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Liu L, Jiang Y, Al-Shabrawey M, Ren X, Wang S, Steinle JJ. EphB1 causes retinal damage through inflammatory pathways in the retina and retinal Müller cells. Mol Vis 2024; 30:167-174. [PMID: 38601015 PMCID: PMC11006007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 03/20/2024] [Indexed: 04/12/2024] Open
Abstract
Purpose To examine whether increased ephrin type-B receptor 1 (EphB1) leads to inflammatory mediators in retinal Müller cells. Methods Diabetic human and mouse retinal samples were examined for EphB1 protein levels. Rat Müller cells (rMC-1) were grown in culture and treated with EphB1 siRNA or ephrin B1-Fc to explore inflammatory mediators in cells grown in high glucose. An EphB1 overexpression adeno-associated virus (AAV) was used to increase EphB1 in Müller cells in vivo. Ischemia/reperfusion (I/R) was performed on mice treated with the EphB1 overexpression AAV to explore the actions of EphB1 on retinal neuronal changes in vivo. Results EphB1 protein levels were increased in diabetic human and mouse retinal samples. Knockdown of EphB1 reduced inflammatory mediator levels in Müller cells grown in high glucose. Ephrin B1-Fc increased inflammatory proteins in rMC-1 cells grown in normal and high glucose. Treatment of mice with I/R caused retinal thinning and loss of cell numbers in the ganglion cell layer. This was increased in mice exposed to I/R and treated with the EphB1 overexpressing AAVs. Conclusions EphB1 is increased in the retinas of diabetic humans and mice and in high glucose-treated Müller cells. This increase leads to inflammatory proteins. EphB1 also enhanced retinal damage in response to I/R. Taken together, inhibition of EphB1 may offer a new therapeutic option for diabetic retinopathy.
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Affiliation(s)
- Li Liu
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI
| | - Youde Jiang
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI
| | - Mohamed Al-Shabrawey
- Eye Research Center and Institute, Oakland University William Beaumont School of Medicine (OUWB-SOM), Oakland University, Oakland, MI
- Department of Foundational Medical Studies, OUWB-SOM, Oakland University, CA
| | - Xiaobai Ren
- Department of Ophthalmology, Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University, Stanford, CA
| | - Sui Wang
- Department of Ophthalmology, Mary M. and Sash A. Spencer Center for Vision Research, Byers Eye Institute, Stanford University, Stanford, CA
| | - Jena J Steinle
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI
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Assali A, Chenaux G, Cho JY, Berto S, Ehrlich NA, Cowan CW. EphB1 controls long-range cortical axon guidance through a cell non-autonomous role in GABAergic cells. Development 2024; 151:dev201439. [PMID: 38345254 PMCID: PMC10946438 DOI: 10.1242/dev.201439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 01/28/2024] [Indexed: 02/29/2024]
Abstract
EphB1 is required for proper guidance of cortical axon projections during brain development, but how EphB1 regulates this process remains unclear. We show here that EphB1 conditional knockout (cKO) in GABAergic cells (Vgat-Cre), but not in cortical excitatory neurons (Emx1-Cre), reproduced the cortical axon guidance defects observed in global EphB1 KO mice. Interestingly, in EphB1 cKOVgat mice, the misguided axon bundles contained co-mingled striatal GABAergic and somatosensory cortical glutamatergic axons. In wild-type mice, somatosensory axons also co-fasciculated with striatal axons, notably in the globus pallidus, suggesting that a subset of glutamatergic cortical axons normally follows long-range GABAergic axons to reach their targets. Surprisingly, the ectopic axons in EphB1 KO mice were juxtaposed to major blood vessels. However, conditional loss of EphB1 in endothelial cells (Tie2-Cre) did not produce the axon guidance defects, suggesting that EphB1 in GABAergic neurons normally promotes avoidance of these ectopic axons from the developing brain vasculature. Together, our data reveal a new role for EphB1 in GABAergic neurons to influence proper cortical glutamatergic axon guidance during brain development.
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Affiliation(s)
- Ahlem Assali
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29425, USA
| | - George Chenaux
- Department of Psychiatry, University of Texas Southwestern Medical School, Dallas, TX 75390, USA
| | - Jennifer Y. Cho
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Stefano Berto
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Nathan A. Ehrlich
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Christopher W. Cowan
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29425, USA
- Department of Psychiatry, University of Texas Southwestern Medical School, Dallas, TX 75390, USA
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3
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Strong TA, Esquivel J, Wang Q, Ledon PJ, Wang H, Gaidosh G, Tse D, Pelaez D. Activation of multiple Eph receptors on neuronal membranes correlates with the onset of optic neuropathy. EYE AND VISION (LONDON, ENGLAND) 2023; 10:42. [PMID: 37779186 PMCID: PMC10544557 DOI: 10.1186/s40662-023-00359-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 09/11/2023] [Indexed: 10/03/2023]
Abstract
BACKGROUND Optic neuropathy is a major cause of irreversible blindness, yet the molecular determinants that contribute to neuronal demise have not been fully elucidated. Several studies have identified 'ephrin signaling' as one of the most dysregulated pathways in the early pathophysiology of optic neuropathy with varied etiologies. Developmentally, gradients in ephrin signaling coordinate retinotopic mapping via repulsive modulation of cytoskeletal dynamics in neuronal membranes. Little is known about the role ephrin signaling plays in the post-natal visual system and its correlation with the onset of optic neuropathy. METHODS Postnatal mouse retinas were collected for mass spectrometry analysis for erythropoietin-producing human hepatocellular (Eph) receptors. Optic nerve crush (ONC) model was employed to induce optic neuropathy, and proteomic changes during the acute phase of neuropathic onset were analyzed. Confocal and super-resolution microscopy determined the cellular localization of activated Eph receptors after ONC injury. Eph receptor inhibitors assessed the neuroprotective effect of ephrin signaling modulation. RESULTS Mass spectrometry revealed expression of seven Eph receptors (EphA2, A4, A5, B1, B2, B3, and B6) in postnatal mouse retinal tissue. Immunoblotting analysis indicated a significant increase in phosphorylation of these Eph receptors 48 h after ONC. Confocal microscopy demonstrated the presence of both subclasses of Eph receptors within the retina. Stochastic optical reconstruction microscopy (STORM) super-resolution imaging combined with optimal transport colocalization analysis revealed a significant co-localization of activated Eph receptors with injured neuronal cells, compared to uninjured neuronal and/or injured glial cells, 48 h post-ONC. Eph receptor inhibitors displayed notable neuroprotective effects for retinal ganglion cells (RGCs) after six days of ONC injury. CONCLUSIONS Our findings demonstrate the functional presence of diverse Eph receptors in the postnatal mammalian retina, capable of modulating multiple biological processes. Pan-Eph receptor activation contributes to the onset of neuropathy in optic neuropathies, with preferential activation of Eph receptors on neuronal processes in the inner retina following optic nerve injury. Notably, Eph receptor activation precedes neuronal loss. We observed a neuroprotective effect on RGCs upon inhibiting Eph receptors. Our study highlights the importance of investigating this repulsive pathway in early optic neuropathies and provides a comprehensive characterization of the receptors present in the developed retina of mice, relevant to both homeostasis and disease processes.
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Affiliation(s)
- Thomas A Strong
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA
- Dr. Nasser Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10th Avenue, Miami, FL, 33136, USA
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, USA
| | - Juan Esquivel
- Department of Physics, University of Florida College of Liberal Arts and Sciences, Gainesville, FL, USA
| | - Qikai Wang
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA
- Dr. Nasser Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10th Avenue, Miami, FL, 33136, USA
| | - Paul J Ledon
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA
- Dr. Nasser Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10th Avenue, Miami, FL, 33136, USA
- Department of Public Health Sciences, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Hua Wang
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA
- Dr. Nasser Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10th Avenue, Miami, FL, 33136, USA
| | - Gabriel Gaidosh
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA
| | - David Tse
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA
- Dr. Nasser Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10th Avenue, Miami, FL, 33136, USA
| | - Daniel Pelaez
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA.
- Dr. Nasser Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10th Avenue, Miami, FL, 33136, USA.
- Department of Biomedical Engineering, University of Miami College of Engineering, University of Miami, Coral Gables, FL, USA.
- Department of Cell Biology, University of Miami Miller School of Medicine, Miami, USA.
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA.
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Strong TA, Esquivel J, Wang Q, Ledon PJ, Wang H, Gaidosh G, Tse D, Pelaez D. Activation of Multiple Eph Receptors on Neuronal Membranes Correlates with The Onset of Traumatic Optic Neuropathy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.05.543735. [PMID: 37333178 PMCID: PMC10274644 DOI: 10.1101/2023.06.05.543735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Background Optic neuropathy (ON) is a major cause of irreversible blindness, yet the molecular determinants that contribute to neuronal demise have not been fully elucidated. Several studies have identified 'ephrin signaling' as one of the most dysregulated pathways in the early pathophysiology of ON with varied etiologies. Developmentally, gradients in ephrin signaling coordinate retinotopic mapping via repulsive modulation of cytoskeletal dynamics in neuronal membranes. Little is known about the role ephrin signaling played in the post-natal visual system and its correlation with the onset of optic neuropathy. Methods Postnatal mouse retinas were collected for mass spectrometry analysis for Eph receptors. Optic nerve crush (ONC) model was employed to induce optic neuropathy, and proteomic changes during the acute phase of neuropathic onset were analyzed. Confocal and super-resolution microscopy determined the cellular localization of activated Eph receptors after ONC injury. Eph receptor inhibitors assessed the neuroprotective effect of ephrin signaling modulation. Results Mass spectrometry revealed expression of seven Eph receptors (EphA2, A4, A5, B1, B2, B3, and B6) in postnatal mouse retinal tissue. Immunoblotting analysis indicated a significant increase in phosphorylation of these Eph receptors 48 hours after ONC. Confocal microscopy demonstrated the presence of both subclasses of Eph receptors in the inner retinal layers. STORM super-resolution imaging combined with optimal transport colocalization analysis revealed a significant co-localization of activated Eph receptors with injured neuronal processes, compared to uninjured neuronal and/or injured glial cells, 48 hours post-ONC. Eph receptor inhibitors displayed notable neuroprotective effects after 6 days of ONC injury. Conclusions Our findings demonstrate the functional presence of diverse Eph receptors in the postnatal mammalian retina, capable of modulating multiple biological processes. Pan-Eph receptor activation contributes to the onset of neuropathy in ONs, with preferential activation of Eph receptors on neuronal processes in the inner retina following optic nerve injury. Notably, Eph receptor activation precedes neuronal loss. We observed neuroprotective effects upon inhibiting Eph receptors. Our study highlights the importance of investigating this repulsive pathway in early optic neuropathies and provides a comprehensive characterization of the receptors present in the developed retina of mice, relevant to both homeostasis and disease processes.
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Affiliation(s)
- Thomas A. Strong
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, United States of America
- Dr. Nasser Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States of America
- Department of Cell Biology, University of Miami Miller School of Medicine
| | - Juan Esquivel
- Department of Public Health Sciences, University of Miami Miller School of Medicine, Miami, FL, United States of America
| | - Qikai Wang
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, United States of America
- Dr. Nasser Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States of America
| | - Paul J. Ledon
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, United States of America
- Department of Public Health Sciences, University of Miami Miller School of Medicine, Miami, FL, United States of America
| | - Hua Wang
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, United States of America
- Dr. Nasser Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States of America
| | - Gabriel Gaidosh
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, United States of America
| | - David Tse
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, United States of America
- Dr. Nasser Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States of America
| | - Daniel Pelaez
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, United States of America
- Dr. Nasser Al-Rashid Orbital Vision Research Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States of America
- Department of Biomedical Engineering, University of Miami College of Engineering, University of Miami, Coral Gables, FL, United States of America
- Department of Cell Biology, University of Miami Miller School of Medicine
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, United States of America
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5
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Lysosomal Function and Axon Guidance: Is There a Meaningful Liaison? Biomolecules 2021; 11:biom11020191. [PMID: 33573025 PMCID: PMC7911486 DOI: 10.3390/biom11020191] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 01/26/2021] [Accepted: 01/26/2021] [Indexed: 01/25/2023] Open
Abstract
Axonal trajectories and neural circuit activities strongly rely on a complex system of molecular cues that finely orchestrate the patterning of neural commissures. Several of these axon guidance molecules undergo continuous recycling during brain development, according to incompletely understood intracellular mechanisms, that in part rely on endocytic and autophagic cascades. Based on their pivotal role in both pathways, lysosomes are emerging as a key hub in the sophisticated regulation of axonal guidance cue delivery, localization, and function. In this review, we will attempt to collect some of the most relevant research on the tight connection between lysosomal function and axon guidance regulation, providing some proof of concepts that may be helpful to understanding the relation between lysosomal storage disorders and neurodegenerative diseases.
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6
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Borges R, Fonseca J, Gomes C, Johnson WE, O'Brien SJ, Zhang G, Gilbert MTP, Jarvis ED, Antunes A. Avian Binocularity and Adaptation to Nocturnal Environments: Genomic Insights from a Highly Derived Visual Phenotype. Genome Biol Evol 2020; 11:2244-2255. [PMID: 31386143 PMCID: PMC6735850 DOI: 10.1093/gbe/evz111] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2019] [Indexed: 01/04/2023] Open
Abstract
Typical avian eyes are phenotypically engineered for photopic vision (daylight). In contrast, the highly derived eyes of the barn owl (Tyto alba) are adapted for scotopic vision (dim light). The dramatic modifications distinguishing barn owl eyes from other birds include: 1) shifts in frontal orientation to improve binocularity, 2) rod-dominated retina, and 3) enlarged corneas and lenses. Some of these features parallel mammalian eye patterns, which are hypothesized to have initially evolved in nocturnal environments. Here, we used an integrative approach combining phylogenomics and functional phenotypes of 211 eye-development genes across 48 avian genomes representing most avian orders, including the stem lineage of the scotopic-adapted barn owl. Overall, we identified 25 eye-development genes that coevolved under intensified or relaxed selection in the retina, lens, cornea, and optic nerves of the barn owl. The agtpbp1 gene, which is associated with the survival of photoreceptor populations, was pseudogenized in the barn owl genome. Our results further revealed that barn owl retinal genes responsible for the maintenance, proliferation, and differentiation of photoreceptors experienced an evolutionary relaxation. Signatures of relaxed selection were also observed in the lens and cornea morphology-associated genes, suggesting that adaptive evolution in these structures was essentially structural. Four eye-development genes (ephb1, phactr4, prph2, and rs1) evolved in positive association with the orbit convergence in birds and under relaxed selection in the barn owl lineage, likely contributing to an increased reliance on binocular vision in the barn owl. Moreover, we found evidence of coevolutionary interactions among genes that are expressed in the retina, lens, and optic nerve, suggesting synergetic adaptive events. Our study disentangles the genomic changes governing the binocularity and low-light perception adaptations of barn owls to nocturnal environments while revealing the molecular mechanisms contributing to the shift from the typical avian photopic vision to the more-novel scotopic-adapted eye.
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Affiliation(s)
- Rui Borges
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Portugal.,Department of Biology, Faculty of Sciences, University of Porto, Portugal
| | - João Fonseca
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Portugal
| | - Cidália Gomes
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Portugal
| | - Warren E Johnson
- Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, Virginia.,Walter Reed Biosystematics Unit, Smithsonian Institution, Suitland, Maryland
| | - Stephen J O'Brien
- Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, Russia.,Guy Harvey Oceanographic Center, Halmos College of Natural Sciences and Oceanography, Nova Southeastern University
| | - Guojie Zhang
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Denmark.,China National GeneBank, BGI-Shenzen, Shenzhen, China.,State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - M Thomas P Gilbert
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Denmark
| | - Erich D Jarvis
- Laboratory of Neurogenetics of Language, Rockefeller University.,Howard Hughes Medical Institute, Chevy Chase, Maryland
| | - Agostinho Antunes
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Portugal.,Department of Biology, Faculty of Sciences, University of Porto, Portugal
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7
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Talebian A, Henkemeyer M. EphB2 receptor cell-autonomous forward signaling mediates auditory memory recall and learning-driven spinogenesis. Commun Biol 2019; 2:372. [PMID: 31633063 PMCID: PMC6789002 DOI: 10.1038/s42003-019-0625-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 09/16/2019] [Indexed: 01/09/2023] Open
Abstract
While ephrin-B ligands and EphB receptors are expressed to high levels in the learning centers of the brain, it remains largely unknown how their trans-synaptic interactions contribute to memory. We find that EphB2 forward signaling is needed for contextual and sound-evoked memory recall and that constitutive over-activation of the receptor's intracellular tyrosine kinase domain results in enhanced memory. Loss of EphB2 expression does not affect the number of neurons activated following encoding, although a reduction of neurons activated after the sound-cued retrieval test was detected in the auditory cortex and hippocampal CA1. Further, spine density and maturation was reduced in the auditory cortex of mutants especially in the neurons that were dual-activated during both encoding and retrieval. Our data demonstrates that trans-synaptic ephrin-B-EphB2 interactions and forward signaling facilitate neural activation and structural plasticity in learning-associated neurons involved in the generation of memories.
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Affiliation(s)
- Asghar Talebian
- Department of Neuroscience and Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Mark Henkemeyer
- Department of Neuroscience and Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
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8
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Niethamer TK, Bush JO. Getting direction(s): The Eph/ephrin signaling system in cell positioning. Dev Biol 2019; 447:42-57. [PMID: 29360434 PMCID: PMC6066467 DOI: 10.1016/j.ydbio.2018.01.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 12/21/2017] [Accepted: 01/18/2018] [Indexed: 12/16/2022]
Abstract
In vertebrates, the Eph/ephrin family of signaling molecules is a large group of membrane-bound proteins that signal through a myriad of mechanisms and effectors to play diverse roles in almost every tissue and organ system. Though Eph/ephrin signaling has functions in diverse biological processes, one core developmental function is in the regulation of cell position and tissue morphology by regulating cell migration and guidance, cell segregation, and boundary formation. Often, the role of Eph/ephrin signaling is to translate patterning information into physical movement of cells and changes in morphology that define tissue and organ systems. In this review, we focus on recent advances in the regulation of these processes, and our evolving understanding of the in vivo signaling mechanisms utilized in distinct developmental contexts.
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Affiliation(s)
- Terren K Niethamer
- Department of Cell and Tissue Biology, Program in Craniofacial Biology, and Institute of Human Genetics, University of California at San Francisco, San Francisco, CA 94143, USA
| | - Jeffrey O Bush
- Department of Cell and Tissue Biology, Program in Craniofacial Biology, and Institute of Human Genetics, University of California at San Francisco, San Francisco, CA 94143, USA.
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9
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Liu XD, Zhu XN, Halford MM, Xu TL, Henkemeyer M, Xu NJ. Retrograde regulation of mossy fiber axon targeting and terminal maturation via postsynaptic Lnx1. J Cell Biol 2018; 217:4007-4024. [PMID: 30185604 PMCID: PMC6219728 DOI: 10.1083/jcb.201803105] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 06/25/2018] [Accepted: 08/14/2018] [Indexed: 11/22/2022] Open
Abstract
Synapse formation relies on the coordination of dynamic pre- and postsynaptic structures during brain development. Liu et al. reveal that presynaptic terminal maturation of mossy fiber axons is retrogradely regulated by postsynaptic scaffold protein Lnx1 via stabilizing EphB receptor kinases. Neuronal connections are initiated by axon targeting to form synapses. However, how the maturation of axon terminals is modulated through interacting with postsynaptic elements remains elusive. In this study, we find that ligand of Numb protein X 1 (Lnx1), a postsynaptic PDZ protein expressed in hippocampal CA3 pyramidal neurons, is essential for mossy fiber (MF) axon targeting during the postnatal period. Lnx1 deletion causes defective synaptic arrangement that leads to aberrant presynaptic terminals. We further identify EphB receptors as novel Lnx1-binding proteins to form a multiprotein complex that is stabilized on the CA3 neuron membrane through preventing proteasome activity. EphB1 and EphB2 are independently required to transduce distinct signals controlling MF pruning and targeting for precise DG-CA3 synapse formation. Furthermore, constitutively active EphB2 kinase rescues structure of the wired MF terminals in Lnx1 mutant mice. Our data thus define a retrograde trans-synaptic regulation required for integration of post- and presynaptic structure that participates in building hippocampal neural circuits during the adolescence period.
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Affiliation(s)
- Xian-Dong Liu
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiao-Na Zhu
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Michael M Halford
- Department of Neuroscience, Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas, TX
| | - Tian-Le Xu
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Mark Henkemeyer
- Department of Neuroscience, Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas, TX
| | - Nan-Jie Xu
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China .,Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Key Laboratory of Cell Differentiation and Apoptosis of the Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai China
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10
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Functional Consequences of Synapse Remodeling Following Astrocyte-Specific Regulation of Ephrin-B1 in the Adult Hippocampus. J Neurosci 2018; 38:5710-5726. [PMID: 29793972 DOI: 10.1523/jneurosci.3618-17.2018] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 05/13/2018] [Accepted: 05/15/2018] [Indexed: 01/22/2023] Open
Abstract
Astrocyte-derived factors can control synapse formation and functions, making astrocytes an attractive target for regulating neuronal circuits and associated behaviors. Abnormal astrocyte-neuronal interactions are also implicated in neurodevelopmental disorders and neurodegenerative diseases associated with impaired learning and memory. However, little is known about astrocyte-mediated mechanisms that regulate learning and memory. Here, we propose astrocytic ephrin-B1 as a regulator of synaptogenesis in adult hippocampus and mouse learning behaviors. We found that astrocyte-specific ablation of ephrin-B1 in male mice triggers an increase in the density of immature dendritic spines and excitatory synaptic sites in the adult CA1 hippocampus. However, the prevalence of immature dendritic spines is associated with decreased evoked postsynaptic firing responses in CA1 pyramidal neurons, suggesting impaired maturation of these newly formed and potentially silent synapses or increased excitatory drive on the inhibitory neurons resulting in the overall decreased postsynaptic firing. Nevertheless, astrocyte-specific ephrin-B1 knock-out male mice exhibit normal acquisition of fear memory but enhanced contextual fear memory recall. In contrast, overexpression of astrocytic ephrin-B1 in the adult CA1 hippocampus leads to the loss of dendritic spines, reduced excitatory input, and impaired contextual memory retention. Our results suggest that astrocytic ephrin-B1 may compete with neuronal ephrin-B1 and mediate excitatory synapse elimination through its interactions with neuronal EphB receptors. Indeed, a deletion of neuronal EphB receptors impairs the ability of astrocytes expressing functional ephrin-B1 to engulf synaptosomes in vitro Our findings demonstrate that astrocytic ephrin-B1 regulates long-term contextual memory by restricting new synapse formation in the adult hippocampus.SIGNIFICANCE STATEMENT These studies address a gap in our knowledge of astrocyte-mediated regulation of learning and memory by unveiling a new role for ephrin-B1 in astrocytes and elucidating new mechanisms by which astrocytes regulate learning. Our studies explore the mechanisms underlying astrocyte regulation of hippocampal circuit remodeling during learning using new genetic tools that target ephrin-B signaling in astrocytes in vivo On a subcellular level, astrocytic ephrin-B1 may compete with neuronal ephrin-B1 and trigger astrocyte-mediated elimination of EphB receptor-containing synapses. Given the role EphB receptors play in neurodevelopmental disorders and neurodegenerative diseases, these findings establish a foundation for future studies of astrocyte-mediated synaptogenesis in clinically relevant conditions that can help to guide the development of clinical applications for a variety of neurological disorders.
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Talebian A, Britton R, Ammanuel S, Bepari A, Sprouse F, Birnbaum SG, Szabó G, Tamamaki N, Gibson J, Henkemeyer M. Autonomous and non-autonomous roles for ephrin-B in interneuron migration. Dev Biol 2017; 431:179-193. [PMID: 28947178 DOI: 10.1016/j.ydbio.2017.09.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Revised: 09/05/2017] [Accepted: 09/18/2017] [Indexed: 11/28/2022]
Abstract
While several studies indicate the importance of ephrin-B/EphB bidirectional signaling in excitatory neurons, potential roles for these molecules in inhibitory neurons are largely unknown. We identify here an autonomous receptor-like role for ephrin-B reverse signaling in the tangential migration of interneurons into the neocortex using ephrin-B (EfnB1/B2/B3) conditional triple mutant (TMlz) mice and a forebrain inhibitory neuron specific Cre driver. Inhibitory neuron deletion of the three EfnB genes leads to reduced interneuron migration, abnormal cortical excitability, and lethal audiogenic seizures. Truncated and intracellular point mutations confirm the importance of ephrin-B reverse signaling in interneuron migration and cortical excitability. A non-autonomous ligand-like role was also identified for ephrin-B2 that is expressed in neocortical radial glial cells and required for proper tangential migration of GAD65-positive interneurons. Our studies thus define both receptor-like and ligand-like roles for the ephrin-B molecules in controlling the migration of interneurons as they populate the neocortex and help establish excitatory/inhibitory (E/I) homeostasis.
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Affiliation(s)
- Asghar Talebian
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Rachel Britton
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Simon Ammanuel
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Asim Bepari
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Francis Sprouse
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Shari G Birnbaum
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Gábor Szabó
- Medical Gene Technology Division, Institute of Experimental Medicine, 1083 Budapest, Hungary
| | - Nobuaki Tamamaki
- Department of Morphological Neural Science, Kumamoto University, Kumamoto 860-8556, Japan
| | - Jay Gibson
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mark Henkemeyer
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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12
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Li L, He Y, Liu D, Li L, Chen F, Ran J, Yang L, Zhang L. Prognostic values of EphB1/B2 and p-EphB1/B2 expression in non-small cell lung cancer. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2017; 10:10092-10101. [PMID: 31966900 PMCID: PMC6965981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Accepted: 08/10/2017] [Indexed: 06/10/2023]
Abstract
Erythropoietin-producing hepatocellular carcinoma (Eph) Receptor, as a family member of receptor tyrosine kinases (RTK), plays a critical role in modulating different cell behaviors. It is also closely related to tumorigenesis. However, little has been known about its prognostic values in non-small cell lung cancer (NSCLC). Thus, we studied the expression levels of EphB1/2 and p-EphB1/2 in both NSCLC tissue and normal lung tissue, and analyzed their correlations with clinicopathological characteristics as well as NSCLC patients' survival. In the present study, 156 NSCLC tissue samples and 28 distal normal lung tissue samples were collected from 156 NSCLC patients. Afterwards, the protein levels of EphB1/2 and p-EphB1/2 were detected by immunohistochemistry. Their prognostic values were also evaluated using both univariate and multivariate survival analysis. According to the results, 44.87% (70/156) NSCLC samples were detected with positive EphB1/2 expression, significantly higher than that in distal normal lung tissue (16%, 4/25); but no difference was found regarding to p-EphB1/2 expression. With respect to the clinicopathological characteristics, there was no significant correlation between protein levels and age, gender, histological type, differentiation status as well as TNM stage. Intriguingly, it showed a clear trend of increased EphB1/2-positive rate when tumor differentiation grade developed. In the survival analysis, a positive correlation was found between positive p-EphB1/2 expression and poor survival in female (P=0.001). Then N stage (P=0.001) and TNM stage (P<0.001) were found significantly related to patients' survival in multivariate analysis. Therefore, p-EphB1/2 may serve as a prognostic predictor in female NSCLC patients.
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Affiliation(s)
- Lei Li
- Department of Pulmonary and Critical Care Medicine, West China Hospital, Sichuan UniversityChengdu, China
| | - Ying He
- West China Medical School, Sichuan UniversityChengdu, Sichuan Province, China
| | - Dan Liu
- Department of Pulmonary and Critical Care Medicine, West China Hospital, Sichuan UniversityChengdu, China
| | - Li Li
- Lab of Pathology, West China Hospital, Sichuan UniversityChengdu, China
- Key Laboratory of Transplantation Engineering and Immunology, Ministry of Health, West China Hospital, Sichuan UniversityChengdu, China
| | - Fei Chen
- Lab of Pathology, West China Hospital, Sichuan UniversityChengdu, China
- Key Laboratory of Transplantation Engineering and Immunology, Ministry of Health, West China Hospital, Sichuan UniversityChengdu, China
| | - Jing Ran
- Lab of Pathology, West China Hospital, Sichuan UniversityChengdu, China
- Key Laboratory of Transplantation Engineering and Immunology, Ministry of Health, West China Hospital, Sichuan UniversityChengdu, China
| | - Lan Yang
- Department of Pulmonary and Critical Care Medicine, West China Hospital, Sichuan UniversityChengdu, China
| | - Li Zhang
- Lab of Pathology, West China Hospital, Sichuan UniversityChengdu, China
- Key Laboratory of Transplantation Engineering and Immunology, Ministry of Health, West China Hospital, Sichuan UniversityChengdu, China
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13
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Eph receptor interclass cooperation is required for the regulation of cell proliferation. Exp Cell Res 2016; 348:10-22. [PMID: 27565439 DOI: 10.1016/j.yexcr.2016.08.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 08/21/2016] [Indexed: 11/21/2022]
Abstract
Cancer often arises by the constitutive activation of mitogenic pathways by mutations in stem cells. Eph receptors are unusual in that although they regulate the proliferation of stem/progenitor cells in many adult organs, they typically fail to transform cells. Multiple ephrins and Eph receptors are often co-expressed and are thought to be redundant, but we here describe an unexpected dichotomy with two homologous ligands, ephrin-B1 and ephrin-B2, regulating specifically migration or proliferation in the intestinal stem cell niche. We demonstrate that the combined activity of two different coexpressed Eph receptors of the A and B class assembled into common signaling clusters in response to ephrin-B2 is required for mitogenic signaling. The requirement of two different Eph receptors to convey mitogenic signals identifies a new type of cooperation within this receptor family and helps explain why constitutive activation of a single receptor fails to transform cells.
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14
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Abstract
Ephrins and Eph receptors enable contact-mediated interactions between cells at every stage of nervous system development. In spite of their broad binding affinities, Eph proteins facilitate specificity in neuronal migration and axon targeting. This review focuses on recent studies that demonstrate how these proteins interact with each other, and with other signaling pathways, to guide specificity in a diverse set of developmental processes.
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Affiliation(s)
- Karina S Cramer
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA
| | - Ilona J Miko
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA
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15
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Xavier GM, Miletich I, Cobourne MT. Ephrin Ligands and Eph Receptors Show Regionally Restricted Expression in the Developing Palate and Tongue. Front Physiol 2016; 7:60. [PMID: 26941654 PMCID: PMC4763095 DOI: 10.3389/fphys.2016.00060] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 02/08/2016] [Indexed: 12/25/2022] Open
Abstract
The Eph family receptor-interacting (ephrin) ligands and erythropoietin-producing hepatocellular carcinoma (Eph) receptors constitute the largest known family of receptor tyrosine kinases. Ephrin ligands and their receptors form an important cell communication system with widespread roles in normal physiology and disease pathogenesis. In order to investigate potential roles of the ephrin-Eph system during palatogenesis and tongue development, we have characterized the cellular mRNA expression of family members EphrinA1-A3, EphA1–A8, and EphrinB2, EphB1, EphB4 during murine embryogenesis between embryonic day 13.5–16.5 using radioactive in situ hybridization. With the exception of EphA6 and ephrinA3, all genes were regionally expressed during the process of palatogenesis, with restricted and often overlapping domains. Transcripts were identified in the palate epithelium, localized at the tip of the palatal shelves, in the mesenchyme and also confined to the medial epithelium seam. Numerous Eph transcripts were also identified during tongue development. In particular, EphA1 and EphA2 demonstrated a highly restricted and specific expression in the tongue epithelium at all stages examined, whereas EphA3 was strongly expressed in the lateral tongue mesenchyme. These results suggest regulatory roles for ephrin-EphA signaling in development of the murine palate and tongue.
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Affiliation(s)
- Guilherme M Xavier
- Department of Craniofacial Development and Stem Cell Biology, King's College London Dental Institute, Guy's HospitalLondon, UK; Department of Orthodontics, King's College London Dental Institute, Guy's HospitalLondon, UK
| | - Isabelle Miletich
- Department of Craniofacial Development and Stem Cell Biology, King's College London Dental Institute, Guy's Hospital London, UK
| | - Martyn T Cobourne
- Department of Craniofacial Development and Stem Cell Biology, King's College London Dental Institute, Guy's HospitalLondon, UK; Department of Orthodontics, King's College London Dental Institute, Guy's HospitalLondon, UK
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16
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Son AI, Hashimoto-Torii K, Rakic P, Levitt P, Torii M. EphA4 has distinct functionality from EphA7 in the corticothalamic system during mouse brain development. J Comp Neurol 2015; 524:2080-92. [PMID: 26587807 DOI: 10.1002/cne.23933] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 11/11/2015] [Accepted: 11/16/2015] [Indexed: 11/11/2022]
Abstract
Deciphering the molecular basis for guiding specific aspects of neocortical development remains a challenge because of the complexity of histogenic events and the vast array of protein interactions mediating these events. The Eph family of receptor tyrosine kinases is implicated in a number of neurodevelopmental activities. Eph receptors have been known to be capable of responding to several ephrin ligands within their subgroups, often eliciting similar downstream effects. However, several recent studies have indicated specificity between receptor-ligand pairs within each subfamily, the functional relevance of which is not defined. Here we show that a receptor of the EphA subfamily, EphA4, has effects distinct from those of its close relative, EphA7, in the developing brain. Both EphA4 and EphA7 interact similarly with corresponding ligands expressed in the developing neocortex. However, only EphA7 shows strong interaction with ligands in the somatosensory thalamic nuclei; EphA4 affects only cortical neuronal migration, with no visible effects on the guidance of corticothalamic (CT) axons, whereas EphA7 affects both cortical neuronal migration and CT axon guidance. Our data provide new evidence that Eph receptors in the same subfamily are not simply interchangeable but are functionally specified through selective interactions with distinct ligands in vivo. J. Comp. Neurol. 524:2080-2092, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Alexander I Son
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Center, Washington, DC, 20010
| | - Kazue Hashimoto-Torii
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Center, Washington, DC, 20010.,Department of Pediatrics, Pharmacology and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, DC, 20010
| | - Pasko Rakic
- Department of Neurobiology and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, Connecticut, 06510
| | - Pat Levitt
- Department of Pediatrics, Children's Hospital Los Angeles and Keck School of Medicine of University of Southern California, Los Angeles, California, 90027
| | - Masaaki Torii
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Center, Washington, DC, 20010.,Department of Pediatrics, Pharmacology and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, DC, 20010
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17
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Robichaux MA, Chenaux G, Ho HYH, Soskis MJ, Greenberg ME, Henkemeyer M, Cowan CW. EphB1 and EphB2 intracellular domains regulate the formation of the corpus callosum and anterior commissure. Dev Neurobiol 2015; 76:405-20. [PMID: 26148571 DOI: 10.1002/dneu.22323] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/28/2015] [Accepted: 06/30/2015] [Indexed: 12/24/2022]
Abstract
The two cortical hemispheres of the mammalian forebrain are interconnected by major white matter tracts, including the corpus callosum (CC) and the posterior branch of the anterior commissure (ACp), that bridge the telencephalic midline. We show here that the intracellular signaling domains of the EphB1 and EphB2 receptors are critical for formation of both the ACp and CC. We observe partial and complete agenesis of the corpus callosum, as well as highly penetrant ACp misprojection phenotypes in truncated EphB1/2 mice that lack intracellular signaling domains. Consistent with the roles for these receptors in formation of the CC and ACp, we detect expression of these receptors in multiple brain regions associated with the formation of these forebrain structures. Taken together, our findings suggest that a combination of forward and reverse EphB1/2 receptor-mediated signaling contribute to ACp and CC axon guidance.
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Affiliation(s)
- Michael A Robichaux
- Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, Massachusetts, 02478.,Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, Texas, 75390
| | - George Chenaux
- Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, Texas, 75390.,Developmental Biology, The University of Texas Southwestern Medical Center, Dallas, Texas, 75390
| | - Hsin-Yi Henry Ho
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, 02115
| | - Michael J Soskis
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, 02115
| | - Michael E Greenberg
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, 02115
| | - Mark Henkemeyer
- Developmental Biology, The University of Texas Southwestern Medical Center, Dallas, Texas, 75390
| | - Christopher W Cowan
- Department of Psychiatry, Harvard Medical School, McLean Hospital, Belmont, Massachusetts, 02478.,Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, Texas, 75390
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18
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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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19
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Cramer KS, Gabriele ML. Axon guidance in the auditory system: multiple functions of Eph receptors. Neuroscience 2014; 277:152-62. [PMID: 25010398 DOI: 10.1016/j.neuroscience.2014.06.068] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 06/05/2014] [Accepted: 06/28/2014] [Indexed: 11/29/2022]
Abstract
The neural pathways of the auditory system underlie our ability to detect sounds and to transform amplitude and frequency information into rich and meaningful perception. While it shares some organizational features with other sensory systems, the auditory system has some unique functions that impose special demands on precision in circuit assembly. In particular, the cochlear epithelium creates a frequency map rather than a space map, and specialized pathways extract information on interaural time and intensity differences to permit sound source localization. The assembly of auditory circuitry requires the coordinated function of multiple molecular cues. Eph receptors and their ephrin ligands constitute a large family of axon guidance molecules with developmentally regulated expression throughout the auditory system. Functional studies of Eph/ephrin signaling have revealed important roles at multiple levels of the auditory pathway, from the cochlea to the auditory cortex. These proteins provide graded cues used in establishing tonotopically ordered connections between auditory areas, as well as discrete cues that enable axons to form connections with appropriate postsynaptic partners within a target area. Throughout the auditory system, Eph proteins help to establish patterning in neural pathways during early development. This early targeting, which is further refined with neuronal activity, establishes the precision needed for auditory perception.
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Affiliation(s)
- K S Cramer
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA 92697, United States.
| | - M L Gabriele
- Department of Biology, James Madison University, Harrisonburg, VA 22807, United States
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20
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EphB receptor forward signaling regulates area-specific reciprocal thalamic and cortical axon pathfinding. Proc Natl Acad Sci U S A 2014; 111:2188-93. [PMID: 24453220 DOI: 10.1073/pnas.1324215111] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In early brain development, ascending thalamocortical axons (TCAs) navigate through the ventral telencephalon (VTel) to reach their target regions in the young cerebral cortex. Descending, deep-layer cortical axons subsequently target appropriate thalamic and subcortical target regions. However, precisely how and when corticothalamic axons (CTAs) identify their appropriate, reciprocal thalamic targets remains unclear. We show here that EphB1 and EphB2 receptors control proper navigation of a subset of TCA and CTA projections through the VTel. We show in vivo that EphB receptor forward signaling and the ephrinB1 ligand are required during the early navigation of L1-CAM(+) thalamic fibers in the VTel, and that the misguided thalamic fibers in EphB1/2 KO mice appear to interact with cortical subregion-specific axon populations during reciprocal cortical axon guidance. As such, our findings suggest that descending cortical axons identify specific TCA subpopulations in the dorsal VTel to coordinate reciprocal cortical-thalamic connectivity in the early developing brain.
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21
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Wang H, Wen J, Wang H, Guo Q, Shi S, Shi Q, Zhou X, Liu Q, Lu G, Wang J. Loss of expression of EphB1 protein in serous carcinoma of ovary associated with metastasis and poor survival. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2013; 7:313-321. [PMID: 24427352 PMCID: PMC3885486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 09/22/2013] [Indexed: 06/03/2023]
Abstract
Aberrant expression of receptors tyrosine kinase of Eph gene in human cancers is extensively documented. We previously found that EphB1 subtype is down-regulated in gastric cancer and colorectal cancer. Fore the more, decreased expression of EphB1 is related to invasion and metastasis in cancers. There is no published data regarding the role of EphB1 in ovarian cancer, which is the focus of the present study. The expression of EphB1 protein was determined in tissues from 74 patients with serous ovarian carcinoma and 12 normal ovarian epithelial tissues. The expression level of EphB1 protein in serous ovarian carcinoma was analyzed with respect to clinicopathological parameters and survival. EphB1 protein was positively stained in 12 normal ovarian epithelial samples, and negatively stained in 32 out of 74 (43.2%) serous ovarian cancers. Loss of expression of EphB1 protein was associated with higher tumor grade (P=0.006), metastasis (P=0.049) and high proliferative index Ki67 expression (P=0.022), but not with FIGO stage (P=0.0937), age at diagnosis (P=0.624), and diameter of carcinoma (P=0.108). In addition, loss of EphB1 protein in serous ovarian carcinoma was associated with a significantly worse overall survival (P=0.015). Our data indicate that loss of EphB1 protein is associated with metastasis and poorer survival in patients with serous ovarian cancer. EphB1 may be used as a prognostic marker and a therapeutic target in serous ovarian carcinoma.
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Affiliation(s)
- Haiyan Wang
- Department of Pathology, Jinling Hospital, Nanjing Clinical School of Southern Medical UniversityNanjing 210002, China
| | - Juanjuan Wen
- Department of Pathology, Jinling Hospital, Nanjing Clinical School of Southern Medical UniversityNanjing 210002, China
| | - Hai Wang
- Department of Pathology, Jinling Hospital, Nanjing Clinical School of Southern Medical UniversityNanjing 210002, China
| | - Qinq Guo
- Department of Pathology, Jinling Hospital, Nanjing Clinical School of Southern Medical UniversityNanjing 210002, China
| | - Shanshan Shi
- Department of Pathology, Jinling Hospital, Nanjing Clinical School of Southern Medical UniversityNanjing 210002, China
| | - Qunli Shi
- Department of Pathology, Jinling Hospital, Nanjing Clinical School of Southern Medical UniversityNanjing 210002, China
| | - Xiaojun Zhou
- Department of Pathology, Jinling Hospital, Nanjing Clinical School of Southern Medical UniversityNanjing 210002, China
| | - Qi Liu
- Department of Obstetrics and Gynecology, Jinling Hospital, Nanjing Clinical School of Southern Medical UniversityNanjing 210002, China
| | - Guangming Lu
- Department of Radiology, Jinling Hospital, Nanjing Clinical School of Southern Medical UniversityNanjing 210002, China
| | - Jiandong Wang
- Department of Pathology, Jinling Hospital, Nanjing Clinical School of Southern Medical UniversityNanjing 210002, China
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Abstract
The integration of newborn neurons into functional neuronal networks requires migration of cells to their final position in the developing brain, the growth and arborization of neuronal processes and the formation of synaptic contacts with other neurons. A central player among the signals that coordinate this complex sequence of differentiation events is the secreted glycoprotein Reelin, which also modulates synaptic plasticity, learning and memory formation in the adult brain. Binding of Reelin to ApoER2 and VLDL receptor, two members of the LDL receptor family, initiates a signaling cascade involving tyrosine phosphorylation of the intracellular cytoplasmic adaptor protein Disabled-1, which targets the neuronal cytoskeleton and ultimately controls the positioning of neurons throughout the developing brain. However, it is possible that Reelin signals interact with other receptor-mediated signaling cascades to regulate different aspects of brain development and plasticity. EphB tyrosine kinases regulate cell adhesion and repulsion-dependent processes via bidirectional signaling through ephrin B transmembrane proteins. Here, we demonstrate that Reelin binds to the extracellular domains of EphB transmembrane proteins, inducing receptor clustering and activation of EphB forward signaling in neurons, independently of the 'classical' Reelin receptors, ApoER2 and VLDLR. Accordingly, mice lacking EphB1 and EphB2 display a positioning defect of CA3 hippocampal pyramidal neurons, similar to that in Reelin-deficient mice, and this cell migration defect depends on the kinase activity of EphB proteins. Together, our data provide biochemical and functional evidence for signal integration between Reelin and EphB forward signaling.
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23
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A chemical genetic approach reveals distinct EphB signaling mechanisms during brain development. Nat Neurosci 2012; 15:1645-54. [PMID: 23143520 PMCID: PMC3509236 DOI: 10.1038/nn.3249] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 10/01/2012] [Indexed: 12/15/2022]
Abstract
EphB receptor tyrosine kinases control multiple steps in nervous system development. However, it remains unclear whether EphBs regulate these different developmental processes directly or indirectly. In addition, as EphBs signal through multiple mechanisms, it has been challenging to define which signaling functions of EphBs regulate particular developmental events. To address these issues, we engineered triple knockin mice in which the kinase activity of three neuronally expressed EphBs can be rapidly, reversibly, and specifically blocked. Using these mice we demonstrate that the tyrosine kinase activity of EphBs is required for axon guidance in vivo. By contrast, EphB-mediated synaptogenesis occurs normally when the kinase activity of EphBs is inhibited suggesting that EphBs mediate synapse development by an EphB tyrosine kinase-independent mechanism. Taken together, these experiments reveal that EphBs control axon guidance and synaptogenesis by distinct mechanisms, and provide a new mouse model for dissecting EphB function in development and disease.
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Benson MD, Opperman LA, Westerlund J, Fernandez CR, San Miguel S, Henkemeyer M, Chenaux G. Ephrin-B stimulation of calvarial bone formation. Dev Dyn 2012; 241:1901-10. [PMID: 23129351 DOI: 10.1002/dvdy.23874] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2012] [Indexed: 12/28/2022] Open
Abstract
INTRODUCTION Ephrin-B2 on osteoclasts was reported to promote bone formation as part of homeostasis by activating the EphB4 tyrosine kinase receptor on osteoblasts. Little is known about the role of ephrin-B signaling to EphBs in developmental bone formation. RESULTS We observed expression of an ephrin-B2 LacZ chimeric allele in the periosteum, sutural bone fronts, and dura mater of embryonic and neonatal mice. Expression in the adult skull was confined to sutures, but was heavily upregulated at sites of bone injury. Culture of embryonic calvariae with soluble recombinant ephrin-B2/Fc doubled their bone content without altering suture width or overall skull morphology. Ephrin-B2/Fc also stimulated osteoblast marker gene expression in cultured MC3T3 preosteoblastic cells without the need for type 1 collagen-induced differentiation. EphB4 was absent in embryonic and adult skulls. However, EphB1 and EphB2, both physiological receptors for ephrin-Bs, were expressed at sites of osteogenesis, and EphB1 knockout mice displayed a reduction in calvarial bone content compared to controls. CONCLUSIONS These data support a role for ephrin-B2 in the development and healing of bone through activation of osteoblast-specific gene expression. EphB1 and EphB2 are likely candidates receptors for the ephrin-B2 in bone.
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Affiliation(s)
- M Douglas Benson
- Department of Biomedical Sciences, Texas A&M Health Science Center Baylor College of Dentistry, Dallas, Texas 75246, USA.
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25
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Harkany T. Molecular mechanisms of neuronal specification. Eur J Neurosci 2011; 34:1513-5. [PMID: 22103409 DOI: 10.1111/j.1460-9568.2011.07912.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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