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Comprehensive Analysis of Procoagulant Platelets Exhibiting Features of Necrosis, Apoptosis and Platelet Activation
Published on: May 23, 2025
Two distinct pathways regulate platelet phosphatidylserine exposure and procoagulant function
Simone M Schoenwaelder1, Yuping Yuan, Emma C Josefsson
1Australian Centre for Blood Diseases, Monash University, 89 Commercial Road, Melbourne, Victoria 3004, Australia.
Blood
|April 24, 2009
Summary
Platelets have two distinct pathways regulating their procoagulant function. Apoptosis induction via ABT-737 activates a Bak/Bax- and caspase-dependent pathway, while platelet activation uses a calcium-dependent pathway.
Area of Science:
- Hematology
- Cell Biology
- Biochemistry
Background:
- Procoagulant platelets share features with apoptotic cells, such as phosphatidylserine (PS) exposure.
- The role of apoptosis regulators in platelet procoagulant function remains largely unknown.
Purpose of the Study:
- To investigate the distinct pathways regulating platelet procoagulant function.
- To determine the role of Bak, Bax, and caspases in apoptosis-induced procoagulant activity.
- To compare apoptosis-mediated procoagulant function with activation-induced procoagulant function.
Main Methods:
- Platelets were treated with the BH3 mimetic ABT-737 to induce apoptosis.
- The role of Bak and Bax was assessed using knockout platelets (Bak(-/-)Bax(-/-)).
- Caspase activity was inhibited, and platelet activation inhibitors and calcium chelators were used.
Main Results:
- ABT-737 treatment induced PS exposure and increased thrombin generation in a Bak/Bax- and caspase-dependent manner.
- This apoptosis-induced procoagulant function was independent of platelet activation pathways and extracellular calcium.
- Agonist-induced procoagulant function was unaffected by Bak/Bax deficiency or caspase inhibition but was abolished by calcium chelation and activation inhibitors.
Conclusions:
- Two distinct pathways regulate platelet procoagulant function: one linked to apoptosis (Bak/Bax/caspase-dependent) and another to platelet activation (calcium/activation-dependent).
- Understanding these pathways is crucial for comprehending hemostasis and thrombosis.
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