The PlA2 polymorphism of integrin β3 enhances outside-in signaling and adhesive functions
K. Vinod Vijayan, … , Christine Roos, Paul F. Bray
K. Vinod Vijayan, … , Christine Roos, Paul F. Bray
Published March 15, 2000
Citation Information: J Clin Invest. 2000;105(6):793-802. https://doi.org/10.1172/JCI6982.
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Article

The PlA2 polymorphism of integrin β3 enhances outside-in signaling and adhesive functions

Abstract

Genetic factors are believed to influence the development of arterial thromboses. Because integrin αIIbβ3 plays a crucial role in thrombus formation, we analyzed receptor adhesive properties using Chinese hamster ovary and human kidney embryonal 293 cells overexpressing the PlA1 or PlA2 polymorphic forms of αIIbβ3. Soluble fibrinogen binding was no different between PlA1 and PlA2 cells, either in a resting state or when αIIbβ3 was activated with anti-LIBS6. PlA1 and PlA2 cells bound equivalently to immobilized fibronectin. In contrast, significantly more PlA2 cells bound to immobilized fibrinogen in an αIIbβ3-dependent manner than did PlA1 cells. Disruption of the actin cytoskeleton by cytochalasin D abolished the increased binding of PlA2 cells. Compared with PlA1 cells, PlA2 cells exhibited a greater extent of polymerized actin and cell spreading, enhanced tyrosine phosphorylation of pp125FAK, and greater fibrin clot retraction. These adhesion differences appear to depend on a signaling mechanism sensitive to receptor occupancy. Thus, the PlA2 polymorphism altered integrin-mediated functions of adhesion, spreading, actin cytoskeleton rearrangement, and clot retraction.

Authors

K. Vinod Vijayan, Pascal J. Goldschmidt-Clermont, Christine Roos, Paul F. Bray

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Figure 1

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Characterization of stable αIIbβ3–expressing CHO cell lines. (a) Flow cy...
Characterization of stable αIIbβ3–expressing CHO cell lines. (a) Flow cytometric analysis. LK444, A1, and A2 cell lines were labeled with 3 μg/mL isotype-matched control IgG (upper panel), 3 μg/mL αIIbβ3 complex–specific mAb P2 (middle panel), or 2 μg/mL SZ21 mAb that distinguishes PlA1 from PlA2 (lower panel). LK444, solid line; A1, heavy dotted line; A2, fine dotted line. (b) Western immunoblotting. Fifteen micrograms of CHO cell lysates or 2 μg of platelet lysates were separated by nonreduced SDS-PAGE, transferred to nitrocellulose, and probed with either 132.1 (αIIb-specific) or AP3 (β3-specific) mAbs.