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alpha IIb beta 3 redistribution triggered by receptor cross-linking
S R Simmons1, P A Sims, R M Albrecht
1Department of Animal Health and Biomedical Sciences, University of Wisconsin, Madison 53706, USA.
Arteriosclerosis, Thrombosis, and Vascular Biology
|December 31, 1997
Summary
Platelet receptor cross-linking, not just ligand binding, initiates fibrinogen redistribution. This movement of fibrinogen/integrin complexes is crucial for platelet function.
Area of Science:
- Biochemistry
- Cell Biology
- Hematology
Background:
- Platelets play a critical role in hemostasis and thrombosis.
- Integrin alpha IIb beta 3 is a key receptor involved in platelet aggregation.
- Fibrinogen binding to alpha IIb beta 3 triggers important cellular responses.
Purpose of the Study:
- To investigate the mechanisms initiating fibrinogen/integrin redistribution on platelets.
- To differentiate the roles of ligand occupancy versus receptor cross-linking in triggering this movement.
Main Methods:
- Utilized gold-conjugated fibrinogen and monoclonal antibodies targeting alpha IIb beta 3.
- Employed monovalent fibrinogen fragments (RGDS, HHLGGAKQAGDV) to assess ligand binding.
- Investigated receptor cross-linking using polyclonal anti-mouse IgG and antibody conjugation to gold particles.
Main Results:
- Monovalent fibrinogen fragments did not induce receptor redistribution.
- Binding of monoclonal antibodies alone did not trigger movement.
- Cross-linking of bound antibodies or fibrinogen initiated redistribution, mimicking fibrinogen's effect.
Conclusions:
- Receptor cross-linking, rather than simple ligand occupancy, is the primary signal for fibrinogen/alpha IIb beta 3 complex redistribution.
- This finding clarifies the initial events in integrin-mediated platelet responses.