Endothelial cells use dynamic actin to facilitate lymphocyte transendothelial migration and maintain the monolayer barrier.
Bottom Line: The actin cytoskeleton of the endothelial cell (EC) is known to facilitate transmigration, but the cellular and molecular mechanisms are not well understood.We found that docking structure formation involves the localization and activation of Arp2/3 complex by WAVE2.Finally, we found that ECs in resting endothelial monolayers use lamellipodial protrusions dependent on WAVE2 to form and maintain contacts and junctions between cells.
Affiliation: Department of Cell Biology and Physiology, Washington University, St. Louis, MO 63110.Show MeSH
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Mentions: On the basis of these observations of EC monolayers, we hypothesized that WAVE2 depletion might cause defects in the overall integrity of the endothelial barrier measured by conventional physiological assays. To test this hypothesis, we first measured electrical resistance across the monolayer (transendothelial resistance [TER]; Figure 5A). WAVE2 depletion caused TER to decrease to levels similar to those caused by chelation of Ca2+, which completely disrupts cadherin-based cell–cell junctions. Depolymerizing actin with latrunculin A (LatA) also decreased TER by a large amount (Figure 5A) and created large gaps between ECs (Supplemental Figure S1B), consistent with previous findings (Prasain and Stevens, 2009). Second, we measured the permeability of the monolayer to fluorescent dextran, as an indicator of barrier integrity. Again, EC monolayers depleted of WAVE2 showed increased permeability compared with control (Supplemental Figure S1C).
Affiliation: Department of Cell Biology and Physiology, Washington University, St. Louis, MO 63110.