Thromb Haemost 2005; 94(03): 620-629
DOI: 10.1160/TH05-01-0015
Cell Signalling and Vessel Remodelling
Schattauer GmbH

Tyrosine phosphorylation and the small GTPase rac cross-talk in regulation of endothelial barrier function

Jochen Seebach
1   Institut of Physiology, TU-Dresden, Dresden, Germany
,
Hans-Jürgen Mädler
1   Institut of Physiology, TU-Dresden, Dresden, Germany
,
Beata Wojciak-Stothard
2   Rayne Institute UCL, London, UK
,
Hans-Joachim Schnittler
1   Institut of Physiology, TU-Dresden, Dresden, Germany
› Author Affiliations
Grant support: Deutsche Forschungsgemeinschaft grants SCHN 430/2-3 and 4 and by the MedDrive Program of the medical faculty of Dresden. Supplementary information to this manuscript is availble online at www.thrombosisonline.com
Further Information

Publication History

Received: 08 January 2005

Accepted after major revision: 24 June 2005

Publication Date:
07 December 2017 (online)

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Summary

Endothelial barrier function depends on the integrity of intercellular adherens junctions controlled by the association of VEcadherin/ catenin complex with cortical actin filaments. Both tyrosine phosphorylation/dephosphorylation of junctional proteins and actin reorganization mediated by rho-GTPases regulate barrier function but the relationship between these regulatory mechanisms is unclear. Here we studied the effects of factors increasing protein tyrosine phosphorylation, pervanadate (PV) and VEGF, on distribution of VE-cadherin, F-actin polymerization and transendothelial electrical resistance (TER) in human umbilical vein endothelial cells (HUVECs). Changes in protein tyrosine phosphorylation of cytoplasmic and junctional proteins, as well as the activity of rho-GTPase rac1, were also measured. We report for the first time that PV and VEGF induced a rapid transient increase in endothelial barrier function accompanied by rac1 activation, a differentiated tyrosine phosphorylation of theVE-cadherin/catenin complex, recruitment of actin filament to cell junctions and ruffle formation. A sustained decrease in endothelial barrier function was observed at later times of PV and VEGF treatment. Expression of dominant negative rac1, N17rac1 abolished the barrier-enhancing effects of PV andVEGF, while the sustained decrease in barrier function was unaffected. These observations bring into focus early shortterm effects of protein tyrosine phosphorylation in cells, often overshadowed by more pronounced and long-lasting later effects and may play an important role in the regulation of endothelial barrier function.