title: Rho-kinase regulates human platelet activation induced by thromboxane A2 independently of p38 MAP kinase.
abstract: We have previously demonstrated that ristocetin, an activator of GPIb/IX/V, induces the release of soluble CD40 ligand (sCD40L) via thromboxane A2 production in human platelets. It has been shown that thromboxane A2 induces the activation of Rho-kinase, a downstream effector of Rho, in human platelets. In the present study, we investigated the exact roles of Rho-kinase in thromboxane A2-induced platelet activation. We found that U46619, a thromboxane receptor (TP) agonist, induced the phosphorylation of cofilin, a target of Rho-kinase signaling, and that the cofilin phosphorylation by U46619 was suppressed by Y27632 or fasudil, specific inhibitors of Rho-kinase. Y27632 and fasudil markedly decreased large platelet aggregate formation by U46619. The release of sCD40L and secretion of platelet-derived growth factor (PDGF)-AB stimulated by U46619 were inhibited by Y27632 and fasudil. SB203580, a specific inhibitor of p38 mitogen-activated protein (MAP) kinase, reduced the sCD40L release and PDGF-AB secretion. Y27632 and fasudil failed to affect the phosphorylation of p38 MAP kinase whereas SB203580 had little effect on the phosphorylation of cofilin induced by U46619. In conclusion, our results strongly suggest that Rho-kinase regulates thromboxane A2-induced human platelet activation independently of p38 MAP kinase.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan; Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Iida
authors.affiliation: Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Doi
authors.affiliation: Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan; Department of Clinical Laboratory, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Tokuda
authors.affiliation: Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Matsushima-Nishiwaki
authors.affiliation: Department of Neurosurgery, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Tsujimoto
authors.affiliation: Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan; Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8603, Japan.
authors.forename: Gen
authors.initials: G
authors.lastname: Kuroyanagi
authors.affiliation: Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan; Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8603, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Yamamoto
authors.affiliation: Department of Neurosurgery, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Enomoto
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Tanabe
authors.affiliation: Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8603, Japan.
authors.forename: Takanobu
authors.initials: T
authors.lastname: Otsuka
authors.affiliation: Department of Neurosurgery, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Iwama
authors.affiliation: Department of Emergency and Disaster Medicine, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Ogura
authors.affiliation: Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan. Electronic address: okozawa@gifu-u.ac.jp.
authors.forename: Osamu
authors.initials: O
authors.lastname: Kozawa
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Iida
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D051339:Actin Depolymerizing Factors / Q000378:metabolism; D000577:Amides / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D010766:Phosphorylation; D015539:Platelet Activation / Q000187:drug effects*; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D013928:Thromboxane A2 / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*; D054460:rho-Associated Kinases / Q000378:metabolism*
chemical_list: D051339:Actin Depolymerizing Factors; D000577:Amides; D004791:Enzyme Inhibitors; D007093:Imidazoles; D011725:Pyridines; C108830:Y 27632; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D054460:rho-Associated Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580
keywords: Cofilin; Fasudil; Platelet; U46619; Y27632; p38 MAP kinase