scholarly journals EphB2 and EphB4 receptors forward signaling promotes SDF-1–induced endothelial cell chemotaxis and branching remodeling

Blood ◽  
2006 ◽  
Vol 108 (9) ◽  
pp. 2914-2922 ◽  
Author(s):  
Ombretta Salvucci ◽  
Maria de la Luz Sierra ◽  
Jose A. Martina ◽  
Peter J. McCormick ◽  
Giovanna Tosato
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cell ◽  
Tyrosine Kinases ◽  
Molecular Mechanisms ◽  
Cell Movement ◽  
Cell Contact ◽  
Eph Receptor ◽  
Cell Clustering ◽  
Chemokine Ligand ◽  
Ephrin Ligands

Abstract The complex molecular mechanisms that drive endothelial cell movement and the formation of new vessels are poorly understood and require further investigation. Eph receptor tyrosine kinases and their membrane-anchored ephrin ligands regulate cell movements mostly by cell–cell contact, whereas the G-protein–coupled receptor CXCR4 and its unique SDF-1 chemokine ligand regulate cell movement mostly through soluble gradients. By using biochemical and functional approaches, we investigated how ephrinB and SDF-1 orchestrate endothelial cell movement and morphogenesis into capillary-like structures. We describe how endogenous EphB2 and EphB4 signaling are required for the formation of extracellular matrix–dependent capillary-like structures in primary human endothelial cells. We further demonstrate that EphB2 and EphB4 activation enhance SDF-1–induced signaling and chemotaxis that are also required for extracellular matrix–dependent endothelial cell clustering. These results support a model in which SDF-1 gradients first promote endothelial cell clustering and then EphB2 and EphB4 critically contribute to subsequent cell movement and alignment into cord-like structures. This study reveals a requirement for endogenous Eph signaling in endothelial cell morphogenic processes, uncovers a novel link between EphB forward signaling and SDF-1–induced signaling, and demonstrates a mechanism for cooperative regulation of endothelial cell movement.

scholarly journals Exosomes mediate cell contact–independent ephrin-Eph signaling during axon guidance

2016 ◽  
Vol 214 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Jingyi Gong ◽  
Roman Körner ◽  
Louise Gaitanos ◽  
Rüdiger Klein
Keyword(s):  
Neural Development ◽  
Tyrosine Kinases ◽  
Neuronal Development ◽  
Cell Types ◽  
Cell Contact ◽  
Eph Receptor ◽  
Endosomal Sorting ◽  
Ephrin Ligands ◽  
Direct Cell ◽  
Mediate Cell

The cellular release of membranous vesicles known as extracellular vesicles (EVs) or exosomes represents a novel mode of intercellular communication. Eph receptor tyrosine kinases and their membrane-tethered ephrin ligands have very important roles in such biologically diverse processes as neuronal development, plasticity, and pathological diseases. Until now, it was thought that ephrin-Eph signaling requires direct cell contact. Although the biological functions of ephrin-Eph signaling are well understood, our mechanistic understanding remains modest. Here we report the release of EVs containing Ephs and ephrins by different cell types, a process requiring endosomal sorting complex required for transport (ESCRT) activity and regulated by neuronal activity. Treatment of cells with purified EphB2+ EVs induces ephrinB1 reverse signaling and causes neuronal axon repulsion. These results indicate a novel mechanism of ephrin-Eph signaling independent of direct cell contact and proteolytic cleavage and suggest the participation of EphB2+ EVs in neural development and synapse physiology.

scholarly journals The Shb scaffold binds the Nck adaptor protein, p120 RasGAP, and Chimaerins and thereby facilitates heterotypic cell segregation by the receptor EphB2

2020 ◽  
Vol 295 (12) ◽  
pp. 3932-3944 ◽  
Author(s):  
Melany J. Wagner ◽  
Marilyn S. Hsiung ◽  
Gerald D. Gish ◽  
Rick D. Bagshaw ◽  
Sasha A. Doodnauth ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Cell Movement ◽  
Adaptor Protein ◽  
Receptor Activation ◽  
Sh2 Domain ◽  
Tumor Formation ◽  
Eph Receptors ◽  
Eph Receptor ◽  
Varied Composition ◽  
Cell Segregation

Eph receptors are a family of receptor tyrosine kinases that control directional cell movement during various biological processes, including embryogenesis, neuronal pathfinding, and tumor formation. The biochemical pathways of Eph receptors are context-dependent in part because of the varied composition of a heterotypic, oligomeric, active Eph receptor complex. Downstream of the Eph receptors, little is known about the essential phosphorylation events that define the context and instruct cell movement. Here, we define a pathway that is required for Eph receptor B2 (EphB2)–mediated cell sorting and is conserved among multiple Eph receptors. Utilizing a HEK293 model of EphB2+/ephrinB1+ cell segregation, we found that the scaffold adaptor protein SH2 domain–containing adaptor protein B (Shb) is essential for EphB2 functionality. Further characterization revealed that Shb interacts with known modulators of cytoskeletal rearrangement and cell mobility, including Nck adaptor protein (Nck), p120-Ras GTPase-activating protein (RasGAP), and the α- and β-Chimaerin Rac GAPs. We noted that phosphorylation of Tyr297, Tyr246, and Tyr336 of Shb is required for EphB2–ephrinB1 boundary formation, as well as binding of Nck, RasGAP, and the chimaerins, respectively. Similar complexes were formed in the context of EphA4, EphA8, EphB2, and EphB4 receptor activation. These results indicate that phosphotyrosine-mediated signaling through Shb is essential in EphB2-mediated heterotypic cell segregation and suggest a conserved function for Shb downstream of multiple Eph receptors.

scholarly journals Allosteric Regulation of the EphA2 Receptor Intracellular Region by Serine/Threonine Kinases

2021 ◽  
Author(s):  
Bernhard C. Lechtenberg ◽  
Marina P. Gehring ◽  
Taylor P. Light ◽  
Mike W. Matsumoto ◽  
Kalina Hristova ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Molecular Mechanisms ◽  
Structural Information ◽  
Cell Communication ◽  
Kinase Domain ◽  
Eph Receptor ◽  
X Ray ◽  
X Ray Crystallography ◽  
Exchange Mass Spectrometry ◽  
Intracellular Region

ABSTRACTEph receptor tyrosine kinases play a key role in cell-cell communication. However, lack of structural information on the entire multi-domain intracellular region of any Eph receptor has hindered detailed understanding of their signaling mechanisms. Here, we use an integrative structural biology approach combining X-ray crystallography, small-angle X-ray scattering and hydrogen-deuterium exchange mass spectrometry, to gain the first insights into the structure and dynamics of the entire EphA2 intracellular region. EphA2 promotes cancer malignancy through a poorly understood non-canonical form of signaling that depends on serine/threonine phosphorylation of the linker connecting the EphA2 kinase and SAM domains. We uncovered two distinct molecular mechanisms that may function in concert to mediate the effects of linker phosphorylation through an orchestrated allosteric regulatory network. The first involves a shift in the equilibrium between a “closed” configuration of the EphA2 intracellular region and an “open” more extended configuration induced by the accumulation of phosphorylation sites in the linker. This implies that cooperation of multiple serine/threonine kinase signaling networks is necessary to promote robust EphA2 non-canonical signaling. The second involves allosteric rearrangements in the kinase domain and juxtamembrane segment induced by phosphorylation of some linker residues, suggesting a link between EphA2 non-canonical signaling and canonical signaling through tyrosine phosphorylation. Given the key role of EphA2 in cancer malignancy, this new knowledge can inform therapeutic strategies.

Dancing with the dead: Eph receptors and their kinase-null partnersThis paper is one of a selection of papers published in a Special Issue entitled CSBMCB 53rd Annual Meeting — Membrane Proteins in Health and Disease, and has undergone the Journal’s usual peer review process.

2011 ◽  
Vol 89 (2) ◽  
pp. 115-129 ◽  
Author(s):  
Luke Truitt ◽  
Andrew Freywald
Keyword(s):  
Membrane Proteins ◽  
Tyrosine Kinases ◽  
Molecular Mechanisms ◽  
Receptor Tyrosine Kinases ◽  
Peer Review Process ◽  
Eph Receptors ◽  
Eph Receptor ◽  
Biological Responses ◽  
Wide Range ◽  
Multicellular Organisms

Eph receptor tyrosine kinases and their ligands, ephrins, are membrane proteins coordinating a wide range of biological functions both in developing embryos and in adult multicellular organisms. Numerous studies have implicated Eph receptors in the induction of opposing responses, including cell adhesion or repulsion, support or inhibition of cell proliferation and cell migration, and progression or suppression of multiple malignancies. Similar to other receptor tyrosine kinases, Eph receptors rely on their ability to catalyze tyrosine phosphorylation for signal transduction. Interestingly, however, Eph receptors also actively utilize three kinase-deficient receptor tyrosine kinases, EphB6, EphA10, and Ryk, in their signaling network. The accumulating evidence suggests that the unusual flexibility of the Eph family, allowing it to initiate antagonistic responses, might be partially explained by the influence of the kinase-dead participants and that the exact outcome of an Eph-mediated action is likely to be defined by the balance between the signaling of catalytically potent and catalytically null receptors. We discuss in this minireview the emerging functions of the kinase-dead EphB6, EphA10, and Ryk receptors both in normal biological responses and in malignancy, and analyze currently available information related to the molecular mechanisms of their action in the context of the Eph family.

PECAM-1 (CD31) functions as a reservoir for and a modulator of tyrosine-phosphorylated beta-catenin

1999 ◽  
Vol 112 (18) ◽  
pp. 3005-3014 ◽  
Author(s):  
N. Ilan ◽  
S. Mahooti ◽  
D.L. Rimm ◽  
J.A. Madri
Keyword(s):  
Endothelial Cell ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Nuclear Translocation ◽  
Adherens Junction ◽  
Cell Contact ◽  
Beta Catenin ◽  
Dependent Manner

Catenins function as regulators of cellular signaling events in addition to their previously documented roles in adherens junction formation and function. Evidence to date suggests that beta and gamma catenins can act as signaling molecules, bind transcriptional factors and translocate to the nucleus. Beta- and gamma-catenin are also major substrates for protein tyrosine kinases, and tyrosine phosphorylation of junctional proteins is correlated with decreased adhesiveness. One way in which catenin functions are modulated is by dynamic incorporation into junctional complexes which controls, in part, the cytoplasmic levels of catenins. Here we show that: (1) vascular endothelial growth factor (VEGF) induces beta-catenin tyrosine phosphorylation in a time-, and dose-dependent manner and that VEGF receptors co-localize to areas of endothelial cell-cell contact in vitro and in vivo. (2) Platelet-endothelial cell adhesion molecule (PECAM)-1 can function as a reservoir for, and modulator of, tyrosine phosphorylated beta-catenin. (3) PECAM-1 can prevent beta-catenin nuclear translocation in transfected SW480 colon carcinoma cells. We suggest that PECAM-1 may play a role in modulating beta-catenin tyrosine phosphorylation levels, localization and signaling and by doing so, functions as an important modulator of the endothelium.

Eph Receptor Tyrosine Kinases and Ephrin Ligands Are Epigenetically Inactivated in Acute Lymphoblastic Leukemia and Are Potential New Tumor Suppressor Genes in Human Leukemia.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2128-2128 ◽  
Author(s):  
Shao-qing Kuang ◽  
Zhi-Hong Fang ◽  
Gonzalo Lopez ◽  
Weigang Tong ◽  
Hui Yang ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Cell Lines ◽  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Leukemia Cell ◽  
Human Leukemia ◽  
Eph Receptor ◽  
Leukemia Cell Lines ◽  
Ephrin Ligands ◽  
Aberrant Dna Methylation

Abstract The Eph (erythroprotein-producing hepatoma amplified sequence) family receptor tyrosine kinases and their ephrin ligands (ephrins) are involved in a variety of functions in normal cell development and cancer. We have identified several members of this family as potential targets of aberrant DNA methylation using Methylated CpG Island Amplification (MCA) / DNA promoter microarray technology. This is of importance as there are no prior reports of potential Eph receptor or Ephrin epigenetic inactivation in human leukemia. To further investigate the role of Eph receptor and ephrin family genes in leukemia, we have analyzed their DNA methylation status in a panel of 23 leukemia cell lines and 65 primary ALL patient samples. Aberrant DNA methylation of 9 of these genes (EPHA4, EPHA5, EPHA6, EPHB2, EPHB3, EPHB4, EphrinA5, Ephrin B2, and EphrinB3) was detected in multiple leukemia cell lines but not in normal samples by bisulfite pyrosequencing. In ALL patient samples, the frequencies of DNA methylation detected in the promoter regions of these genes ranged from 23% to 87% for EPHA4, EPHA5, EPHA6, EPHB2, EPHB3, EPHB4, EphrinA5, Ephrin B2, and EphrinB3. Expression analysis of 3 of these genes (EPHA5, EPHB4 and Ephrin B2) in leukemia cell lines by real-time PCR further confirmed methylation associated gene silencing. Treatment of methylated/silenced cell lines with DNA methyltransferase inhibitor 5′-aza-2′-deoxycytidine resulted in gene re-expression. Forced overexpression of EPHB4 using a lentivirus transduction system in Raji cell lines resulted in decreased cell proliferation and adhesion-independent cell growth, as well as in an increase in staurosporine induction of apoptosis. In addition, EPHB4 overexpression resulted in a significant downregulation of phosphorylated Akt pathway but had no effect on mitogen-activated protein kinase pathway. In summary, we describe for the first time the epigenetic suppression of Ephrin receptors and their ligands in human leukemia, indicating that these genes may be potential tumor suppressors in leukemia. Targeting of these pathways may result in the development of new potential therapies and biomarkers for patients with ALL.

scholarly journals N-Isopropylacrylamide-co-glycidylmethacrylate as a Thermoresponsive Substrate for Corneal Endothelial Cell Sheet Engineering

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Bernadette K. Madathil ◽  
Pallickaveedu RajanAsari Anil Kumar ◽  
Thrikkovil Variyath Kumary
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cell ◽  
Cell Sheet ◽  
Corneal Endothelial Cell ◽  
Solution Temperature ◽  
Pcr Analysis ◽  
Cell Contact ◽  
Endothelial Keratoplasty ◽  
Matrix Deposition ◽  
Stimuli Responsive Polymers

Endothelial keratoplasty is a recent shift in the surgical treatment of corneal endothelial dystrophies, where the dysfunctional endothelium is replaced whilst retaining the unaffected corneal layers. To overcome the limitation of donor corneal shortage, alternative use of tissue engineered constructs is being researched. Tissue constructs with intact extracellular matrix are generated using stimuli responsive polymers. In this study we evaluated the feasibility of using the thermoresponsive poly(N-isopropylacrylamide-co-glycidylmethacrylate) polymer as a culture surface to harvest viable corneal endothelial cell sheets. Incubation below the lower critical solution temperature of the polymer allowed the detachment of the intact endothelial cell sheet. Phase contrast and scanning electron microscopy revealed the intact architecture, cobble stone morphology, and cell-to-cell contact in the retrieved cell sheet. Strong extracellular matrix deposition was also observed. The RT-PCR analysis confirmed functionally active endothelial cells in the cell sheet as evidenced by the positive expression of aquaporin 1, collagen IV, Na+-K+ATPase, and FLK-1. Na+-K+ATPase protein expression was also visualized by immunofluorescence staining. These results suggest that the in-house developed thermoresponsive culture dish is a suitable substrate for the generation of intact corneal endothelial cell sheet towards transplantation for endothelial keratoplasty.

scholarly journals Ubiquitin ligase SPSB4 diminishes cell repulsive responses mediated by EphB2

2017 ◽  
Vol 28 (24) ◽  
pp. 3532-3541 ◽  
Author(s):  
Fumihiko Okumura ◽  
Akiko Joo-Okumura ◽  
Keisuke Obara ◽  
Alexander Petersen ◽  
Akihiko Nishikimi ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Receptor Tyrosine Kinases ◽  
Cancer Development ◽  
Tyrosine Kinase Activity ◽  
Eph Receptor ◽  
Ephrin Ligands ◽  
Dependent Cell ◽  
Socs Box

Eph receptor tyrosine kinases and their ephrin ligands are overexpressed in various human cancers, including colorectal malignancies, suggesting important roles in many aspects of cancer development and progression as well as in cellular repulsive responses. The ectodomain of EphB2 receptor is cleaved by metalloproteinases (MMPs) MMP-2/MMP-9 and released into the extracellular space after stimulation by its ligand. The remaining membrane-associated fragment is further cleaved by the presenilin-dependent γ-secretase and releases an intracellular peptide that has tyrosine kinase activity. Although the cytoplasmic fragment is degraded by the proteasome, the responsible ubiquitin ligase has not been identified. Here, we show that SOCS box-containing protein SPSB4 polyubiquitinates EphB2 cytoplasmic fragment and that SPSB4 knockdown stabilizes the cytoplasmic fragment. Importantly, SPSB4 down-regulation enhances cell repulsive responses mediated by EphB2 stimulation. Altogether, we propose that SPSB4 is a previously unidentified ubiquitin ligase regulating EphB2-dependent cell repulsive responses.

scholarly journals EphrinB reverse signaling contributes to endothelial and mural cell assembly into vascular structures

Blood ◽  
2009 ◽  
Vol 114 (8) ◽  
pp. 1707-1716 ◽  
Author(s):  
Ombretta Salvucci ◽  
Dragan Maric ◽  
Matina Economopoulou ◽  
Shuhei Sakakibara ◽  
Simone Merlin ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Tyrosine Kinases ◽  
Cell Contact ◽  
Cell Assembly ◽  
Mural Cell ◽  
Reverse Signaling ◽  
Contact Points ◽  
Ephb Receptor ◽  
Vascular Structures

Abstract EphrinB transmembrane ligands and their cognate EphB receptor tyrosine kinases regulate vascular development through bidirectional cell-to-cell signaling, but little is known about the role of EphrinB during postnatal vascular remodeling. We report that EphrinB is a critical mediator of postnatal pericyte-to-endothelial cell assembly into vascular structures. This function is dependent upon extracellular matrix-supported cell-to-cell contact, engagement of EphrinB by EphB receptors expressed on another cell, and Src-dependent phosphorylation of the intracytoplasmic domain of EphrinB. Phosphorylated EphrinB marks angiogenic blood vessels in the developing and hypoxic retina, the wounded skin, and tumor tissue, and is detected at contact points between endothelial cells and pericytes. Furthermore, inhibition ofEphrinB activity prevents proper assembly of pericytes and endothelial cells into vascular structures. These results reveal a role for EphrinB signaling in orchestrating pericyte/endothelial cell assembly, and suggest that therapeutic targeting of EphrinB may prove useful for disrupting angiogenesis when it contributes to disease.

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