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: As noted earlier, we observed many intercellular gaps in WAVE2-depleted monolayers (Supplemental Movie S4 and Figure 4). Cells within WAVE2-depleted endothelial monolayers also displayed a wide range of individual morphologies. Many were rounded up and no longer in contact with their neighbors. In movies, these cells were often blebbing very actively, and they made frequent attempts to spread back down onto the surface (Supplemental Movie S4). Scoring cells on their morphology, we found that WAVE2-depleted monolayers had 34.7 ± 23.8% (mean ± SEp, 814 cells, four movies) rounded-up or blebbing cells, whereas control monolayers had only 0.20% ± 1.99% (968 cells, five movies). This difference was statistically significant, with p < 0.01. Expression of siRNA-resistant WAVE2-GFP rescued this phenotype, leading to nearly complete absence of cells with the rounded-up and blebbing morphology (1.8 ± 0.8%, 402 cells, three movies; Supplemental Movie S6). The p value for control versus WAVE2 rescue was 0.13.
Affiliation: Department of Cell Biology and Physiology, Washington University, St. Louis, MO 63110.