1.Proteinase-activated receptors 1 and 2 mediate contraction of human oesophageal muscularis mucosae.
Chang BS;Chang JC;Huang SC Neurogastroenterol Motil. 2010 Jan;22(1):93-7, e32. doi: 10.1111/j.1365-2982.2009.01380.x. Epub 2009 Aug 20.
Proteinase-activated receptors 1 and 2 mediate contraction of the human gallbladder. In the present study, we investigated effects mediated by proteinase-activated receptors (PARs) in the human oesophagus by measuring contraction of muscularis mucosae strips isolated from the human oesophagus. Both PAR(1) agonists (thrombin, SFLLRN-NH(2) and TFLLR-NH(2)) and PAR(2) agonists (trypsin, 2-furoyl-LIGRLO-NH(2) and SLIGKV-NH(2)) caused concentration-dependent contraction. In contrast, PAR(1) and PAR(2) control peptides did not cause contraction. The existence of PAR(1) and PAR(2) in the human oesophageal muscularis mucosae was confirmed by immunohistochemistry and reverse transcription-polymerase chain reaction. On the other hand, PAR(4) agonists, GYPGKF-NH(2), GYPGQV-NH(2) and AYPGKF-NH(2), did not cause contraction or relaxation in resting or carbachol-contracted muscularis mucosae strips, suggesting that PAR(4) is not involved in human oesophageal motility. The contractile responses to SFLLRN-NH(2) and trypsin in the human oesophagus were insensitive to atropine and tetrodotoxin, indicating that the contractile response was not neurally mediated. Taken together, these results demonstrate that PAR(1) and PAR(2) but not PAR(4) mediate contraction in human oesophageal muscularis mucosae.
2.Thrombin stimulates proinflammatory and proliferative responses in primary cultures of human proximal tubule cells.
Vesey DA;Cheung CW;Kruger WA;Poronnik P;Gobe G;Johnson DW Kidney Int. 2005 Apr;67(4):1315-29.
BACKGROUND: ;Fibrin deposition is frequently observed within the tubulointerstitium in various forms of chronic renal disease. This suggests the presence of active components of the coagulation pathway, which may contribute to the progressive deterioration in renal function. The aim of this study was to investigate the proinflammatory and fibroproliferative effects of the coagulation protease thrombin on human proximal tubular cells (PTC) in culture.;METHODS: ;Primary cultures of PTC were established from normal kidney tissue and grown under serum-free conditions with or without thrombin or the protease-activated receptor (PAR) activating peptides TFLLRN-NH(2), SLIGKV-NH(2), and SFLLRN-NH(2) (100 to 400 micromol/L). DNA synthesis (thymidine incorporation), intracellular Ca(2+) mobilization (fura-2 fluorimetry), fibronectin secretion [enzyme-linked immunosorbent assay (ELISA), immunoblotting], monocyte chemoattractant protein-1 (MCP-1) secretion (ELISA), and transforming growth factor-beta1 (TGF-beta1) secretion (ELISA) were measured. Reverse transcription-polymerase chain reaction (RT-PCR) was used to assess PAR mRNA expression in these cells.;RESULTS: ;Thrombin enhanced DNA synthesis, fibronectin secretion, MCP-1 secretion, and TGF-beta1 secretion in a concentration-dependent manner.
3.Proteinase-activated receptor 2 (PAR(2)): development of a ligand-binding assay correlating with activation of PAR(2) by PAR(1)- and PAR(2)-derived peptide ligands.
Al-Ani B;Saifeddine M;Kawabata A;Renaux B;Mokashi S;Hollenberg MD J Pharmacol Exp Ther. 1999 Aug;290(2):753-60.
A cloned rat proteinase-activated receptor (PAR)(2)-expressing cell line (KNRK-rPAR(2)) was used to study the structure-activity relationships (elevated intracellular Ca(2+)) for a series of: 1) PAR(1)-derived receptor-activating ligands (PAR(1)-APs) [SFLLR (P5), SFLLR-NH(2) (P5-NH(2)), SFLLRNP (P7), SFLLRNP-NH(2) (P7-NH(2)), and TFLLR-NH(2) (TF-NH(2))] and 2) PAR(2)-derived-activating-peptides (PAR(2)-APs) [SLIGRL-NH(2) (SL-NH(2)), SLIGR-NH(2) (GR-NH(2)), and SLIGKV-NH(2) (KV-NH(2))]. The activities of the PAR-APs were compared with the PAR(2)-AP analog trans-cinnamoyl-Leu-Ile-Gly-Arg-Leu-Orn-NH(2) tc-NH(2)), which as a [(3)H]propionyl derivative ([(3)H]propionyl-tc-NH(2)) was used to develop a radioligand-binding assay for PAR(2). The relative potencies of the PAR-APs in the Ca(2+)-signaling assay were tc-NH(2) = SL-NH(2) > KV-NH(2) congruent with P5-NH(2) > GR-NH(2) > P7-NH(2) > P7 > P5 > TF-NH(2). The reverse sequence PAR-APs, LSIGRL-NH(2) (LS-NH(2)), LRGILS-NH(2) (LR-NH(2)), FSLLRY-NH(2) (FSY-NH(2)), and FSLLR-NH(2) (FS-NH(2)), as well as the Xenopus PAR(1)-AP TFRIFD-NH(2), were inactive. The relative biological potencies of the peptides were in accord with their ability to compete for the binding of [(3)H]propionyl-tc-NH(2) (tc-NH(2) = SL-NH(2) > GR-NH(2) congruent with P5-NH(2) > P5) to KNRK-rPAR(2) cells, whereas inactive peptides (FS-NH(2); LR-NH(2)) showed no appreciable binding competition.
