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Thrombin increases expression of fibronectin antigen on the platelet surface
Summary
Fibronectins (fn) are crucial for cell adhesion. Thrombin stimulation increases fn antigen on platelet surfaces, enhancing their adhesive properties and potential interactions with fibrin and connective tissues.
Area of Science:
- Biochemistry
- Cell Biology
- Hematology
Background:
- Fibronectins (fn) are adhesive glycoproteins mediating cell adhesion.
- Fn-related antigen is found in human platelets, suggesting a role in platelet adhesion.
Purpose of the Study:
- To investigate the localization of fibronectin (fn) in resting and thrombin-stimulated human platelets.
- To determine the effect of thrombin stimulation on fn expression on the platelet surface.
Main Methods:
- Immunofluorescence staining of fn in resting and stimulated platelets.
- Quantitative binding assays using radiolabeled anti-fn antibodies.
- Assessment of platelet membrane integrity using 51Cr release and F-actin staining.
Main Results:
- Resting platelets show intracellular fn staining upon permeabilization.
- Thrombin stimulation significantly increases fn antigen accessibility on the intact platelet surface.
- Quantitative binding confirmed a 15-fold increase in radiolabeled antibody binding to stimulated platelets.
Conclusions:
- Thrombin stimulation leads to increased expression of fibronectin (fn) antigen on the platelet surface.
- This enhanced surface fn may play a role in platelet interactions with fibrin and connective tissues.
- Fibronectin's role in platelet adhesion is modulated by activation state.