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Endothelial cells use dynamic actin to facilitate lymphocyte transendothelial migration and maintain the monolayer barrier.

Mooren OL, Li J, Nawas J, Cooper JA - Mol. Biol. Cell (2014)

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.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and Physiology, Washington University, St. Louis, MO 63110.

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WAVE2 localization to membrane protrusions that close gaps and form at sites of transcellular pores. (A) WAVE2 is not recruited to paracellular pores during PBL transmigration. Frames from Supplemental Movie S2. Asterisk indicates a gap between ECs that persists after transmigration. Scale bar, 3 μm. (B) WAVE2 localizes to endothelial monolayer gaps that close after lymphocyte transmigration. Frames from Supplemental Movie S3. Asterisks indicate the gap, which closes after a wave of membrane protrusion. Red arrows indicate membrane waves, where WAVE2 has accumulated. Scale bar, 3 μm. (C) WAVE2 localizes to docking structures at sites of transcellular migration. ECs expressing WAVE2-GFP and immunolabeled for ICAM-1. Transmigrating lymphocyte is shown in the DIC image. The yz- and xz-projections from a 3D data set reveal WAVE2 in membrane protrusions that cup the PBL.
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Figure 2: WAVE2 localization to membrane protrusions that close gaps and form at sites of transcellular pores. (A) WAVE2 is not recruited to paracellular pores during PBL transmigration. Frames from Supplemental Movie S2. Asterisk indicates a gap between ECs that persists after transmigration. Scale bar, 3 μm. (B) WAVE2 localizes to endothelial monolayer gaps that close after lymphocyte transmigration. Frames from Supplemental Movie S3. Asterisks indicate the gap, which closes after a wave of membrane protrusion. Red arrows indicate membrane waves, where WAVE2 has accumulated. Scale bar, 3 μm. (C) WAVE2 localizes to docking structures at sites of transcellular migration. ECs expressing WAVE2-GFP and immunolabeled for ICAM-1. Transmigrating lymphocyte is shown in the DIC image. The yz- and xz-projections from a 3D data set reveal WAVE2 in membrane protrusions that cup the PBL.

Mentions: For the paracellular route, PBLs migrated over the course of 2–5 min through a pore that formed between two ECs. The pore often remained open for several minutes after the PBL moved away from the transmigration site (Figure 2A; asterisk indicates a persisting pore). WAVE2-GFP did not accumulate at the transmigration site either before or during transmigration (Figure 2A and Supplemental Movie S2). When the pores closed, if the pore size was large, ECs produced waves of membrane protrusion as they closed the gap. WAVE2-GFP localized at the front of these protrusions, which traveled laterally along the edge of the EC (Figure 2B and Supplemental Movie S3). This dynamic behavior is consistent with the idea that WAVE2 activates Arp2/3 complex and promotes actin assembly to drive the formation and extension of membrane protrusions. Small pores sometimes closed rapidly, without membrane protrusions, and WAVE2-GFP did not accumulate.


Endothelial cells use dynamic actin to facilitate lymphocyte transendothelial migration and maintain the monolayer barrier.

Mooren OL, Li J, Nawas J, Cooper JA - Mol. Biol. Cell (2014)

WAVE2 localization to membrane protrusions that close gaps and form at sites of transcellular pores. (A) WAVE2 is not recruited to paracellular pores during PBL transmigration. Frames from Supplemental Movie S2. Asterisk indicates a gap between ECs that persists after transmigration. Scale bar, 3 μm. (B) WAVE2 localizes to endothelial monolayer gaps that close after lymphocyte transmigration. Frames from Supplemental Movie S3. Asterisks indicate the gap, which closes after a wave of membrane protrusion. Red arrows indicate membrane waves, where WAVE2 has accumulated. Scale bar, 3 μm. (C) WAVE2 localizes to docking structures at sites of transcellular migration. ECs expressing WAVE2-GFP and immunolabeled for ICAM-1. Transmigrating lymphocyte is shown in the DIC image. The yz- and xz-projections from a 3D data set reveal WAVE2 in membrane protrusions that cup the PBL.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Figure 2: WAVE2 localization to membrane protrusions that close gaps and form at sites of transcellular pores. (A) WAVE2 is not recruited to paracellular pores during PBL transmigration. Frames from Supplemental Movie S2. Asterisk indicates a gap between ECs that persists after transmigration. Scale bar, 3 μm. (B) WAVE2 localizes to endothelial monolayer gaps that close after lymphocyte transmigration. Frames from Supplemental Movie S3. Asterisks indicate the gap, which closes after a wave of membrane protrusion. Red arrows indicate membrane waves, where WAVE2 has accumulated. Scale bar, 3 μm. (C) WAVE2 localizes to docking structures at sites of transcellular migration. ECs expressing WAVE2-GFP and immunolabeled for ICAM-1. Transmigrating lymphocyte is shown in the DIC image. The yz- and xz-projections from a 3D data set reveal WAVE2 in membrane protrusions that cup the PBL.
Mentions: For the paracellular route, PBLs migrated over the course of 2–5 min through a pore that formed between two ECs. The pore often remained open for several minutes after the PBL moved away from the transmigration site (Figure 2A; asterisk indicates a persisting pore). WAVE2-GFP did not accumulate at the transmigration site either before or during transmigration (Figure 2A and Supplemental Movie S2). When the pores closed, if the pore size was large, ECs produced waves of membrane protrusion as they closed the gap. WAVE2-GFP localized at the front of these protrusions, which traveled laterally along the edge of the EC (Figure 2B and Supplemental Movie S3). This dynamic behavior is consistent with the idea that WAVE2 activates Arp2/3 complex and promotes actin assembly to drive the formation and extension of membrane protrusions. Small pores sometimes closed rapidly, without membrane protrusions, and WAVE2-GFP did not accumulate.

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.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and Physiology, Washington University, St. Louis, MO 63110.

Show MeSH
Related in: MedlinePlus