title: Small GTPase Rho regulates thrombin-induced platelet aggregation.
abstract: Platelets play essential roles in hemostasis and thrombosis by aggregating with each other. However, the molecular mechanism governing platelet aggregation is not yet fully understood. Here, we established an assay system using platelets permeabilized with streptolysin-O to analyze mechanism of the thrombin-induced aggregation, focusing upon a controversial issue in the field whether small GTPase Rho regulates the aggregation. Incubation of the permeabilized platelets with Rho GDP-dissociation inhibitor, an inhibitory regulator for Rho family GTPases, extracted Rho family proteins extensively from the plasma and intracellular membranes, and inhibited the thrombin-induced aggregation. Incubation of the permeabilized platelets with botulinum exoenzyme C3, which specifically inhibits Rho function by ADP-ribosylating it, abolished the thrombin-induced aggregation. Thus, Rho is involved in thrombin-induced aggregation of platelets.
authors.affiliation: Department of Geriatric Medicine, Graduate School of Medicine, Kyoto, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nishioka
authors.forename: H
authors.initials: H
authors.lastname: Horiuchi
authors.forename: A
authors.initials: A
authors.lastname: Tabuchi
authors.forename: A
authors.initials: A
authors.lastname: Yoshioka
authors.forename: R
authors.initials: R
authors.lastname: Shirakawa
authors.forename: T
authors.initials: T
authors.lastname: Kita
mesh_terms: D036002:ADP Ribose Transferases / Q000494:pharmacology; D000577:Amides / Q000494:pharmacology; D001426:Bacterial Proteins; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D001905:Botulinum Toxins; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000494:pharmacology; D006531:HEPES / Q000494:pharmacology; D006801:Humans; D010974:Platelet Aggregation / Q000187:drug effects / Q000502:physiology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013301:Streptolysins / Q000378:metabolism; D013917:Thrombin / Q000378:metabolism* / Q000494:pharmacology; D013997:Time Factors; D020741:rho GTP-Binding Proteins / Q000502:physiology*; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors
chemical_list: D000577:Amides; D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D020730:Guanine Nucleotide Dissociation Inhibitors; D011725:Pyridines; D013301:Streptolysins; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; C025964:streptolysin O; C108830:Y 27632; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D011065:Poly(ADP-ribose) Polymerases; D005982:Glutathione Transferase; D013917:Thrombin; D001905:Botulinum Toxins; D020741:rho GTP-Binding Proteins; D006531:HEPES