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Stergiou IE, Papadakos SP, Karyda A, Tsitsilonis OE, Dimopoulos MA, Theocharis S. EPH/Ephrin Signaling in Normal Hematopoiesis and Hematologic Malignancies: Deciphering Their Intricate Role and Unraveling Possible New Therapeutic Targets. Cancers (Basel) 2023; 15:3963. [PMID: 37568780 PMCID: PMC10417178 DOI: 10.3390/cancers15153963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Revised: 08/02/2023] [Accepted: 08/03/2023] [Indexed: 08/13/2023] Open
Abstract
Erythropoietin-producing hepatocellular carcinoma receptors (EPHs) represent the largest family of receptor tyrosine kinases (RTKs). EPH interaction with ephrins, their membrane-bound ligands, holds a pivotal role in embryonic development, while, though less active, it is also implicated in various physiological functions during adult life. In normal hematopoiesis, different patterns of EPH/ephrin expression have been correlated with hematopoietic stem cell (HSC) maintenance and lineage-committed hematopoietic progenitor cell (HPC) differentiation, as well as with the functional properties of their mature offspring. Research in the field of hematologic malignancies has unveiled a rather complex involvement of the EPH/ephrinsignaling pathway in the pathophysiology of these neoplasms. Aberrations in genetic, epigenetic, and protein levels have been identified as possible players implicated both in tumor progression and suppression, while correlations have also been highlighted regarding prognosis and response to treatment. Initial efforts to therapeutically target the EPH/ephrin axis have been undertaken in the setting of hematologic neoplasia but are mainly confined to the preclinical level. To this end, deciphering the complexity of this signaling pathway both in normal and malignant hematopoiesis is necessary.
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Affiliation(s)
- Ioanna E. Stergiou
- Department of Pathophysiology, School of Medicine, National and Kapodistrian University of Athens, 11527 Athens, Greece;
| | - Stavros P. Papadakos
- First Department of Pathology, School of Medicine, National and Kapodistrian University of Athens, 11527 Athens, Greece; (S.P.P.); (A.K.)
| | - Anna Karyda
- First Department of Pathology, School of Medicine, National and Kapodistrian University of Athens, 11527 Athens, Greece; (S.P.P.); (A.K.)
| | - Ourania E. Tsitsilonis
- Flow Cytometry Unit, Department of Biology, School of Science, National and Kapodistrian University of Athens, 15784 Athens, Greece;
| | - Meletios-Athanasios Dimopoulos
- Department of Clinical Therapeutics, School of Medicine, National and Kapodistrian University of Athens, Alexandra Hospital, 11528 Athens, Greece
| | - Stamatios Theocharis
- First Department of Pathology, School of Medicine, National and Kapodistrian University of Athens, 11527 Athens, Greece; (S.P.P.); (A.K.)
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2
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EphA3 Pay-Loaded Antibody Therapeutics for the Treatment of Glioblastoma. Cancers (Basel) 2018; 10:cancers10120519. [PMID: 30562956 PMCID: PMC6316644 DOI: 10.3390/cancers10120519] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 12/03/2018] [Accepted: 12/11/2018] [Indexed: 11/29/2022] Open
Abstract
The EphA3 receptor has recently emerged as a functional tumour-specific therapeutic target in glioblastoma (GBM). EphA3 is significantly elevated in recurrent disease, is most highly expressed on glioma stem cells (GSCs), and has a functional role in maintaining self-renewal and tumourigenesis. An unlabelled EphA3-targeting therapeutic antibody is currently under clinical assessment in recurrent GBM patients. In this study, we assessed the efficacy of EphA3 antibody drug conjugate (ADC) and radioimmunotherapy (RIT) approaches using orthotopic animal xenograft models. Brain uptake studies, using positron emission tomography/computed tomography (PET/CT) imaging, show EphA3 antibodies are effectively delivered across the blood-tumour barrier and accumulate at the tumour site with no observed normal brain reactivity. A robust anti-tumour response, with no toxicity, was observed using EphA3, ADC, and RIT approaches, leading to a significant increase in overall survival. Our current research provides evidence that GBM patients may benefit from pay-loaded EphA3 antibody therapies.
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Tanabe S, Aoyagi K, Yokozaki H, Sasaki H. Molecular pathway network of EFNA1 in cancer and mesenchymal stem cells. ACTA ACUST UNITED AC 2018. [DOI: 10.3934/celltissue.2018.2.58] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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4
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Forse GJ, Uson ML, Nasertorabi F, Kolatkar A, Lamberto I, Pasquale EB, Kuhn P. Distinctive Structure of the EphA3/Ephrin-A5 Complex Reveals a Dual Mode of Eph Receptor Interaction for Ephrin-A5. PLoS One 2015; 10:e0127081. [PMID: 25993310 PMCID: PMC4439037 DOI: 10.1371/journal.pone.0127081] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 04/11/2015] [Indexed: 11/19/2022] Open
Abstract
The Eph receptor tyrosine kinase/ephrin ligand system regulates a wide spectrum of physiological processes, while its dysregulation has been implicated in cancer progression. The human EphA3 receptor is widely upregulated in the tumor microenvironment and is highly expressed in some types of cancer cells. Furthermore, EphA3 is among the most highly mutated genes in lung cancer and it is also frequently mutated in other cancers. We report the structure of the ligand-binding domain of the EphA3 receptor in complex with its preferred ligand, ephrin-A5. The structure of the complex reveals a pronounced tilt of the ephrin-A5 ligand compared to its orientation when bound to the EphA2 and EphB2 receptors and similar to its orientation when bound to EphA4. This tilt brings an additional area of ephrin-A5 into contact with regions of EphA3 outside the ephrin-binding pocket thereby enlarging the size of the interface, which is consistent with the high binding affinity of ephrin-A5 for EphA3. This large variation in the tilt of ephrin-A5 bound to different Eph receptors has not been previously observed for other ephrins.
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Affiliation(s)
- Garry Jason Forse
- Dornsife College of Letters, Arts and Sciences, University of Southern California, 3430 S. Vermont Ave., Suite 105 (110), MC3301, Los Angeles, CA, 90089–3301, United States of America
| | - Maria Loressa Uson
- Dornsife College of Letters, Arts and Sciences, University of Southern California, 3430 S. Vermont Ave., Suite 105 (110), MC3301, Los Angeles, CA, 90089–3301, United States of America
| | - Fariborz Nasertorabi
- Dornsife College of Letters, Arts and Sciences, University of Southern California, 3430 S. Vermont Ave., Suite 105 (110), MC3301, Los Angeles, CA, 90089–3301, United States of America
| | - Anand Kolatkar
- Dornsife College of Letters, Arts and Sciences, University of Southern California, 3430 S. Vermont Ave., Suite 105 (110), MC3301, Los Angeles, CA, 90089–3301, United States of America
| | - Ilaria Lamberto
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, California, 92037, United States of America
| | - Elena Bianca Pasquale
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, California, 92037, United States of America
- Department of Pathology, University of California San Diego, La Jolla, California, 92093, United States of America
| | - Peter Kuhn
- Dornsife College of Letters, Arts and Sciences, University of Southern California, 3430 S. Vermont Ave., Suite 105 (110), MC3301, Los Angeles, CA, 90089–3301, United States of America
- * E-mail:
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5
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Tomasevic N, Luehrsen K, Baer M, Palath V, Martinez D, Williams J, Yi C, Sujatha-Bhaskar S, Lanke R, Leung J, Ching W, Lee A, Bai L, Yarranton G, Bebbington C. A high affinity recombinant antibody to the human EphA3 receptor with enhanced ADCC activity. Growth Factors 2014; 32:223-35. [PMID: 25413948 DOI: 10.3109/08977194.2014.984808] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
EphA3 is expressed in solid tumors and leukemias and is an attractive target for the therapy. We have generated a panel of Humaneered® antibodies to the ligand-binding domain using a Fab epitope-focused library that has the same specificity as monoclonal antibody mIIIA4. A high-affinity antibody was selected that competes with the mIIIA4 antibody for binding to EphA3 and has an improved affinity of ∼1 nM. In order to generate an antibody with potent cell-killing activity the variable regions were assembled with human IgG1k constant regions and expressed in a Chinese hamster ovary (CHO) cell line deficient in fucosyl transferase. Non-fucosylated antibodies have been reported to have enhanced binding affinity for the IgG receptor CD16a (FcγRIIIa). The affinity of the antibody for recombinant CD16a was enhanced approximately 10-fold. This resulted in enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) activity against EphA3-expressing leukemic cells, providing a potent antibody for the evaluation as a therapeutic agent.
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6
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Abstract
Eph receptor tyrosine kinases control cell-cell interactions during normal and oncogenic development, and are implicated in a range of processes including angiogenesis, stem cell maintenance and metastasis. They are thus of great interest as targets for cancer therapy. EphA3, originally isolated from leukemic and melanoma cells, is presently one of the most promising therapeutic targets, with multiple tumor-promoting roles in a variety of cancer types. This review focuses on EphA3, its functions in controlling cellular behavior, both in normal and pathological development, and most particularly in cancer.
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Affiliation(s)
- Peter W Janes
- Department of Biochemistry and Molecular Biology, Monash University , Victoria , Australia and
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7
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To C, Farnsworth RH, Vail ME, Chheang C, Gargett CE, Murone C, Llerena C, Major AT, Scott AM, Janes PW, Lackmann M. Hypoxia-controlled EphA3 marks a human endometrium-derived multipotent mesenchymal stromal cell that supports vascular growth. PLoS One 2014; 9:e112106. [PMID: 25420155 PMCID: PMC4242616 DOI: 10.1371/journal.pone.0112106] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 10/13/2014] [Indexed: 12/21/2022] Open
Abstract
Eph and ephrin proteins are essential cell guidance cues that orchestrate cell navigation and control cell-cell interactions during developmental tissue patterning, organogenesis and vasculogenesis. They have been extensively studied in animal models of embryogenesis and adult tissue regeneration, but less is known about their expression and function during human tissue and organ regeneration. We discovered the hypoxia inducible factor (HIF)-1α-controlled expression of EphA3, an Eph family member with critical functions during human tumour progression, in the vascularised tissue of regenerating human endometrium and on isolated human endometrial multipotent mesenchymal stromal cells (eMSCs), but not in other highly vascularised human organs. EphA3 affinity-isolation from human biopsy tissue yielded multipotent CD29+/CD73+/CD90+/CD146+ eMSCs that can be clonally propagated and respond to EphA3 agonists with EphA3 phosphorylation, cell contraction, cell-cell segregation and directed cell migration. EphA3 silencing significantly inhibited the ability of transplanted eMSCs to support neovascularisation in immunocompromised mice. In accord with established roles of Eph receptors in mediating interactions between endothelial and perivascular stromal cells during mouse development, our findings suggest that HIF-1α-controlled expression of EphA3 on human MSCs functions during the hypoxia-initiated early stages of adult blood vessel formation.
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MESH Headings
- Adult
- Animals
- Blotting, Western
- Cell Hypoxia
- Cells, Cultured
- Endometrium/cytology
- Female
- Gene Expression
- Heterografts/blood supply
- Humans
- Hypoxia-Inducible Factor 1, alpha Subunit/genetics
- Hypoxia-Inducible Factor 1, alpha Subunit/metabolism
- Male
- Mesenchymal Stem Cell Transplantation/methods
- Mesenchymal Stem Cells/metabolism
- Mice, Inbred BALB C
- Mice, Nude
- Microscopy, Fluorescence
- Multipotent Stem Cells/metabolism
- Multipotent Stem Cells/transplantation
- Neovascularization, Physiologic
- RNA Interference
- Receptor, EphA3/genetics
- Receptor, EphA3/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Transplantation, Heterologous
- Young Adult
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Affiliation(s)
- Catherine To
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Rae H. Farnsworth
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Victoria, Australia
- * E-mail:
| | - Mary E. Vail
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Chanly Chheang
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | | | - Carmel Murone
- Ludwig Institute for Cancer Research, Olivia Newton-John Cancer & Wellness Centre, Melbourne, Victoria, Australia
| | - Carmen Llerena
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Andrew T. Major
- Department of Anatomy & Developmental Biology, Monash University, Melbourne, Victoria, Australia
| | - Andrew M. Scott
- Ludwig Institute for Cancer Research, Olivia Newton-John Cancer & Wellness Centre, Melbourne, Victoria, Australia
| | - Peter W. Janes
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Martin Lackmann
- Department of Biochemistry & Molecular Biology, Monash University, Melbourne, Victoria, Australia
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8
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Duggineni S, Mitra S, Lamberto I, Han X, Xu Y, An J, Pasquale EB, Huang Z. Design and Synthesis of Potent Bivalent Peptide Agonists Targeting the EphA2 Receptor. ACS Med Chem Lett 2013; 4. [PMID: 24167659 DOI: 10.1021/ml3004523] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Designing potent and selective peptides and small molecules that target Eph receptor tyrosine kinases remains a challenge and new strategies are needed for developing novel and potent ligands for these receptors. In this study, we performed a structure-activity relationship study of a previously identified 12 amino acid-long peptide, SWL, by alanine scanning to identify residues important for receptor binding. To further enhance and optimize the receptor binding affinity of the SWL peptide, we applied the concept of bivalent ligand design to synthesize several SWL-derived dimeric peptides as novel ligands capable of binding simultaneously to two EphA2 receptor molecules. The dimeric peptides possess higher receptor binding affinity than the original monomeric SWL peptide, consistent with bivalent binding. The most potent dimeric peptide, a SWL dimer with a 6 carbon linker, has about 13 fold increased potency compared to SWL. Furthermore, similar to SWL, the dimeric peptide is an agonist and can promote EphA2 tyrosine phosphorylation (activation) in cultured cells.
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Affiliation(s)
- Srinivas Duggineni
- SUNY Upstate Cancer Research Institute,
Department of Pharmacology, State University of New York, Syracuse,
New York 13210, United States
| | - Sayantan Mitra
- Sanford-Burnham Medical Research Institute,
La Jolla, California 92037, United States
| | - Ilaria Lamberto
- Sanford-Burnham Medical Research Institute,
La Jolla, California 92037, United States
| | - Xiaofeng Han
- SUNY Upstate Cancer Research Institute,
Department of Pharmacology, State University of New York, Syracuse,
New York 13210, United States
| | - Yan Xu
- SUNY Upstate Cancer Research Institute,
Department of Pharmacology, State University of New York, Syracuse,
New York 13210, United States
| | - Jing An
- SUNY Upstate Cancer Research Institute,
Department of Pharmacology, State University of New York, Syracuse,
New York 13210, United States
| | - Elena B. Pasquale
- Sanford-Burnham Medical Research Institute,
La Jolla, California 92037, United States
- Department of Pathology, University
of California, San Diego, California 92093, United States
| | - Ziwei Huang
- SUNY Upstate Cancer Research Institute,
Department of Pharmacology, State University of New York, Syracuse,
New York 13210, United States
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9
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Harrison OJ, Vendome J, Brasch J, Jin X, Hong S, Katsamba PS, Ahlsen G, Troyanovsky RB, Troyanovsky SM, Honig B, Shapiro L. Nectin ectodomain structures reveal a canonical adhesive interface. Nat Struct Mol Biol 2012; 19:906-15. [PMID: 22902367 PMCID: PMC3443293 DOI: 10.1038/nsmb.2366] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 07/19/2012] [Indexed: 11/21/2022]
Abstract
Nectins are immunoglobulin superfamily glycoproteins that mediate intercellular adhesion in many vertebrate tissues. Homophilic and heterophilic interactions between nectin family members help to mediate tissue patterning. We determined homophilic binding affinities and heterophilic specificities of all four nectins and the related protein nectin-like 5 from human and mouse, revealing a range of homophilic strengths and a defined heterophilic specificity pattern. To understand the molecular basis of adhesion and specificity, we determined crystal structures of natively glycosylated full ectodomains or adhesive fragments of nectins 1–4 and nectin-like 5. All crystal structures reveal dimeric nectins bound through a stereotyped interface previously proposed to represent a cis dimer. However, conservation of this interface and results of targeted cross-linking experiments show that this dimer likely represents the adhesive trans interaction. Its structure provides a simple molecular explanation for the adhesive binding specificity of nectins.
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Affiliation(s)
- Oliver J Harrison
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York, USA
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10
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Xu Q, Lin WC, Petit RS, Groves JT. EphA2 receptor activation by monomeric Ephrin-A1 on supported membranes. Biophys J 2012; 101:2731-9. [PMID: 22261062 DOI: 10.1016/j.bpj.2011.10.039] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 10/07/2011] [Accepted: 10/31/2011] [Indexed: 01/22/2023] Open
Abstract
The receptor tyrosine kinase EphA2 interacts with its glycosylphosphatidylinositol (GPI)-linked ephrin-A1 ligand in a juxtacrine configuration. The soluble ephrin-A1 protein, without its GPI membrane linker, fails to activate EphA2. However, preclustered ephrin-A1 protein is active in solution and has been frequently used to trigger the EphA2 receptor. Although this approach has yielded insights into EphA2 signaling, preclustered ligands bypass natural receptor clustering processes and thus mask any role of clustering as a signal regulatory mechanism. Here, we present EphA2-expressing cells with a fusion protein of monomeric ephrin-A1 (mEA1) and enhanced monomeric yellow fluorescent protein that is linked to a supported lipid bilayer via a nickel-decahistidine anchor. The mEA1 is homogeneously dispersed, laterally mobile, and monomeric as measured by fluorescence imaging, correlation spectroscopy, and photon counting histogram analysis, respectively. Ephrin-A1 presented in this manner activates EphA2 on the surface of MDA-MB-231 human breast cancer cells, as measured by EphA2 phosphorylation and degradation. Spatial mutation experiments in which nanopatterns on the underlying substrate restrict mEA1 movement in the supported lipid bilayer reveal spatio-mechanical regulation of this signaling pathway, consistent with recently reported observations using a synthetically cross-linked ephrin-A1 dimer.
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Affiliation(s)
- Qian Xu
- Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, California, USA
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11
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Noberini R, Rubio de la Torre E, Pasquale EB. Profiling Eph receptor expression in cells and tissues: a targeted mass spectrometry approach. Cell Adh Migr 2012; 6:102-12. [PMID: 22568954 DOI: 10.4161/cam.19620] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The Eph receptor tyrosine kinase family includes many members, which are often expressed together in various combinations and can promiscuously interact with multiple ephrin ligands, generating intricate networks of intracellular signals that control physiological and pathological processes. Knowing the entire repertoire of Eph receptors and ephrins expressed in a biological sample is important when studying their biological roles. Moreover, given the correlation between Eph receptor/ephrin expression and cancer pathogenesis, their expression patterns could serve important diagnostic and prognostic purposes. However, profiling Eph receptor and ephrin expression has been challenging. Here we describe a novel and straightforward approach to catalog the Eph receptors present in cultured cells and tissues. By measuring the binding of ephrin Fc fusion proteins to Eph receptors in ELISA and pull-down assays, we determined that a mixture of four ephrins is suitable for isolating both EphA and EphB receptors in a single pull-down. We then used mass spectrometry to identify the Eph receptors present in the pull-downs and estimate their relative levels. This approach was validated in cultured human cancer cell lines, human tumor xenograft tissue grown in mice, and mouse brain tissue. The new mass spectrometry approach we have developed represents a useful tool for the identification of the spectrum of Eph receptors present in a biological sample and could also be extended to profiling ephrin expression.
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12
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Abstract
The family of Eph tyrosine kinase receptors is an important part of signaling pathways involved in development, tissue homeostasis and tumorigenesis. Binding and activation of the receptors by their ligands, the ephrins, result in bidirectional signaling into both receptor and ligand expressing cells. Adult stem cell niches and tumors frequently express receptors and ligands, although their function is only beginning to be understood. Thus, Eph receptors and ephrins have become important molecules for understanding basic biological processes as well as tumorigenesis, and are promising targets for potential therapeutic intervention in human disease.
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Affiliation(s)
- Maria Genander
- Howard Hughes Medical Institute, Laboratory of Mammalian Cell Biology & Development, The Rockefeller University, New York, NY, USA.
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13
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Lisabeth EM, Fernandez C, Pasquale EB. Cancer somatic mutations disrupt functions of the EphA3 receptor tyrosine kinase through multiple mechanisms. Biochemistry 2012; 51:1464-75. [PMID: 22242939 DOI: 10.1021/bi2014079] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The Eph receptor tyrosine kinases make up an important family of signal transduction molecules that control many cellular processes, including cell adhesion and movement, cell shape, and cell growth. All of these are important aspects of cancer progression, but the relationship between Eph receptors and cancer is complex and not fully understood. Genetic screens of tumor specimens from cancer patients have revealed somatic mutations in many Eph receptors. The most highly mutated Eph receptor is EphA3, but its functional role in cancer is currently not well established. Here we show that many EphA3 mutations identified in lung, colorectal, and hepatocellular cancers, melanoma, and glioblastoma impair kinase activity or ephrin ligand binding and/or decrease the level of receptor cell surface localization. These results suggest that EphA3 has ephrin- and kinase-dependent tumor suppressing activities, which are disrupted by somatic cancer mutations.
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Affiliation(s)
- Erika M Lisabeth
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, United States
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14
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Concepts and consequences of Eph receptor clustering. Semin Cell Dev Biol 2012; 23:43-50. [PMID: 22261642 DOI: 10.1016/j.semcdb.2012.01.001] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Accepted: 01/04/2012] [Indexed: 12/31/2022]
Abstract
Polymeric receptor-ligand complexes between interacting Eph and ephrin-expressing cells are regarded as dynamic intercellular signalling scaffolds that control cell-to-cell contact: the resulting Eph-ephrin signalling clusters function as positional cues that facilitate cell navigation and tissue patterning during normal and oncogenic development. The considerable complexity of this task, coordinating a multitude of cell movements and cellular interactions, is achieved by accurate translation of spatial information from Eph and ephrin expression gradients into fine-tuned changes in cell-cell adhesion and position. Here we review emerging evidence suggesting that the required combinatorial diversity is not only achieved by the large number of possible Eph-ephrin interactions and selective use of Eph forward and ephrin reverse signals, but in particular through the composition and signal capacity of Eph-ephrin clusters, which is adjusted dynamically to reflect overall Eph and ephrin surface densities on interacting cells. Fine-tuning is provided through multi-layered cluster assembly, where homo- and heterotypic Eph and ephrin interactions define the composition - whilst intracellular signalling feedbacks determine the size and lifetime - of signalling clusters.
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15
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Janes PW, Griesshaber B, Atapattu L, Nievergall E, Hii LL, Mensinga A, Chheang C, Day BW, Boyd AW, Bastiaens PI, Jørgensen C, Pawson T, Lackmann M. Eph receptor function is modulated by heterooligomerization of A and B type Eph receptors. ACTA ACUST UNITED AC 2011; 195:1033-45. [PMID: 22144690 PMCID: PMC3241718 DOI: 10.1083/jcb.201104037] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Beyond homotypic receptor interactions that are required for Eph signaling, ligand-independent association and crosstalk between members of the EphA and -B subclasses determine cell signaling outcomes. Eph receptors interact with ephrin ligands on adjacent cells to facilitate tissue patterning during normal and oncogenic development, in which unscheduled expression and somatic mutations contribute to tumor progression. EphA and B subtypes preferentially bind A- and B-type ephrins, respectively, resulting in receptor complexes that propagate via homotypic Eph–Eph interactions. We now show that EphA and B receptors cocluster, such that specific ligation of one receptor promotes recruitment and cross-activation of the other. Remarkably, coexpression of a kinase-inactive mutant EphA3 with wild-type EphB2 can cause either cross-activation or cross-inhibition, depending on relative expression. Our findings indicate that cellular responses to ephrin contact are determined by the EphA/EphB receptor profile on a given cell rather than the individual Eph subclass. Importantly, they imply that in tumor cells coexpressing different Ephs, functional mutations in one subtype may cause phenotypes that are a result of altered signaling from heterotypic rather from homotypic Eph clusters.
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Affiliation(s)
- Peter W Janes
- Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
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16
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Himanen JP. Ectodomain structures of Eph receptors. Semin Cell Dev Biol 2011; 23:35-42. [PMID: 22044883 DOI: 10.1016/j.semcdb.2011.10.025] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 10/17/2011] [Indexed: 11/25/2022]
Abstract
Eph receptors, the largest subfamily of receptor tyrosine kinases (RTKs), and their ephrin ligands are important mediators of cell-cell communication that regulate axon guidance, long-term potentiation, and stem cell development, among others. By now, many Eph receptors and ephrins have also been found to play important roles in the progression of cancer. Since both the receptor and the ligand are membrane-bound, their interaction leads to the multimerization of both molecules to distinct clusters within their respective plasma membranes, resulting in the formation of discrete signaling centers. In addition, and unique to Eph receptors and ephrins, their interaction initiates bi-directional signaling cascades where information is transduced in the direction of both the receptor- and the ligand-bearing cells. The Ephs and the ephrins are divided into two subclasses, A and B, based on their affinities for each other and on sequence conservation. Crystal structures and other biophysical studies have indicated that isolated extracellular Eph and ephrin domains initially form high-affinity heterodimers around a hydrophobic loop of the ligand that is buried in a hydrophobic pocket on the surface of the receptor. The dimers can then further arrange by weaker interactions into higher-order Eph/ephrin clusters observed in vivo at the sites of cell-cell contact. Although the hetero-dimerization is a universal way to initiate signaling, other extracellular domains of Ephs are involved in the formation of higher-order clusters. The structures also show important differences defining the unique partner preferences of the two ligand and receptor subclasses, namely, how subclass specificity is determined both by individual interacting residues and by the precise architectural arrangement of ligands and receptors within the complexes.
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Affiliation(s)
- Juha P Himanen
- Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
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17
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Mitra S, Duggineni S, Koolpe M, Zhu X, Huang Z, Pasquale EB. Structure-activity relationship analysis of peptides targeting the EphA2 receptor. Biochemistry 2010; 49:6687-95. [PMID: 20677833 DOI: 10.1021/bi1006223] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The EphA2 receptor tyrosine kinase has emerged as a promising new therapeutic target in cancer because of its high level of expression in tumors. EphA2-specific antibodies have been used to deliver drugs and toxins to tumor cells, leading to inhibition of tumor growth and metastatic dissemination. We previously identified two related peptides, YSA and SWL, that selectively bind to the ligand-binding domain of EphA2 but not other Eph receptors and could therefore be useful as selective targeting agents. Here we characterize the two peptides and a series of derivatives. On the basis of systematic amino acid replacements, only five YSA residues appear to be critical for high-affinity receptor binding. Furthermore, a peptide comprising only the first five residues of YSA retains selectivity for EphA2. Similar to ephrin-A1, the physiological ligand for EphA2, both YSA and SWL activate EphA2 and inhibit downstream oncogenic signaling pathways in PC3 cancer cells. The two peptides and derivatives are quite stable in conditioned cell culture medium and show promise for delivering drugs and imaging agents to EphA2-expressing tumors.
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Affiliation(s)
- Sayantan Mitra
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, USA
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18
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Ting MJ, Day BW, Spanevello MD, Boyd AW. Activation of ephrin A proteins influences hematopoietic stem cell adhesion and trafficking patterns. Exp Hematol 2010; 38:1087-98. [PMID: 20655977 DOI: 10.1016/j.exphem.2010.07.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2009] [Revised: 07/09/2010] [Accepted: 07/14/2010] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine if Eph receptors and ephrins can modulate the homing of hematopoietic cells in a murine bone marrow transplantation model. MATERIALS AND METHODS EphA and ephrin A gene expression by mouse hematopoietic stem cells and the progenitor cell line FDCP-1 was determined by real-time reverse transcription polymerase chain reaction and flow cytometry. The effect of ephrin A activation on adhesion of hematopoietic progenitors was determined by in vitro adhesion assays in which cells were exposed to fibronectin or vascular cell adhesion molecule-1 (VCAM-1) and an increasing gradient of immobilized EphA3-Fc. Adhesion to fibronectin and VCAM-1 was further investigated using soluble preclustered EphA3-Fc. We used soluble unclustered EphA3-Fc as an antagonist to block endogenous EphA-ephrin A interactions in vivo. The effect of injecting soluble EphA3-Fc on the mobilization of hematopoietic progenitor cells was examined. We determined the effect on short-term homing by pretreating bone marrow cells with EphA3-Fc or the control IgG before infusion into lethally irradiated mice. RESULTS Preclustered and immobilized EphA3-Fc increased adhesion of progenitor cells and FDCP-1 to fibronectin and VCAM-1 (1.6- to 2-fold higher adhesion; p < 0.05) relative to control (0 μ/cm(2) EphA3-Fc extracellular molecule alone). Injection of the antagonist soluble EphA3-Fc increased progenitor cell and colony-forming unit-spleen cells in the peripheral blood (42% greater colony-forming unit in culture; p < 0.05, 3.8-fold higher colony-forming unit-spleen) relative to control. CONCLUSION Treating bone marrow cells with EphA3-Fc resulted in a reduction by 31% in donor stem cells homing to the bone marrow and accumulation of donor cells in recipient spleens (50% greater than control) and greater recovery of donor stem cells from the peripheral blood.
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Affiliation(s)
- Michael J Ting
- Leukaemia Foundation of Queensland Research Unit, Queensland Institute of Medical Research, Brisbane, Australia.
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19
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Chen Y, Xiong DH, Guo YF, Pan F, Zhou Q, Zhang F, Deng HW. Pathway-based genome-wide association analysis identified the importance of EphrinA-EphR pathway for femoral neck bone geometry. Bone 2010; 46:129-36. [PMID: 19786129 PMCID: PMC2818219 DOI: 10.1016/j.bone.2009.09.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 09/09/2009] [Accepted: 09/22/2009] [Indexed: 02/07/2023]
Abstract
Femoral neck (FN) bone geometry is an important predictor of bone strength with high heritability. Previous studies have revealed certain candidate genes for FN bone geometry. However, the majority of the underlying genetic factors remain to be discovered. In this study, pathway-based genome-wide association analysis was performed to explore the joint effects of genes within biological pathways on FN bone geometry variations in a cohort of 1000 unrelated US whites. Nominal significant associations (nominal p value<0.05) were observed between 76 pathways and a key FN bone geometry variable-section modulus (Z), biomechanically indicative of bone strength subject to bending. Among them, EphrinA-EphR pathway was most significantly associated with FN Z even after multiple testing adjustments (p(FWER) value=0.035). The association of EphrinA-EphR pathway with FN Z was also observed in an independent sample from Framingham Osteoporosis Study. Overall, these results suggest the significant genetic contribution of EphrinA-EphR pathway to femoral neck bone geometry.
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Affiliation(s)
- Yuan Chen
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education and Institute of Molecular Genetics, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, P. R. China
| | - Dong-Hai Xiong
- Departments of Orthopedic Surgery and Basic Medical Sciences, University of Missouri - Kansas City, Kansas City, MO 64108, USA
| | - Yan-Fang Guo
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education and Institute of Molecular Genetics, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, P. R. China
| | - Feng Pan
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education and Institute of Molecular Genetics, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, P. R. China
| | - Qi Zhou
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education and Institute of Molecular Genetics, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, P. R. China
| | - Feng Zhang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education and Institute of Molecular Genetics, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, P. R. China
| | - Hong-Wen Deng
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education and Institute of Molecular Genetics, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, P. R. China
- Departments of Orthopedic Surgery and Basic Medical Sciences, University of Missouri - Kansas City, Kansas City, MO 64108, USA
- College of Life Sciences and Engineering, Beijing Jiaotong University, Beijing 100044, P. R. China
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20
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Pulkkinen K, Malm T, Turunen M, Koistinaho J, Ylä-Herttuala S. Hypoxia induces microRNA miR-210 in vitro and in vivo ephrin-A3 and neuronal pentraxin 1 are potentially regulated by miR-210. FEBS Lett 2008; 582:2397-401. [PMID: 18539147 DOI: 10.1016/j.febslet.2008.05.048] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Revised: 05/29/2008] [Accepted: 05/29/2008] [Indexed: 12/11/2022]
Abstract
Shortage of oxygen is one of the prime stress conditions in tissues. In this study, we looked for microRNAs expressed during hypoxia and showed that miR-210 expression was upregulated in response to hypoxia in vitro and in vivo. An active form of the HIF-1alpha induced the expression of miR-210, showing the involvement of the HIF-1 signaling pathway in miR-210 gene transcription. Furthermore, miR-210 was shown to bind to the predicted target sites of ephrin-A3 or neuronal pentraxin 1, causing repression in luciferase reporter activity. Contrary to the microRNA-mediated repression hypothesis, ephrin-A3 was expressed at very high levels in post-ischemic mouse hippocampus in vivo. Thus, the regulatory effects of miR-210 on its targets in vivo need to be further characterized.
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Affiliation(s)
- Kati Pulkkinen
- Department of Biotechnology and Molecular Medicine, A. I. Virtanen Institute for Molecular Sciences, Kuopio University, P.O. Box 1627, FIN-70211 Kuopio, Finland
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21
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Lackmann M, Boyd AW. Eph, a protein family coming of age: more confusion, insight, or complexity? Sci Signal 2008; 1:re2. [PMID: 18413883 DOI: 10.1126/stke.115re2] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Since the mid-1980s, Eph receptors have evolved from being regarded as orphan receptors with unknown functions and ligands to becoming one of the most complex "global positioning systems" that regulates cell traffic in multicellular organisms. During this time, there has been an exponentially growing interest in Ephs and ephrin ligands, coinciding with important advances in the way biological function is interrogated through mapping of genomes and manipulation of genes. As a result, many of the original concepts that used to define Eph signaling and function went overboard. Clearly, the need for progress in understanding Eph-ephrin biology and the underlying molecular principles involved has been compelling. Many cell-positioning programs during normal and oncogenic development-in particular, the patterning of skeletal, vascular, and nervous systems-are modulated in some way by Eph-ephrin function. Undeniably, the complexity of the underlying signaling networks is considerable, and it seems probable that systems biology approaches are required to further improve our understanding of Eph function.
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Affiliation(s)
- Martin Lackmann
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia.
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22
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Pabbisetty KB, Yue X, Li C, Himanen JP, Zhou R, Nikolov DB, Hu L. Kinetic analysis of the binding of monomeric and dimeric ephrins to Eph receptors: correlation to function in a growth cone collapse assay. Protein Sci 2007; 16:355-61. [PMID: 17322526 PMCID: PMC2203307 DOI: 10.1110/ps.062608807] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Eph receptors and ephrins play important roles in regulating cell migration and positioning during both normal and oncogenic tissue development. Using a surface plasma resonance (SPR) biosensor, we examined the binding kinetics of representative monomeric and dimeric ephrins to their corresponding Eph receptors and correlated the apparent binding affinity with their functional activity in a neuronal growth cone collapse assay. Our results indicate that the Eph receptor binding of dimeric ephrins, formed through fusion with disulfide-linked Fc fragments, is best described using a bivalent analyte model as a two-step process involving an initial monovalent 2:1 binding followed by a second bivalent 2:2 binding. The bivalent binding dramatically decreases the apparent dissociation rate constants with little effect on the initial association rate constants, resulting in a 30- to 6000-fold decrease in apparent equilibrium dissociation constants for the binding of dimeric ephrins to Eph receptors relative to their monomeric counterparts. Interestingly, the change was more prominent in the A-class ephrin/Eph interactions than in the B-class of ephrins to Eph receptors. The increase in apparent binding affinities correlated well with increased activation of Eph receptors and the resulting growth cone collapse. Our kinetic analysis and correlation of binding affinity with function helped us better understand the interactions between ephrins and Eph receptors and should be useful in the design of inhibitors that interfere with the interactions.
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Affiliation(s)
- Kumar B Pabbisetty
- Department of Pharmaceutical Chemistry, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
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23
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Zhang J, Hughes S. Role of the ephrin and Eph receptor tyrosine kinase families in angiogenesis and development of the cardiovascular system. J Pathol 2006; 208:453-61. [PMID: 16470907 DOI: 10.1002/path.1937] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Angiogenesis is a highly complex orchestrated process that plays a critical role in normal development and in the pathophysiology of multiple disease processes, including tumour neovascularization, ischaemic recovery, and wound healing. In recent years there has been a resurgence of interest in Eph receptors and their ligands, ephrins, as their participation in vasculogenesis and angiogenesis has become apparent. The Eph receptor family is the largest family of receptor tyrosine kinases identified to date. The Eph receptors and their membrane-anchored ligands, ephrins, are unique in that they mediate bi-directional signalling. This is concomitant with activation of the Eph receptor tyrosine kinase domain and transduction of the typical forward signal into the receptor-bearing cell. The ligand-receptor interaction also leads to transduction of a reverse signal into the ephrin-bearing cell. The Eph/ephrin signalling mechanism is responsible for diverse and complex biological functions mediated by Eph receptors and ephrin ligands. These include vascular development, tissue-border formation, cell migration, axon guidance, and synaptic plasticity. The role of Eph receptors and ephrins in the processes of development of the cardiovascular system, angiogenesis, and vascular remodelling has been the subject of intense investigation since they were first identified in 1987. This review addresses the role of this new growth factor receptor tyrosine kinase family in those processes and provides new insights into the way in which Eph receptors and ephrin ligands modulate the angiogenic response and participate in vascular remodelling and vascular boundary formation during development of the cardiovascular system and vascularization of cancer.
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Affiliation(s)
- J Zhang
- Department of Pathology, Royal Free and University College Medical School, London, WC1E 6JJ, UK.
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24
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Otal R, Burgaya F, Frisén J, Soriano E, Martínez A. Ephrin-A5 modulates the topographic mapping and connectivity of commissural axons in murine hippocampus. Neuroscience 2006; 141:109-21. [PMID: 16690216 DOI: 10.1016/j.neuroscience.2006.03.052] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2005] [Revised: 02/17/2006] [Accepted: 03/20/2006] [Indexed: 10/24/2022]
Abstract
Entorhinal and commissural/associational projections show a non-overlapping distribution in the hippocampus proper and the dentate gyrus. The expression of Ephrins and their Eph receptors in the developing hippocampus indicates that this family of axonal guidance molecules may modulate the formation of these connections. Here we focused on the role of the ephrin-A5 ligand in the development of the main hippocampal afferents. In situ hybridization showed that ephrin-A5 mRNA was detected mainly in the principal cells of the hippocampus proper and in the dentate gyrus throughout postnatal development. Immunocytochemical analyses revealed prominent expression of the EphA3 receptor, a putative receptor for ephrin-A5, in the main cells and the neuropil of the developing hippocampus. Tracing experiments in ephrin-A5(-/-) mice showed that commissural projections were transiently altered in the hippocampus proper at P5, but they were mistargeted throughout the postnatal development in the dentate gyrus. Immunocytochemistry with anti-calbindin antibodies revealed that the dentate mossy fiber projection was not altered in ephrin-A5(-/-) mice. Electron microscopy studies showed alterations in the density of synapses and spines in commissural/associational layers, but not in entorhinal layers, and in the mossy fibers in these animals. Taken together, these findings indicate that ephrin-A5 signaling is involved in the formation and maturation of synapses in the hippocampus.
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Affiliation(s)
- R Otal
- Department of Cell Biology, University of Barcelona and Institut de Recerca Biomèdica, Parc Científic de Barcelona, E-08028 Barcelona, Spain
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25
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Nikolov DB, Li C, Barton WA, Himanen JP. Crystal structure of the ephrin-B1 ectodomain: implications for receptor recognition and signaling. Biochemistry 2005; 44:10947-53. [PMID: 16101278 DOI: 10.1021/bi050789w] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Eph receptors and their ephrin ligands are involved in various aspects of cell-cell communication during development, including axonal pathfinding in the nervous system and cell-cell interactions of the vascular endothelial cells. Recent structural studies revealed unique molecular features, not previously seen in any other receptor-ligand families, and explained many of the biochemical and signaling properties of Ephs and ephrins. However, unresolved questions remain regarding the potential oligomerization and clustering of these important signaling molecules. In this study, the biophysical properties and receptor-binding preferences of the extracellular domain of ephrin-B1 were investigated and its crystal structure was determined at 2.65 A resolution. Ephrin-B1 is a monomer both in solution and in the crystals, while it was previously shown that the closely related ephrin-B2 forms homodimers. The main structural difference between ephrin-B1 and ephrin-B2 is the conformation of the receptor-binding G-H loop and the partially disordered N-terminal tetramerization region of ephrin-B1. The G-H loop is structurally rigid in ephrin-B2 and adopts the same conformation in both the receptor-bound and unbound ligand, where it mediates receptor-independent homodimerization. In the ephrin-B1 structure, on the other hand, the G-H loop is not involved in any homotypic interactions and adopts a new, distinct conformation. The implications of the ephrin-B1 structure, in context of available ephrin-B1 mutagenesis data, for the mechanism of Eph-ephrin recognition and signaling initiation are discussed.
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Affiliation(s)
- Dimitar B Nikolov
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA
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26
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Vearing C, Lee FT, Wimmer-Kleikamp S, Spirkoska V, To C, Stylianou C, Spanevello M, Brechbiel M, Boyd AW, Scott AM, Lackmann M. Concurrent binding of anti-EphA3 antibody and ephrin-A5 amplifies EphA3 signaling and downstream responses: potential as EphA3-specific tumor-targeting reagents. Cancer Res 2005; 65:6745-54. [PMID: 16061656 DOI: 10.1158/0008-5472.can-05-0758] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Eph receptor tyrosine kinases and their membrane-bound ephrin ligands form a unique cell-cell contact-mediated system for controlling cell localization and organization. Their high expression in a wide variety of human tumors indicates a role in tumor progression, and relatively low Eph and ephrin levels in normal tissues make these proteins potential targets for anticancer therapies. The monoclonal antibody IIIA4, previously used to isolate EphA3, binds with subnanomolar affinity to a conformation-specific epitope within the ephrin-binding domain that is closely adjacent to the "low-affinity" ephrin-A5 heterotetramerization site. We show that similar to ephrin-A5, preclustered IIIA4 effectively triggers EphA3 activation, contraction of the cytoskeleton, and cell rounding. BIAcore analysis, immunoblot, and confocal microscopy of wild-type and mutant EphA3 with compromised ephrin-A5 or IIIA4-binding capacities indicate that IIIA4 binding triggers an EphA3 conformation which is permissive for the assembly of EphA3/ephrin-A5-type signaling clusters. Furthermore, unclustered IIIA4 and ephrin-A5 Fc applied in combination initiate greatly enhanced EphA3 signaling. Radiometal conjugates of ephrin-A5 and IIIA4 retain their affinity, and in mouse xenografts localize to, and are internalized rapidly into EphA3-positive, human tumors. These findings show the biological importance of EphA3/ephrin-A5 interactions and that ephrin-A5 and IIIA4 have great potential as tumor targeting reagents.
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MESH Headings
- Animals
- Antibodies, Monoclonal/metabolism
- Antibodies, Monoclonal/pharmacokinetics
- Antibodies, Monoclonal/pharmacology
- Cell Line, Tumor
- Ephrin-A5/metabolism
- Humans
- Immunoconjugates/pharmacokinetics
- Immunoconjugates/pharmacology
- Indium Radioisotopes/pharmacokinetics
- Melanoma/diagnostic imaging
- Melanoma/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Nude
- Precursor B-Cell Lymphoblastic Leukemia-Lymphoma/diagnostic imaging
- Precursor B-Cell Lymphoblastic Leukemia-Lymphoma/metabolism
- Protein Structure, Tertiary
- Radionuclide Imaging
- Receptor Protein-Tyrosine Kinases/immunology
- Receptor Protein-Tyrosine Kinases/metabolism
- Receptor, EphA3
- Receptors, Fc/metabolism
- Signal Transduction
- Substrate Specificity
- Tissue Distribution
- Transplantation, Heterologous
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Affiliation(s)
- Christopher Vearing
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia.
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27
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Day B, To C, Himanen JP, Smith FM, Nikolov DB, Boyd AW, Lackmann M. Three Distinct Molecular Surfaces in Ephrin-A5 Are Essential for a Functional Interaction with EphA3. J Biol Chem 2005; 280:26526-32. [PMID: 15901737 DOI: 10.1074/jbc.m504972200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Eph receptor tyrosine kinases (Ephs) function as molecular relays that interact with cell surface-bound ephrin ligands to direct the position of migrating cells. Structural studies revealed that, through two distinct contact surfaces on opposite sites of each protein, Eph and ephrin binding domains assemble into symmetric, circular heterotetramers. However, Eph signal initiation requires the assembly of higher order oligomers, suggesting additional points of contact. By screening a random library of EphA3 binding-compromised ephrin-A5 mutants, we have now determined ephrin-A5 residues that are essential for the assembly of high affinity EphA3 signaling complexes. In addition to the two interfaces predicted from the crystal structure of the homologous EphB2.ephrin-B2 complex, we identified a cluster of 10 residues on the ephrin-A5 E alpha-helix, the E-F loop, the underlying H beta-strand, as well as the nearby B-C loop, which define a distinct third surface required for oligomerization and activation of EphA3 signaling. Together with a corresponding third surface region identified recently outside of the minimal ephrin binding domain of EphA3, our findings provide experimental evidence for the essential contribution of three distinct protein-interaction interfaces to assemble functional EphA3 signaling complexes.
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Affiliation(s)
- Bryan Day
- Queensland Institute of Medical Research, P. O. Royal Brisbane Hospital 4029, Queensland, Australia
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28
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Martínez A, Soriano E. Functions of ephrin/Eph interactions in the development of the nervous system: emphasis on the hippocampal system. ACTA ACUST UNITED AC 2005; 49:211-26. [PMID: 16111551 DOI: 10.1016/j.brainresrev.2005.02.001] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2004] [Revised: 02/01/2005] [Accepted: 02/04/2005] [Indexed: 12/20/2022]
Abstract
Ephrins and their Eph receptors are membrane-anchored proteins that have key roles in the development of the Central Nervous System. The main characteristics of ephrin/Eph interactions are that their effect is mediated by cell-to-cell contacts and that they can propagate bidirectional signals downstream of the ligand-receptor complex. These characteristics make ephrins and Eph receptors critical cues in the regulation of migrating cells or axons, and in the establishment of tissue patterns and topographic maps in distinct regions of the developing brain. In addition, ephrins and Eph receptors regulate synapse formation and plasticity. These roles would be promoted by complementary gradual expression of receptors and ligands in the neurons involved. Although, historically, ephrins and Eph receptors have been considered as repulsion signals through barriers or gradients, new evidence indicates that they may be both inhibitory and permissive/active cues depending on expression levels. The expression of distinct ligands and receptors in the developing and mature hippocampus suggests that these proteins are involved in distinct processes during the development and maturation of the hippocampal region. In fact, recent studies have shown that ephrin/Eph signaling participates in the formation of the layer-specific patterns of hippocampal afferents, in synaptogenesis and in plasticity. Therefore, ephrin/Eph interactions should be considered a crucial system in the development and maturation of the brain regions, including the hippocampus.
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Affiliation(s)
- Albert Martínez
- Neuronal Development and Regeneration Group (S1-A1), Department of Cell Biology, University of Barcelona/Barcelona Science Park, Josep Samitier 1-5, Barcelona E-08028, Spain.
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29
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Koolpe M, Burgess R, Dail M, Pasquale EB. EphB receptor-binding peptides identified by phage display enable design of an antagonist with ephrin-like affinity. J Biol Chem 2005; 280:17301-11. [PMID: 15722342 DOI: 10.1074/jbc.m500363200] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Eph receptor tyrosine kinases are overexpressed in many pathologic tissues and have therefore emerged as promising drug target candidates. However, there are few molecules available that can selectively bind to a single Eph receptor and not other members of this large receptor family. Here we report the identification by phage display of peptides that bind selectively to different receptors of the EphB class, including EphB1, EphB2, and EphB4. Peptides with the same EphB receptor specificity compete with each other for binding, suggesting that they have partially overlapping binding sites. In addition, several of the peptides contain amino acid motifs found in the G-H loop of the ephrin-B ligands, which is the region that mediates high-affinity interaction with the EphB receptors. Consistent with targeting the ephrin-binding site, the higher affinity peptides antagonize ephrin binding to the EphB receptors. We also designed an optimized EphB4-binding peptide with affinity comparable with that of the natural ligand, ephrin-B2. These peptides should be useful as selective inhibitors of the pathological activities of EphB receptors and as targeting agents for imaging probes and therapeutic drugs.
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MESH Headings
- Amino Acid Motifs
- Animals
- Binding Sites
- Binding, Competitive
- COS Cells
- Cell Line
- Cell Line, Tumor
- Dose-Response Relationship, Drug
- Enzyme-Linked Immunosorbent Assay
- Ephrins/chemistry
- Humans
- Immunoblotting
- Immunoprecipitation
- Ligands
- Microscopy, Fluorescence
- Peptide Library
- Peptides/chemistry
- Protein Binding
- Protein Structure, Tertiary
- Receptor, EphB1/chemistry
- Receptor, EphB2/chemistry
- Receptor, EphB4/chemistry
- Receptors, Eph Family/metabolism
- Receptors, Eph Family/physiology
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30
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Jayasena CS, Flood WD, Koblar SA. High EphA3 expressing ophthalmic trigeminal sensory axons are sensitive to ephrin-A5-Fc: Implications for lobe specific axon guidance. Neuroscience 2005; 135:97-109. [PMID: 16054765 DOI: 10.1016/j.neuroscience.2005.05.052] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2005] [Revised: 05/16/2005] [Accepted: 05/16/2005] [Indexed: 11/17/2022]
Abstract
The ophthalmic, maxillary and mandibular axon branches of the trigeminal ganglion provide cutaneous sensory innervation to the vertebrate face. In the chick embryo, the trigeminal ganglion is bilobed, with ophthalmic axons projecting from the ophthalmic lobe, while maxillary and mandibular projections emerge from the maxillomandibular lobe. To date, target tissue specific guidance cues that discriminately guide the axon projections from the two trigeminal ganglion lobes are unknown. EphA receptor tyrosine kinases and ephrin-A ligands are excellent candidates for this process as they are known to mediate axon guidance in the developing nervous system. Accordingly, the expression of EphAs and ephrin-As was investigated at stages 13, 15, 20 of chick embryogenesis when peripheral axons from the trigeminal ganglion are pathfinding. EphA3 is expressed highly in the ophthalmic trigeminal ganglion lobe neurons in comparison to maxillomandibular trigeminal ganglion lobe neurons. Furthermore, from stages 13-20 ephrin-A2 and ephrin-A5 ligands are only localized to the mesenchyme of the first branchial arch (maxillary and mandibular processes), the target fields for maxillomandibular trigeminal ganglion axons. We found that ophthalmic and not maxillomandibular lobe axons were responsive to ephrin-A5-Fc utilizing a substratum choice assay. The implication of these results is that EphA3 forward signaling in ophthalmic sensory axons may be an important mechanism in vivo for lobe specific guidance of trigeminal ganglion ophthalmic projections.
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Affiliation(s)
- C S Jayasena
- ARC Centre for Molecular Genetics of Development (CMGD), School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, South Australia 5005, Australia
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Poliakov A, Cotrina M, Wilkinson DG. Diverse roles of eph receptors and ephrins in the regulation of cell migration and tissue assembly. Dev Cell 2004; 7:465-80. [PMID: 15469835 DOI: 10.1016/j.devcel.2004.09.006] [Citation(s) in RCA: 339] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Eph receptor tyrosine kinases and ephrins have key roles in regulation of the migration and adhesion of cells required to form and stabilize patterns of cell organization during development. Activation of Eph receptors or ephrins can lead either to cell repulsion or to cell adhesion and invasion, and recent work has found that cells can switch between these distinct responses. This review will discuss biochemical mechanisms and developmental roles of the diverse cell responses controlled by Eph receptors and ephrins.
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Affiliation(s)
- Alexei Poliakov
- Division of Developmental Neurobiology, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
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Wimmer-Kleikamp SH, Janes PW, Squire A, Bastiaens PIH, Lackmann M. Recruitment of Eph receptors into signaling clusters does not require ephrin contact. ACTA ACUST UNITED AC 2004; 164:661-6. [PMID: 14993233 PMCID: PMC2172175 DOI: 10.1083/jcb.200312001] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Eph receptors and their cell membrane-bound ephrin ligands regulate cell positioning and thereby establish or stabilize patterns of cellular organization. Although it is recognized that ephrin clustering is essential for Eph function, mechanisms that relay information of ephrin density into cell biological responses are poorly understood. We demonstrate by confocal time-lapse and fluorescence resonance energy transfer microscopy that within minutes of binding ephrin-A5-coated beads, EphA3 receptors assemble into large clusters. While remaining positioned around the site of ephrin contact, Eph clusters exceed the size of the interacting ephrin surface severalfold. EphA3 mutants with compromised ephrin-binding capacity, which alone are incapable of cluster formation or phosphorylation, are recruited effectively and become phosphorylated when coexpressed with a functional receptor. Our findings reveal consecutive initiation of ephrin-facilitated Eph clustering and cluster propagation, the latter of which is independent of ephrin contacts and cytosolic Eph signaling functions but involves direct Eph-Eph interactions.
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Affiliation(s)
- Sabine H Wimmer-Kleikamp
- Dept. of Biochemistry and Molecular Biology, P.O. Box 13D, Monash University, Clayton, Victoria 3800, Australia
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Smith LM, Walsh PT, Rüdiger T, Cotter TG, Mc Carthy TV, Marx A, O'Connor R. EphA3 is induced by CD28 and IGF-1 and regulates cell adhesion. Exp Cell Res 2004; 292:295-303. [PMID: 14697337 DOI: 10.1016/j.yexcr.2003.08.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Stimulation of CD28 alone has been shown to regulate cytokine gene transcription and expression of the type 1 insulin-like growth factor receptor (IGF-1R) in lymphocytes. In this study, the ephrin receptor tyrosine kinase ephA3, was identified as a new CD28-responsive gene in Jurkat cells by using a human cytokine/receptor array. EphA3 was not detected in normal peripheral T cells, in any subset of thymus-derived developing T cells, or in Hodgkin's lymphoma. However, contrary to previous findings, EphA3 was detected in a panel of T-cell lymphomas. Stimulation of Jurkat cells with ephrin-A5 resulted in loss of cell adhesion to fibronectin and recruitment of the adapter protein CrkII to EphA3. Interestingly, EphA3 expression in CD28-stimulated Jurkat cells was enhanced by IGF-1 or by overexpression of the IGF-1R, and was suppressed by anti-IGF-1R blocking antibodies. The data suggest that CD28- and IGF-1-regulated expression of EphA3 is associated with adherence and that it may be involved in the motility of malignant T cells.
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Affiliation(s)
- Loraine M Smith
- Department of Biochemistry, Biosciences Institute, National University of Ireland, Cork, Ireland
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Abstract
Bcl-2-family members (Bcl-2, Bax, Bcl-w and Bcl-x(L)) are crucial integrators of signals for cell survival and death; the pro- or antiapoptotic activities of these proteins are regulated by their subcellular localization. Bcl-2 directly inserts into the membranes, where it acts; however, Bax requires a stimulus-dependent translocation from an inactive cytosolic to an active membrane-inserted state. Recently, a novel mechanism is described for the survival factor Bcl-w, which is active while weakly associated with mitochondria. In apoptotic cells, a BH3-only protein neutralizes the survival activity of Bcl-w by binding to its "hydrophobic pockets", thereby releasing its C-terminal domain and allowing its insertion into the membrane. Here, we discuss the importance of this finding for a better understanding of the action mode of Bcl-w and other Bcl-2-family members.
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Affiliation(s)
- Thomas Kaufmann
- Institute of Molecular Medicine and Cell Research, Zentrale Klinische Forschung (ZKF), Albert-Ludwigs-University Freiburg, Breisacherstrasse 66, 79106 Freiburg, Germany
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35
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Barton WA, Himanen JP, Antipenko A, Nikolov DB. Structures of Axon Guidance Molecules and their Neuronal Receptors. CELL SURFACE RECEPTORS 2004; 68:65-106. [PMID: 15500859 DOI: 10.1016/s0065-3233(04)68003-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- William A Barton
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA
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36
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Smith FM, Vearing C, Lackmann M, Treutlein H, Himanen J, Chen K, Saul A, Nikolov D, Boyd AW. Dissecting the EphA3/Ephrin-A5 interactions using a novel functional mutagenesis screen. J Biol Chem 2003; 279:9522-31. [PMID: 14660665 DOI: 10.1074/jbc.m309326200] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The EphA3 receptor tyrosine kinase preferentially binds ephrin-A5, a member of the corresponding subfamily of membrane-associated ligands. Their interaction regulates critical cell communication functions in normal development and may play a role in neoplasia. Here we describe a random mutagenesis approach, which we employed to study the molecular determinants of the EphA3/ephrin-A5 recognition. Selection and functional characterization of EphA3 point mutants with impaired ephrin-A5 binding from a yeast expression library defined three EphA3 surface areas that are essential for the EphA3/ephrin-A5 interaction. Two of these map to regions identified previously in the crystal structure of the homologous EphB2-ephrin-B2 complex as potential ligand/receptor interfaces. In addition, we identify a third EphA3/ephrin-A5 interface that falls outside the structurally characterized interaction domains. Functional analysis of EphA3 mutants reveals that all three Eph/ephrin contact areas are essential for the assembly of signaling-competent, oligomeric receptor-ligand complexes.
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Affiliation(s)
- Fiona M Smith
- Leukaemia Foundation of Queensland Laboratory, Queensland Institute of Medical Research, P. O. Royal Brisbane Hospital, Queensland 4029, Australia
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Wilson-Annan J, O'Reilly LA, Crawford SA, Hausmann G, Beaumont JG, Parma LP, Chen L, Lackmann M, Lithgow T, Hinds MG, Day CL, Adams JM, Huang DCS. Proapoptotic BH3-only proteins trigger membrane integration of prosurvival Bcl-w and neutralize its activity. J Cell Biol 2003; 162:877-87. [PMID: 12952938 PMCID: PMC2172834 DOI: 10.1083/jcb.200302144] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Prosurvival Bcl-2-like proteins, like Bcl-w, are thought to function on organelles such as the mitochondrion and to be targeted to them by their hydrophobic COOH-terminal domain. We unexpectedly found, however, that the membrane association of Bcl-w was enhanced during apoptosis. In healthy cells, Bcl-w was loosely attached to the mitochondrial membrane, but it was converted into an integral membrane protein by cytotoxic signals that induce binding of BH3-only proteins, such as Bim, or by the addition of BH3 peptides to lysates. As the structure of Bcl-w has revealed that its COOH-terminal domain occupies the hydrophobic groove where BH3 ligands bind, displacement of that domain by a BH3 ligand would displace the hydrophobic COOH-terminal residues, allowing their insertion into the membrane. To determine whether BH3 ligation is sufficient to induce the enhanced membrane affinity, or to render Bcl-w proapoptotic, we mimicked their complex by tethering the Bim BH3 domain to the NH2 terminus of Bcl-w. The chimera indeed bound avidly to membranes, in a fashion requiring the COOH-terminal domain, but neither promoted nor inhibited apoptosis. These results suggest that ligation of a proapoptotic BH3-only protein alters the conformation of Bcl-w, enhances membrane association, and neutralizes its survival function.
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Affiliation(s)
- Julie Wilson-Annan
- Walter and Eliza Hall Institute of Medical Research, Victoria 3050, Australia
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38
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Hinds MG, Lackmann M, Skea GL, Harrison PJ, Huang DCS, Day CL. The structure of Bcl-w reveals a role for the C-terminal residues in modulating biological activity. EMBO J 2003; 22:1497-507. [PMID: 12660157 PMCID: PMC152889 DOI: 10.1093/emboj/cdg144] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Pro-survival Bcl-2-related proteins, critical regulators of apoptosis, contain a hydrophobic groove targeted for binding by the BH3 domain of the pro-apoptotic BH3-only proteins. The solution structure of the pro-survival protein Bcl-w, presented here, reveals that the binding groove is not freely accessible as predicted by previous structures of pro-survival Bcl-2-like molecules. Unexpectedly, the groove appears to be occluded by the C-terminal residues. Binding and kinetic data suggest that the C-terminal residues of Bcl-w and Bcl-x(L) modulate pro-survival activity by regulating ligand access to the groove. Binding of the BH3-only proteins, critical for cell death initiation, is likely to displace the hydrophobic C-terminal region of Bcl-w and Bcl-x(L). Moreover, Bcl-w does not act only by sequestering the BH3-only proteins. There fore, pro-survival Bcl-2-like molecules probably control the activation of downstream effectors by a mechanism that remains to be elucidated.
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Affiliation(s)
- Mark G Hinds
- The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3050, Australia
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Abstract
Eph receptors, the largest subfamily of receptor tyrosine kinases, and their ephrin ligands are important mediators of cell-cell communication regulating cell attachment, shape and mobility. Both Ephs and ephrins are membrane-bound and their interactions at sites of cell-cell contact initiate unique bidirectional signaling cascades, with information transduced in both the receptor-expressing and the ligand-expressing cells. Recent structural and biophysical studies summarized in this review reveal unique molecular features not previously observed in any other receptor-ligand families and explain many of the biochemical and signaling properties of Ephs and ephrins. Of particular importance is the insight into how approximation of ligand-expressing and receptor-expressing cells could lead to the formation and activation of highly ordered signaling centers at cell-cell interfaces.
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Affiliation(s)
- Juha-Pekka Himanen
- Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA
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40
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Abstract
The past decade has seen remarkable advances in identification of the proteins regulating axon guidance and synapse formation. Understanding the structural and molecular basis of their signaling properties is now the task at hand. The recently characterized crystal structure of the complex formed between the ligand-binding domain of EphB2 and the ectodomain of its binding partner ephrin-B2 provides an insight into the recognition and signal transduction mechanisms of this large multifunctional family of surface receptors. This heterotetrameric complex reveals a cyclic arrangement of subunits not previously seen in any receptor-ligand structure, and provides a basis for class specificity of binding.
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Affiliation(s)
- Tyler Cutforth
- Center for Neurobiology and Behavior, Columbia University, 701 W. 168 St, New York, NY 10032, USA
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41
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Lawrenson ID, Wimmer-Kleikamp SH, Lock P, Schoenwaelder SM, Down M, Boyd AW, Alewood PF, Lackmann M. Ephrin-A5 induces rounding, blebbing and de-adhesion of EphA3-expressing 293T and melanoma cells by CrkII and Rho-mediated signalling. J Cell Sci 2002; 115:1059-72. [PMID: 11870224 DOI: 10.1242/jcs.115.5.1059] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Eph receptor tyrosine kinases and ephrins regulate morphogenesis in the developing embryo where they effect adhesion and motility of interacting cells. Although scarcely expressed in adult tissues, Eph receptors and ephrins are overexpressed in a range of tumours. In malignant melanoma, increased Eph and ephrin expression levels correlate with metastatic progression. We have examined cellular and biochemical responses of EphA3-expressing melanoma cell lines and human epithelial kidney 293T cells to stimulation with polymeric ephrin-A5 in solution and with surfaces of defined ephrin-A5 densities. Within minutes, rapid reorganisation of the actin and myosin cytoskeleton occurs through activation of RhoA, leading to the retraction of cellular protrusions,membrane blebbing and detachment, but not apoptosis. These responses are inhibited by monomeric ephrin-A5, showing that receptor clustering is required for this EphA3 response. Furthermore, the adapter CrkII, which associates with tyrosine-phosphorylated EphA3 in vitro, is recruited in vivo to ephrin-A5-stimulated EphA3. Expression of an SH3-domain mutated CrkII ablates cell rounding, blebbing and detachment. Our results suggest that recruitment of CrkII and activation of Rho signalling are responsible for EphA3-mediated cell rounding, blebbing and de-adhesion, and that ephrin-A5-mediated receptor clustering and EphA3 tyrosine kinase activity are essential for this response.
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Affiliation(s)
- Isobel D Lawrenson
- Ludwig Institute for Cancer Research, PO Box 2008, Royal Melbourne Hospital, Victoria 3050, Australia
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42
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Himanen JP, Rajashankar KR, Lackmann M, Cowan CA, Henkemeyer M, Nikolov DB. Crystal structure of an Eph receptor-ephrin complex. Nature 2001; 414:933-8. [PMID: 11780069 DOI: 10.1038/414933a] [Citation(s) in RCA: 252] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The Eph family of receptor tyrosine kinases and their membrane-anchored ephrin ligands are important in regulating cell-cell interactions as they initiate a unique bidirectional signal transduction cascade whereby information is communicated into both the Eph-expressing and the ephrin-expressing cells. Initially identified as regulators of axon pathfinding and neuronal cell migration, Ephs and ephrins are now known to have roles in many other cell-cell interactions, including those of vascular endothelial cells and specialized epithelia. Here we report the crystal structure of the complex formed between EphB2 and ephrin-B2, determined at 2.7 A resolution. Each Eph receptor binds an ephrin ligand through an expansive dimerization interface dominated by the insertion of an extended ephrin loop into a channel at the surface of the receptor. Two Eph-Ephrin dimers then join to form a tetramer, in which each ligand interacts with two receptors and each receptor interacts with two ligands. The Eph and ephrin molecules are precisely positioned and orientated in these complexes, promoting higher-order clustering and the initiation of bidirectional signalling.
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Affiliation(s)
- J P Himanen
- Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10021, USA
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Boyd AW, Lackmann M. Signals from Eph and ephrin proteins: a developmental tool kit. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2001; 2001:re20. [PMID: 11741094 DOI: 10.1126/stke.2001.112.re20] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Interactions between Eph receptors and their ligands the ephrin proteins are critically important in many key developmental processes. Emerging evidence also supports a role for these molecules in postembryonic tissues, particularly in pathological processes, including tissue injury and tumor metastasis. We review the signaling mechanisms that allow the 14 Eph and nine ephrin proteins to deliver intracellular signals that regulate cell shape and movement. What emerges is that the initiation of these signals is critically dependent on which Eph and ephrin proteins are expressed, the level of their expression, and, in some cases, which splice variants are expressed. Diversity at the level of initial interaction and in the downstream signaling processes regulated by Eph-ephrin signaling provides a subtle, versatile system of regulation of intercellular adhesion, cell shape, and cell motility.
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Affiliation(s)
- A W Boyd
- Leukaemia Foundation Laboratory, Queensland Institute of Medical Research, P.O. Royal Brisbane Hospital, Australia.
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45
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Li YY, Mi Z, Feng Y, McTiernan CF, Zhou R, Robbins PD, Watkins SC, Feldman AM. Differential effects of overexpression of two forms of ephrin-A5 on neonatal rat cardiomyocytes. Am J Physiol Heart Circ Physiol 2001; 281:H2738-46. [PMID: 11709443 DOI: 10.1152/ajpheart.2001.281.6.h2738] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Eph receptors constitute the largest family of receptor tyrosine kinases. Multiple transcripts of ephrin-A5, the cognate ligand of the EphA3 receptor, were found in neonatal rat cardiomyocytes. Two cDNA clones encoding the full-length ephrin-A5 (ephrin-A5 alpha) and a 27-amino acid deletion form (ephrin-A5 beta) were isolated. To examine the role of ephrin-A5 in cardiomyocytes, the cDNAs were inserted into adenoviral vectors, termed Ad.ephrin-A5 alpha and Ad.ephrin-A5 beta, respectively, and overexpressed in cardiomyocytes. The effect of ephrin-A5 on cardiomyocyte gene expression was investigated using a cDNA expression array and Western blot analysis. The results showed that both ephrin-A5 alpha and ephrin-A5 beta downregulated cyclin D2, cyclin-dependent kinase-4 proteins, and their cognate receptor EphA3, which were associated with reduced bromodeoxyuridine incorporation in cardiomyocytes. Whereas ephrin-A5 alpha and ephrin-A5 beta also induced differential gene expression, only ephrin-A5 beta significantly upregulated the transcription of brain natriuretic peptide and downregulated ras-related protein RAB2, protein kinase C inhibitor protein-1, clusterin, and insulin-like growth factor-binding protein. The results suggest that the two forms of ephrin-A5 share similar function while differ in regulating different sets of genes in cardiomyocytes.
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Affiliation(s)
- Y Y Li
- Cardiovascular Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
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46
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Abstract
Eph receptor tyrosine kinases and their membrane-associated ligands, the ephrins, are essential regulators of axon guidance, cell migration, segmentation, and angiogenesis. There are two classes of vertebrate ephrin ligands which have distinct binding specificities for their cognate receptors. Multimerization of the ligands is required for receptor activation, and ephrin ligands themselves signal intracellularly upon binding Eph receptors. We have determined the structure of the extracellular domain of mouse ephrin-B2. The ephrin ectodomain is an eight-stranded beta barrel with topological similarity to plant nodulins and phytocyanins. Based on the structure, we have identified potential surface determinants of Eph/ephrin binding specificity and a ligand dimerization region. The high sequence similarity among ephrin ectodomains indicates that all ephrins may be modeled upon the ephrin-B2 structure presented here.
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Affiliation(s)
- J Toth
- Boston Biomedical Research Institute, Watertown, Massachusetts 02472, USA
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47
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Coulthard MG, Lickliter JD, Subanesan N, Chen K, Webb GC, Lowry AJ, Koblar S, Bottema CD, Boyd AW. Characterization of the Epha1 receptor tyrosine kinase: expression in epithelial tissues. Growth Factors 2001; 18:303-17. [PMID: 11519828 DOI: 10.3109/08977190109029118] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The Eph family of receptor tyrosine kinases plays a crucial role during development and is implicated in oncogenesis. Using a partial cDNA clone of an Eph-related kinase (Esk) we isolated the complete coding region of a gene which we show to be murine EphA1 by both structural and functional criteria. The chromosomal localization is shown to be syntenic to hEphA1 and the genomic organization also shows distinct features found in the hEphA1 gene. Functionally, in keeping with findings for the human homologue, both soluble recombinant and "native" mEphA1 show preferential binding to ephrin A1. However, we also observed significant binding to other A-type ligands as has been observed for other Eph receptors. We analysed the expression of mEphA1 mRNA by in situ hybridization on tissue sections. mEphA1 was expressed in epithelial elements of skin, adult thymus, kidney and adrenal cortex. Taken together with previous Northern blotting data these results suggest that mEphA1 is expressed widely in differentiated epithelial cells.
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Affiliation(s)
- M G Coulthard
- Leukaemia Foundation Laboratory, Queensland Institute of Medical Research, Royal Brisbane Hospital, Australia
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49
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Holder N, Durbin L, Cooke J. Eph receptors and ephrins are key regulators of morphogenesis. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2000:123-47. [PMID: 10943308 DOI: 10.1007/978-3-662-04264-9_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- N Holder
- Department of Anatomy and Developmental Biology, University College, London, UK
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50
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Abstract
Contact-mediated axon repulsion by ephrins raises an unresolved question: these cell surface ligands form a high-affinity multivalent complex with their receptors present on axons, yet rather than being bound, axons can be rapidly repelled. We show here that ephrin-A2 forms a stable complex with the metalloprotease Kuzbanian, involving interactions outside the cleavage region and the protease domain. Eph receptor binding triggered ephrin-A2 cleavage in a localized reaction specific to the cognate ligand. A cleavage-inhibiting mutation in ephrin-A2 delayed axon withdrawal. These studies reveal mechanisms for protease recognition and control of cell surface proteins, and, for ephrin-A2, they may provide a means for efficient axon detachment and termination of signaling.
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Affiliation(s)
- M Hattori
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
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