Roles of SLP-76, phosphoinositide 3-kinase, and gelsolin in the platelet shape changes initiated by the collagen receptor GPVI/FcR gamma-chain complex

How platelet shape change initiated by a collagen-related peptide (CRP) spe cific for the GPVI/FcR gamma -chain complex (GPVI/FcR gamma -chain) is coup led to SLP-76, phosphoinositide (PI) 3-kinase, and gelsolin is reported. As shown by video microscopy, platelets rapidly round and grow dynamic filopo dial projections that rotate around the periphery of the cell after they co ntact a CRP-coated surface. Lamellae subsequently spread between the projec tions. All the actin-driven shape changes require SLP-76 expression. SLP-76 is essential for the Ca++ mobilization induced by CRP, whereas PI 3-kinase only modulates it, The extension of lamellae requires net actin assembly a nd an exposure of actin filament barbed ends downstream of PI 3-kinase, Gel solin expression is also required for the extension of lamellae, but not fo r the formation of filopodia, Altogether, the data describe the role of SLP -76 in the platelet activation initiated by GPVI/FcR gamma -chain and the r oles of PI 3-kinase and gelsolin in lamellae spreading. (C) 2000 by The Ame rican Society of Hematology.