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Bourgeois NM, Wei L, Ho NNT, Neal ML, Seferos D, Tongogara T, Mast FD, Aitchison JD, Kaushansky A. Multiple receptor tyrosine kinases regulate dengue infection of hepatocytes. Front Cell Infect Microbiol 2024; 14:1264525. [PMID: 38585651 PMCID: PMC10995305 DOI: 10.3389/fcimb.2024.1264525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 02/27/2024] [Indexed: 04/09/2024] Open
Abstract
Introduction Dengue is an arboviral disease causing severe illness in over 500,000 people each year. Currently, there is no way to constrain dengue in the clinic. Host kinase regulators of dengue virus (DENV) infection have the potential to be disrupted by existing therapeutics to prevent infection and/or disease progression. Methods To evaluate kinase regulation of DENV infection, we performed kinase regression (KiR), a machine learning approach that predicts kinase regulators of infection using existing drug-target information and a small drug screen. We infected hepatocytes with DENV in vitro in the presence of a panel of 38 kinase inhibitors then quantified the effect of each inhibitor on infection rate. We employed elastic net regularization on these data to obtain predictions of which of 291 kinases are regulating DENV infection. Results Thirty-six kinases were predicted to have a functional role. Intriguingly, seven of the predicted kinases - EPH receptor A4 (EPHA4), EPH receptor B3 (EPHB3), EPH receptor B4 (EPHB4), erb-b2 receptor tyrosine kinase 2 (ERBB2), fibroblast growth factor receptor 2 (FGFR2), Insulin like growth factor 1 receptor (IGF1R), and ret proto-oncogene (RET) - belong to the receptor tyrosine kinase (RTK) family, which are already therapeutic targets in the clinic. We demonstrate that predicted RTKs are expressed at higher levels in DENV infected cells. Knockdown of EPHB4, ERBB2, FGFR2, or IGF1R reduces DENV infection in hepatocytes. Finally, we observe differential temporal induction of ERBB2 and IGF1R following DENV infection, highlighting their unique roles in regulating DENV. Discussion Collectively, our findings underscore the significance of multiple RTKs in DENV infection and advocate further exploration of RTK-oriented interventions against dengue.
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Affiliation(s)
- Natasha M. Bourgeois
- Department of Global Health, University of Washington, Seattle, WA, United States
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Ling Wei
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Nhi N. T. Ho
- Department of Global Health, University of Washington, Seattle, WA, United States
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Maxwell L. Neal
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Denali Seferos
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Tinotenda Tongogara
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - Fred D. Mast
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
| | - John D. Aitchison
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
- Department of Pediatrics, University of Washington, Seattle, WA, United States
| | - Alexis Kaushansky
- Department of Global Health, University of Washington, Seattle, WA, United States
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, WA, United States
- Department of Pediatrics, University of Washington, Seattle, WA, United States
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2
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Pasquale EB. Eph receptors and ephrins in cancer progression. Nat Rev Cancer 2024; 24:5-27. [PMID: 37996538 PMCID: PMC11015936 DOI: 10.1038/s41568-023-00634-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/03/2023] [Indexed: 11/25/2023]
Abstract
Evidence implicating Eph receptor tyrosine kinases and their ephrin ligands (that together make up the 'Eph system') in cancer development and progression has been accumulating since the discovery of the first Eph receptor approximately 35 years ago. Advances in the past decade and a half have considerably increased the understanding of Eph receptor-ephrin signalling mechanisms in cancer and have uncovered intriguing new roles in cancer progression and drug resistance. This Review focuses mainly on these more recent developments. I provide an update on the different mechanisms of Eph receptor-ephrin-mediated cell-cell communication and cell autonomous signalling, as well as on the interplay of the Eph system with other signalling systems. I further discuss recent advances in elucidating how the Eph system controls tumour expansion, invasiveness and metastasis, supports cancer stem cells, and drives therapy resistance. In addition to functioning within cancer cells, the Eph system also mediates the reciprocal communication between cancer cells and cells of the tumour microenvironment. The involvement of the Eph system in tumour angiogenesis is well established, but recent findings also demonstrate roles in immune cells, cancer-associated fibroblasts and the extracellular matrix. Lastly, I discuss strategies under evaluation for therapeutic targeting of Eph receptors-ephrins in cancer and conclude with an outlook on promising future research directions.
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Affiliation(s)
- Elena B Pasquale
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
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3
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Ullah A, Razzaq A, Zhou C, Ullah N, Shehzadi S, Aziz T, Alfaifi MY, Elbehairi SEI, Iqbal H. Biological Significance of EphB4 Expression in Cancer. Curr Protein Pept Sci 2024; 25:244-255. [PMID: 37909437 DOI: 10.2174/0113892037269589231017055642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/03/2023] [Accepted: 09/15/2023] [Indexed: 11/03/2023]
Abstract
Eph receptors and their Eph receptor-interacting (ephrin) ligands comprise a vital cell communication system with several functions. In cancer cells, there was evidence of bilateral Eph receptor signaling with both tumor-suppressing and tumor-promoting actions. As a member of the Eph receptor family, EphB4 has been linked to tumor angiogenesis, growth, and metastasis, which makes it a viable and desirable target for drug development in therapeutic applications. Many investigations have been conducted over the last decade to elucidate the structure and function of EphB4 in association with its ligand ephrinB2 for its involvement in tumorigenesis. Although several EphB4-targeting drugs have been investigated, and some selective inhibitors have been evaluated in clinical trials. This article addresses the structure and function of the EphB4 receptor, analyses its possibility as an anticancer therapeutic target, and summarises knowledge of EphB4 kinase inhibitors. To summarise, EphB4 is a difficult but potential treatment option for cancers.
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Affiliation(s)
- Asmat Ullah
- Clinical Research Institute, Zhejiang Provincial People's Hospital, Hangzhou, 310014, Zhejiang, China
| | - Anam Razzaq
- College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Chuanzan Zhou
- Clinical Research Institute, Zhejiang Provincial People's Hospital, Hangzhou, 310014, Zhejiang, China
| | - Najeeb Ullah
- Department of Biomedical Engineering, Louisiana Tech University, Ruston, LA, 818 Nelson Ave, 71272, USA
| | - Somia Shehzadi
- University Institute of Medical Laboratory Technology, The University of Lahore, Lahore 54000, Pakistan
| | - Tariq Aziz
- Westlake University, School of Engineering, Hangzhou, Zhejiang Province, 310024, China
| | - Mohammad Y Alfaifi
- Department of Biology, Faculty of Science, King Khalid University, Abha 9004, Saudi Arabia
| | | | - Haroon Iqbal
- Zhejiang Cancer Hospital, Institute of Basic Medicine and Cancer (IBMC), Chinese Academy of Sciences Hangzhou, Zhejiang, 310022, China
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4
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Shin JM, Han MS, Park JH, Lee SH, Kim TH, Lee SH. The EphA1 and EphA2 Signaling Modulates the Epithelial Permeability in Human Sinonasal Epithelial Cells and the Rhinovirus Infection Induces Epithelial Barrier Dysfunction via EphA2 Receptor Signaling. Int J Mol Sci 2023; 24:ijms24043629. [PMID: 36835041 PMCID: PMC9962399 DOI: 10.3390/ijms24043629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/08/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
Deficiencies in epithelial barrier integrity are involved in the pathogenesis of chronic rhinosinusitis (CRS). This study aimed to investigate the role of ephrinA1/ephA2 signaling on sinonasal epithelial permeability and rhinovirus-induced epithelial permeability. This role in the process of epithelial permeability was evaluated by stimulating ephA2 with ephrinA1 and inactivating ephA2 with ephA2 siRNA or inhibitor in cells exposed to rhinovirus infection. EphrinA1 treatment increased epithelial permeability, which was associated with decreased expression of ZO-1, ZO-2, and occludin. These effects of ephrinA1 were attenuated by blocking the action of ephA2 with ephA2 siRNA or inhibitor. Furthermore, rhinovirus infection upregulated the expression levels of ephrinA1 and ephA2, increasing epithelial permeability, which was suppressed in ephA2-deficient cells. These results suggest a novel role of ephrinA1/ephA2 signaling in epithelial barrier integrity in the sinonasal epithelium, suggesting their participation in rhinovirus-induced epithelial dysfunction.
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Affiliation(s)
| | | | | | | | | | - Sang Hag Lee
- Correspondence: ; Tel.: +82-2-920-5486; Fax: +82-2-925-5233
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5
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Liu L, Li X, Zhao Q, Yang L, Jiang X. Pathogenesis of Port-Wine Stains: Directions for Future Therapies. Int J Mol Sci 2022; 23:ijms232012139. [PMID: 36292993 PMCID: PMC9603382 DOI: 10.3390/ijms232012139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 10/04/2022] [Accepted: 10/10/2022] [Indexed: 11/26/2022] Open
Abstract
Port-wine stains (PWSs) are congenital vascular malformations that involve the skin and mucosa. To date, the mechanisms underlying the pathogenesis and progression of PWSs are yet to be clearly elucidated. The potential reasons for dilated vessels are as follows: (1) somatic GNAQ (R183Q) mutations that form enlarged capillary malformation-like vessels through angiopoietin-2, (2) decreased perivascular nerve elements, (3) the coexistence of Eph receptor B1 and ephrin B2, and (4) the deficiency of αSMA expression in pericytes. In addition, ERK, c-JNK, P70S6K, AKT, PI3K, and PKC are assumed to be involved in PWS development. Although pulsed-dye laser (PDL) remains the gold standard for treating PWSs, the recurrence rate is high. Topical drugs, including imiquimod, axitinib, and rapamycin, combined with PDL treatments, are expected to alter the recurrence rate and reduce the number of PDL sessions for PWSs. For the deep vascular plexus, photosensitizers or photothermal transduction agents encapsulated by nanocarriers conjugated to surface markers (CD133/CD166/VEGFR-2) possess a promising therapeutic potential in photodynamic therapy or photothermal therapy for PWSs. The pathogenesis, progression, and treatment of PWSs should be extensively investigated.
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Affiliation(s)
- Lian Liu
- Department of Dermatology, West China Hospital, Sichuan University, Chengdu 610017, China
- Laboratory of Dermatology, Clinical Institute of Inflammation and Immunology (CIII), Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu 610017, China
| | - Xiaoxue Li
- Department of Dermatology, West China Hospital, Sichuan University, Chengdu 610017, China
- Laboratory of Dermatology, Clinical Institute of Inflammation and Immunology (CIII), Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu 610017, China
| | - Qian Zhao
- Department of Dermatology, West China Hospital, Sichuan University, Chengdu 610017, China
- Laboratory of Dermatology, Clinical Institute of Inflammation and Immunology (CIII), Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu 610017, China
- Department of Medical Cosmetology, Chengdu Second People’s Hospital, Chengdu 610056, China
| | - Lihua Yang
- Department of Dermatology, West China Hospital, Sichuan University, Chengdu 610017, China
- Laboratory of Dermatology, Clinical Institute of Inflammation and Immunology (CIII), Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu 610017, China
| | - Xian Jiang
- Department of Dermatology, West China Hospital, Sichuan University, Chengdu 610017, China
- Laboratory of Dermatology, Clinical Institute of Inflammation and Immunology (CIII), Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu 610017, China
- Correspondence: ; Tel.: +86-028-8542-3315; Fax: +86-028-8542-2560
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6
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Li Y, Su P, Chen Y, Nie J, Yuan TF, Wong AH, Liu F. The Eph receptor A4 plays a role in demyelination and depression-related behavior. J Clin Invest 2022; 132:161559. [PMID: 35575094 PMCID: PMC9106339 DOI: 10.1172/jci161559] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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7
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Abstract
The maturation of T cells is an intricate process involving the interaction of developing thymocytes with discrete microenvironments within the thymus. Numerous studies have indicated that distinct thymic compartments provide signals required for each stage of thymocyte maturation. In this study we performed a comprehensive analysis of the expression patterns of Eph-A receptors and ephrins-A in the thymus using in situ hybridization and reverse transcription-polymerase chain reaction, and show that expression of these molecules is highly compartmentalized. Based on these expression patterns and the known mechanisms of action of Eph receptor/ephrin interactions in other organs, these data suggest that differential Eph receptor expression on discrete subsets of thymic stromal cells may be important in establishing compartment boundaries and preventing intermingling of stromal cell subtypes. Further, together with chemotactic signals such as those provided by chemokines, regulated Eph receptor/ephrin expression on thymocytes may play a role in thymocyte migration.
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Affiliation(s)
- Andrea Vergara-Silva
- Department of Pathology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
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8
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Brantley DM, Cheng N, Thompson EJ, Lin Q, Brekken RA, Thorpe PE, Muraoka RS, Cerretti DP, Pozzi A, Jackson D, Lin C, Chen J. Soluble Eph A receptors inhibit tumor angiogenesis and progression in vivo. Oncogene 2002; 21:7011-26. [PMID: 12370823 DOI: 10.1038/sj.onc.1205679] [Citation(s) in RCA: 253] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2002] [Revised: 05/15/2002] [Accepted: 05/20/2002] [Indexed: 01/19/2023]
Abstract
The Eph family of receptor tyrosine kinases and their ligands, known as ephrins, play a crucial role in vascular development during embryogenesis. The function of these molecules in adult angiogenesis has not been well characterized. Here, we report that blocking Eph A class receptor activation inhibits angiogenesis in two independent tumor types, the RIP-Tag transgenic model of angiogenesis-dependent pancreatic islet cell carcinoma and the 4T1 model of metastatic mammary adenocarcinoma. Ephrin-A1 ligand was expressed in both tumor and endothelial cells, and EphA2 receptor was localized primarily in tumor-associated vascular endothelial cells. Soluble EphA2-Fc or EphA3-Fc receptors inhibited tumor angiogenesis in cutaneous window assays, and tumor growth in vivo. EphA2-Fc or EphA3-Fc treatment resulted in decreased tumor vascular density, tumor volume, and cell proliferation, but increased cell apoptosis. However, EphA2-Fc had no direct effect on tumor cell growth or apoptosis in culture, yet inhibited migration of endothelial cells in response to tumor cells, suggesting that the soluble receptor inhibited blood vessel recruitment by the tumor. These data provide the first functional evidence for Eph A class receptor regulation of pathogenic angiogenesis induced by tumors and support the function of A class Eph receptors in tumor progression.
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MESH Headings
- Adenoma, Islet Cell/blood supply
- Animals
- Cell Movement
- Endothelial Growth Factors/physiology
- Endothelium, Vascular/cytology
- Female
- In Situ Nick-End Labeling
- Lymphokines/physiology
- Mammary Neoplasms, Experimental/blood supply
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Neoplasms, Experimental/blood supply
- Neoplasms, Experimental/prevention & control
- Neovascularization, Pathologic/prevention & control
- Platelet Endothelial Cell Adhesion Molecule-1/analysis
- Proliferating Cell Nuclear Antigen/analysis
- Receptor Protein-Tyrosine Kinases/physiology
- Receptor, EphA1
- Receptor, EphA2
- Tumor Cells, Cultured
- Vascular Endothelial Growth Factor A
- Vascular Endothelial Growth Factors
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Affiliation(s)
- Dana M Brantley
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, TN 37232, USA
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9
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Mann F, Peuckert C, Dehner F, Zhou R, Bolz J. Ephrins regulate the formation of terminal axonal arbors during the development of thalamocortical projections. Development 2002; 129:3945-55. [PMID: 12135931 DOI: 10.1242/dev.129.16.3945] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The development of connections between thalamic afferents and their cortical target cells occurs in a highly precise manner. Thalamic axons enter the cortex through deep cortical layers, then stop their growth in layer 4 and elaborate terminal arbors specifically within this layer. The mechanisms that underlie target layer recognition for thalamocortical projections are not known. We compared the growth pattern of thalamic explants cultured on membrane substrates purified from cortical layer 4, the main recipient layer for thalamic axons, and cortical layer 5, a non-target layer. Thalamic axons exhibited a reduced growth rate and an increased branching density on their appropriate target membranes compared with non-target substrate. When confronted with alternating stripes of both membrane substrates, thalamic axons grew preferentially on their target membrane stripes. Enzymatic treatment of cortical membranes revealed that growth, branching and guidance of thalamic axons are independently regulated by attractive and repulsive cues differentially expressed in distinct cortical layers. These results indicate that multiple membrane-associated molecules collectively contribute to the laminar targeting of thalamic afferents. Furthermore, we found that interfering with the function of Eph tyrosine kinase receptors and their ligands, ephrins, abolished the preferential branching of thalamic axons on their target membranes, and that recombinant ephrin-A5 ligand elicited a branch-promoting activity on thalamic axons. We conclude that interactions between Eph receptors and ephrins mediate branch formation of thalamic axons and thereby may play a role in the establishment of layer-specific thalamocortical connections.
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Affiliation(s)
- Fanny Mann
- Institut National de la Santé et de la Recherche Médicale Unité 371, 18 avenue du Doyen Lépine, 69500 Bron, France
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10
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Affiliation(s)
- Klas Kullander
- AstraZeneca Transgenics & Comparative Genomics, S-431 83 Mölndal, Sweden.
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11
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Yamaguchi Y, Irie F. [Roles of Eph receptors and the cell surface heparan sulfate proteoglycan syndecan-2 in dendritic spine morphogenesis]. Seikagaku 2002; 74:391-5. [PMID: 12073610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Affiliation(s)
- Yu Yamaguchi
- Neurobiology Program, Burnham Institute, 10901 N. Torrey Pines Road, La Jolla, CA 92037, USA
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12
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Abstract
The Eph family of receptor tyrosine kinases and their 'ligands', the ephrins, have been implicated in a large number of developmental processes, such as boundary formation, cell migration, axon guidance and vasculogenesis. A characteristic of the EphB subclass is that both EphBs and transmembrane-anchored ephrin-Bs function as receptors and as ligands, a phenomenon commonly described as 'bi-directional signalling'. Here we review recent data indicating that EphA receptors and glycosylphosphatidylinositol (GPI)-anchored ephrin-As can also mediate bi-directional signalling. Moreover, characterization of the expression of ephrin-As on axons of the retinotectal and vomeronasal projections suggests that the EphA subfamily is involved in both repulsive and attractive guidance mechanisms during establishment of neuronal connections.
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Affiliation(s)
- Bernd Knöll
- MRC Centre for Developmental Neurobiology, King's College London, 4th Floor, New Hunt's House, London, UK
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13
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Dearborn R, He Q, Kunes S, Dai Y. Eph receptor tyrosine kinase-mediated formation of a topographic map in the Drosophila visual system. J Neurosci 2002; 22:1338-49. [PMID: 11850461 PMCID: PMC6757577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
Roles for Eph receptor tyrosine kinase signaling in the formation of topographic patterns of axonal connectivity have been well established in vertebrate visual systems. Here we describe a role for a Drosophila Eph receptor tyrosine kinase (EPH) in the control of photoreceptor axon and cortical axon topography in the developing visual system. Although uniform across the developing eye, EPH is expressed in a concentration gradient appropriate for conveying positional information during cortical axon guidance in the second-order optic ganglion, the medulla. Disruption of this graded pattern of EPH activity by double-stranded RNA interference or by ectopic expression of wild-type or dominant-negative transgenes perturbed the establishment of medulla cortical axon topography. In addition, abnormal midline fasciculation of photoreceptor axons resulted from the eye-specific expression of the dominant-negative EPH transgene. These observations reveal a conserved role for Eph kinases as determinants of topographic map formation in vertebrates and invertebrates.
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MESH Headings
- Animals
- Animals, Genetically Modified
- Axons/enzymology
- Brain Mapping
- Cell Differentiation/physiology
- Cloning, Molecular
- Crosses, Genetic
- Drosophila
- Ganglia, Invertebrate/cytology
- Ganglia, Invertebrate/physiology
- Gene Expression Regulation, Developmental/drug effects
- Genes, Dominant
- Growth Cones/enzymology
- Immunohistochemistry
- In Situ Hybridization
- Molecular Sequence Data
- Morphogenesis
- Neurons/cytology
- Neurons/enzymology
- Phenotype
- Photoreceptor Cells, Invertebrate/cytology
- Photoreceptor Cells, Invertebrate/enzymology
- RNA, Double-Stranded/pharmacology
- RNA, Messenger
- Receptor Protein-Tyrosine Kinases/antagonists & inhibitors
- Receptor Protein-Tyrosine Kinases/genetics
- Receptor Protein-Tyrosine Kinases/metabolism
- Receptor, EphA1
- Synapses/physiology
- Transgenes
- Visual Pathways/cytology
- Visual Pathways/growth & development
- Visual Pathways/physiology
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Affiliation(s)
- Richard Dearborn
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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14
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Yates PA, Roskies AL, McLaughlin T, O'Leary DD. Topographic-specific axon branching controlled by ephrin-As is the critical event in retinotectal map development. J Neurosci 2001; 21:8548-63. [PMID: 11606643 PMCID: PMC6762786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
The retinotectal projection is the predominant model for studying molecular mechanisms controlling development of topographic axonal connections. Our analyses of topographic mapping of retinal ganglion cell (RGC) axons in chick optic tectum indicate that a primary role for guidance molecules is to regulate topographic branching along RGC axons, a process that imposes unique requirements on the molecular control of map development. We show that topographically appropriate connections are established exclusively by branches that form along the axon shaft. Initially, RGC axons overshoot their appropriate termination zone (TZ) along the anterior-posterior (A-P) tectal axis; temporal axons overshoot the greatest distance and nasal axons the least, which correlates with the nonlinear increasing A-P gradient of ephrin-A repellents. In contrast, branches form along the shaft of RGC axons with substantial A-P topographic specificity. Topography is enhanced through the preferential arborization of appropriately positioned branches and elimination of ectopic branches. Using a membrane stripe assay and time-lapse microscopy, we show that branches form de novo along retinal axons. Temporal axons preferentially branch on their topographically appropriate anterior tectal membranes. After the addition of soluble EphA3-Fc, which blocks ephrin-A function, temporal axons branch equally on anterior and posterior tectal membranes, indicating that the level of ephrin-As in posterior tectum is sufficient to inhibit temporal axon branching and generate branching specificity in vitro. Our findings indicate that topographic branch formation and arborization along RGC axons are critical events in retinotectal mapping. Ephrin-As inhibit branching along RGC axons posterior to their correct TZ, but alone cannot account for topographic branching and must cooperate with other molecular activities to generate appropriate mapping along the A-P tectal axis.
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Affiliation(s)
- P A Yates
- Molecular Neurobiology Laboratory, The Salk Institute, La Jolla, California 92037, USA
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15
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Abstract
Despite over one hundred years of research, the duplication of the centrosome is a poorly understood process. Three recent papers--exploring three different kinases--may have provided the answer.
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Affiliation(s)
- E H Hinchcliffe
- University of Massachusetts Medical School, Department of Cell Biology, 377 Plantation Street, Worcester, Massachusetts 01605, USA
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16
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Greaves S. All for one and one for all. Nat Cell Biol 2001; 3:E184. [PMID: 11483975 DOI: 10.1038/35087123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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17
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Miao H, Wei BR, Peehl DM, Li Q, Alexandrou T, Schelling JR, Rhim JS, Sedor JR, Burnett E, Wang B. Activation of EphA receptor tyrosine kinase inhibits the Ras/MAPK pathway. Nat Cell Biol 2001; 3:527-30. [PMID: 11331884 DOI: 10.1038/35074604] [Citation(s) in RCA: 265] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Interactions between Eph receptor tyrosine kinases (RTKs) and membrane-anchored ephrin ligands critically regulate axon pathfinding and development of the cardiovascular system, as well as migration of neural cells. Similar to other RTKs, ligand-activated Eph kinases recruit multiple signalling and adaptor proteins, several of which are involved in growth regulation. However, in contrast to other RTKs, activation of Eph receptors fails to promote cell proliferation or to transform rodent fibroblasts, indicating that Eph kinases may initiate signalling pathways that are distinct from those transmitted by other RTKs. Here we show that stimulation of endogenous EphA kinases with ephrin-A1 potently inhibits the Ras/MAPK cascade in a range of cell types, and attenuates activation of mitogen-activated protein kinase (MAPK) by receptors for platelet-derived growth factor (PDGF), epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF). In prostatic epithelial cells and endothelial cells, but not fibroblasts, treatment with ephrin-A1 inhibits cell proliferation. Our results identify EphA kinases as negative regulators of the Ras/MAPK pathway that exert anti-mitogenic functions in a cell-type-specific manner.
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Affiliation(s)
- H Miao
- Rammelkamp Center for Research, MetroHealth Campus, Case Western Reserve University School of Medicine, 2500 MetroHealth Drive, Cleveland, Ohio 44109 USA
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18
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Abstract
Metamorphosis in frogs is a critical developmental process through which a tadpole changes into an adult froglet. Metamorphic changes include external morphological transformations as well as important changes in the wiring of sensory organs and central nervous system. This review aims to provide an overview on the events that occur in the visual system of metamorphosing amphibians and to discuss recent studies that provide new insight into the molecular mechanisms that control changes in the retinal growth pattern as well as the formation of new axonal pathways in the central nervous system. BioEssays 23:319-326, 2001.
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Affiliation(s)
- F Mann
- Department of Anatomy, University of Cambridge, Cambridge, UK
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19
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Abstract
Ephrins are cell surface associated ligands for Eph receptor tyrosine kinases and are implicated in repulsive axon guidance, cell migration, topographic mapping and angiogenesis. During the past year, Eph receptors have been shown to associate with glutamate receptors in excitatory neurons, suggesting a role in synapse formation or function. Moreover, ephrin/Eph signaling appears to regulate neural stem cell proliferation and migration in adult mouse brains. The mode of action of ephrin/Ephs has been expanded from repulsion to adhesion and from cell surface attachment to regulated cleavage.
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Affiliation(s)
- R Klein
- European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany.
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20
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Abstract
The control of cell movement during development is essential for forming and stabilizing the spatial organization of tissues and cell types. During initial steps of tissue patterning, distinct regional domains or cell types arise at appropriate locations, and the movement of cells is constrained in order to maintain spatial relationships during growth. In other situations, the guidance of migrating cells or neuronal growth cones to specific destinations underlies the establishment or remodeling of a pattern. Eph receptor tyrosine kinases and their ephrin ligands are key players in controlling these cell movements in many tissues and at multiple stages of patterning.
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Affiliation(s)
- D G Wilkinson
- Division of Developmental Neurobiology, National Institute for Medical Research, Ridgeway, Mill Hill, London NW7 1AA, UK.
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21
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Abstract
Eph receptor tyrosine kinases are largely known for their involvement in brain development but, as some of these receptor tyrosine kinases are also expressed in adults, their possible role in the mature nervous system has begun to be explored. Evidence for the involvement of Eph receptors in synaptic plasticity, learning and memory is only emerging and needs corroboration. However, it is likely that the actions of Eph kinases in the adult brain will attract significant attention and become a fertile research area, as occurred in the case of the neurotrophins.
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Affiliation(s)
- R Gerlai
- Neuroscience Department, Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, Indiana 46285, USA.
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22
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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23
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Kong H, Boulter J, Weber JL, Lai C, Chao MV. An evolutionarily conserved transmembrane protein that is a novel downstream target of neurotrophin and ephrin receptors. J Neurosci 2001; 21:176-85. [PMID: 11150334 PMCID: PMC6762419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
Appropriate development of nervous system connectivity involves a variety of processes, including neuronal life-and-death decisions, differentiation, axon guidance and migration, and synaptogenesis. Although these activities likely require specialized signaling events, few substrates unique to these neurotrophic functions have been identified. Here we describe the cloning of ankyrin repeat-rich membrane spanning (ARMS), which encodes a novel downstream target of neurotrophin and ephrin receptor tyrosine kinases, Trk and Eph, respectively. The amino acid sequence of ARMS is highly conserved from nematode to human, suggesting an evolutionarily conserved role for this protein. The ARMS protein consists of 1715 amino acids containing four putative transmembrane domains, multiple ankyrin repeats, a sterile alpha motif domain, and a potential PDZ-binding motif. In the rat, ARMS is specifically expressed in the developing nervous system and in highly plastic areas of the adult brain, regions enriched in Trks and Eph receptors. ARMS can physically associate with TrkA and p75 neurotrophin receptors. Moreover, endogenous ARMS protein is tyrosine phosphorylated after neurotrophin treatment of pheochromocytoma 12 cells and primary hippocampal neurons or ephrin B treatment of NG108-15 cells, demonstrating that ARMS is a downstream target for both neurotrophin and ephrin receptors.
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Affiliation(s)
- H Kong
- Molecular Neurobiology Program, Skirball Institute for Biomolecular Medicine, New York University School of Medicine, New York, New York, USA
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24
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Abstract
Significant progress has been made over the last decade in elucidating the mechanisms employed by receptor protein tyrosine kinases (RTKs) in transducing extracellular signals critical for the regulation of diverse cellular activities. Nevertheless, revealing the biological significance of a subset of the RTKs that contain catalytically inactive protein tyrosine kinase domains has proven more elusive. ErbB3 has served as the prototype for models of catalytically inactive RTK function, performing the role of signal diversification in heterodimeric receptor complexes with other ErbB subfamily members. The receptor related to tyrosine kinases (RYK) is unique amongst the catalytically inactive RTKs. Based on structural or functional properties of the extracellular domain, RYK cannot be classified into an existing RTK subfamily. Recent genetic analyses of mouse Ryk and its Drosophila orthologue derailed have defined a role for this novel subfamily of receptors in the control of craniofacial development and neuronal pathway selection, respectively. Recent biochemical data lead us to propose a model that involves RYK in signal crosstalk and scaffold assembly with Eph receptors. This model is consistent with the established roles of Eph receptors and ephrins in craniofacial and nervous system morphogenesis. BioEssays 23:34-45, 2001.
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Affiliation(s)
- M M Halford
- Ludwig Institute for Cancer Research, Royal Melbourne Hospital, Victoria, Australia
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25
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Affiliation(s)
- U Drescher
- MRC Centre for Developmental Neurobiology, King's College London, 4th Floor, New Hunts House, Guy's Campus, London SE1 1UL, United Kingdom.
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26
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Abstract
The ephrins are membrane-tethered ligands for the Eph receptor tyrosine kinases, which play important roles in patterning of the nervous and vascular systems. It is now clear that ephrins are more than just ligands and can also act as signalling-competent receptors, participating in bidirectional signalling. We have recently shown that ephrin-A5 signals within caveola-like domains of the plasma membrane upon engagement with its cognate Eph receptor, leading to increased adhesion of the cells to fibronectin. Here we show that ephrin-A5 controls sequential biological events that are consistent with its role in neuronal guidance. Activation of ephrin-A5 induces an initial change in cell adhesion followed by changes in cell morphology. Both effects are dependent on the activation of beta1 integrin involving members of the Src family of protein tyrosine kinases. The prolonged activation of ERK-1 and ERK-2 is required for the change in cell morphology. Our work suggests a new role for class A ephrins in specifying the affinity of the cells towards various extracellular substrates by regulating integrin function.
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Affiliation(s)
- A Davy
- Departments of Oncology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
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27
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Abstract
The molecular and cellular mechanisms governing vascular development are still poorly understood. Prominent among the intercellular signals that control the initial establishment of the vascular network (termed vasculogenesis) and the subsequent remodeling process (called angiogenesis) are soluble ligands that signal through receptor tyrosine kinases (RTKs). Recent reports have added cell-bound ephrin ligands and their cognate Eph RTKs to the list of key players in vascular development.
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Affiliation(s)
- R H Adams
- Developmental Biology Program, Heidelberg, Germany
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28
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Marcus RC, Matthews GA, Gale NW, Yancopoulos GD, Mason CA. Axon guidance in the mouse optic chiasm: retinal neurite inhibition by ephrin "A"-expressing hypothalamic cells in vitro. Dev Biol 2000; 221:132-47. [PMID: 10772797 DOI: 10.1006/dbio.2000.9660] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the mammalian visual system, retinal axons undergo temporal and spatial rearrangements as they project bilaterally to targets on the brain. Retinal axons cross the neuraxis to form the optic chiasm on the hypothalamus in a position defined by overlapping domains of regulatory gene expression. However, the downstream molecules that direct these processes remain largely unknown. Here we use a novel in vitro paradigm to study possible roles of the Eph family of receptor tyrosine kinases in chiasm formation. In vivo, Eph receptors and their ligands distribute in complex patterns in the retina and hypothalamus. In vitro, retinal axons are inhibited by reaggregates of isolated hypothalamic, but not dorsal diencephalic or cerebellar cells. Furthermore, temporal retinal neurites are more inhibited than nasal neurites by hypothalamic cells. Addition of soluble EphA5-Fc to block Eph "A" subclass interactions decreases both the inhibition and the differential response of retinal neurites by hypothalamic reaggregates. These data show that isolated hypothalamic cells elicit specific, position-dependent inhibitory responses from retinal neurites in culture. Moreover, these responses are mediated, in part, by Eph interactions. Together with the in vivo distributions, these data suggest possible roles for Eph family members in directing retinal axon growth and/or reorganization during optic chiasm formation.
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Affiliation(s)
- R C Marcus
- Departments of Pathology, Anatomy and Cell Biology, Center for Neurobiology and Behavior, Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York 10032, New York, USA
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29
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Abstract
Recent advances have started to elucidate the developmental functions and biochemistry of Eph receptor tyrosine kinases and their membrane-bound ligands, ephrins. Interactions between these molecules are promiscuous, but they largely fall into two groups: EphA receptors bind to GPI-anchored ephrin-A ligands, while EphB receptors bind to ephrin-B proteins that have a transmembrane and cytoplasmic domain. Remarkably, ephrin-B proteins transduce signals, such that bidirectional signaling can occur upon interaction with Eph receptor. In many tissues, specific Eph receptors and ephrins have complementary domains, whereas other family members may overlap in their expression. An important role of Eph receptors and ephrins is to mediate cell-contact-dependent repulsion. Complementary and overlapping gradients of expression underlie establishment of a topographic map of neuronal projections in the retinotectal system. Eph receptors and ephrins also act at boundaries to channel neuronal growth cones along specific pathways, restrict the migration of neural crest cells, and via bidirectional signaling prevent intermingling between hindbrain segments. Intriguingly, Eph receptors and ephrins can also trigger an adhesive response of endothelial cells and are required for the remodeling of blood vessels. Biochemical studies suggest that the extent of multimerization of Eph receptors modulates the cellular response and that the actin cytoskeleton is one major target of the intracellular pathways activated by Eph receptors. Eph receptors and ephrins have thus emerged as key regulators of the repulsion and adhesion of cells that underlie the establishment, maintenance, and remodeling of patterns of cellular organization.
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Affiliation(s)
- D G Wilkinson
- Division of Developmental Neurobiology, National Institute for Medical Research, London, United Kingdom
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30
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Affiliation(s)
- P L Jensen
- R&D Systems, Inc., Minneapolis, Minnesota, USA.
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31
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Dütting D, Handwerker C, Drescher U. Topographic targeting and pathfinding errors of retinal axons following overexpression of ephrinA ligands on retinal ganglion cell axons. Dev Biol 1999; 216:297-311. [PMID: 10588880 DOI: 10.1006/dbio.1999.9489] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the retinotectal projection, the Eph receptor tyrosine kinase ligands ephrinA2 and ephrinA5 are differentially expressed not only in the tectum, but also in a high-nasal-to-low-temporal pattern in the retina. Recently, we have shown that retrovirally driven overexpression of ephrinA2 on retinal axons leads to topographic targeting errors of temporal axons in that they overshoot their normal termination zones in the rostral tectum and project onto the mid- and caudal tectum. The behavior of nasal axons, however, was only marginally affected. Here, we show that overexpression of ephrinA5 affects the topographic targeting behavior of both temporal and nasal axons. These data reinforce the idea that differential ligand expression on retinal axons contributes to topographic targeting in the retinotectal projection. Additionally, we found that ectopic expression of ephrinA2 and ephrinA5 frequently leads to pathfinding errors at the chiasm, resulting in an increased stable ipsilateral projection.
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Affiliation(s)
- D Dütting
- Department of Physical Biology, Max-Planck-Institute for Developmental Biology, Spemannstrasse 35, Tübingen, FRG-72076, Germany
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32
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Iwamasa H, Ohta K, Yamada T, Ushijima K, Terasaki H, Tanaka H. Expression of Eph receptor tyrosine kinases and their ligands in chick embryonic motor neurons and hindlimb muscles. Dev Growth Differ 1999; 41:685-98. [PMID: 10646798 DOI: 10.1046/j.1440-169x.1999.00468.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Evidence is accumulating that Eph receptor tyrosine kinases and their ligands regulate cell migration and axonal guidance during development. It was previously found that one of the Eph receptors, EphA4, is transiently expressed in subsets of chick embryonic motor neurons. Here, the expression of EphA and ephrin-A subfamily members was further examined, and the dynamic patterns of expression in chick embryonic motor neurons found. EphA3, EphA4, ephrin-A2, and ephrin-A5 were also expressed in the connective tissues of limb muscles and EphA3 and EphA4 expressing motor neurons innervated EphA3 and EphA4 expressing limb muscles, respectively. These spatiotemporal expression patterns suggest that EphA and ephrin-A proteins play important roles in muscle patterning and motor axonal guidance.
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Affiliation(s)
- H Iwamasa
- Division of Developmental Neurobiology, Kumamoto University Graduate School of Medical Sciences, Honjo, Japan
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33
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Kalo MS, Pasquale EB. Signal transfer by Eph receptors. Cell Tissue Res 1999; 298:1-9. [PMID: 10555534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
The Eph receptors are a unique family of receptor tyrosine kinases that enforce cellular position in tissues through mainly repulsive signals generated upon cell-cell contact. Together, Eph receptors and their membrane-anchored ligands. the ephrins, are key molecules for establishing tissue organization through signaling pathways that control axonal projection, cell migration, and the maintenance of cellular boundaries. Through their SH2 (Src Homology 2) and PDZ (postsynaptic density protein, disks large, zona occludens) domains, several signaling molecules have been demonstrated to interact with the activated cytoplasmic domain of Eph receptors by using the yeast two-hybrid system and in vitro biochemical assays. Most proteins found to interact with Eph receptors are well-known regulators of cytoskeletal organization and cell adhesion, and also cell proliferation. Promoting growth, however, does not appear to be a primary role of Eph receptors. Explaining which signaling interactions identified for the Eph receptors have physiological significance, how Eph receptor signaling cascades are propagated, and characterizing the intrinsic signaling properties of the ephrins are all exciting questions currently being investigated.
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Affiliation(s)
- M S Kalo
- The Burnham Institute, La Jolla, CA 92037, USA
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34
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Abstract
Diffusible and substrate-bound cues can guide axonal pathway choice via attractive and repulsive signals. A number of families of signalling molecules have been identified, including netrins and their receptors, semaphorins, neuropilins, Eph receptor tyrosine kinases, ephrins and CAMs. Many of these signalling molecules can have a dual role, functioning either as attractants or as repellents. Direction of growth cone extension requires reorganization of the cytoskeleton, which may be directed by the Rho family of GTPases.
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Affiliation(s)
- G Tear
- Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, U.K
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35
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36
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37
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Abstract
Some receptor tyrosine kinase genes are mutated in inherited and somatically acquired human cancers. To permit mutational analysis, the complete genomic structure of the human EPHA1 gene on chromosome 7q34 was determined and oligonucleotide pairs were designed to amplify coding regions. The gene contains 18 exons, two more than the related tyrosine kinase, EPHB2. Presumed sequencing errors in the published cDNA sequence of EPHA1 were identified in exons 10 and 11. Availability of this information will facilitate mutational analysis of EPHA1.
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Affiliation(s)
- D Owshalimpur
- Lung Cancer Biology Section, National Cancer Institute, Bethesda, MD 20889-5105, USA
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38
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Lickliter JD, Smith FM, Olsson JE, Mackwell KL, Boyd AW. Embryonic stem cells express multiple Eph-subfamily receptor tyrosine kinases. Proc Natl Acad Sci U S A 1996; 93:145-50. [PMID: 8552593 PMCID: PMC40195 DOI: 10.1073/pnas.93.1.145] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Eph and its homologues form the largest subfamily of receptor tyrosine kinases. Normal expression patterns of this subfamily indicate roles in differentiation and development, whereas their overexpression has been linked to oncogenesis. This study investigated the potential role of Eph-related molecules during very early embryonic development by examining their expression in embryonic stem (ES) cells and embryoid bodies differentiated from ES cells in vitro. By use of a strategy based on reverse transcriptase-mediated PCR, nine clones containing Eph-subfamily sequence were isolated from ES cells. Of these, eight were almost identical to one of four previously identified molecules (Sek, Nuk, Eck, and Mek4). However, one clone contained sequence from a novel Eph-subfamily member, which was termed embryonic stem-cell kinase or Esk. Northern analysis showed expression of Esk in ES cells, embryoid bodies, day 12 mouse embryos, and some tissues of the adult animal. Levels of expression were similar in ES cells and embryoid bodies. By comparison, Mek4 showed no significant transcription in the ES cell cultures by Northern analysis, whereas Eck displayed stronger signals in ES cells than in the embryoid bodies. These results suggest that Eph-subfamily molecules may play roles during the earliest phases of embryogenesis. Furthermore, the relative importance of different members of this subfamily appears to change as development proceeds.
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Affiliation(s)
- J D Lickliter
- Lions Cancer Research Laboratory, Walter and Eliza Hall Institute of Medical Research, P.O. Royal Melbourne Hospital, Victoria, Australia
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