Details

Autor(en) / Beteiligte

• Litvinov, Rustem I.
• Vilaire, Gaston
• Shuman, Henry
• Bennett, Joel S.
• Weisel, John W.

Titel

Quantitative Analysis of Platelet αvβ3 Binding to Osteopontin Using Laser Tweezers

Ist Teil von

• The Journal of biological chemistry, 2003-12, Vol.278 (51), p.51285-51290

Ort / Verlag

Elsevier Inc

Erscheinungsjahr

2003

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• To determine whether platelet adhesion to surfaces coated with the matrix protein osteopontin requires an agonist-induced increase in the affinity of the integrin αvβ3 for this ligand, we used laser tweezers to measure the rupture force between single αvβ3 molecules on the platelet surface and osteopontin-coated beads. Virtually all platelets stimulated with 10 μm ADP bound strongly to osteopontin, producing rupture forces as great as 100 piconewtons (pN) with a peak at 45-50 pN. By contrast, 90% of unstimulated, resting non-reactive platelets bound weakly to osteopontin, with rupture forces rarely exceeding 30-35 pN. However, ≈10% of unstimulated platelets, resting reactive platelets, exhibited rupture force distributions similar to stimulated platelets. Moreover, ADP stimulation resulted in a 12-fold increase in the probability of detecting rupture forces >30 pN compared with resting non-reactive platelets. Pre-incubating stimulated platelets with the inhibitory prostaglandin E1, a cyclic RGD peptide, the monoclonal antibody abciximab, or the αvβ3-specific cyclic peptide XJ735 returned force histograms to those of non-reactive platelets. These experiments demonstrate that ADP stimulation increases the strength of the interaction between platelet αvβ3 and osteopontin. Furthermore, they indicate that platelet adhesion to osteopontin-coated surfaces requires an agonist-induced exposure of αvβ3-binding sites for this ligand.