Molecular mechanisms underlying the proangiogenic effect of factor XIII.
OBJECTIVE
Coagulation Factor XIII (FXIII) was previously shown by us to induce angiogenesis. The aim of this study was to elucidate the molecular events underlying the proangiogenic effects of activated FXIII (FXIIIa) on human umbilical vein endothelial cells (HUVECs).


RESULTS
As shown by coimmunoprecipitation studies, FXIIIa crosslinked alpha(v)beta3 with vascular endothelial growth factor receptor 2 (VEGFR-2) and enhanced the noncovalent interaction between the 2 receptors. In addition, FXIIIa induced tyrosine phosphorylation of VEGFR-2 in both the crosslinked high-molecular-weight and the noncovalent VEGFR-2/alpha(v)beta3 complexes. These effects as well as FXIIIa-induced proliferation and migration of HUVECs were abolished by iodoacetamide treatment of FXIIIa (I-FXIII) or by PTKI, an inhibitor of VEGFR-2. FXIIIa induced upregulation of c-Jun and Egr-1 as revealed by quantitative RT-PCR. Electrophoretic mobility-shift assay experiments showed that FXIIIa treatment of HUVECs enhanced binding of Wilm's tumor-1 (WT-1) but not of early growth response (Egr)-1 to the thrombospondin-1 (TSP-1) promoter sequence, suggesting that WT-1 but not Egr-1 is involved in downregulation of TSP-1 expression.


CONCLUSIONS
The proangiogenic effect of FXIIIa is mediated by (1) enhancement of crosslinked and noncovalent alpha(v)beta3/VEGFR-2 complex formation; (2) tyrosine phosphorylation and activation of VEGFR-2; (3) upregulation of c-Jun and Egr-1; and (4) downregulation of TSP-1 induced indirectly by c-Jun through WT-1. These processes may clarify FXIII role in vascular remodeling and tissue repair.
Dardik
Rima
R
Institute of Thrombosis and Hemostasis, Sheba Medical Center, Tel Hashomer, Israel.
Loscalzo
Joseph
J
Eskaraev
Regina
R
Inbal
Aida
A
D002478:Cells, Cultured; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics; D051766:Early Growth Response Protein 1; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D005176:Factor XIII / Q000494:pharmacology* / Q000502:physiology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics; D039302:Integrin alphaVbeta3 / Q000378:metabolism; D018919:Neovascularization, Physiologic / Q000187:drug effects* / Q000502:physiology*; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000502:physiology; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D019700:Thrombospondin 1 / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D014443:Tyrosine / Q000378:metabolism; D014471:Umbilical Veins / Q000166:cytology; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D025721:WT1 Proteins / Q000378:metabolism
D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D017874:Immediate-Early Proteins; D039302:Integrin alphaVbeta3; D009687:Nuclear Proteins; D016755:Proto-Oncogene Proteins c-jun; D019700:Thrombospondin 1; D014157:Transcription Factors; D025721:WT1 Proteins; D014443:Tyrosine; D005176:Factor XIII; D040301:Vascular Endothelial Growth Factor Receptor-2