title: Critical role of Src-Syk-PLC{gamma}2 signaling in megakaryocyte migration and thrombopoiesis.
abstract: Migration of megakaryocytes (MKs) from the proliferative osteoblastic niche to the capillary-rich vascular niche is essential for proplatelet formation and platelet release. In this study, we explore the role of surface glycoprotein receptors and signaling proteins in regulating MK migration and platelet recovery after immune-induced thrombocytopenia. We show that spreading and migration of mouse primary bone marrow-derived MKs on a fibronectin matrix are abolished by the Src family kinases inhibitor PP1, the Syk kinase inhibitor R406 and the integrin alphaIIbbeta3 antagonist lotrafiban. We also demonstrate that these responses are inhibited in primary phospholipase C gamma2 (PLCgamma2)-deficient MKs. Conversely, MK spreading and migration were unaltered in the absence of the collagen receptor, the glycoprotein VI-FcRgamma-chain complex. We previously reported a correlation between a defect in MK migration and platelet recovery in the absence of platelet endothelial cell adhesion molecule-1 and the tyrosine phosphatase CD148. This correlation also holds for mice deficient in PLCgamma2. This study identifies a model in which integrin signaling via Src family kinases and Syk kinase to PLCgamma2 is required for MK spreading, migration, and platelet formation.
authors.affiliation: Centre for Cardiovascular Sciences, Institute of Biomedical Research, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, United Kingdom. a.mazharian@bham.ac.uk
authors.forename: Alexandra
authors.initials: A
authors.lastname: Mazharian
authors.forename: Steve G
authors.initials: SG
authors.lastname: Thomas
authors.forename: Tarvinder S
authors.initials: TS
authors.lastname: Dhanjal
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Buckley
authors.forename: Steve P
authors.initials: SP
authors.lastname: Watson
mesh_terms: D000818:Animals; D001569:Benzodiazepines / Q000494:pharmacology; D001792:Blood Platelets / Q000166:cytology*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D048430:Cell Shape; D002478:Cells, Cultured / Q000166:cytology / Q000201:enzymology; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D008533:Megakaryocytes / Q000166:cytology* / Q000201:enzymology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010078:Oxazines / Q000494:pharmacology; D051966:Phospholipase C gamma / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D010880:Piperidines / Q000494:pharmacology; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000037:antagonists & inhibitors / Q000502:physiology*; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000139:chemically induced / Q000473:pathology; D011720:Pyrazoles / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D000072377:Syk Kinase; D034061:Thrombopoiesis / Q000502:physiology*
chemical_list: C108123:4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine; D047908:Intracellular Signaling Peptides and Proteins; C510788:N4-(2,2-dimethyl-3-oxo-4H-pyrid(1,4)oxazin-6-yl)-5-fluoro-N2-(3,4,5-trimethoxyphenyl)-2,4-pyrimidinediamine; D010078:Oxazines; D010880:Piperidines; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D047428:Protein Kinase Inhibitors; D011720:Pyrazoles; D011725:Pyridines; D011743:Pyrimidines; D001569:Benzodiazepines; D011505:Protein-Tyrosine Kinases; D016392:Proto-Oncogene Proteins pp60(c-src); D000072377:Syk Kinase; C000606897:Syk protein, mouse; D051966:Phospholipase C gamma; C412702:lotrafiban