title: Hyperglycemia potentiates collagen-induced platelet activation through mitochondrial superoxide overproduction.
abstract: Alteration of platelet function contributes to microthrombus formation and may play an important role in the pathogenesis of diabetic micro- and macroangiopathies. However, the molecular mechanism for platelet dysfunction observed in patients with diabetes has not been fully elucidated. In this study, the direct effects of hyperglycemia on platelet function in vitro were investigated. Hyperglycemia increased reactive oxygen species generation in human platelets, and this effect was additive with that of collagen. Thenoyltrifluoroacetone (TTFA), an inhibitor of mitochondrial electron transport chain complex II, and carbonyl cyanide m-chlorophenylhydrazone (CCCP), an uncoupler of oxidative phosphorylation, completely prevented the effects of hyperglycemia, suggesting that reactive oxygen species arise from the mitochondrial electron transport chain. Hyperglycemia potentiated both platelet aggregation and the subsequent release of platelet-derived growth factor AB induced by a nonaggregating subthreshold concentration of collagen, which were also completely inhibited by TTFA or CCCP. Furthermore, hyperglycemia was found to inhibit protein tyrosine phosphatase (PTP) activity and increase phosphorylation of the tyrosine kinase Syk in platelets exposed to collagen. Hyperglycemia-induced PTP inhibition and Syk phosphorylation were found to be completely prevented by TTFA, CCCP, or Mn(III)tetrakis (4-benzoic acid) porphyrin, a stable cell-permeable superoxide dismutase mimetic. These results suggest that hyperglycemia-induced mitochondrial superoxide generation may play an important role in platelet dysfunction observed in patients with diabetes.
authors.affiliation: Department of Medicine, Diabetes Research Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
authors.forename: S I
authors.initials: SI
authors.lastname: Yamagishi
authors.forename: D
authors.initials: D
authors.lastname: Edelstein
authors.forename: X L
authors.initials: XL
authors.lastname: Du
authors.forename: M
authors.initials: M
authors.lastname: Brownlee
mesh_terms: D001792:Blood Platelets / Q000378:metabolism; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D003094:Collagen / Q000494:pharmacology*; D004792:Enzyme Precursors / Q000097:blood; D006801:Humans; D006943:Hyperglycemia / Q000097:blood / Q000503:physiopathology*; D007425:Intracellular Membranes / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008928:Mitochondria / Q000378:metabolism*; D010085:Oxidative Phosphorylation / Q000187:drug effects; D015539:Platelet Activation / Q000187:drug effects*; D010974:Platelet Aggregation; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000097:blood; D011505:Protein-Tyrosine Kinases / Q000097:blood; D017382:Reactive Oxygen Species / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D000072377:Syk Kinase; D013804:Thenoyltrifluoroacetone / Q000494:pharmacology
chemical_list: D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D010982:Platelet-Derived Growth Factor; D017382:Reactive Oxygen Species; C095477:platelet-derived growth factor AB; D013481:Superoxides; D013804:Thenoyltrifluoroacetone; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D003094:Collagen; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; D017027:Protein Tyrosine Phosphatases