Molecular cloning, expression and potential functions of the human proteinase-activated receptor-2

Abstract

We used PCR to amplify proteinase activated receptor-2 (PAR-2) from human kidney cDNA. The open reading frame comprised 1191 bp and encoded a protein of 397 residues with 83% identity with mouse PAR-2. In KNRK cells (a line of kirsten murine sarcoma virus-transformed rat kidney epithelial cells) transfected with this cDNA, trypsin and activating peptide (AP) corresponding to the tethered ligand exposed by trypsin cleavage (SLIGKV-NH2) induced a prompt increase in cytosolic calcium ion concentration ([Ca2+]i). Human PAR-2 (hPAR-2) resided both on the plasma membrane and in the Golgi apparatus. hPAR-2 mRNA was highly expressed in human pancreas, kidney, colon, liver and small intestine, and by A549 lung and SW480 colon adenocarcinoma cells. Hybridization in situ revealed high expression in intestinal epithelial cells throughout the gut. Trypsin and AP stimulated an increase in [Ca2+]i in a rat intestinal epithelial cell line (hBRIE 380) and stimulated amylase secretion in isolated pancreatic acini. In A549 cells, which also responded to trypsin and AP with mobilization of cytosolic Ca2+, AP inhibited colony formation. Thus PAR-2 may serve as a trypsin sensor in the gut. Its expression by cells and tissues not normally exposed to pancreatic trypsin suggests that other proteases could serve as physiological activators.

Initiation of human colon cancer cell proliferation by trypsin acting at protease-activated receptor-2

“…Indeed, it has long been known that trypsin stimulates cell division of fibroblasts by acting at the cell surface (Blumberg and Robbins, 1975;Carney and Cunningham, 1977). This is in line with recent studies suggesting that the action of trypsin can be mediated not only by its classical ability to catalyze the hydrolysis of various proteins, but also through specific cleavage and activation of a cell surface receptor, the protease-activated receptor-2 (PAR-2) (Nystedt et al, 1994;Bohm et al, 1996b;Hollenberg, 1996). PAR-2 is the second member of a new subfamily of G proteincoupled receptors activated by proteolytic cleavage (Dery et al, 1998) that also includes PAR-1, PAR-3 and PAR-4 (Vu et al, 1991;Ishihara et al, 1997;Xu et al, 1998), which are receptors for thrombin.…”

“…PAR-2 is the second member of a new subfamily of G proteincoupled receptors activated by proteolytic cleavage (Dery et al, 1998) that also includes PAR-1, PAR-3 and PAR-4 (Vu et al, 1991;Ishihara et al, 1997;Xu et al, 1998), which are receptors for thrombin. PAR-2 cleavage by trypsin exposes a new amino terminus peptide that functions as tethered ligand (Nystedt et al, 1994;Bohm et al, 1996b). This new ligand binds to the core of the receptor and initiates signal transduction resulting in stimulation of phosphoinositide breakdown and cytosolic calcium mobilization (Nystedt et al, 1994;Dery et al, 1998).…”

Keratinocyte–Melanocyte Interactions During Melanosome Transfer

“…Using synthetic peptides that correspond to the newly created N-termini, PARs could also be activated without receptor cleavage. SLIGRL and SLIGKV, the mouse and human PAR-2-activating peptides, are specific for PAR-2 activation and are equipotent in the activation of the human PAR-2 (20,21). The cleaved-activated receptors are physically coupled to their tethered activating ligands.…”

Glycosylation and the activation of proteinase‐activated receptor 2 (PAR2) by human mast cell tryptase

“…Activation occurs by proteolysis of the aminoterminal exodomain resulting in the exposure of a tethered ligand, which presumably binds to, and activates the receptor. There are currently three active members of the PAR family, PAR 1, 2 and 4 (Bohm et al, 1996;Ishihara et al, 1997;Vu et al, 1991;Kahn et al, 1998;Xu et al, 1998). Family member, PAR 3 , has been found to be a co-factor for PAR 4 and as such may not be considered as an active receptor in its own right (Nakanishi-Matsui et al, 2000).…”