title: Proteinase-activated receptors (PARs)--the PAR3 Neo-N-terminal peptide TFRGAP interacts with PAR1.
abstract: Thrombin activates proteinase-activated receptor (PAR)1, PAR3 and PAR4 by a unique mechanism that involves cleavage of the receptor and exposure of a new N-terminal domain acting as a tethered ligand. Synthetic peptides based on the proteolytically revealed receptor sequence can selectively activate PAR1 or PAR4 independently of receptor cleavage. However, corresponding peptides for PAR3 have not been identified thus far. Here, we demonstrate that the synthetic peptide TFRGAP representing the 1st six residues of the new amino terminus of PAR3 induced ERK activation in human A-498 carcinoma cells endogeneously expressing PAR1 and PAR3. This effect was completely abolished by single alanine substitution at positions 3, 4 and 6 in the peptide. Since the specific PAR1 antagonist RWJ 56110 completely abolished TFRGAP-induced ERK activation in A-498 cells we speculate that TFRGAP does signal MAPK via interaction with PAR1. This was underlined by experiments on PAR1-/- mouse lung fibroblasts (KOLF cells) that stably overexpress human PAR1 and PAR3, respectively. While TFRGAP was without effect on ERK activation in PAR3+ KOLF cells, it induced MAPK activation in KOLF cells transfected with PAR1. These studies provide evidence that analogues of the PAR3 tethered ligand can mediate cell signaling by interaction with PAR1-type thrombin receptors.
authors.affiliation: Department of General and Visceral Surgery, Research Center Lobeda, Medical Faculty at the Friedrich Schiller University Jena, Erlanger Allee 101, 07747 Jena, Germany. roland.kaufmann@med.uni-jena.de
authors.forename: Roland
authors.initials: R
authors.lastname: Kaufmann
authors.forename: Beate
authors.initials: B
authors.lastname: Schulze
authors.forename: Gerd
authors.initials: G
authors.lastname: Krause
authors.forename: Lorenz M
authors.initials: LM
authors.lastname: Mayr
authors.forename: Utz
authors.initials: U
authors.lastname: Settmacher
authors.forename: Peter
authors.initials: P
authors.lastname: Henklein
mesh_terms: D000409:Alanine / Q000737:chemistry; D000818:Animals; D015153:Blotting, Western; D002277:Carcinoma / Q000378:metabolism; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004587:Electrophoresis, Agar Gel; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007680:Kidney Neoplasms / Q000378:metabolism; D008024:Ligands; D020935:MAP Kinase Signaling System; D051379:Mice; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D044462:Receptors, Proteinase-Activated / Q000378:metabolism*; D018179:Receptors, Thrombin / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013917:Thrombin / Q000737:chemistry; D013997:Time Factors; D014162:Transfection
chemical_list: D008024:Ligands; D010455:Peptides; D012333:RNA, Messenger; D044462:Receptors, Proteinase-Activated; D018179:Receptors, Thrombin; D011994:Recombinant Proteins; C105295:protease-activated receptor 3; D013917:Thrombin; D000409:Alanine