The PlA2 polymorphism of integrin β3 enhances outside-in signaling and adhesive functions
K. Vinod Vijayan, Pascal J. Goldschmidt-Clermont, Christine Roos, Paul F. Bray
K. Vinod Vijayan, Pascal J. Goldschmidt-Clermont, Christine Roos, Paul F. Bray
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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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Effect of cytochalasin D on CHO cell adhesion. Cells were treated with e...
Effect of cytochalasin D on CHO cell adhesion. Cells were treated with either DMSO or 10 μg/mL of cytochalasin D for 30 minutes, washed twice, and adhesion assays performed as above. (a) Adhesion for 5 minutes to different concentrations of fibrinogen. *P ≤ 0.008 for A1 vs. A2; †P > 0.46 for A1 vs. A2; #P < 0.03 for A1 (DMSO vs. cyto-D), and P < 0.001 for A2 (DMSO vs. cyto-D). The results are expressed as ± SEM of 6 observations. (b) Adhesion to 12.5 μg/mL fibrinogen for different time points. *P ≤ 0.007 for A1 vs. A2; †P ≤ 0.08 for A1 vs. A2; #P ≤ 0.0008 for A1 and A2 (DMSO vs. cyto-D at 5 minutes), and P > 0.19 for A1 (DMSO vs. cyto-D at 10 and 15 minutes), and P = 0.06 for A2 (DMSO vs. cyto-D at 10 and 15 minutes). (c) Mean fluorescence intensity of P2 binding to the 3 CHO cell lines. Error bars are too narrow to be seen.