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Tetraspanin CD9 is required for microparticle release from coated-platelets
George L Dale1, Gyula Remenyi, Paul Friese
1Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma, OK 73104, USA. george-dale@ouhsc.edu
Platelets
|August 7, 2009
Summary
The tetraspanin CD9 protein is essential for releasing microparticles from activated platelets. Blocking CD9 significantly inhibits this microparticle release process.
Area of Science:
- Biochemistry
- Cell Biology
- Hematology
Background:
- CD9 is a tetraspanin superfamily protein abundant on platelet surfaces.
- The precise function of CD9 in platelet biology is largely unknown.
- Platelets release microparticles upon activation, a process with implications in various physiological and pathological conditions.
Purpose of the Study:
- To investigate the role of CD9 in the release of microparticles from activated platelets.
- To determine if CD9 influences the membrane vesiculation process during platelet activation.
Main Methods:
- Utilized dual agonist activation (collagen and thrombin) to form coated-platelets.
- Assessed microparticle release using monoclonal antibodies targeting CD9 and integrin alpha(IIb)beta(3).
- Quantified the inhibition of microparticle release and determined IC(50) values for specific antibodies.
Main Results:
- CD9 was found to be required for microparticle release from coated-platelets.
- Four distinct anti-CD9 monoclonal antibodies inhibited microparticle release by 72-102%.
- The anti-alpha(IIb)beta(3) antibody AP2 also inhibited release, suggesting a cooperative role with CD9.
Conclusions:
- CD9 plays a critical role in the membrane vesiculation and microparticle release from activated platelets.
- The integrin alpha(IIb)beta(3) may also participate in this process, potentially in conjunction with CD9.
- These findings elucidate a novel function for CD9 in platelet biology and microparticle formation.
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