title: Evidence for functionally active protease-activated receptor-3 (PAR-3) in human vascular smooth muscle cells.
abstract: The present study investigates whether vascular smooth muscle cells of the human saphenous vein (SMC) express a functionally active protease-activated receptor-3 (PAR-3). PAR-3 mRNA was detected by RT-PCR. In the presence of thrombin, a rapid and transient increase in PAR-3 mRNA was observed. Stimulation of SMC with thrombin or the synthetic PAR-3-activating peptide, TFRGAP, resulted in transient mobilization of intracellular calcium. After a preceding challenge with thrombin, the calcium signal to TFRGAP was abolished, suggesting cleavage and subsequent desensitization of PAR-3 by thrombin. Activation of PAR-3 by TFRGAP elicited a time-dependent activation of the extracellular-signal-regulated kinase (ERK)-1/2 with a maximum response 10-20 min after stimulation. At 200 microM, TFRGAP increased [3H]-thymidine incorporation into cellular DNA about two-fold. These data indicate that PAR-3 is expressed in human SMC and triggers intracellular signaling. Thus, in the SMC PAR-3 might contribute to thrombin-induced responses.
mesh_terms: D020013:Calcium Signaling; D004261:DNA Replication / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000737:chemistry / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000737:chemistry*; D012333:RNA, Messenger / Q000032:analysis / Q000187:drug effects; D018179:Receptors, Thrombin / Q000032:analysis* / Q000235:genetics / Q000502:physiology; D012501:Saphenous Vein; D013917:Thrombin / Q000494:pharmacology
chemical_list: D012333:RNA, Messenger; D018179:Receptors, Thrombin; C105295:protease-activated receptor 3; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D013917:Thrombin