title: Targeting a Proteinase-Activated Receptor 4 (PAR4) Carboxyl Terminal Motif to Regulate Platelet Function.
abstract: Thrombin initiates human platelet aggregation by coordinately activating proteinase-activated receptors (PARs) 1 and 4. However, targeting PAR1 with an orthosteric-tethered ligand binding-site antagonist results in bleeding, possibly owing to the important role of PAR1 activation on cells other than platelets. Because of its more restricted tissue expression profile, we have therefore turned to PAR4 as an antiplatelet target. We have identified an intracellular PAR4 C-terminal motif that regulates calcium signaling andβ-arrestin interactions. By disrupting this PAR4 calcium/β-arrestin signaling process with a novel cell-penetrating peptide, we were able to inhibit both thrombin-triggered platelet aggregation in vitro and clot consolidation in vivo. We suggest that targeting PAR4 represents an attractive alternative to blocking PAR1 for antiplatelet therapy in humans.
authors.affiliation: Snyder Institute for Chronic Diseases and Department of Physiology and Pharmacology (R.R., K.M., M.S., M.D.H.), Mouse Phenomics Resource Laboratory, Snyder Institute for Chronic Diseases and Department of Microbiology, Immunology, and Infectious Diseases (B.P.), and Department of Medicine (M.D.H.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada (R.R., P.T., C.M.V.); and IRIC-Université de Montréal, Montréal, Québec, Canada (M.B.) rramach@uwo.ca.
authors.forename: Rithwik
authors.initials: R
authors.lastname: Ramachandran
authors.affiliation: Snyder Institute for Chronic Diseases and Department of Physiology and Pharmacology (R.R., K.M., M.S., M.D.H.), Mouse Phenomics Resource Laboratory, Snyder Institute for Chronic Diseases and Department of Microbiology, Immunology, and Infectious Diseases (B.P.), and Department of Medicine (M.D.H.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada (R.R., P.T., C.M.V.); and IRIC-Université de Montréal, Montréal, Québec, Canada (M.B.).
authors.forename: Koichiro
authors.initials: K
authors.lastname: Mihara
authors.affiliation: Snyder Institute for Chronic Diseases and Department of Physiology and Pharmacology (R.R., K.M., M.S., M.D.H.), Mouse Phenomics Resource Laboratory, Snyder Institute for Chronic Diseases and Department of Microbiology, Immunology, and Infectious Diseases (B.P.), and Department of Medicine (M.D.H.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada (R.R., P.T., C.M.V.); and IRIC-Université de Montréal, Montréal, Québec, Canada (M.B.).
authors.forename: Pierre
authors.initials: P
authors.lastname: Thibeault
authors.affiliation: Snyder Institute for Chronic Diseases and Department of Physiology and Pharmacology (R.R., K.M., M.S., M.D.H.), Mouse Phenomics Resource Laboratory, Snyder Institute for Chronic Diseases and Department of Microbiology, Immunology, and Infectious Diseases (B.P.), and Department of Medicine (M.D.H.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada (R.R., P.T., C.M.V.); and IRIC-Université de Montréal, Montréal, Québec, Canada (M.B.).
authors.forename: Christina M
authors.initials: CM
authors.lastname: Vanderboor
authors.affiliation: Snyder Institute for Chronic Diseases and Department of Physiology and Pharmacology (R.R., K.M., M.S., M.D.H.), Mouse Phenomics Resource Laboratory, Snyder Institute for Chronic Diseases and Department of Microbiology, Immunology, and Infectious Diseases (B.P.), and Department of Medicine (M.D.H.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada (R.R., P.T., C.M.V.); and IRIC-Université de Montréal, Montréal, Québec, Canada (M.B.).
authors.forename: Björn
authors.initials: B
authors.lastname: Petri
authors.affiliation: Snyder Institute for Chronic Diseases and Department of Physiology and Pharmacology (R.R., K.M., M.S., M.D.H.), Mouse Phenomics Resource Laboratory, Snyder Institute for Chronic Diseases and Department of Microbiology, Immunology, and Infectious Diseases (B.P.), and Department of Medicine (M.D.H.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada (R.R., P.T., C.M.V.); and IRIC-Université de Montréal, Montréal, Québec, Canada (M.B.).
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Saifeddine
authors.affiliation: Snyder Institute for Chronic Diseases and Department of Physiology and Pharmacology (R.R., K.M., M.S., M.D.H.), Mouse Phenomics Resource Laboratory, Snyder Institute for Chronic Diseases and Department of Microbiology, Immunology, and Infectious Diseases (B.P.), and Department of Medicine (M.D.H.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada (R.R., P.T., C.M.V.); and IRIC-Université de Montréal, Montréal, Québec, Canada (M.B.).
authors.forename: Michel
authors.initials: M
authors.lastname: Bouvier
authors.affiliation: Snyder Institute for Chronic Diseases and Department of Physiology and Pharmacology (R.R., K.M., M.S., M.D.H.), Mouse Phenomics Resource Laboratory, Snyder Institute for Chronic Diseases and Department of Microbiology, Immunology, and Infectious Diseases (B.P.), and Department of Medicine (M.D.H.), Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada (R.R., P.T., C.M.V.); and IRIC-Université de Montréal, Montréal, Québec, Canada (M.B.).
authors.forename: Morley D
authors.initials: MD
authors.lastname: Hollenberg
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D057846:Cell-Penetrating Peptides / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D018179:Receptors, Thrombin / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013927:Thrombosis / Q000473:pathology; D000071557:beta-Arrestins / Q000378:metabolism
chemical_list: D057846:Cell-Penetrating Peptides; D050505:Mutant Proteins; D018179:Receptors, Thrombin; D000071557:beta-Arrestins; C112908:protease-activated receptor 4