title: Proteinase-activated receptors, targets for kallikrein signaling.
abstract: Serine proteinases like thrombin can signal to cells by the cleavage/activation of proteinase-activated receptors (PARs). Although thrombin is a recognized physiological activator of PAR(1) and PAR(4), the endogenous enzymes responsible for activating PAR(2) in settings other than the gastrointestinal system, where trypsin can activate PAR(2), are unknown. We tested the hypothesis that the human tissue kallikrein (hK) family of proteinases regulates PAR signaling by using the following: 1) a high pressure liquid chromatography (HPLC)-mass spectral analysis of the cleavage products yielded upon incubation of hK5, -6, and -14 with synthetic PAR N-terminal peptide sequences representing the cleavage/activation motifs of PAR(1), PAR(2), and PAR(4); 2) PAR-dependent calcium signaling responses in cells expressing PAR(1), PAR(2), and PAR(4) and in human platelets; 3) a vascular ring vasorelaxation assay; and 4) a PAR(4)-dependent rat and human platelet aggregation assay. We found that hK5, -6, and -14 all yielded PAR peptide cleavage sequences consistent with either receptor activation or inactivation/disarming. Furthermore, hK14 was able to activate PAR(1), PAR(2), and PAR(4) and to disarm/inhibit PAR(1). Although hK5 and -6 were also able to activate PAR(2), they failed to cause PAR(4)-dependent aggregation of rat and human platelets, although hK14 did. Furthermore, the relative potencies and maximum effects of hK14 and -6 to activate PAR(2)-mediated calcium signaling differed. Our data indicate that in physiological settings, hKs may represent important endogenous regulators of the PARs and that different hKs can have differential actions on PAR(1), PAR(2), and PAR(4).
authors.affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5G 1L5, Canada.
authors.forename: Katerina
authors.initials: K
authors.lastname: Oikonomopoulou
authors.forename: Kristina K
authors.initials: KK
authors.lastname: Hansen
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Saifeddine
authors.forename: Illa
authors.initials: I
authors.lastname: Tea
authors.forename: Michael
authors.initials: M
authors.lastname: Blaber
authors.forename: Sachiko I
authors.initials: SI
authors.lastname: Blaber
authors.forename: Isobel
authors.initials: I
authors.lastname: Scarisbrick
authors.forename: Patricia
authors.initials: P
authors.lastname: Andrade-Gordon
authors.forename: Graeme S
authors.initials: GS
authors.lastname: Cottrell
authors.forename: Nigel W
authors.initials: NW
authors.lastname: Bunnett
authors.forename: Eleftherios P
authors.initials: EP
authors.lastname: Diamandis
authors.forename: Morley D
authors.initials: MD
authors.lastname: Hollenberg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D001013:Aorta, Thoracic / Q000187:drug effects; D016367:Baculoviridae / Q000235:genetics; D001792:Blood Platelets / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects; D006801:Humans; D007610:Kallikreins / Q000138:chemical synthesis / Q000737:chemistry / Q000145:classification / Q000494:pharmacology*; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D010974:Platelet Aggregation / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D044462:Receptors, Proteinase-Activated / Q000737:chemistry / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D013552:Swine; D013917:Thrombin / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology
chemical_list: D044462:Receptors, Proteinase-Activated; D011994:Recombinant Proteins; D007610:Kallikreins; D014357:Trypsin; D013917:Thrombin