular and cell biology.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Experimental Cardiovascular Sciences Study Section (ECS)
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Deatherage, James F
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University of Iowa
Internal Medicine/Medicine
Schools of Medicine
Iowa City
United States
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Moy, Alan B; Blackwell, Ken; Wu, Mack H et al. (2006) Growth factor- and heparin-dependent regulation of constitutive and agonist-mediated human endothelial barrier function. Am J Physiol Heart Circ Physiol 291:H2126-35
Breslin, Jerome W; Sun, Hengrui; Xu, Wenjuan et al. (2006) Involvement of ROCK-mediated endothelial tension development in neutrophil-stimulated microvascular leakage. Am J Physiol Heart Circ Physiol 290:H741-50
Bodmer, James E; English, Anthony; Brady, Megan et al. (2005) Modeling error and stability of endothelial cytoskeletal membrane parameters based on modeling transendothelial impedance as resistor and capacitor in series. Am J Physiol Cell Physiol 289:C735-47
Moy, Alan B; Blackwell, Ken; Wang, Ning et al. (2004) Phorbol ester-mediated pulmonary artery endothelial barrier dysfunction through regulation of actin cytoskeletal mechanics. Am J Physiol Lung Cell Mol Physiol 287:L153-67
Haxhinasto, Kari; Kamath, Anant; Blackwell, Ken et al. (2004) Gene delivery of l-caldesmon protects cytoskeletal cell membrane integrity against adenovirus infection independently of myosin ATPase and actin assembly. Am J Physiol Cell Physiol 287:C1125-38
Moy, Alan B; Blackwell, Ken; Kamath, Anant (2002) Differential effects of histamine and thrombin on endothelial barrier function through actin-myosin tension. Am J Physiol Heart Circ Physiol 282:H21-9