title: Protease-activating receptor-4 induces full platelet spreading on a fibrinogen matrix: involvement of ERK2 and p38 and Ca2+ mobilization.
abstract: Although the involvement of protease-activating receptor PAR1 and PAR4 is well established in platelet aggregation, their role in platelet adhesion and spreading has yet to be characterized. We investigated platelet adhesion and spreading on a fibrinogen matrix after PAR1 and PAR4 stimulation in correlation with the activation of two MAPKs, ERK2 and p38. Of the two PAR-activating peptides (PAR-APs), PAR1-AP and PAR4-AP, which both induce adhesion, only PAR4-AP induced full platelet spreading. Although both PAR1-AP and PAR4-AP induced ADP secretion, which is required for platelet spreading, only PAR4-AP induced sustained Ca(2+) mobilization. In these conditions of PAR4 induction, ERK2 and p38 activation were involved in platelet spreading but not in platelet adhesion. p38 phosphorylation was dependent on ADP signaling through P2Y12, its receptor. ERK2 phosphorylation was triggered through integrin alphaIIbbeta3 outside-in signaling and was dependent on the Rho pathway. ERK2 and p38 activation induced phosphorylation of the myosin light chain and actin polymerization, respectively, necessary for cytoskeleton reorganization. These findings provide the first evidence that thrombin requires PAR4 for the full spreading response. ERK2 and p38 and sustained Ca(2+) mobilization, involved in PAR4-induced platelet spreading, contribute to the stabilization of platelet thrombi at sites of high thrombin production.
authors.affiliation: U689 INSERM, IFR139, Hôpital Lariboisière, 8 rue Guy Patin, 75010 Paris, France.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Mazharian
authors.forename: Séverine
authors.initials: S
authors.lastname: Roger
authors.forename: Eliane
authors.initials: E
authors.lastname: Berrou
authors.forename: Frédéric
authors.initials: F
authors.lastname: Adam
authors.forename: Alexandre
authors.initials: A
authors.lastname: Kauskot
authors.forename: Paquita
authors.initials: P
authors.lastname: Nurden
authors.forename: Martine
authors.initials: M
authors.lastname: Jandrot-Perrus
authors.forename: Marijke
authors.initials: M
authors.lastname: Bryckaert
mesh_terms: D000199:Actins / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000378:metabolism; D001792:Blood Platelets / Q000166:cytology / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D003599:Cytoskeleton / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D005340:Fibrinogen; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010973:Platelet Adhesiveness / Q000502:physiology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism; D044463:Receptor, PAR-1 / Q000378:metabolism; D018179:Receptors, Thrombin / Q000819:agonists / Q000378:metabolism*; D013917:Thrombin / Q000096:biosynthesis; D013927:Thrombosis / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000199:Actins; D018994:Myosin Light Chains; D010455:Peptides; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin; D000244:Adenosine Diphosphate; D005340:Fibrinogen; D019950:Mitogen-Activated Protein Kinase 1; D048051:p38 Mitogen-Activated Protein Kinases; D013917:Thrombin; C112908:protease-activated receptor 4; D002118:Calcium