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Zhou ZX, Xu LJ, Wang HN, Cheng S, Li F, Miao Y, Lei B, Gao F, Wang Z. EphA4/ephrinA3 reverse signaling mediated downregulation of glutamate transporter GLAST in Müller cells in an experimental glaucoma model. Glia 2023; 71:720-741. [PMID: 36416239 DOI: 10.1002/glia.24307] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Revised: 11/07/2022] [Accepted: 11/12/2022] [Indexed: 11/24/2022]
Abstract
Deficiency of glutamate transporter GLAST in Müller cells may be culpable for excessive extracellular glutamate, which involves in retinal ganglion cell (RGC) damage in glaucoma. We elucidated how GLAST was regulated in rat chronic ocular hypertension (COH) model. Western blot and whole-cell patch-clamp recordings showed that GLAST proteins and GLAST-mediated current densities in Müller cells were downregulated at the early stages of COH. In normal rats, intravitreal injection of the ephrinA3 activator EphA4-Fc mimicked the changes of GLAST in COH retinas. In purified cultured Müller cells, EphA4-Fc treatment reduced GLAST expression at mRNA and protein levels, which was reversed by the tyrosine kinase inhibitor PP2 or transfection with ephrinA3-siRNA (Si-EFNA3), suggesting that EphA4/ephrinA3 reverse signaling mediated GLAST downregulation. EphA4/ephrinA3 reverse signaling-induced GLAST downregulation was mediated by inhibiting PI3K/Akt/NF-κB pathways since EphA4-Fc treatment of cultured Müller cells reduced the levels of p-Akt/Akt and NF-κB p65, which were reversed by transfecting Si-EFNA3. In Müller cells with ephrinA3 knockdown, the PI3K inhibitor LY294002 still decreased the protein levels of NF-κB p65 in the presence of EphA4-Fc, and the mRNA levels of GLAST were reduced by LY294002 and the NF-κB inhibitor SN50, respectively. Pre-injection of the PI3K/Akt pathway activator 740 Y-P reversed the GLAST downregulation in COH retinas. Western blot and TUNEL staining showed that transfecting of Si-EFNA3 reduced Müller cell gliosis and RGC apoptosis in COH retinas. Our results suggest that activated EphA4/ephrinA3 reverse signaling induces GLAST downregulation in Müller cells via inhibiting PI3K/Akt/NF-κB pathways, thus contributing to RGC damage in glaucoma.
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Affiliation(s)
- Zhi-Xin Zhou
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Lin-Jie Xu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Hong-Ning Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Shuo Cheng
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Fang Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Yanying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Bo Lei
- Institutes of Neuroscience and Third Affiliated Hospital, Henan Provincial People's Hospital, Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Feng Gao
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, NHC Key Laboratory of Myopia, Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Zhongfeng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
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2
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Xu LJ, Wang HN, Zhou H, Li SY, Li F, Miao Y, Lei B, Sun XH, Gao F, Wang Z. EphA4/ephrinA3 reverse signaling induced Müller cell gliosis and production of pro-inflammatory cytokines in experimental glaucoma. Brain Res 2023; 1801:148204. [PMID: 36529265 DOI: 10.1016/j.brainres.2022.148204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/18/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
Previous work showed that ephrinA3/EphA4 forward signaling contributed to retinal ganglion cell (RGC) damage in experimental glaucoma. Since up-regulated patterns of ephrinA3 and EphA4 were observed in Müller cells and RGCs, an EphA4/ephrinA3 reverse signaling may exist in Müller cells of chronic ocular hypertension (COH) retina. We investigated effects of EphA4/ephrinA3 reverse signaling activation on Müller cells in COH retina. Intravitreal injection of the ephrinA3 agonist EphA4-Fc increased glial fibrillary acidic protein (GFAP) levels in normal retinas, suggestive of Müller cell gliosis, which was confirmed in purified cultured Müller cells treated with EphA4-Fc. These effects were mediated by intracellular STAT3 signaling pathway as phosphorylated STAT3 (p-STAT3) levels and ratios of p-STAT3/STAT3 were significantly increased in both COH retinas and EphA4-Fc intravitreally injected retinas, as well as in EphA4-Fc treated purified cultured Müller cells. The increase of GFAP protein levels in EphA4-Fc-injected retinas and EphA4-Fc treated purified cultured Müller cells could be partially eliminated by stattic, a selective STAT3 blocker. Co-immunoprecipitation results testified to the presence of interaction between ephrinA3 and STAT3/p-STAT3. In addition, intravitreal injection of EphA4-Fc or EphA4-Fc treatment of cultured Müller cells significantly up-regulated mRNA and protein contents of pro-inflammatory cytokines. Moreover, intravitreal injection of EphA4-Fc increased the number of apoptotic RGCs, which could be reversed by the tyrosine kinase blocker PP2. Overall, EphA4/ephrinA3 reverse signaling may induce Müller cell gliosis and increases release of pro-inflammatory factors, which could contribute to RGC death in glaucoma. Inhibition of EphA4/ephrinA3 signaling may provide an effective neuroprotection in glaucoma.
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Affiliation(s)
- Lin-Jie Xu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Hong-Ning Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Han Zhou
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Shu-Ying Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Fang Li
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Yanying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
| | - Bo Lei
- Institute of Neuroscience and Third Affiliated Hospital, Henan Provincial People's Hospital, Henan Eye Institute, Henan Eye Hospital, People's Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou 450003, China
| | - Xing-Huai Sun
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, NHC Key Laboratory of Myopia, Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai 200031, China.
| | - Feng Gao
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, NHC Key Laboratory of Myopia, Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai 200031, China.
| | - Zhongfeng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
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3
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Hoshino N, Altarshan Y, Alzein A, Fernando AM, Nguyen HT, Majewski EF, Chen VCF, William Rochlin M, Yu WM. Ephrin-A3 is required for tonotopic map precision and auditory functions in the mouse auditory brainstem. J Comp Neurol 2021; 529:3633-3654. [PMID: 34235739 PMCID: PMC8490280 DOI: 10.1002/cne.25213] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/22/2021] [Accepted: 07/02/2021] [Indexed: 01/09/2023]
Abstract
Tonotopy is a prominent feature of the vertebrate auditory system and forms the basis for sound discrimination, but the molecular mechanism that underlies its formation remains largely elusive. Ephrin/Eph signaling is known to play important roles in axon guidance during topographic mapping in other sensory systems, so we investigated its possible role in the establishment of tonotopy in the mouse cochlear nucleus. We found that ephrin-A3 molecules are differentially expressed along the tonotopic axis in the cochlear nucleus during innervation. Ephrin-A3 forward signaling is sufficient to repel auditory nerve fibers in a developmental stage-dependent manner. In mice lacking ephrin-A3, the tonotopic map is degraded and isofrequency bands of neuronal activation upon pure tone exposure become imprecise in the anteroventral cochlear nucleus. Ephrin-A3 mutant mice also exhibit a delayed second wave in auditory brainstem responses upon sound stimuli and impaired detection of sound frequency changes. Our findings establish an essential role for ephrin-A3 in forming precise tonotopy in the auditory brainstem to ensure accurate sound discrimination.
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Affiliation(s)
- Natalia Hoshino
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
| | - Yazan Altarshan
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
| | - Ahmad Alzein
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
| | - Amali M. Fernando
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
| | - Hieu T. Nguyen
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
| | - Emma F. Majewski
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
| | | | | | - Wei-Ming Yu
- Department of Biology, Loyola University of Chicago, Chicago, Illinois
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4
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Xu LJ, Gao F, Cheng S, Zhou ZX, Li F, Miao Y, Niu WR, Yuan F, Sun XH, Wang Z. Activated ephrinA3/EphA4 forward signaling induces retinal ganglion cell apoptosis in experimental glaucoma. Neuropharmacology 2020; 178:108228. [PMID: 32745487 DOI: 10.1016/j.neuropharm.2020.108228] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 06/16/2020] [Accepted: 07/01/2020] [Indexed: 12/12/2022]
Abstract
Previous studies have demonstrated that EphA4 participates in neuronal injury, and there is a strong interaction between ephrinA3 and EphA4. In this study, we showed that in a rat chronic ocular hypertension (COH) experimental glaucoma model, expression of EphA4 and ephrinA3 proteins was increased in retinal cells, including retinal ganglion cells (RGCs) and Müller cells, which may result in ephrinA3/EphA4 forward signaling activation on RGCs, as evidenced by increased p-EphA4/EphA4 ratio. Intravitreal injection of ephrinA3-Fc, an activator of EphA4, mimicked the effect of COH on p-EphA4/EphA4 and induced an increase in TUNEL-positive signals in normal retinas, which was accompanied by dendritic spine retraction and thinner dendrites in RGCs. Furthermore, Intravitreal injection of ephrinA3-Fc increased the levels of phosphorylated src and GluA2 (p-src and p-GluA2). Co-immunoprecipitation assay demonstrated interactions between EphA4, p-src and GluA2. Intravitreal injection of ephrinA3-Fc reduced the expression of GluA2 proteins on the surface of normal retinal cells, which was prevented by intravitreal injection of PP2, an inhibitor of src-family tyrosine kinases. Pre-injection of PP2 or the Ca2+-permeable GluA2-lacking AMPA receptor inhibitor Naspm significantly and partially reduced the number of TUNEL-positive RGCs in the ephrinA3-Fc-injected and COH retinas. Our results suggest that activated ephrinA3/EphA4 forward signaling promoted GluA2 endocytosis, then resulted in dendritic spine retraction of RGCs, thus contributing to RGC apoptosis in COH rats. Attenuation of the strength of ephrinA/EphA signaling in an appropriate manner may be an effective way for preventing the loss of RGCs in glaucoma.
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Affiliation(s)
- Lin-Jie Xu
- Department of Ophthalmology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Feng Gao
- Department of Ophthalmology and Visual Science, Eye & ENT Hospital, Shanghai Key Laboratory of Visual Impairment and Restoration, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200031, China
| | - Shuo Cheng
- Department of Ophthalmology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Zhi-Xin Zhou
- Department of Ophthalmology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Fang Li
- Department of Ophthalmology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Yanying Miao
- Department of Ophthalmology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Wei-Ran Niu
- Department of Ophthalmology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Fei Yuan
- Department of Ophthalmology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Xing-Huai Sun
- Department of Ophthalmology and Visual Science, Eye & ENT Hospital, Shanghai Key Laboratory of Visual Impairment and Restoration, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200031, China.
| | - Zhongfeng Wang
- Department of Ophthalmology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, 200032, China.
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5
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Valenzuela JI, Perez F. Localized Intercellular Transfer of Ephrin-As by Trans-endocytosis Enables Long-Term Signaling. Dev Cell 2019; 52:104-117.e5. [PMID: 31866204 DOI: 10.1016/j.devcel.2019.11.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 09/02/2019] [Accepted: 11/19/2019] [Indexed: 12/14/2022]
Abstract
Ephrins can elicit either contact-mediated cell-cell adhesion or repulsion, depending on the efficiency of the removal of their ligand-receptor complexes from the cell surface, thus controlling tissue morphogenesis and oncogenic development. However, the dynamic of the turnover of newly assembled ephrin-Eph complexes during cell-cell interactions remains mostly unexplored. Here, we show that ephrin-A1-EphA2 complexes are locally formed at the tip of the filopodia, at cell-to-cell contacts. Clusters of ephrin-A1 from donor cells surf on filopodia associated to EphA2-bearing subdomains of acceptor cells. Full-length ephrin-A1 is transferred to acceptor cells by trans-endocytosis through a proteolysis-independent mechanism. Trans-endocytosed ephrin-A1 bound to its receptor enables signaling to be emitted from endo-lysosomes of acceptor cells. Localized trans-endocytosis of ephrin-A1 sustains contact-mediated repulsion on cancer cells. Our results uncover the essential role played by local concentration at the tip of filopodia and the trans-endocytosis of full-length ephrin to maintain long-lasting ephrin signaling.
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Affiliation(s)
| | - Franck Perez
- Institut Curie, PSL Research University, CNRS, UMR144, 26 rue d'Ulm, 75005 Paris, France.
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6
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Savier E, Reber M. Visual Maps Development: Reconsidering the Role of Retinal Efnas and Basic Principle of Map Alignment. Front Cell Neurosci 2018; 12:77. [PMID: 29618973 PMCID: PMC5871686 DOI: 10.3389/fncel.2018.00077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/06/2018] [Indexed: 11/13/2022] Open
Affiliation(s)
- Elise Savier
- Centre National de la Recherche Scientifique, UPR3212 - Institute of Cellular and Integrative Neurosciences, University of Strasbourg, Strasbourg, France.,Neuroscience, Department of Biology, University of Virginia, Charlottesville, VA, United States
| | - Michael Reber
- Centre National de la Recherche Scientifique, UPR3212 - Institute of Cellular and Integrative Neurosciences, University of Strasbourg, Strasbourg, France.,Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, ON, Canada
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7
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Savier E, Eglen SJ, Bathélémy A, Perraut M, Pfrieger FW, Lemke G, Reber M. A molecular mechanism for the topographic alignment of convergent neural maps. eLife 2017; 6. [PMID: 28322188 PMCID: PMC5360444 DOI: 10.7554/elife.20470] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 02/26/2017] [Indexed: 12/01/2022] Open
Abstract
Sensory processing requires proper alignment of neural maps throughout the brain. In the superficial layers of the superior colliculus of the midbrain, converging projections from retinal ganglion cells and neurons in visual cortex must be aligned to form a visuotopic map, but the basic mechanisms mediating this alignment remain elusive. In a new mouse model, ectopic expression of ephrin-A3 (Efna3) in a subset of retinal ganglion cells, quantitatively altering the retinal EFNAs gradient, disrupts cortico-collicular map alignment onto the retino-collicular map, creating a visuotopic mismatch. Genetic inactivation of ectopic EFNA3 restores a wild-type cortico-collicular map. Theoretical analyses using a new mapping algorithm model both map formation and alignment, and recapitulate our experimental observations. The algorithm is based on an initial sensory map, the retino-collicular map, which carries intrinsic topographic information, the retinal EFNAs, to the superior colliculus. These EFNAs subsequently topographically align ingrowing visual cortical axons to the retino-collicular map. DOI:http://dx.doi.org/10.7554/eLife.20470.001
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Affiliation(s)
- Elise Savier
- CNRS UPR3212 - Institute of Cellular and Integrative Neuroscience, University of Strasbourg, Strasbourg, France
| | - Stephen J Eglen
- Department of Applied Mathematics and Theoretical Physics, Cambridge Computational Biology Institute, University of Cambridge, Cambridge, United Kingdom.,University of Strasbourg Institute of Advanced Study, Strasbourg, France
| | - Amélie Bathélémy
- CNRS UPR3212 - Institute of Cellular and Integrative Neuroscience, University of Strasbourg, Strasbourg, France
| | - Martine Perraut
- CNRS UPR3212 - Institute of Cellular and Integrative Neuroscience, University of Strasbourg, Strasbourg, France
| | - Frank W Pfrieger
- CNRS UPR3212 - Institute of Cellular and Integrative Neuroscience, University of Strasbourg, Strasbourg, France
| | - Greg Lemke
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, San Diego, United States
| | - Michael Reber
- CNRS UPR3212 - Institute of Cellular and Integrative Neuroscience, University of Strasbourg, Strasbourg, France.,University of Strasbourg Institute of Advanced Study, Strasbourg, France
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8
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Noh H, Lee H, Park E, Park S. Proper closure of the optic fissure requires ephrin A5-EphB2-JNK signaling. Development 2016; 143:461-72. [PMID: 26839344 DOI: 10.1242/dev.129478] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The development of complex organs such as the eye requires a delicate and coordinated balance of cell division and cell death. Although apoptosis is prevalent in the proximoventral optic cup, the precise role it plays in eye development needs to be investigated further. In this study, we show that reduced apoptosis in the proximoventral optic cup prevents closure of the optic fissure. We also show that expression of ephrin A5 (Efna5) partially overlaps with Eph receptor B2 (Ephb2) expression in the proximoventral optic cup and that binding of EphB2 to ephrin A5 induces a sustained activation of JNK. This prolonged JNK signal promotes apoptosis and prevents cell proliferation. Thus, we propose that the unique cross-subclass interaction of EphB2 with ephrin A5 has evolved to function upstream of JNK signaling for the purpose of maintaining an adequate pool of progenitor cells to ensure proper closure of the optic fissure.
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Affiliation(s)
- Hyuna Noh
- Department of Biological Science, Sookmyung Women's University, Chungpa-ro 47gil 100, Yongsan-gu, Seoul 140-742, Korea
| | - Haeryung Lee
- Department of Biological Science, Sookmyung Women's University, Chungpa-ro 47gil 100, Yongsan-gu, Seoul 140-742, Korea
| | - Eunjeong Park
- Department of Biological Science, Sookmyung Women's University, Chungpa-ro 47gil 100, Yongsan-gu, Seoul 140-742, Korea
| | - Soochul Park
- Department of Biological Science, Sookmyung Women's University, Chungpa-ro 47gil 100, Yongsan-gu, Seoul 140-742, Korea
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9
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Noh H, Park S. Over-Expression of Ephrin-A5 in Mice Results in Decreasing the Size of Progenitor Pool through Inducing Apoptosis. Mol Cells 2016; 39:136-40. [PMID: 26674965 PMCID: PMC4757801 DOI: 10.14348/molcells.2016.2245] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/11/2015] [Accepted: 11/16/2015] [Indexed: 11/27/2022] Open
Abstract
Eph receptors and their ligands, ephrins, mediate cell-to-cell contacts in a specific brain region and their bidirectional signaling is implicated in the regulation of apoptosis during early brain development. In this report, we used the alpha(α)-Cre transgenic line to induce ephrin-A5 over-expression in the distal region of the neural retina. Using this double transgenic embryo, we show that the over-expression of ephrin-A5 was responsible for inducing massive apoptosis in both the nasal and temporal retinas. In addition, the number of differentiated retinal neurons with the exception of the bipolar neuron was significantly reduced, whereas the laminar organization of the mature retina remained intact. Consistent with this finding, an analysis of the mature retina revealed that the size of the whole retina--particularly the nasal and temporal regions--is markedly reduced. These results strongly suggest that the level of ephrin-A5 expression plays a role in the regulation of the size of the retinal progenitor pool in the neural retina.
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Affiliation(s)
- Hyuna Noh
- Department of Biological Science, Sookmyung Women’s University, Seoul 140-742,
Korea
| | - Soochul Park
- Department of Biological Science, Sookmyung Women’s University, Seoul 140-742,
Korea
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10
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Chance RK, Bashaw GJ. Slit-Dependent Endocytic Trafficking of the Robo Receptor Is Required for Son of Sevenless Recruitment and Midline Axon Repulsion. PLoS Genet 2015; 11:e1005402. [PMID: 26335920 PMCID: PMC4559387 DOI: 10.1371/journal.pgen.1005402] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 06/26/2015] [Indexed: 01/07/2023] Open
Abstract
Understanding how axon guidance receptors are activated by their extracellular ligands to regulate growth cone motility is critical to learning how proper wiring is established during development. Roundabout (Robo) is one such guidance receptor that mediates repulsion from its ligand Slit in both invertebrates and vertebrates. Here we show that endocytic trafficking of the Robo receptor in response to Slit-binding is necessary for its repulsive signaling output. Dose-dependent genetic interactions and in vitro Robo activation assays support a role for Clathrin-dependent endocytosis, and entry into both the early and late endosomes as positive regulators of Slit-Robo signaling. We identify two conserved motifs in Robo's cytoplasmic domain that are required for its Clathrin-dependent endocytosis and activation in vitro; gain of function and genetic rescue experiments provide strong evidence that these trafficking events are required for Robo repulsive guidance activity in vivo. Our data support a model in which Robo's ligand-dependent internalization from the cell surface to the late endosome is essential for receptor activation and proper repulsive guidance at the midline by allowing recruitment of the downstream effector Son of Sevenless in a spatially constrained endocytic trafficking compartment.
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Affiliation(s)
- Rebecca K. Chance
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Greg J. Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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11
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Abstract
The visual system is beautifully crafted to transmit information of the external world to visual processing and cognitive centers in the brain. For visual information to be relayed to the brain, a series of axon pathfinding events must take place to ensure that the axons of retinal ganglion cells, the only neuronal cell type in the retina that sends axons out of the retina, find their way out of the eye to connect with targets in the brain. In the past few decades, the power of molecular and genetic tools, including the generation of genetically manipulated mouse lines, have multiplied our knowledge about the molecular mechanisms involved in the sculpting of the visual system. Here, we review major advances in our understanding of the mechanisms controlling the differentiation of RGCs, guidance of their axons from the retina to the primary visual centers, and the refinement processes essential for the establishment of topographic maps and eye-specific axon segregation. Human disorders, such as albinism and achiasmia, that impair RGC axon growth and guidance and, thus, the establishment of a fully functioning visual system will also be discussed.
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Affiliation(s)
- Lynda Erskine
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Scotland, UK
| | - Eloisa Herrera
- Instituto de Neurosciencias de Alicante, CSIC-UMH, San Juan de Alicante, Spain
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12
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Suetterlin P, Drescher U. Target-independent ephrina/EphA-mediated axon-axon repulsion as a novel element in retinocollicular mapping. Neuron 2014; 84:740-52. [PMID: 25451192 PMCID: PMC4250266 DOI: 10.1016/j.neuron.2014.09.023] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2014] [Indexed: 11/29/2022]
Abstract
EphrinAs and EphAs play critical roles during topographic map formation in the retinocollicular projection; however, their complex expression patterns in both the retina and superior colliculus (SC) have made it difficult to uncover their precise mechanisms of action. We demonstrate here that growth cones of temporal axons collapse when contacting nasal axons in vitro, and removing ephrinAs from axonal membranes by PI-PLC treatment abolishes this response. In conditional knockout mice, temporal axons display no major targeting defects when ephrinA5 is removed only from the SC, but substantial mapping defects were observed when ephrinA5 expression was removed from both the SC and from the retina, with temporal axons invading the target areas of nasal axons. Together, these data indicate that ephrinA5 drives repellent interactions between temporal and nasal axons within the SC, and demonstrates for the first time that target-independent mechanisms play an essential role in retinocollicular map formation in vivo. EphrinA expression on nasal axons mediates growth cone collapse of temporal axons Analysis of retinocollicular projection in a conditional knockout of ephrinA5 Disruption of repellent axon-axon interactions leads to mapping defects In vivo evidence for target-independent mapping mechanisms in visual system
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Affiliation(s)
- Philipp Suetterlin
- MRC Centre for Developmental Neurobiology, New Hunt's House, Guy's Campus, Kings College London, London SE1 1UL, UK
| | - Uwe Drescher
- MRC Centre for Developmental Neurobiology, New Hunt's House, Guy's Campus, Kings College London, London SE1 1UL, UK.
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13
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Um K, Niu S, Duman JG, Cheng JX, Tu YK, Schwechter B, Liu F, Hiles L, Narayanan AS, Ash RT, Mulherkar S, Alpadi K, Smirnakis SM, Tolias KF. Dynamic control of excitatory synapse development by a Rac1 GEF/GAP regulatory complex. Dev Cell 2014; 29:701-15. [PMID: 24960694 DOI: 10.1016/j.devcel.2014.05.011] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 04/23/2014] [Accepted: 05/14/2014] [Indexed: 11/18/2022]
Abstract
The small GTPase Rac1 orchestrates actin-dependent remodeling essential for numerous cellular processes including synapse development. While precise spatiotemporal regulation of Rac1 is necessary for its function, little is known about the mechanisms that enable Rac1 activators (GEFs) and inhibitors (GAPs) to act in concert to regulate Rac1 signaling. Here, we identify a regulatory complex composed of a Rac-GEF (Tiam1) and a Rac-GAP (Bcr) that cooperate to control excitatory synapse development. Disruption of Bcr function within this complex increases Rac1 activity and dendritic spine remodeling, resulting in excessive synaptic growth that is rescued by Tiam1 inhibition. Notably, EphB receptors utilize the Tiam1-Bcr complex to control synaptogenesis. Following EphB activation, Tiam1 induces Rac1-dependent spine formation, whereas Bcr prevents Rac1-mediated receptor internalization, promoting spine growth over retraction. The finding that a Rac-specific GEF/GAP complex is required to maintain optimal levels of Rac1 signaling provides an important insight into the regulation of small GTPases.
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Affiliation(s)
- Kyongmi Um
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Sanyong Niu
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Joseph G Duman
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Jinxuan X Cheng
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Yen-Kuei Tu
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Integrative Molecular and Biomedical Sciences Program, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Brandon Schwechter
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Feng Liu
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Laura Hiles
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Anjana S Narayanan
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Ryan T Ash
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Shalaka Mulherkar
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Kannan Alpadi
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Stelios M Smirnakis
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Kimberley F Tolias
- Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Integrative Molecular and Biomedical Sciences Program, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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14
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Abstract
The elongation rate of axons is tightly regulated during development. Recycling of the plasma membrane is known to regulate axon extension; however, the specific molecules involved in recycling within the growth cone have not been fully characterized. Here, we investigated whether the small GTPases Rab4 and Rab5 involved in short-loop recycling regulate the extension of Xenopus retinal axons. We report that, in growth cones, Rab5 and Rab4 proteins localize to endosomes, which accumulate markers that are constitutively recycled. Fluorescence recovery after photo-bleaching experiments showed that Rab5 and Rab4 are recruited to endosomes in the growth cone, suggesting that they control recycling locally. Dynamic image analysis revealed that Rab4-positive carriers can bud off from Rab5 endosomes and move to the periphery of the growth cone, suggesting that both Rab5 and Rab4 contribute to recycling within the growth cone. Inhibition of Rab4 function with dominant-negative Rab4 or Rab4 morpholino and constitutive activation of Rab5 decreases the elongation of retinal axons in vitro and in vivo, but, unexpectedly, does not disrupt axon pathfinding. Thus, Rab5- and Rab4-mediated control of endosome trafficking appears to be crucial for axon growth. Collectively, our results suggest that recycling from Rab5-positive endosomes via Rab4 occurs within the growth cone and thereby supports axon elongation.
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15
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Noh H, Park E, Park S. In vivo expression of ephrinA5-Fc in mice results in cephalic neural crest agenesis and craniofacial abnormalities. Mol Cells 2014; 37:59-65. [PMID: 24552711 PMCID: PMC3907003 DOI: 10.14348/molcells.2014.2279] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 11/08/2013] [Accepted: 11/26/2013] [Indexed: 01/10/2023] Open
Abstract
Eph receptors and their ligands ephrins have been implicated in guiding the directed migration of neural crest cells (NCCs). In this study, we found that Wnt1-Cre-mediated expression of ephrinA5-Fc along the dorsal midline of the dien- and mesencephalon resulted in severe craniofacial malformation of mouse embryo. Interestingly, expression of cephalic NCC markers decreased significantly in the frontonasal process and branchial arches 1 and 2, which are target areas for the migratory cephalic NCCs originating in the dien- and mesencephalon. In addition, these craniofacial tissues were much smaller in mutant embryos expressing ephrinA5-Fc. Importantly, EphA7-positive cephalic NCCs were absent along the dorsal dien- and mesencephalon of mutant embryos expressing ephrinA5-Fc, suggesting that the generation of cephalic NCCs is disrupted due to ephrinA5-Fc expression. NCC explant experiments suggested that ephrinA5-Fc perturbed survival of cephalic NCC precursors in the dorsal midline tissue rather than affecting their migratory capacity, which was consistent with our previous report that expression of ephrinA5-Fc in the dorsal midline is responsible for severe neuroepithelial cell apoptotic death. Taken together, our findings strongly suggest that expression of ephrinA5-Fc decreases a population of cephalic NCC precursors in the dorsal midline of the dien- and mesencephalon, thereby disrupting craniofacial development in the mouse embryos.
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Affiliation(s)
- Hyuna Noh
- Department of Biological Science, Sookmyung Women’s University, Seoul 140-742,
Korea
| | - Eunjeong Park
- Department of Biological Science, Sookmyung Women’s University, Seoul 140-742,
Korea
| | - Soochul Park
- Department of Biological Science, Sookmyung Women’s University, Seoul 140-742,
Korea
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16
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Goichberg P, Kannappan R, Cimini M, Bai Y, Sanada F, Sorrentino A, Signore S, Kajstura J, Rota M, Anversa P, Leri A. Age-associated defects in EphA2 signaling impair the migration of human cardiac progenitor cells. Circulation 2013; 128:2211-23. [PMID: 24141256 DOI: 10.1161/circulationaha.113.004698] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Aging negatively impacts on the function of resident human cardiac progenitor cells (hCPCs). Effective regeneration of the injured heart requires mobilization of hCPCs to the sites of damage. In the young heart, signaling by the guidance receptor EphA2 in response to the ephrin A1 ligand promotes hCPC motility and improves cardiac recovery after infarction. METHODS AND RESULTS We report that old hCPCs are characterized by cell-autonomous inhibition of their migratory ability ex vivo and impaired translocation in vivo in the damaged heart. EphA2 expression was not decreased in old hCPCs; however, the elevated level of reactive oxygen species in aged cells induced post-translational modifications of the EphA2 protein. EphA2 oxidation interfered with ephrin A1-stimulated receptor auto-phosphorylation, activation of Src family kinases, and caveolin-1-mediated internalization of the receptor. Cellular aging altered the EphA2 endocytic route, affecting the maturation of EphA2-containing endosomes and causing premature signal termination. Overexpression of functionally intact EphA2 in old hCPCs corrected the defects in endocytosis and downstream signaling, enhancing cell motility. Based on the ability of phenotypically young hCPCs to respond efficiently to ephrin A1, we developed a novel methodology for the prospective isolation of live hCPCs with preserved migratory capacity and growth reserve. CONCLUSIONS Our data demonstrate that the ephrin A1/EphA2 pathway may serve as a target to facilitate trafficking of hCPCs in the senescent myocardium. Importantly, EphA2 receptor function can be implemented for the selection of hCPCs with high therapeutic potential, a clinically relevant strategy that does not require genetic manipulation of stem cells.
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Affiliation(s)
- Polina Goichberg
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (P.G., R.K., M.C., Y.B., F.S., A.S., S.S., J.K., M.R., PA., A.L.); and the Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai, China (Y.B.)
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17
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Xiaodong H, Zhen H, Min S, Zhiming C, Hongyan J, Chong Z, Xuefeng T, Guohua J. Direct inhibition of cell surface ephrin-B2 by recombinant ephrin-B2/FC. Biochem Biophys Res Commun 2013; 440:300-5. [PMID: 24076390 DOI: 10.1016/j.bbrc.2013.09.070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 09/13/2013] [Indexed: 10/26/2022]
Abstract
First messengers and viral transfection are the two most common ways to stimulate cells for signal output, although their applications are limited. We investigated mechanisms of inducing neural stem cell differentiation using recombinant ephrin-B2/Fc and found that it acted as a ligand and inhibited endogenous ephrin-B2, which maintenance of the neural progenitor cell state, by direct interference. Our results showed the movement of ephrin-B2/Fc within the cell and indicated that it recycled to the plasma membrane surface, revealing a possible pattern of ephrin trafficking. Our results also serve as proof of concept for the reconstruction of the intracellular domain of ephrin using an artificial receptor to direct input signals in future studies.
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Affiliation(s)
- Hu Xiaodong
- Department of Anatomy and Neurobiology, The Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, Jiangsu Province 226001, China
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18
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Lisabeth EM, Falivelli G, Pasquale EB. Eph receptor signaling and ephrins. Cold Spring Harb Perspect Biol 2013; 5:5/9/a009159. [PMID: 24003208 DOI: 10.1101/cshperspect.a009159] [Citation(s) in RCA: 281] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The Eph receptors are the largest of the RTK families. Like other RTKs, they transduce signals from the cell exterior to the interior through ligand-induced activation of their kinase domain. However, the Eph receptors also have distinctive features. Instead of binding soluble ligands, they generally mediate contact-dependent cell-cell communication by interacting with surface-associated ligands-the ephrins-on neighboring cells. Eph receptor-ephrin complexes emanate bidirectional signals that affect both receptor- and ephrin-expressing cells. Intriguingly, ephrins can also attenuate signaling by Eph receptors coexpressed in the same cell. Additionally, Eph receptors can modulate cell behavior independently of ephrin binding and kinase activity. The Eph/ephrin system regulates many developmental processes and adult tissue homeostasis. Its abnormal function has been implicated in various diseases, including cancer. Thus, Eph receptors represent promising therapeutic targets. However, more research is needed to better understand the many aspects of their complex biology that remain mysterious.
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Affiliation(s)
- Erika M Lisabeth
- Cancer Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA
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19
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Kim Y, Park E, Noh H, Park S. Expression of EphA8-Fc in transgenic mouse embryos induces apoptosis of neural epithelial cells during brain development. Dev Neurobiol 2013; 73:702-12. [PMID: 23696555 DOI: 10.1002/dneu.22092] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 04/04/2013] [Accepted: 05/13/2013] [Indexed: 12/17/2022]
Abstract
EphAs and ephrin-As are expressed in multiple regions of the developing brain and have been implicated in regulating brain size. Here, we report the identification of a novel mechanism in which reverse signaling through ephrin-As controls neural epithelial cell number in the developing brain. Ectopic expression of EphA8-Fc in transgenic embryos induced apoptosis of neural epithelial cells, which was accompanied by a dramatic decrease in brain size. The number of ephrin-A5-expressing cells was significantly reduced in the brain region where EphA8-Fc was ectopically expressed. Furthermore, in vitro culture of the dissociated neuroepithelial cells revealed that EphA8-Fc enhanced apoptotic cell death of the ephrinA5-expressing cells in a caspase-dependent manner. Thus, our results suggest that reverse signaling through ephrin-As is biochemically linked with caspase-dependent proapoptotic signaling during early brain development.
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Affiliation(s)
- Yujin Kim
- Department of Biological Science, Sookmyung Women's University, Yongsan-gu, Seoul 140-742, Korea
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20
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EphA/ephrin-A signaling is critically involved in region-specific apoptosis during early brain development. Cell Death Differ 2012; 20:169-80. [PMID: 22976838 DOI: 10.1038/cdd.2012.121] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
EphAs and ephrin-As have been implicated in the morphogenesis of the developing brain. We found that EphA7 and ephrin-A5 are coexpressed in the dorsal midline (DM) of the diencephalon and anterior mesencephalon. Interestingly, programmed cell death (PCD) of the neural epithelial cells normally found in this region was reduced in ephrin-A5/ephrin-A2 dual-deficient embryos. In contrast, in vivo expression of ephrin-A5-Fc or full-length ephrin-A5 strongly induced apoptosis in neural epithelial cells and was accompanied by severe brain malformation during embryonic development. Expression of ephrinA5-Fc correlated with apoptosis of EphA7-expressing cells, whereas null mutation of ephrin-A5 resulted in the converse phenotype. Importantly, null mutation of caspase-3 or endogenous ephrin-A5 attenuated the PCD induced by ectopically overexpressed ephrin-A5. Together, our results suggest that brain region-specific PCD may occur in a region where EphAs cluster with neighboring ephrin-As through cell-cell contact.
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21
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Ortalli AL, Fiore L, Di Napoli J, Rapacioli M, Salierno M, Etchenique R, Flores V, Sanchez V, Carri NG, Scicolone G. EphA3 expressed in the chicken tectum stimulates nasal retinal ganglion cell axon growth and is required for retinotectal topographic map formation. PLoS One 2012; 7:e38566. [PMID: 22685584 PMCID: PMC3369860 DOI: 10.1371/journal.pone.0038566] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 05/07/2012] [Indexed: 11/29/2022] Open
Abstract
Background Retinotopic projection onto the tectum/colliculus constitutes the most studied model of topographic mapping and Eph receptors and their ligands, the ephrins, are the best characterized molecular system involved in this process. Ephrin-As, expressed in an increasing rostro-caudal gradient in the tectum/colliculus, repel temporal retinal ganglion cell (RGC) axons from the caudal tectum and inhibit their branching posterior to their termination zones. However, there are conflicting data regarding the nature of the second force that guides nasal axons to invade and branch only in the caudal tectum/colliculus. The predominant model postulates that this second force is produced by a decreasing rostro-caudal gradient of EphA7 which repels nasal optic fibers and prevents their branching in the rostral tectum/colliculus. However, as optic fibers invade the tectum/colliculus growing throughout this gradient, this model cannot explain how the axons grow throughout this repellent molecule. Methodology/Principal Findings By using chicken retinal cultures we showed that EphA3 ectodomain stimulates nasal RGC axon growth in a concentration dependent way. Moreover, we showed that nasal axons choose growing on EphA3-expressing cells and that EphA3 diminishes the density of interstitial filopodia in nasal RGC axons. Accordingly, in vivo EphA3 ectodomain misexpression directs nasal optic fibers toward the caudal tectum preventing their branching in the rostral tectum. Conclusions We demonstrated in vitro and in vivo that EphA3 ectodomain (which is expressed in a decreasing rostro-caudal gradient in the tectum) is necessary for topographic mapping by stimulating the nasal axon growth toward the caudal tectum and inhibiting their branching in the rostral tectum. Furthermore, the ability of EphA3 of stimulating axon growth allows understanding how optic fibers invade the tectum growing throughout this molecular gradient. Therefore, opposing tectal gradients of repellent ephrin-As and of axon growth stimulating EphA3 complement each other to map optic fibers along the rostro-caudal tectal axis.
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Affiliation(s)
- Ana Laura Ortalli
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences “Prof. E. De Robertis” (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | - Luciano Fiore
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences “Prof. E. De Robertis” (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | - Jennifer Di Napoli
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences “Prof. E. De Robertis” (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | - Melina Rapacioli
- Interdisciplinary Group in Theoretical Biology, Department of Bioestructural Sciences, Favaloro University, Buenos Aires, Argentina
| | - Marcelo Salierno
- Department of Inorganic, Analytical and Physical Chemistry (INQUIMAE), Faculty of Exact and Natural Sciences, University of Buenos Aires, Buenos Aires, Argentina
| | - Roberto Etchenique
- Department of Inorganic, Analytical and Physical Chemistry (INQUIMAE), Faculty of Exact and Natural Sciences, University of Buenos Aires, Buenos Aires, Argentina
| | - Vladimir Flores
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences “Prof. E. De Robertis” (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
- Interdisciplinary Group in Theoretical Biology, Department of Bioestructural Sciences, Favaloro University, Buenos Aires, Argentina
| | - Viviana Sanchez
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences “Prof. E. De Robertis” (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | | | - Gabriel Scicolone
- Laboratory of Developmental Neurobiology, Institute of Cell Biology and Neurosciences “Prof. E. De Robertis” (UBA-CONICET), School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
- * E-mail:
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22
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Eph and ephrin signaling in the formation of topographic maps. Semin Cell Dev Biol 2011; 23:7-15. [PMID: 22044886 DOI: 10.1016/j.semcdb.2011.10.026] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2011] [Accepted: 10/17/2011] [Indexed: 11/20/2022]
Abstract
The axonal connections between the retina and its midbrain target, the superior colliculus (SC), is mapped topographically, such that the spatial relationships of cell bodies in the retina are maintained when terminating in the SC. Topographic map development uses a Cartesian mapping system such that each axis of the retina is mapped independently. Along the nasal-temporal mapping axis, EphAs and ephrin-As, are graded molecular cues required for topographic mapping while the dorsal-ventral axis is mapped in part via EphB and ephrin-Bs. Because both Ephs and ephrins are cell surface molecules they can signal in the forward and reverse directions. Eph/ephrin signaling leads to changes in cytoskeletal dynamics that lead to actin depolymerization and endocytosis guiding axons via attraction and repulsion.
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Suetterlin P, Marler KM, Drescher U. Axonal ephrinA/EphA interactions, and the emergence of order in topographic projections. Semin Cell Dev Biol 2011; 23:1-6. [PMID: 22040913 DOI: 10.1016/j.semcdb.2011.10.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 10/17/2011] [Indexed: 12/31/2022]
Abstract
In the classical view of axon guidance, neurons send out axons which are endowed with guidance receptors enabling them to find their (distant) target areas by an interaction with their ligands expressed in specific spatio-temporal patterns along their pathways and in their target area. However, this view has recently been confounded by more detailed analyses of, for example, the expression patterns of EphAs and ephrinAs in the retinotectal projection. Here ephrinA 'ligands' are expressed not only in the target area but also on the projecting RGC axons, and EphA 'receptors' not only on retinal ganglion cell (RGC) axons but also in the target area itself. This review describes the on-going functional characterisation of the surprising co-expression of ephrinAs and EphAs on retinal ganglion cell (RGC) axons and other cell types. It also investigates the function of ephrinAs as receptors and describes their interaction with co-receptors involved in mediating this function.
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Affiliation(s)
- Philipp Suetterlin
- MRC Centre for Developmental Neurobiology, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK
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24
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Eph/ephrin signaling in epidermal differentiation and disease. Semin Cell Dev Biol 2011; 23:92-101. [PMID: 22040910 DOI: 10.1016/j.semcdb.2011.10.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 10/17/2011] [Indexed: 01/09/2023]
Abstract
Eph receptor tyrosine kinases mediate cell-cell communication by interacting with ephrin ligands residing on adjacent cell surfaces. In doing so, these juxtamembrane signaling complexes provide important contextual information about the cellular microenvironment that helps orchestrate tissue morphogenesis and maintain homeostasis. Eph/ephrin signaling has been implicated in various aspects of mammalian skin physiology, with several members of this large family of receptor tyrosine kinases and their ligands present in the epidermis, hair follicles, sebaceous glands, and underlying dermis. This review focuses on the emerging role of Eph receptors and ephrins in epidermal keratinocytes where they can modulate proliferation, migration, differentiation, and death. The activation of Eph receptors by ephrins at sites of cell-cell contact also appears to play a key role in the maturation of intercellular junctional complexes as keratinocytes move out of the basal layer and differentiate in the suprabasal layers of this stratified, squamous epithelium. Furthermore, alterations in the epidermal Eph/ephrin axis have been associated with cutaneous malignancy, wound healing defects and inflammatory skin conditions. These collective observations suggest that the Eph/ephrin cell-cell communication pathway may be amenable to therapeutic intervention for the purpose of restoring epidermal tissue homeostasis and integrity in dermatological disorders.
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25
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D-Eph-ective endocytosis disrupts topographic mapping. EMBO J 2011; 30:1422-4. [PMID: 21505521 DOI: 10.1038/emboj.2011.87] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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