title: GPVI and alpha2beta1 play independent critical roles during platelet adhesion and aggregate formation to collagen under flow.
abstract: The roles of the 2 major platelet-collagen receptors, glycoprotein VI (GPVI) and integrin alpha2beta1, have been intensely investigated using a variety of methods over the past decade. In the present study, we have used pharmacologic and genetic approaches to study human and mouse platelet adhesion to collagen under flow conditions. Our studies demonstrate that both GPVI and integrin alpha2beta1 play significant roles for platelet adhesion to collagen under flow and that the loss of both receptors completely ablates this response. Intracellular signaling mediated by the cytoplasmic adaptor Src homology 2 domain-containing leukocyte protein of 76 kDa (SLP-76) but not by the transmembrane adaptor linker for activation of T cells (LAT) is critical for platelet adhesion to collagen under flow. In addition, reduced GPVI receptor density results in severe defects in platelet adhesion to collagen under flow. Defective adhesion to collagen under flow is associated with prolonged tail-bleeding times in mice lacking one or both collagen receptors. These studies establish platelet-collagen responses under physiologic flow as the consequence of a close partnership between 2 structurally distinct receptors and suggest that both receptors play significant hemostatic roles in vivo.
authors.affiliation: Department of Bioengineering, Division of Cardiology, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Kendra L
authors.initials: KL
authors.lastname: Sarratt
authors.forename: Hong
authors.initials: H
authors.lastname: Chen
authors.forename: Mary M
authors.initials: MM
authors.lastname: Zutter
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Santoro
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Hammer
authors.forename: Mark L
authors.initials: ML
authors.lastname: Kahn
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology; D000818:Animals; D001777:Blood Coagulation; D003094:Collagen / Q000494:pharmacology*; D006801:Humans; D038982:Integrin alpha2beta1 / Q000172:deficiency / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D010477:Perfusion; D010750:Phosphoproteins / Q000502:physiology; D010973:Platelet Adhesiveness / Q000187:drug effects; D010974:Platelet Aggregation / Q000187:drug effects; D010980:Platelet Membrane Glycoproteins / Q000172:deficiency / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D038982:Integrin alpha2beta1; C491734:Lat protein, mouse; D008565:Membrane Proteins; D010750:Phosphoproteins; D010980:Platelet Membrane Glycoproteins; C092947:SLP-76 signal Transducing adaptor proteins; C098341:platelet membrane glycoprotein VI; D003094:Collagen