Abstract
The role of the chemokine binding stromal-derived factor 1 (SDF-1) in normal human megakaryopoiesis at the cellular and molecular levels and its comparison with that of thrombopoietin (TPO) have not been determined. In this study it was found that SDF-1, unlike TPO, does not stimulate alpha(IIb)beta(3)(+) cell proliferation or differentiation or have an antiapoptotic effect. However, it does induce chemotaxis, trans-Matrigel migration, and secretion of matrix metalloproteinase 9 (MMP-9) and vascular endothelial growth factor (VEGF) by these cells, and both SDF-1 and TPO increase the adhesion of alpha(IIb)beta(3)(+) cells to fibrinogen and vitronectin. Investigating the intracellular signaling pathways induced by SDF-1 and TPO revealed some overlapping patterns of protein phosphorylation/activation (mitogen-activated protein kinase [MAPK] p42/44, MAPK p38, and AKT [protein kinase B]) and some that were distinct for TPO (eg, JAK-STAT) and for SDF-1 (eg, NF-kappa B). It was also found that though inhibition of phosphatidyl-inositol 3-kinase (PI-3K) by LY294002 in alpha(IIb)beta(3)(+) cells induced apoptosis and inhibited chemotaxis adhesion and the secretion of MMP-9 and VEGF, the inhibition of MAPK p42/44 (by the MEK inhibitor U0126) had no effect on the survival, proliferation, and migration of these cells. Hence, it is suggested that the proliferative effect of TPO is more related to activation of the JAK-STAT pathway (unique to TPO), and the PI-3K-AKT axis is differentially involved in TPO- and SDF-1-dependent signaling. Accordingly, PI-3K is involved in TPO-mediated inhibition of apoptosis, TPO- and SDF-1-regulated adhesion to fibrinogen and vitronectin, and SDF-1-mediated migration. This study expands the understanding of the role of SDF-1 and TPO in normal human megakaryopoiesis and indicates the molecular basis of the observed differences in cellular responses. (Blood. 2000;96:4142-4151)
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adult
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Apoptosis / drug effects
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Blood Platelets / drug effects
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Blood Platelets / metabolism
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Calcium / metabolism
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Calcium Signaling / drug effects
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Caspase 3
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Caspases / metabolism
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Cell Adhesion / drug effects
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Cell Cycle / drug effects
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Chemokine CXCL12
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Chemokines, CXC / pharmacology
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Chemokines, CXC / physiology*
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Chemotaxis / drug effects
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Chromones / pharmacology
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Collagen
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Drug Combinations
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Endothelial Growth Factors / biosynthesis
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Endothelial Growth Factors / genetics
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Enzyme Activation / drug effects
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Enzyme Inhibitors / pharmacology
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Fibrinogen / metabolism
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Gene Expression Regulation / drug effects
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Humans
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Ion Transport / drug effects
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Laminin
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Lymphokines / biosynthesis
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Lymphokines / genetics
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MAP Kinase Signaling System / drug effects
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Megakaryocytes / cytology*
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Megakaryocytes / drug effects
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Metalloendopeptidases / biosynthesis
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Metalloendopeptidases / genetics
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Morpholines / pharmacology
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Phosphoinositide-3 Kinase Inhibitors
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Phosphorylation / drug effects
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Platelet Glycoprotein GPIIb-IIIa Complex / physiology
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Poly(ADP-ribose) Polymerases / metabolism
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Protein Kinases / metabolism
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Protein Processing, Post-Translational / drug effects
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Proteoglycans
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Recombinant Proteins / pharmacology
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Thrombopoietin / pharmacology
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Thrombopoietin / physiology*
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Transcription Factors / metabolism
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Vascular Endothelial Growth Factor A
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Vascular Endothelial Growth Factors
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Vitronectin / metabolism
Substances
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CXCL12 protein, human
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Chemokine CXCL12
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Chemokines, CXC
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Chromones
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Drug Combinations
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Endothelial Growth Factors
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Enzyme Inhibitors
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Laminin
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Lymphokines
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Morpholines
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Phosphoinositide-3 Kinase Inhibitors
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Platelet Glycoprotein GPIIb-IIIa Complex
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Proteoglycans
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Recombinant Proteins
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Transcription Factors
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Vascular Endothelial Growth Factor A
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Vascular Endothelial Growth Factors
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Vitronectin
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matrigel
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2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
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Fibrinogen
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Collagen
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Thrombopoietin
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Poly(ADP-ribose) Polymerases
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Protein Kinases
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CASP3 protein, human
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Caspase 3
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Caspases
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Metalloendopeptidases
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Calcium