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On the mode of action of thrombin-induced angiogenesis: thrombin peptide,TP508, mediates effects in endothelial cells via αvβ3 integrin

Journal: Thrombosis and Haemostasis
ISSN: 0340-6245
Topic:

Paediatric Haemostasis

DOI: https://doi.org/10.1160/TH04-04-0208
Issue: 2004: 92/4 (Oct) pp. 672-895
Pages: 846-857

On the mode of action of thrombin-induced angiogenesis: thrombin peptide,TP508, mediates effects in endothelial cells via αvβ3 integrin

Nikos E.Tsopanoglou, Matthew E. Papaconstantinou, Christodoulos S. Flordellis, Michael E. Maragoudakis
Department of Pharmacology, Medical School, University of Patras, Rio Patras, Greece

Summary

In a previous report we have presented evidence that thrombin interacts with αvβ3 integrin in endothelial cells at the molecular and cellular level.This interaction was shown to be of functional significance in vitro and in vivo and contributed to activation of angiogenesis by thrombin. In the present study, we have used a synthetic thrombin peptide, TP508, which represents residues 183 to 200 of human thrombin.This peptide lacks the catalytic site of thrombin but contains the thrombin RGD sequence. Immobilized (surface-coated) TP508 peptide, like thrombin, supported αvβ3 integrin-dependent endothelial cell attachment and haptotactic migration. These effects were specific (a scrambled TP508 peptide was without effect), and dosedependent. The RGD sequence was essential since a modified TP508 peptide, which contained RAD sequence instead of RGD, was inactive. Immobilized TP508 peptide stimulated phos phorylation of mitogen-activated protein kinases and focal adhesion kinase, the signal transduction pathways characteristic for integrin activation. On the other hand,TP508 peptide, when in solution, did not mimic other thrombin-promoted angiogenic effects, such as that of activation gelatinase A, upregulation of expression of vascular endothelial growth factor receptor mRNA or prostacyclin PGI2 release in endothelial cells.On the contrary, soluble TP508 acted as an antagonist for the aforementioned effects of thrombin. TP508 peptide inhibited these thrombin-induced effects through a RGD and αvβ3-related mechanism.The antagonism with thrombin or thrombin receptor activating peptide was specific and involved at least in part mitogen-activated protein kinases activation. These results point to the importance of RGD sequence of thrombin in mediating effects on endothelial cells and angiogenesis.