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Thrombin induces apoptotic events through the generation of reactive oxygen species in human platelets
Author(s) -
LOPEZ J. J.,
SALIDO G. M.,
GÓMEZARTETA E.,
ROSADO J. A.,
PARIENTE J. A.
Publication year - 2007
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/j.1538-7836.2007.02505.x
Subject(s) - cytochrome c , apoptosis , thrombin , microbiology and biotechnology , phosphatidylserine , annexin , reactive oxygen species , chemistry , platelet , platelet activation , intrinsic apoptosis , mitochondrion , caspase , biochemistry , biology , programmed cell death , immunology , membrane , phospholipid
Summary. Background: Thrombin is a major physiological platelet agonist that activates a number of cell functions including aggregation. Platelet stimulation with thrombin has been shown to result in the development of apoptotic events, including activation of caspases‐3 and ‐9, cytochrome c release and phosphatidylserine (PS) exposure; however, the mechanism underlying the activation of apoptosis remains unclear. Objectives: In the present study, we aim to investigate whether endogenously generated reactive oxygen species upon thrombin stimulation is required for the activation of apoptosis in human platelets. Methods: Changes in the mitochondrial membrane potential were registered using the dye JC‐1; caspase‐3 and ‐9 activity was determined from the cleavage of their respective specific fluorogenic substrates; PS externalization was estimated using annexin V‐fluorescein isothicyanate and cytochrome c release was detected by Western blotting in samples from the mitochondrial and cytosolic fractions. Results: Treatment of platelets with thrombin stimulates mitochondrial membrane potential depolarization and endogenous generation of H 2 O 2 . Platelet exposure to exogenous H 2 O 2 results in cytochrome c release and activation of caspases‐9. In addition, H 2 O 2 induces the activation of caspase‐3 and PS exposure by a mechanism dependent on cytochrome c release and caspase‐9 activation. Finally, thrombin‐evoked development of apoptotic events was impaired by treatment with catalase. Conclusion: Our results indicate that thrombin‐induced apoptosis is likely mediated by endogenous generation of H 2 O 2 in human platelets.