title: Phosphatidylinositol-4-phosphate 5-kinase and GEP100/Brag2 protein mediate antiangiogenic signaling by semaphorin 3E-plexin-D1 through Arf6 protein.
abstract: The semaphorins are a family of secreted or membrane-bound proteins that are known to guide axons in the developing nervous system. Genetic evidence revealed that a class III semaphorin, semaphorin 3E (Sema3E), and its receptor Plexin-D1 also control the vascular patterning during development. At the molecular level, we have recently shown that Sema3E acts on Plexin-D1 expressed in endothelial cells, thus initiating a novel antiangiogenic signaling pathway that results in the retraction of filopodia in endothelial tip cells. Sema3E induces the rapid disassembly of integrin-mediated adhesive structures, thereby inhibiting endothelial cell adhesion to the extracellular matrix. This process requires the activation of small GTPase Arf6 (ADP-ribosylation factor 6), which regulates intracellular trafficking of β1 integrin. However, the molecular mechanisms by which Sema3E-Plexin-D1 activates Arf6 remained to be identified. Here we show that GEP100 (guanine nucleotide exchange protein 100)/Brag2, a guanine nucleotide exchange factor for Arf6, mediates Sema3E-induced Arf6 activation in endothelial cells. We provide evidence that upon activation by Sema3E, Plexin-D1 recruits phosphatidylinositol-4-phosphate 5-kinase, and its enzymatic lipid product, phosphatidylinositol 4,5-bisphosphate, binds to the pleckstrin homology domain of GEP100. Phosphatidylinositol 4,5-bisphosphate binding to GEP100 enhances its guanine nucleotide exchange factor activity toward Arf6, thus resulting in the disassembly of integrin-mediated focal adhesions and endothelial cell collapse. Our present study reveals a novel phospholipid-regulated antiangiogenic signaling pathway whereby Sema3E activates Arf6 through Plexin-D1 and consequently controls integrin-mediated endothelial cell attachment to the extracellular matrix and migration.
authors.affiliation: Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Sakurai
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Jian
authors.forename: Charity J
authors.initials: CJ
authors.lastname: Lee
authors.forename: Yosif
authors.initials: Y
authors.lastname: Manavski
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Chavakis
authors.forename: Julie
authors.initials: J
authors.lastname: Donaldson
authors.forename: Paul A
authors.initials: PA
authors.lastname: Randazzo
authors.forename: J Silvio
authors.initials: JS
authors.lastname: Gutkind
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D019556:COS Cells; D002448:Cell Adhesion / Q000502:physiology; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology; D002522:Chlorocebus aethiops; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D016023:Integrins / Q000235:genetics / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D039961:Semaphorins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D000089982:ADP-Ribosylation Factor 6; D015816:Cell Adhesion Molecules, Neuronal; D020662:Guanine Nucleotide Exchange Factors; C504483:IQSEC1 protein, human; D016023:Integrins; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; C493082:PLXND1 protein, human; C494123:SEMA3E protein, human; D039961:Semaphorins; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase; D020727:ADP-Ribosylation Factors; C000715348:ARF6 protein, human