title: Thymidine phosphorylase participates in platelet signaling and promotes thrombosis.
abstract: BACKGROUND
  Platelets contain abundant thymidine phosphorylase (TYMP), which is highly expressed in diseases with high risk of thrombosis, such as atherosclerosis and type II diabetes mellitus.
  
  
  OBJECTIVE
  To test the hypothesis that TYMP participates in platelet signaling and promotes thrombosis.
  
  
  RESULTS
  By using a ferric chloride (FeCl3)-induced carotid artery injury thrombosis model, we found time to blood flow cessation was significantly prolonged in Tymp(-/-) and Tymp(+/-) mice compared with wild-type mice. Bone marrow transplantation and platelet transfusion studies demonstrated that platelet TYMP was responsible for the antithrombotic phenomenon in the TYMP-deficient mice. Collagen-, collagen-related peptide-, adenosine diphosphate-, or thrombin-induced platelet aggregation were significantly attenuated in Tymp(+/-) and Tymp(-/-) platelets, and in wild type or human platelets pretreated with TYMP inhibitor KIN59. Tymp deficiency also significantly decreased agonist-induced P-selectin expression. TYMP contains an N-terminal SH3 domain-binding proline-rich motif and forms a complex with the tyrosine kinases Lyn, Fyn, and Yes in platelets. TYMP-associated Lyn was inactive in resting platelets, and TYMP trapped and diminished active Lyn after collagen stimulation. Tymp/Lyn double haploinsufficiency diminished the antithrombotic phenotype of Tymp(+/-) mice. TYMP deletion or inhibition of TYMP with KIN59 dramatically increased platelet-endothelial cell adhesion molecule 1 tyrosine phosphorylation and diminished collagen-related peptide- or collagen-induced AKT phosphorylation. In vivo administration of KIN59 significantly inhibited FeCl3-induced carotid artery thrombosis without affecting hemostasis.
  
  
  CONCLUSIONS
  TYMP participates in multiple platelet signaling pathways and regulates platelet activation and thrombosis. Targeting TYMP might be a novel antiplatelet and antithrombosis therapy.
authors.affiliation: From the Department of Cellular and Molecular Medicine, Lerner Research Institute, The Cleveland Clinic, OH (W.L., T.M.M.); Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, OH (W.L., T.M.M.); Instituto de Quimica Medica, Consejo Superior De Investigaciones Cientificas (IQM-CSIC), Madrid, Spain (A.G.,M.-J.P.-P.); Department of Biological Sciences, Case Western Reserve University, Cleveland, OH (H.Y.); Department of Neurology, Columbia University Medical Center, New York, NY (M.H.); and Department of Medicine, Medical College of Wisconsin and Blood Research Institute, Blood Center of Wisconsin, Milwaukee (R.L.S.) liw4@ccf.org.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: From the Department of Cellular and Molecular Medicine, Lerner Research Institute, The Cleveland Clinic, OH (W.L., T.M.M.); Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, OH (W.L., T.M.M.); Instituto de Quimica Medica, Consejo Superior De Investigaciones Cientificas (IQM-CSIC), Madrid, Spain (A.G.,M.-J.P.-P.); Department of Biological Sciences, Case Western Reserve University, Cleveland, OH (H.Y.); Department of Neurology, Columbia University Medical Center, New York, NY (M.H.); and Department of Medicine, Medical College of Wisconsin and Blood Research Institute, Blood Center of Wisconsin, Milwaukee (R.L.S.).
authors.forename: Alba
authors.initials: A
authors.lastname: Gigante
authors.affiliation: From the Department of Cellular and Molecular Medicine, Lerner Research Institute, The Cleveland Clinic, OH (W.L., T.M.M.); Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, OH (W.L., T.M.M.); Instituto de Quimica Medica, Consejo Superior De Investigaciones Cientificas (IQM-CSIC), Madrid, Spain (A.G.,M.-J.P.-P.); Department of Biological Sciences, Case Western Reserve University, Cleveland, OH (H.Y.); Department of Neurology, Columbia University Medical Center, New York, NY (M.H.); and Department of Medicine, Medical College of Wisconsin and Blood Research Institute, Blood Center of Wisconsin, Milwaukee (R.L.S.).
authors.forename: Maria-Jesus
authors.initials: MJ
authors.lastname: Perez-Perez
authors.affiliation: From the Department of Cellular and Molecular Medicine, Lerner Research Institute, The Cleveland Clinic, OH (W.L., T.M.M.); Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, OH (W.L., T.M.M.); Instituto de Quimica Medica, Consejo Superior De Investigaciones Cientificas (IQM-CSIC), Madrid, Spain (A.G.,M.-J.P.-P.); Department of Biological Sciences, Case Western Reserve University, Cleveland, OH (H.Y.); Department of Neurology, Columbia University Medical Center, New York, NY (M.H.); and Department of Medicine, Medical College of Wisconsin and Blood Research Institute, Blood Center of Wisconsin, Milwaukee (R.L.S.).
authors.forename: Hong
authors.initials: H
authors.lastname: Yue
authors.affiliation: From the Department of Cellular and Molecular Medicine, Lerner Research Institute, The Cleveland Clinic, OH (W.L., T.M.M.); Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, OH (W.L., T.M.M.); Instituto de Quimica Medica, Consejo Superior De Investigaciones Cientificas (IQM-CSIC), Madrid, Spain (A.G.,M.-J.P.-P.); Department of Biological Sciences, Case Western Reserve University, Cleveland, OH (H.Y.); Department of Neurology, Columbia University Medical Center, New York, NY (M.H.); and Department of Medicine, Medical College of Wisconsin and Blood Research Institute, Blood Center of Wisconsin, Milwaukee (R.L.S.).
authors.forename: Michio
authors.initials: M
authors.lastname: Hirano
authors.affiliation: From the Department of Cellular and Molecular Medicine, Lerner Research Institute, The Cleveland Clinic, OH (W.L., T.M.M.); Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, OH (W.L., T.M.M.); Instituto de Quimica Medica, Consejo Superior De Investigaciones Cientificas (IQM-CSIC), Madrid, Spain (A.G.,M.-J.P.-P.); Department of Biological Sciences, Case Western Reserve University, Cleveland, OH (H.Y.); Department of Neurology, Columbia University Medical Center, New York, NY (M.H.); and Department of Medicine, Medical College of Wisconsin and Blood Research Institute, Blood Center of Wisconsin, Milwaukee (R.L.S.).
authors.forename: Thomas M
authors.initials: TM
authors.lastname: McIntyre
authors.affiliation: From the Department of Cellular and Molecular Medicine, Lerner Research Institute, The Cleveland Clinic, OH (W.L., T.M.M.); Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, OH (W.L., T.M.M.); Instituto de Quimica Medica, Consejo Superior De Investigaciones Cientificas (IQM-CSIC), Madrid, Spain (A.G.,M.-J.P.-P.); Department of Biological Sciences, Case Western Reserve University, Cleveland, OH (H.Y.); Department of Neurology, Columbia University Medical Center, New York, NY (M.H.); and Department of Medicine, Medical College of Wisconsin and Blood Research Institute, Blood Center of Wisconsin, Milwaukee (R.L.S.).
authors.forename: Roy L
authors.initials: RL
authors.lastname: Silverstein
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology*; D016026:Bone Marrow Transplantation; D002712:Chlorides; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005290:Ferric Compounds; D057895:Haploinsufficiency; D006801:Humans; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D010641:Phenotype; D010766:Phosphorylation; D010974:Platelet Aggregation; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D017713:Platelet Transfusion; D051057:Proto-Oncogene Proteins c-akt / Q000097:blood; D051076:Proto-Oncogene Proteins c-fyn / Q000097:blood / Q000235:genetics; D051575:Proto-Oncogene Proteins c-yes / Q000097:blood; D051149:Selenoprotein P / Q000097:blood; D015398:Signal Transduction / Q000187:drug effects; D013927:Thrombosis / Q000097:blood / Q000139:chemically induced / Q000201:enzymology* / Q000517:prevention & control; D013939:Thymidine Phosphorylase / Q000037:antagonists & inhibitors / Q000097:blood / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D019061:src-Family Kinases / Q000097:blood / Q000235:genetics
chemical_list: D002712:Chlorides; D004791:Enzyme Inhibitors; D005290:Ferric Compounds; D010975:Platelet Aggregation Inhibitors; D051149:Selenoprotein P; C543750:TYMP protein, human; D013939:Thymidine Phosphorylase; C543751:Tymp protein, mouse; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D051575:Proto-Oncogene Proteins c-yes; C496639:Yes1 protein, mouse; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt; C024555:ferric chloride
keywords: intracellular signaling; platelet; thrombosis; thymidine phosphorylase