Nuclear targeting of beta-catenin and p120ctn during thrombin-induced endothelial barrier dysfunction.
OBJECTIVE
Cytosolic and nuclear localization of beta-catenin was observed in leaky vessels and in tumours. Several lines of evidence indicate that nuclear beta-catenin facilitates angiogenesis. We hypothesized that nuclear beta-catenin liberated from endothelial junctional complexes marks the transition from hyperpermeability to angiogenesis. The aim of this study was, therefore, to investigate the fate of beta-catenin and the related catenin p120catenin (p120ctn), during disruption of the endothelial barrier function in human umbilical vein endothelial cells (ECs).


RESULTS
The hyperpermeability-inducer thrombin caused a Rho kinase-dependent redistribution of beta-catenin from the membrane to the cytosol as evidenced by the western blot analysis of membrane and cytosol fractions and by immunohistochemistry. Glycogen synthase kinase 3beta, which phosphorylates cytosolic beta-catenin and thereby facilitates its proteasomal degradation, was inhibited by thrombin. The analysis of nuclear extracts demonstrated a thrombin-induced nuclear accumulation of beta-catenin as well as p120ctn. Thrombin stimulation activated beta-catenin-mediated transcriptional activity as evidenced by reporter assays. Finally, real-time-PCR revealed increased mRNA levels of several beta-catenin target genes.


CONCLUSIONS
Thrombin induced a cytosolic stabilization of membrane-liberated beta-catenin, which, together with p120ctn, subsequently translocated to the nucleus where it induces several beta-catenin target genes. This supports the suggestion that membrane-liberated beta-catenin and p120ctn contribute to angiogenic responses of ECs following episodes of vascular leakage.
Beckers
Cora M L
CM
Department for Physiology, VU University Medical Center, Institute for Cardiovascular Research, van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands.
García-Vallejo
Juan J
JJ
van Hinsbergh
Victor W M
VW
van Nieuw Amerongen
Geerten P
GP
D021581:Active Transport, Cell Nucleus; D002199:Capillary Permeability; D051177:Catenins; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D042783:Endothelial Cells / Q000201:enzymology / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000503:physiopathology; D004789:Enzyme Activation; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007365:Intercellular Junctions / Q000378:metabolism; D018919:Neovascularization, Physiologic; D010750:Phosphoproteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D013917:Thrombin / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*; D054460:rho-Associated Kinases / Q000378:metabolism; D000095002:Delta Catenin
C495270:CTNNB1 protein, human; D051177:Catenins; D015815:Cell Adhesion Molecules; D010750:Phosphoproteins; D012333:RNA, Messenger; D051176:beta Catenin; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D054460:rho-Associated Kinases; D038362:Glycogen Synthase Kinase 3; D013917:Thrombin; D000095002:Delta Catenin; C000722347:CTNND1 protein, human