RATIONALE: Platelets are anuclear cell fragments derived from bone marrow megakaryocytes (MKs) that safeguard vascular integrity but may also cause pathological vessel occlusion. One major pathway of platelet activation is triggered by 2 receptors that signal through an (hem)immunoreceptor tyrosine-based activation motif (ITAM), the activating collagen receptor glycoprotein (GP) VI and the C-type lectin-like receptor 2 (CLEC-2). Growth factor receptor-bound protein 2 (Grb2) is a ubiquitously expressed adapter molecule involved in signaling processes of numerous receptors in different cell types, but its function in platelets and MKs is unknown. OBJECTIVE: We tested the hypothesis that Grb2 is a crucial adapter protein in (hem)immunoreceptor tyrosine-based activation motif signaling in platelets. METHODS AND RESULTS: Here, we show that genetic ablation of Grb2 in MKs and platelets did not interfere with MK differentiation or platelet production. However, Grb2-deficiency severely impaired glycoprotein VI-mediated platelet activation because of defective stabilization of the linker of activated T-cell (LAT) signalosome and activation of downstream signaling proteins that resulted in reduced adhesion, aggregation, and coagulant activity on collagen in vitro. Similarly, CLEC-2-mediated signaling was impaired in Grb2-deficient platelets, whereas the cells responded normally to stimulation of G protein-coupled receptors. In vivo, this selective (hem)immunoreceptor tyrosine-based activation motif signaling defect resulted in prolonged bleeding times but affected arterial thrombus formation only after concomitant treatment with acetylsalicylic acid, indicating that defective glycoprotein VI signaling in the absence of Grb2 can be compensated through thromboxane A2-induced G protein-coupled receptor signaling pathways. CONCLUSIONS: These results reveal an important contribution of Grb2 in (hem)immunoreceptor tyrosine-based activation motif signaling in platelets in hemostasis and thrombosis by stabilizing the LAT signalosome.
RATIONALE: Platelets are anuclear cell fragments derived from bone marrow megakaryocytes (MKs) that safeguard vascular integrity but may also cause pathological vessel occlusion. One major pathway of platelet activation is triggered by 2 receptors that signal through an (hem)immunoreceptor tyrosine-based activation motif (ITAM), the activating collagen receptor glycoprotein (GP) VI and the C-type lectin-like receptor 2 (CLEC-2). Growth factor receptor-bound protein 2 (Grb2) is a ubiquitously expressed adapter molecule involved in signaling processes of numerous receptors in different cell types, but its function in platelets and MKs is unknown. OBJECTIVE: We tested the hypothesis that Grb2 is a crucial adapter protein in (hem)immunoreceptor tyrosine-based activation motif signaling in platelets. METHODS AND RESULTS: Here, we show that genetic ablation of Grb2 in MKs and platelets did not interfere with MK differentiation or platelet production. However, Grb2-deficiency severely impaired glycoprotein VI-mediated platelet activation because of defective stabilization of the linker of activated T-cell (LAT) signalosome and activation of downstream signaling proteins that resulted in reduced adhesion, aggregation, and coagulant activity on collagen in vitro. Similarly, CLEC-2-mediated signaling was impaired in Grb2-deficient platelets, whereas the cells responded normally to stimulation of G protein-coupled receptors. In vivo, this selective (hem)immunoreceptor tyrosine-based activation motif signaling defect resulted in prolonged bleeding times but affected arterial thrombus formation only after concomitant treatment with acetylsalicylic acid, indicating that defective glycoprotein VI signaling in the absence of Grb2 can be compensated through thromboxane A2-induced G protein-coupled receptor signaling pathways. CONCLUSIONS: These results reveal an important contribution of Grb2 in (hem)immunoreceptor tyrosine-based activation motif signaling in platelets in hemostasis and thrombosis by stabilizing the LAT signalosome.
Entities:
Keywords:
blood platelets; hemostasis; mice; signal transduction; thrombosis
Authors: Lorian C Hartgroves; Joseph Lin; Hanno Langen; Tobias Zech; Arthur Weiss; Thomas Harder Journal: J Biol Chem Date: 2003-03-19 Impact factor: 5.157
Authors: Farhad Abtahian; Anastasia Guerriero; Eric Sebzda; Min-Min Lu; Rong Zhou; Attila Mocsai; Erin E Myers; Bin Huang; David G Jackson; Victor A Ferrari; Victor Tybulewicz; Clifford A Lowell; John J Lepore; Gary A Koretzky; Mark L Kahn Journal: Science Date: 2003-01-10 Impact factor: 47.728
Authors: Julia Volz; Charly Kusch; Sarah Beck; Michael Popp; Timo Vögtle; Mara Meub; Inga Scheller; Hannah S Heil; Julia Preu; Michael K Schuhmann; Katherina Hemmen; Thomas Premsler; Albert Sickmann; Katrin G Heinze; David Stegner; Guido Stoll; Attila Braun; Markus Sauer; Bernhard Nieswandt Journal: J Clin Invest Date: 2020-11-02 Impact factor: 14.808
Authors: Shuchi Gupta; Deya Cherpokova; Markus Spindler; Martina Morowski; Markus Bender; Bernhard Nieswandt Journal: Blood Date: 2018-01-02 Impact factor: 25.476
Authors: Sebastian Dütting; Frederique Gaits-Iacovoni; David Stegner; Michael Popp; Adrien Antkowiak; Judith M M van Eeuwijk; Paquita Nurden; Simon Stritt; Tobias Heib; Katja Aurbach; Oguzhan Angay; Deya Cherpokova; Niels Heinz; Ayesha A Baig; Maximilian G Gorelashvili; Frank Gerner; Katrin G Heinze; Jerry Ware; Georg Krohne; Zaverio M Ruggeri; Alan T Nurden; Harald Schulze; Ute Modlich; Irina Pleines; Cord Brakebusch; Bernhard Nieswandt Journal: Nat Commun Date: 2017-06-15 Impact factor: 14.919
Authors: Inga Scheller; Simon Stritt; Sarah Beck; Bing Peng; Irina Pleines; Katrin G Heinze; Attila Braun; Oliver Otto; Robert Ahrends; Albert Sickmann; Markus Bender; Bernhard Nieswandt Journal: Haematologica Date: 2019-10-03 Impact factor: 9.941