Syndecan 4 Regulates FGFR1 Signaling in Endothelial Cells by Directing Macropinocytosis

Macropinocytosis controls the kinetics of endothelial signaling initiated by a fibroblast growth factor receptor. Limiting the Signal Through Macropinocytosis Fibroblast growth factor 2 (FGF2) triggers migration and proliferation of endothelial cells by binding to fibroblast growth factor receptor 1 (FGFR1) and the co-receptor syndecan 4 (S4). Activation of FGFR1 initiates signaling through mitogen-activated protein kinases (MAPKs). Elfenbein et al. found that S4 decreased the internalization of FGFR1 through a process called macropinocytosis. Furthermore, S4-mediated macropinocytosis of FGFR1 decreased the amplitude and increased the deactivation kinetics of MAPK signaling. Thus, these results indicate that S4 controls the duration of MAPK activation in response to binding of FGF2 to FGFR1. Fibroblast growth factor 2 (FGF2) induces endothelial cell migration and angiogenesis through two classes of receptors: receptor tyrosine kinases, such as FGF receptor 1 (FGFR1), and heparan sulfate proteoglycans, such as syndecan 4 (S4). We examined the distinct contributions of FGFR1 and S4 in shaping the endothelial response to FGF2. S4 determined the kinetics and magnitude of FGF2-induced mitogen-activated protein kinase (MAPK) signaling by promoting the macropinocytosis of the FGFR1-S4-FGF2 signaling complex. Internalization of the S4 receptor complex was independent of clathrin and dynamin, proceeded from lipid raft–enriched membranes, and required activation of the guanosine triphosphatases RhoG and Rab5. Genetic knockout of S4, disruption of S4 function, or inhibition of Rab5 led to increased endocytosis and MAPK signaling. These data define the mechanism by which FGFR1 and S4 coordinate downstream signaling upon FGF2 stimulation: FGFR1 initiates MAPK signaling, whereas S4-dependent FGFR1 macropinocytosis modulates the kinetics of MAPK activation. Our studies identify S4 as a regulator of MAPK signaling and address the question of how distinct classes of FGFRs individually contribute to signal transduction in endothelial cells.

[1]  Kazuhiro Aoki,et al.  Development of an optimized backbone of FRET biosensors for kinases and GTPases , 2011, Molecular biology of the cell.

[2]  Paul Martin,et al.  A Syndecan-4 Hair Trigger Initiates Wound Healing through Caveolin- and RhoG-Regulated Integrin Endocytosis , 2011, Developmental cell.

[3]  B. Hausott,et al.  Inhibition of fibroblast growth factor receptor 1 endocytosis promotes axonal branching of adult sensory neurons , 2011, Neuroscience.

[4]  Y. Matsui,et al.  Syndecan-4 Prevents Cardiac Rupture and Dysfunction After Myocardial Infarction , 2011, Circulation research.

[5]  Steve Jean,et al.  Extended-synaptotagmin-2 mediates FGF receptor endocytosis and ERK activation in vivo. , 2010, Developmental cell.

[6]  P. Carmeliet,et al.  VEGF receptor 2 endocytic trafficking regulates arterial morphogenesis. , 2010, Developmental cell.

[7]  K. Hahn,et al.  Amiloride inhibits macropinocytosis by lowering submembranous pH and preventing Rac1 and Cdc42 signaling , 2010, The Journal of cell biology.

[8]  I. Madshus,et al.  Internalization and intracellular sorting of the EGF receptor: a model for understanding the mechanisms of receptor trafficking , 2009, Journal of Cell Science.

[9]  Michiyuki Matsuda,et al.  Suppression of RhoG activity is mediated by a syndecan 4–synectin–RhoGDI1 complex and is reversed by PKCα in a Rac1 activation pathway , 2009, The Journal of cell biology.

[10]  J. Dennis,et al.  Lattices, rafts, and scaffolds: domain regulation of receptor signaling at the plasma membrane , 2009, The Journal of cell biology.

[11]  Mark R Morgan,et al.  Syndecans Shed Their Reputation as Inert Molecules , 2009, Science Signaling.

[12]  Gordon B. Mills,et al.  Derailed endocytosis: an emerging feature of cancer , 2008, Nature Reviews Cancer.

[13]  M. Simons,et al.  Syndecan-4 regulates subcellular localization of mTOR Complex2 and Akt activation in a PKCalpha-dependent manner in endothelial cells. , 2008, Molecular cell.

[14]  P. Carmeliet,et al.  The FGF system has a key role in regulating vascular integrity. , 2008, The Journal of clinical investigation.

[15]  J. Wesche,et al.  Ubiquitination of fibroblast growth factor receptor 1 is required for its intracellular sorting but not for its endocytosis. , 2008, Molecular biology of the cell.

[16]  M. Schwartz,et al.  Endogenous RhoG is dispensable for integrin-mediated cell spreading but contributes to Rac-independent migration , 2008, Journal of Cell Science.

[17]  Helen K. Matthews,et al.  Directional migration of neural crest cells in vivo is regulated by Syndecan-4/Rac1 and non-canonical Wnt signaling/RhoA , 2008, Development.

[18]  S. Nagata,et al.  Imaging of Rab5 activity identifies essential regulators for phagosome maturation , 2008, Nature.

[19]  H. Cooper,et al.  Protein partners in the life history of activated fibroblast growth factor receptors , 2007, Proteomics.

[20]  M. Humphries,et al.  Synergistic control of cell adhesion by integrins and syndecans , 2007, Nature Reviews Molecular Cell Biology.

[21]  John K Heath,et al.  Src kinase modulates the activation, transport and signalling dynamics of fibroblast growth factor receptors , 2007, EMBO reports.

[22]  Satyajit Mayor,et al.  Pathways of clathrin-independent endocytosis , 2007, Nature Reviews Molecular Cell Biology.

[23]  M. Sonka,et al.  Synectin/syndecan‐4 regulate coronary arteriolar growth during development , 2007, Developmental dynamics : an official publication of the American Association of Anatomists.

[24]  Arwyn Tomos Jones,et al.  Macropinocytosis: searching for an endocytic identity and role in the uptake of cell penetrating peptides , 2007, Journal of cellular and molecular medicine.

[25]  Peter Novick,et al.  Rabs and their effectors: Achieving specificity in membrane traffic , 2006, Proceedings of the National Academy of Sciences.

[26]  P. Carmeliet,et al.  Selective regulation of arterial branching morphogenesis by synectin. , 2006, Developmental cell.

[27]  M. McNiven,et al.  A novel endocytic mechanism of epidermal growth factor receptor sequestration and internalization. , 2006, Cancer research.

[28]  P. Prasad,et al.  Factors controlling fibroblast growth factor receptor-1's cytoplasmic trafficking and its regulation as revealed by FRAP analysis. , 2006, Molecular biology of the cell.

[29]  R. Stan,et al.  Structure of caveolae. , 2005, Biochimica et biophysica acta.

[30]  A. Gressner,et al.  Expression pattern of fibroblast growth factors (FGFs), their receptors and antagonists in primary endothelial cells and vascular smooth muscle cells , 2005, Growth factors.

[31]  K. Aoki,et al.  Local phosphatidylinositol 3,4,5-trisphosphate accumulation recruits Vav2 and Vav3 to activate Rac1/Cdc42 and initiate neurite outgrowth in nerve growth factor-stimulated PC12 cells. , 2005, Molecular biology of the cell.

[32]  E. Tkachenko,et al.  Syndecans: new kids on the signaling block. , 2005, Circulation research.

[33]  P. Maher,et al.  Ligand dependent and independent internalization and nuclear translocation of fibroblast growth factor (FGF) receptor 1. , 2004, DNA and cell biology.

[34]  F. Wylie,et al.  Regulation of endocytosis, nuclear translocation, and signaling of fibroblast growth factor receptor 1 by E-cadherin. , 2004, Molecular biology of the cell.

[35]  K. Wennerberg,et al.  SGEF, a RhoG guanine nucleotide exchange factor that stimulates macropinocytosis. , 2004, Molecular biology of the cell.

[36]  R. Stan,et al.  Fibroblast growth factor 2 endocytosis in endothelial cells proceed via syndecan-4-dependent activation of Rac1 and a Cdc42-dependent macropinocytic pathway , 2004, Journal of Cell Science.

[37]  G. Scita,et al.  Rab5 is a signalling GTPase involved in actin remodelling by receptor tyrosine kinases , 2004, Nature.

[38]  Steven F Dowdy,et al.  Transducible TAT-HA fusogenic peptide enhances escape of TAT-fusion proteins after lipid raft macropinocytosis , 2004, Nature Medicine.

[39]  Jeffrey L. Wrana,et al.  Distinct endocytic pathways regulate TGF-β receptor signalling and turnover , 2003, Nature Cell Biology.

[40]  S. Robbins,et al.  Fibroblast Growth Factor-2-induced Signaling through Lipid Raft-associated Fibroblast Growth Factor Receptor Substrate 2 (FRS2)* , 2003, The Journal of Biological Chemistry.

[41]  D. Teis,et al.  Localization of the MP1-MAPK scaffold complex to endosomes is mediated by p14 and required for signal transduction. , 2002, Developmental cell.

[42]  M. Humphries,et al.  Cytoplasmic interactions of syndecan-4 orchestrate adhesion receptor and growth factor receptor signalling. , 2002, The Biochemical journal.

[43]  M. Simons,et al.  Protein Kinase C (PKC) δ Regulates PKCα Activity in a Syndecan-4-dependent Manner* , 2002, The Journal of Biological Chemistry.

[44]  E. Tkachenko,et al.  Clustering Induces Redistribution of Syndecan-4 Core Protein into Raft Membrane Domains* , 2002, The Journal of Biological Chemistry.

[45]  Michael Simons,et al.  Fibroblast growth factor–specific modulation of cellular response by syndecan-4 , 2002, The Journal of cell biology.

[46]  S. Robbins,et al.  Lipid rafts and little caves , 2002 .

[47]  H. Saito,et al.  Syndecan-4 Deficiency Leads to High Mortality of Lipopolysaccharide-injected Mice* , 2001, The Journal of Biological Chemistry.

[48]  Marino Zerial,et al.  Rab proteins as membrane organizers , 2001, Nature Reviews Molecular Cell Biology.

[49]  M. Simons,et al.  Synectin, syndecan‐4 cytoplasmic domain binding PDZ protein, inhibits cell migration , 2000, Journal of cellular physiology.

[50]  A. Debant,et al.  TrioGEF1 controls Rac- and Cdc42-dependent cell structures through the direct activation of rhoG. , 2000, Journal of cell science.

[51]  J. Wesche,et al.  Uptake and intracellular transport of acidic fibroblast growth factor: evidence for free and cytoskeleton-anchored fibroblast growth factor receptors. , 1999, Molecular biology of the cell.

[52]  H. McMahon.  Endocytosis: An assembly protein for clathrin cages , 1999, Current Biology.

[53]  S. Schmid,et al.  Control of EGF Receptor Signaling by Clathrin-Mediated Endocytosis , 1996, Science.

[54]  J. Lavail,et al.  Endocytosis of Activated TrkA: Evidence that Nerve Growth Factor Induces Formation of Signaling Endosomes , 1996, The Journal of Neuroscience.

[55]  J. Swanson,et al.  A role for phosphoinositide 3-kinase in the completion of macropinocytosis and phagocytosis by macrophages , 1996, The Journal of cell biology.

[56]  M. Simons,et al.  Auxiliary and autonomous proteoglycan signaling networks. , 2010, Methods in enzymology.

[57]  L. Schaefer,et al.  Proteoglycans: from structural compounds to signaling molecules , 2009, Cell and Tissue Research.

[58]  J. Couchman,et al.  Syndecans in wound healing, inflammation and vascular biology. , 2007, The international journal of biochemistry & cell biology.

[59]  S. Robbins,et al.  Lipid rafts and little caves. Compartmentalized signalling in membrane microdomains. , 2002, European journal of biochemistry.

[60]  J. Thiery,et al.  Fibroblast growth factor-2. , 2000, The international journal of biochemistry & cell biology.

[61]  J. Swanson.  Fluorescent labeling of endocytic compartments. , 1989, Methods in cell biology.