Targeted null-mutation in the vascular endothelial–cadherin gene impairs the organization of vascular-like structures in embryoid bodies

Targeted null-mutation in the vascular endothelial–cadherin gene impairs the organization of vascular-like structures in embryoid bodies

Commissariat à l’Energie Atomique, Laboratoire d’Hématologie, Institut National de la Santé et de la Recherche Médicale U217, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France

Abstract

Vascular endothelial–cadherin (VE–cadherin) is exclusively expressed in endothelial cells and is strictly located at cell-to-cell junctions. As the other members of the cadherin family, VE–cadherin is able to mediate a homotypic type of cellular interaction in a Ca²⁺-dependent manner. In the mouse embryo, VE–cadherin transcripts are detected at the earliest stages of vascular development. To ascertain if VE–cadherin expression is required for the assembly of endothelial cells into vascular structures, we generated VE–cadherin-negative mouse embryonic stem cells (VE–cadherin ^−/− ES cells) by gene targeting and examined the consequences on vascular development of ES-derived embryoid bodies (EBs). In contrast to wild-type EBs, we observed that endothelial cells remained dispersed and failed to organize a vessel-like pattern in VE–cadherin ^−/− ES-derived EBs. However, dispersed VE–cadherin ^−/− ES-derived endothelial cells expressed a large range of other endothelial markers. Moreover, the targeted null-mutation in the VE–cadherin locus did not interfere with the hematopoietic differentiation potential of ES cells. These in vitro experiments are consistent with a pivotal role of VE–cadherin in vascular structure assembly.

Footnotes

↵ * D.V. and T.B. contributed equally to this work.
↵ † To whom reprint requests should be addressed. e-mail: vittet@géant.ceng.cea.fr.
↵ ‡ Present address: Istituto di Ricerche Farmacologiche Mario Negri, Vascular Biology Laboratory, via Eritrea 62, 20157 Milan, Italy.
George E. Palade, University of California School of Medicine, La Jolla, CA
ABBREVIATIONS:

VE–cadherin,

vascular–endothelial cadherin;

ES cells,

embryonic stem cells;

EBs,

embryoid bodies;

VEGF,

vascular endothelial growth factor;

RT,

reverse transcriptase;

PECAM,

platelet endothelial cell adhesion molecule;

vWf,

von Willebrand factor