Abstract
Several receptor tyrosine kinases require heparan sulfate proteoglycans (HSPGs) as coreceptors for efficient signal transduction. We have studied the role of HSPGs in the development of blood capillary structures from embryonic stem cells, a process strictly dependent on signaling via vascular endothelial growth factor receptor-2 (VEGFR-2). We show, by using chimeric cultures of embryonic stem cells defective in either HS production or VEGFR-2 synthesis, that VEGF signaling in endothelial cells is fully supported by HS expressed in trans by adjacent perivascular smooth muscle cells. Transactivation of VEGFR-2 leads to prolonged and enhanced signal transduction due to HS-dependent trapping of the active VEGFR-2 signaling complex. Our data imply that direct signaling via HSPG core proteins is dispensable for a functional VEGF response in endothelial cells. We propose that transactivation of tyrosine kinase receptors by HSPGs constitutes a mechanism for crosstalk between adjacent cells.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amidohydrolases / deficiency
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Animals
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Cells, Cultured
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Chimera / genetics
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Collagen / chemistry
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Endothelial Cells / cytology
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Endothelial Cells / drug effects
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Gels / chemistry
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Genes, Developmental / genetics
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Heparin / pharmacology
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Heparitin Sulfate / pharmacology*
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Mice
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Models, Genetic
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Neovascularization, Physiologic / drug effects*
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Pericytes / metabolism
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Signal Transduction
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Solubility
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Stem Cells / cytology
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Sulfotransferases / deficiency
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Transcriptional Activation / genetics*
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Vascular Endothelial Growth Factor A / pharmacology
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Vascular Endothelial Growth Factor Receptor-2 / deficiency
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Vascular Endothelial Growth Factor Receptor-2 / metabolism*
Substances
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Gels
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RNA, Messenger
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Vascular Endothelial Growth Factor A
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Heparin
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Collagen
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Heparitin Sulfate
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Vascular Endothelial Growth Factor Receptor-2
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Ndst2 protein, mouse
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Sulfotransferases
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heparitin sulfotransferase
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Amidohydrolases