Thromb Haemost 1995; 74(05): 1340-1347
DOI: 10.1055/s-0038-1649937
Original Article
Vessel Wall
Schattauer GmbH Stuttgart

Thrombin Receptor Activating Peptide (TRAP) Stimulates Mitogenesis, c-fos and PDGF-A Gene Expression in Human Vascular Smooth Muscle Cells

Chryso Kanthou
The Vascular Biology Laboratory, Thrombosis Research Institute, Chelsea, London, UK
,
Omar Benzakour
The Vascular Biology Laboratory, Thrombosis Research Institute, Chelsea, London, UK
,
Geeta Patel
The Vascular Biology Laboratory, Thrombosis Research Institute, Chelsea, London, UK
,
John Deadman
The Vascular Biology Laboratory, Thrombosis Research Institute, Chelsea, London, UK
,
Vijay Vir Kakkar
The Vascular Biology Laboratory, Thrombosis Research Institute, Chelsea, London, UK
,
Florea Lupu
The Vascular Biology Laboratory, Thrombosis Research Institute, Chelsea, London, UK
› Author Affiliations
Further Information

Publication History

Received 17 May 1995

Accepted after revision 14 July 1995

Publication Date:
10 July 2018 (online)

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Summary

The synthetic peptide SFLLRNPNDKYEPF, identical in sequence to the new amino-terminus of the thrombin receptor generated following cleavage by thrombin, acts as a thrombin receptor agonist/ activating peptide (TRAP). In this study, Northern blot analysis showed that cultured human vascular smooth muscle cells (HVSMC) express a thrombin receptor transcript. TRAP, in contrast to thrombin was shown to be a weak mitogen for HVSMC. A combination of TRAP and enzymatically-inactivated thrombin (PPACK-thrombin) which provides receptor occupancy, did not potentiate TRAP-induced mitogenesis, indicating that TRAP and PPACK-thrombin do not reproduce the mitogenic effect of enzymatically-active thrombin. Both thrombin and TRAP, induced the expression of c-fos and the PDGF-A gene in a pertussis toxin (PTX)-insensitive manner. Examination of thrombin and TRAP-treated cells by immunofluorescence staining followed by computer assisted image analysis revealed that thrombin and to a lesser extent TRAP induced PDGF-AA protein expression. Antibodies to PDGF-AA partially inhibited thrombin but not TRAP-induced mitogenesis in HVSMC. This study indicates that in addition to the common signalling pathways utilised by thrombin and TRAP, enzymatically-active thrombin activates other signalling pathways and hence TRAP does not mimic fully the biological effect of thrombin on HVSMC.