PT  - JOURNAL ARTICLE
AU  - Bahjat Al-Ani
AU  - Mahmoud Saifeddine
AU  - Suranga J. Wijesuriya
AU  - Morley D. Hollenberg
TI  - Modified Proteinase-Activated Receptor-1 and -2 Derived Peptides Inhibit Proteinase-Activated Receptor-2 Activation by Trypsin
AID  - 10.1124/jpet.300.2.702
DP  - 2002 Feb 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 702--708
VI  - 300
IP  - 2
4099  - http://jpet.aspetjournals.org/content/300/2/702.short
4100  - http://jpet.aspetjournals.org/content/300/2/702.full
SO  - J Pharmacol Exp Ther2002 Feb 01; 300
AB  - Trypsin activates proteinase-activated receptor-2 (PAR2) by a mechanism that involves the release of a tethered receptor-activating sequence. We have identified two peptides, FSLLRY-NH2(FSY-NH2) and LSIGRL-NH2 (LS-NH2) that block the ability of trypsin to activate PAR2 either in PAR2-expressing Kirsten virus-transformed kidney (KNRK) cell lines or in a rat aorta ring preparation. The reverse PAR2 peptide, LRGILS-NH2 (LRG-NH2) did not do so and FSY-NH2 failed to block thrombin activation of PAR1 in the aorta ring or in PAR1-expressing human embryonic kidney cells. Half-maximal inhibition (IC50) by FSY-NH2 and LS-NH2 of the activation of PAR2 by trypsin in a PAR2 KNRK calcium-signaling assay was observed at about 50 and 200 μM, respectively. In contrast, the activation of PAR2 by the PAR2-activating peptide, SLIGRL-NH2 (SL-NH2) was not inhibited by FSY-NH2, LS-NH2, or LRG-NH2. In a casein proteolysis assay, neither FSY-NH2 nor LS-NH2 inhibited the proteolytic action of trypsin on its substrate. In addition, FSY-NH2 and LS-NH2 were unable to prevent trypsin from hydrolyzing a 20-amino acid peptide, GPNSKGR/SLIGRLDTPYGGC representing the trypsin cleavage/activation site of rat PAR2. Similarly, FSY-NH2 and LS-NH2 failed to block the ability of trypsin to release the PAR2 N-terminal epitope that is cleaved from the receptor upon proteolytic activation of receptor-expressing KNRK cells. We conclude that the peptides FSY-NH2 and LS-NH2 block the ability of trypsin to activate PAR2 by a mechanism that does not involve a simple inhibition of trypsin proteolytic activity, but possibly by interacting with a tethered ligand receptor-docking site. The American Society for Pharmacology and Experimental Therapeutics