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Mol Biol Cell. 2017 Jul 1;28(13):1745-1753. doi: 10.1091/mbc.E16-06-0389. Epub 2017 May 17.

Flow-induced endothelial cell alignment requires the RhoGEF Trio as a scaffold protein to polarize active Rac1 distribution.

Author information

1
Department of Plasma Proteins and Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam 1066 CX, Netherlands.
2
Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam 1105 AZ, Netherlands.
3
Department of Plasma Proteins and Department of Molecular Cell Biology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center, University of Amsterdam, Amsterdam 1066 CX, Netherlands j.vanbuul@sanquin.nl.

Abstract

Endothelial cells line the lumen of the vessel wall and are exposed to flow. In linear parts of the vessel, the endothelial cells experience laminar flow, resulting in endothelial cell alignment in the direction of flow, thereby protecting the vessel wall from inflammation and permeability. In order for endothelial cells to align, they undergo rapid remodeling of the actin cytoskeleton by local activation of the small GTPase Rac1. However, it is not clear whether sustained and local activation of Rac1 is required for long-term flow-induced cell alignment. Using a FRET-based DORA Rac1 biosensor, we show that local Rac1 activity remains for 12 h upon long-term flow. Silencing studies show that the RhoGEF Trio is crucial for keeping active Rac1 at the downstream side of the cell and, as a result, for long-term flow-induced cell alignment. Surprisingly, Trio appears to be not involved in flow-induced activation of Rac1. Our data show that flow induces Rac1 activity at the downstream side of the cell in a Trio-dependent manner and that Trio functions as a scaffold protein rather than a functional GEF under long-term flow conditions.

PMID:
28515142
PMCID:
PMC5491183
DOI:
10.1091/mbc.E16-06-0389
[Indexed for MEDLINE]
Free PMC Article

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