Protease‐activated receptor‐2 turnover stimulated independently of receptor activation in porcine coronary endothelial cells
- 1 June 1999
- journal article
- Published by Wiley in British Journal of Pharmacology
- Vol. 127 (3), 617-622
- https://doi.org/10.1038/sj.bjp.0702583
Abstract
1. Protease-activated receptors (PARs) are activated by an irreversible proteolytic mechanism which renders cleaved receptors unresponsive to subsequent challenges with activating enzymes. Non-specific proteolysis of PARs downstream of the activation site also prevents subsequent enzymic activation. Therefore, we investigated the effects of non-activating amino-terminal proteolysis with the bacterial protease thermolysin on PAR-mediated relaxation of porcine coronary artery ring preparations contracted with the thromboxane A2 mimetic U46619 (1-10 nM). 2. Treatment of contracted artery ring segments with thermolysin (0.01-1 u ml-1, 20 min) caused no response, but abolished endothelium-dependent relaxations induced by the enzymic activators of PAR-1, and PAR-2, thrombin (0.01-0.3 u ml-1) and trypsin (0.003-0.1 u ml-1) respectively. The same treatment, however, did not affect similar responses to the proteolysis-independent PAR-1 and PAR-2 activating peptides, SFLLRN-NH2 and SLIGRL-NH2 respectively (0.1-10 microM). 3. The inhibition of responsiveness to trypsin after thermolysin treatment recovered in a time-dependent manner, with maximal recovery (77.3 +/- 8.0% of time controls) occurring 150 min after thermolysin treatment. No recovery of responsiveness to thrombin after thermolysin treatment was observed within this time, however, the thrombin response returned to control levels after 20 h. 4. The recovery of responsiveness to trypsin was inhibited by the translation inhibitor cycloheximide (100 microM; 17.3 +/- 4.7%) and the protein trafficking inhibitor brefeldin A (10 microM; 12.1 +/- 4.8%) but was unaffected by the transcription inhibitor actinomycin D (2 microM; 65.1 +/- 3.6%), which did, however, abolish upregulation of B1-kinin receptors in this preparation. 5. In conclusion, our findings indicate that activation-independent amino-terminal proteolysis of PARs stimulates selective recovery of endothelial cell PAR-2 responsiveness, which appears to be regulated by translation. Such a novel mechanism for the maintenance of responsiveness to enzymic PAR-2 activators may imply that these receptors play important roles in vascular homeostasis.Keywords
This publication has 38 references indexed in Scilit:
- Cloning and characterization of human protease-activated receptor 4Proceedings of the National Academy of Sciences, 1998
- Proteinase-activated receptors: novel mechanisms of signaling by serine proteasesAmerican Journal of Physiology-Cell Physiology, 1998
- Protease-activated receptor 3 is a second thrombin receptor in humansNature, 1997
- Specific Inhibition of Thrombin-Induced Cell Activation by the Neutrophil Proteinases Elastase, Cathepsin G, and Proteinase 3: Evidence for Distinct Cleavage Sites Within the Aminoterminal Domain of the Thrombin ReceptorBlood, 1997
- Interactions of Mast Cell Tryptase with Thrombin Receptors and PAR-2Journal of Biological Chemistry, 1997
- Role of the Thrombin Receptor's Cytoplasmic Tail in Intracellular TraffickingPublished by Elsevier ,1996
- Mechanisms of Desensitization and Resensitization of Proteinase-activated Receptor-2Journal of Biological Chemistry, 1996
- Rat proteinase‐activated receptor‐2 (PAR‐2): cDNA sequence and activity of receptor‐derived peptides in gastric and vascular tissueBritish Journal of Pharmacology, 1996
- Evidence for mediation by endothelium‐derived hyperpolarizing factor of relaxation to bradykinin in the bovine isolated coronary artery independently of voltage‐operated Ca2+ channelsBritish Journal of Pharmacology, 1996
- SPECIAL REPORT Endothelium‐dependent relaxation to the B1 kinin receptor agonist des‐Arg ‐bradykinin in human coronary arteriesBritish Journal of Pharmacology, 1995