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Martins-Costa C, Wiegers A, Pham VA, Sidhaye J, Doleschall B, Novatchkova M, Lendl T, Piber M, Peer A, Möseneder P, Stuempflen M, Chow SYA, Seidl R, Prayer D, Höftberger R, Kasprian G, Ikeuchi Y, Corsini NS, Knoblich JA. ARID1B controls transcriptional programs of axon projection in an organoid model of the human corpus callosum. Cell Stem Cell 2024; 31:866-885.e14. [PMID: 38718796 DOI: 10.1016/j.stem.2024.04.014] [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: 05/17/2023] [Revised: 02/13/2024] [Accepted: 04/17/2024] [Indexed: 06/09/2024]
Abstract
Mutations in ARID1B, a member of the mSWI/SNF complex, cause severe neurodevelopmental phenotypes with elusive mechanisms in humans. The most common structural abnormality in the brain of ARID1B patients is agenesis of the corpus callosum (ACC), characterized by the absence of an interhemispheric white matter tract that connects distant cortical regions. Here, we find that neurons expressing SATB2, a determinant of callosal projection neuron (CPN) identity, show impaired maturation in ARID1B+/- neural organoids. Molecularly, a reduction in chromatin accessibility of genomic regions targeted by TCF-like, NFI-like, and ARID-like transcription factors drives the differential expression of genes required for corpus callosum (CC) development. Through an in vitro model of the CC tract, we demonstrate that this transcriptional dysregulation impairs the formation of long-range axonal projections, causing structural underconnectivity. Our study uncovers new functions of the mSWI/SNF during human corticogenesis, identifying cell-autonomous axonogenesis defects in SATB2+ neurons as a cause of ACC in ARID1B patients.
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Affiliation(s)
- Catarina Martins-Costa
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria; Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, 1030 Vienna, Austria
| | - Andrea Wiegers
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Vincent A Pham
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Jaydeep Sidhaye
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Balint Doleschall
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria; Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, 1030 Vienna, Austria
| | - Maria Novatchkova
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Thomas Lendl
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Marielle Piber
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Angela Peer
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Paul Möseneder
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Marlene Stuempflen
- Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Vienna, Austria
| | - Siu Yu A Chow
- Institute of Industrial Science, The University of Tokyo, 153-8505 Tokyo, Japan; Institute for AI and Beyond, The University of Tokyo, 113-0032 Tokyo, Japan
| | - Rainer Seidl
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Daniela Prayer
- Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Vienna, Austria
| | - Romana Höftberger
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, 1090 Vienna, Austria
| | - Gregor Kasprian
- Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, 1090 Vienna, Austria
| | - Yoshiho Ikeuchi
- Institute of Industrial Science, The University of Tokyo, 153-8505 Tokyo, Japan; Institute for AI and Beyond, The University of Tokyo, 113-0032 Tokyo, Japan
| | - Nina S Corsini
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria.
| | - Jürgen A Knoblich
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria; Department of Neurology, Medical University of Vienna, 1090 Vienna, Austria.
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Yang M, Wang Q, Chen J, Wang Y, Zhang Y, Qin Q. Identification of candidate SNPs and genes associated with anti-RGNNV using GWAS in the red-spotted grouper, Epinephelus akaara. FISH & SHELLFISH IMMUNOLOGY 2021; 112:31-37. [PMID: 33609701 DOI: 10.1016/j.fsi.2021.02.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 02/03/2021] [Accepted: 02/14/2021] [Indexed: 06/12/2023]
Abstract
The red-spotted grouper, Epinephelus akaara, has been cultured widely in China, and in several countries of Southeast Asia, due to its important economic value. However, in recent years the outbreak of disease caused by red-spotted grouper nervous necrosis virus (RGNNV) has caused mass mortality in the stage of the grouper lifecycle from fry to juvenile, resulting in considerable economic loss in commercial aquaculture. However, the molecular mechanism underlying anti-RGNNV infection in red-spotted grouper has never been fully understood. To identify the anti-RGNNV related markers and candidate genes, we performed a genome-wide association study (GWAS) on a natural population of 100 individuals for a full-genome screen of the red-spotted grouper. In this research, 36,311 single, high quality nucleotide polymorphisms (SNPs) were developed. Two significantly associated SNPs and three suggestively associated SNPs were identified at the genome level. From these identified SNPs, five candidate genes were annotated: EPHA7, Osbpl2, GPC5, CDH4 and Pou3f1. These genes are involved in nervous system development, retinal formation, and lipid metabolism regulation. In combination with studies on the characteristics of NNV infection, it was speculated that in the fry stage of the grouper lifecycle, the immune system is not fully developed. Therefore, improved resistance to RGNNV may come through regulating nervous system development or lipid metabolism related pathways. In addition, the genotypes of SNPs associated with disease-resistant traits were analyzed. The markers and genes obtained in this study may facilitate a marker-assisted selection for red-spotted grouper aiming at disease resistance to RGNNV.
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Affiliation(s)
- Min Yang
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Qing Wang
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Jinpeng Chen
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Yuxin Wang
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Yong Zhang
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266000, China; Guangdong Key Laboratory of Animal Conservation and Resource Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangdong, Institute of Applied Biological Resources, Guangzhou, 510260, China; State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory for Aquatic Economic Animals and Southern Marine Science and Engineering Guangdong, Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China.
| | - Qiwei Qin
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266000, China.
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3
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Leonard CE, Baydyuk M, Stepler MA, Burton DA, Donoghue MJ. EphA7 isoforms differentially regulate cortical dendrite development. PLoS One 2020; 15:e0231561. [PMID: 33275600 PMCID: PMC7717530 DOI: 10.1371/journal.pone.0231561] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 11/22/2020] [Indexed: 02/06/2023] Open
Abstract
The shape of a neuron facilitates its functionality within neural circuits. Dendrites integrate incoming signals from axons, receiving excitatory input onto small protrusions called dendritic spines. Therefore, understanding dendritic growth and development is fundamental for discerning neural function. We previously demonstrated that EphA7 receptor signaling during cortical development impacts dendrites in two ways: EphA7 restricts dendritic growth early and promotes dendritic spine formation later. Here, the molecular basis for this shift in EphA7 function is defined. Expression analyses reveal that EphA7 full-length (EphA7-FL) and truncated (EphA7-T1; lacking kinase domain) isoforms are dynamically expressed in the developing cortex. Peak expression of EphA7-FL overlaps with dendritic elaboration around birth, while highest expression of EphA7-T1 coincides with dendritic spine formation in early postnatal life. Overexpression studies in cultured neurons demonstrate that EphA7-FL inhibits both dendritic growth and spine formation, while EphA7-T1 increases spine density. Furthermore, signaling downstream of EphA7 shifts during development, such that in vivo inhibition of mTOR by rapamycin in EphA7-mutant neurons ameliorates dendritic branching, but not dendritic spine phenotypes. Finally, direct interaction between EphA7-FL and EphA7-T1 is demonstrated in cultured cells, which results in reduction of EphA7-FL phosphorylation. In cortex, both isoforms are colocalized to synaptic fractions and both transcripts are expressed together within individual neurons, supporting a model where EphA7-T1 modulates EphA7-FL repulsive signaling during development. Thus, the divergent functions of EphA7 during cortical dendrite development are explained by the presence of two variants of the receptor.
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Affiliation(s)
- Carrie E. Leonard
- Department of Biology, Georgetown University, Washington, DC, United States of America
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, United States of America
| | - Maryna Baydyuk
- Department of Biology, Georgetown University, Washington, DC, United States of America
| | - Marissa A. Stepler
- Department of Biology, Georgetown University, Washington, DC, United States of America
| | - Denver A. Burton
- Department of Biology, Georgetown University, Washington, DC, United States of America
| | - Maria J. Donoghue
- Department of Biology, Georgetown University, Washington, DC, United States of America
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, United States of America
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Glendining KA, Liu SC, Nguyen M, Dharmaratne N, Nagarajah R, Iglesias MA, Sawatari A, Leamey CA. Downstream mediators of Ten-m3 signalling in the developing visual pathway. BMC Neurosci 2017; 18:78. [PMID: 29207951 PMCID: PMC5718065 DOI: 10.1186/s12868-017-0397-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 11/28/2017] [Indexed: 11/14/2022] Open
Abstract
Background The formation of visuotopically-aligned projections in the brain is required for the generation of functional binocular circuits. The mechanisms which underlie this process are unknown. Ten-m3 is expressed in a broad high-ventral to low-dorsal gradient across the retina and in topographically-corresponding gradients in primary visual centres. Deletion of Ten-m3 causes profound disruption of binocular visual alignment and function. Surprisingly, one of the most apparent neuroanatomical changes—dramatic mismapping of ipsilateral, but not contralateral, retinal axons along the representation of the nasotemporal retinal axis—does not correlate well with Ten-m3’s expression pattern, raising questions regarding mechanism. The aim of this study was to further our understanding of the molecular interactions which enable the formation of functional binocular visual circuits. Methods Anterograde tracing, gene expression studies and protein pull-down experiments were performed. Statistical significance was tested using a Kolmogorov–Smirnov test, pairwise-fixed random reallocation tests and univariate ANOVAs. Results We show that the ipsilateral retinal axons in Ten-m3 knockout mice are mismapped as a consequence of early axonal guidance defects. The aberrant invasion of the ventral-most region of the dorsal lateral geniculate nucleus by ipsilateral retinal axons in Ten-m3 knockouts suggested changes in the expression of other axonal guidance molecules, particularly members of the EphA–ephrinA family. We identified a consistent down-regulation of EphA7, but none of the other EphA–ephrinA genes tested, as well as an up-regulation of ipsilateral-determinants Zic2 and EphB1 in visual structures. We also found that Zic2 binds specifically to the intracellular domain of Ten-m3 in vitro. Conclusion Our findings suggest that Zic2, EphB1 and EphA7 molecules may work as effectors of Ten-m3 signalling, acting together to enable the wiring of functional binocular visual circuits. Electronic supplementary material The online version of this article (10.1186/s12868-017-0397-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kelly A Glendining
- Discipline of Physiology, School of Medical Sciences and Bosch Institute, F13, University of Sydney, Sydney, NSW, 2006, Australia
| | - Sam C Liu
- Discipline of Physiology, School of Medical Sciences and Bosch Institute, F13, University of Sydney, Sydney, NSW, 2006, Australia
| | - Marvin Nguyen
- Discipline of Physiology, School of Medical Sciences and Bosch Institute, F13, University of Sydney, Sydney, NSW, 2006, Australia
| | - Nuwan Dharmaratne
- Discipline of Physiology, School of Medical Sciences and Bosch Institute, F13, University of Sydney, Sydney, NSW, 2006, Australia
| | - Rajini Nagarajah
- Discipline of Physiology, School of Medical Sciences and Bosch Institute, F13, University of Sydney, Sydney, NSW, 2006, Australia
| | - Miguel A Iglesias
- Discipline of Physiology, School of Medical Sciences and Bosch Institute, F13, University of Sydney, Sydney, NSW, 2006, Australia
| | - Atomu Sawatari
- Discipline of Physiology, School of Medical Sciences and Bosch Institute, F13, University of Sydney, Sydney, NSW, 2006, Australia
| | - Catherine A Leamey
- Discipline of Physiology, School of Medical Sciences and Bosch Institute, F13, University of Sydney, Sydney, NSW, 2006, Australia.
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Theis T, Yoo M, Park CS, Chen J, Kügler S, Gibbs KM, Schachner M. Lentiviral Delivery of miR-133b Improves Functional Recovery After Spinal Cord Injury in Mice. Mol Neurobiol 2017; 54:4659-4671. [PMID: 27412702 DOI: 10.1007/s12035-016-0007-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 06/05/2016] [Indexed: 02/05/2023]
Abstract
Based on the observation that microRNA (miRNA) 133b enhances regeneration after spinal cord injury in the adult zebrafish, we investigated whether this miRNA would be beneficial in a mammalian system in vitro and in vivo. We found that infection of cultured neurons with miR-133b promotes neurite outgrowth in vitro on an inhibitory substrate consisting of mixed chondroitin sulfate proteoglycans, when compared to infection with green fluorescent protein (GFP) for control. In vivo, viral infection of the injured adult mouse spinal cord at the time of injury at and in the vicinity of the lesion site enhanced expression of miR-133b. Measurements of locomotor recovery by Basso Mouse Scale (BMS) showed improvement of recovery starting at 4 weeks after injury and virus injection. This improvement was associated with downregulation of the expression levels of Ras homolog gene family member A (RhoA), chondroitin sulfate proteoglycans, and microglia/macrophage marker in the spinal cord as assayed 6 weeks after injury. Potential inhibitory molecules carrying consensus sequences for binding of miR-133b were identified in silico and verified in a reporter assay in vitro showing reductions in expression of RhoA, xylosyltransferase 1 (Xylt1), ephrin receptor A7 (Epha7), and purinergic receptor P2X ligand-gated ion channel 4 (P2RX4). These results encourage targeting miR-133 for therapy.
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Affiliation(s)
- Thomas Theis
- Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, 08554, USA
| | - Myung Yoo
- Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, 08554, USA
| | - Christopher S Park
- Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, 08554, USA
| | - Jian Chen
- Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, 08554, USA
| | - Sebastian Kügler
- Department of Neurology, Center Nanoscale Microscopy and Physiology of the Brain, University Medicine, Göttingen, Germany
| | - Kurt M Gibbs
- Morehead State University, Morehead, KY, 40351, USA
| | - Melitta Schachner
- Keck Center for Collaborative Neuroscience and Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, 08554, USA.
- Zentrum für Molekulare Neurobiologie, Universitätsklinikum Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany.
- Center for Neuroscience, Shantou University Medical College, 22 Xin Ling Road, Shantou, Guangdong, 515041, China.
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6
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Amegandjin CA, Jammow W, Laforest S, Riad M, Baharnoori M, Badeaux F, DesGroseillers L, Murai KK, Pasquale EB, Drolet G, Doucet G. Regional expression and ultrastructural localization of EphA7 in the hippocampus and cerebellum of adult rat. J Comp Neurol 2016; 524:2462-78. [PMID: 26780036 DOI: 10.1002/cne.23962] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 12/18/2015] [Accepted: 01/04/2016] [Indexed: 11/06/2022]
Abstract
EphA7 is expressed in the adult central nervous system (CNS), where its roles are yet poorly defined. We mapped its distribution using in situ hybridization (ISH) and immunohistochemistry (IHC) combined with light (LM) and electron microscopy (EM) in adult rat and mouse brain. The strongest ISH signal was in the hippocampal pyramidal and granule cell layers. Moderate levels were detected in habenula, striatum, amygdala, the cingulate, piriform and entorhinal cortex, and in cerebellum, notably the Purkinje cell layer. The IHC signal distribution was consistent with ISH results, with transport of the protein to processes, as exemplified in the hippocampal neuropil layers and weakly stained pyramidal cell layers. In contrast, in the cerebellum, the Purkinje cell bodies were the most strongly immunolabeled elements. EM localized the cell surface-expression of EphA7 essentially in postsynaptic densities (PSDs) of dendritic spines and shafts, and on some astrocytic leaflets, in both hippocampus and cerebellum. Perikaryal and dendritic labeling was mostly intracellular, associated with the synthetic and trafficking machineries. Immunopositive vesicles were also observed in axons and axon terminals. Quantitative analysis in EM showed significant differences in the frequency of labeled elements between regions. Notably, labeled dendrites were ∼3-5 times less frequent in cerebellum than in hippocampus, but they were individually endowed with ∼10-40 times higher frequencies of PSDs, on their shafts and spines. The cell surface localization of EphA7, being preferentially in PSDs, and in perisynaptic astrocytic leaflets, provides morphologic evidence that EphA7 plays key roles in adult CNS synaptic maintenance, plasticity, or function. J. Comp. Neurol. 524:2462-2478, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Clara A Amegandjin
- Département de neurosciences and Groupe de recherche sur le système nerveux central (GRSNC), Université de Montréal, Montréal, QC, Canada
| | - Wafaa Jammow
- Département de neurosciences and Groupe de recherche sur le système nerveux central (GRSNC), Université de Montréal, Montréal, QC, Canada
| | - Sylvie Laforest
- Centre hospitalier de l'Université Laval (CHUL), Québec, QC, Canada
| | - Mustapha Riad
- Département de neurosciences and Groupe de recherche sur le système nerveux central (GRSNC), Université de Montréal, Montréal, QC, Canada
| | - Moogeh Baharnoori
- Département de neurosciences and Groupe de recherche sur le système nerveux central (GRSNC), Université de Montréal, Montréal, QC, Canada
| | - Frédérique Badeaux
- Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, QC, Canada
| | - Luc DesGroseillers
- Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, QC, Canada
| | - Keith K Murai
- Department of Neurology and Neurosurgery, McGill University, and Center for Research in Neuroscience, Montréal, QC, Canada
| | - Elena B Pasquale
- Sanford-Burnham Medical Research Institute, La Jolla, California, and Pathology Department, University of California, San Diego, La Jolla, California, USA
| | - Guy Drolet
- Centre hospitalier de l'Université Laval (CHUL), Québec, QC, Canada
| | - Guy Doucet
- Département de neurosciences and Groupe de recherche sur le système nerveux central (GRSNC), Université de Montréal, Montréal, QC, Canada
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Bai YQ, Zhang JY, Bai CY, Xu XE, Wu JY, Chen B, Wu ZY, Wang SH, Shen J, Shen JH, Yao XD, Gao LZ, Wu B, Gu HL, Liu XH, Li X, Li EM, Xu LY. Low EphA7 Expression Correlated with Lymph Node Metastasis and Poor Prognosis of Patients with Esophageal Squamous Cell Carcinoma. Acta Histochem Cytochem 2015; 48:75-81. [PMID: 26160986 PMCID: PMC4491497 DOI: 10.1267/ahc.14054] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 04/20/2015] [Indexed: 02/05/2023] Open
Abstract
As a member of the Eph family of receptor tyrosine kinases, EphA7 plays an important role in cancer. However, the expression and significance of Eph receptors in esophageal squamous cell carcinoma (ESCC) remain unclear. Here, we detected the expression of EphA7 by immunohistochemistry in a sample of 352 patients with ESCC, and aimed to investigate the expression status of EphA7 in ESCC and its impact on prognosis. The results showed that low EphA7 expression significantly correlated with lymph node metastases (N0: 29%; N1: 64%. p<0.001), poor degree of tumor differentiation (G1: 31%; G2: 49%; G3: 58%. p=0.009) and pTNM staging (I+II: 33%; III+IV: 58%. p<0.001). Furthermore, in a combined analysis, patients with low EphA7-expressing tumors showed a shorter overall survival than those with high expression, resulting in a five-year overall survival rate of 47.4% vs. 52.6%, respectively (p=0.016). Consequently, patients with a low EphA7 expression have poorer prognosis in ESCC compared with those manifesting high expression.
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Affiliation(s)
- Yu-Qin Bai
- Department of Pathology, Medical College of Chifeng University
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
| | - Jun-Yi Zhang
- Department of Pathology, Medical College of Chifeng University
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
| | - Chun-Ying Bai
- Research Centre of Molecular Medicine, Medical College of Chifeng University
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
| | - Xiu-E Xu
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
- Institute of Oncologic Pathology, Medical College of Shantou University
| | - Jian-Yi Wu
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
- Department of Biochemistry and Molecular Biology, Medical College of Shantou University, Shantou 515041, China
| | - Bo Chen
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
- Institute of Oncologic Pathology, Medical College of Shantou University
| | - Zhi-Yong Wu
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
- Department of Pathology, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University
| | - Shao-Hong Wang
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
- Oncology Surgery, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University, Shantou 515041, China
| | - Jian Shen
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
- Institute of Oncologic Pathology, Medical College of Shantou University
| | - Jin-Hui Shen
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
- Oncology Surgery, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University, Shantou 515041, China
| | - Xiao-Dong Yao
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
- Department of Pathology, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University
| | - Lian-Zhu Gao
- Department of Pathology, The Second Hospital of Chifeng City, Chifeng 024000, China
| | - Bao Wu
- Department of Histology and Embryology, Medical College of Chifeng University, Chifeng 024000, China
| | - Hong-Li Gu
- Department of Pediatrics, Affiliated Hospital of Chifeng University, Chifeng 024000, China
| | - Xiao-Hui Liu
- Department of Pathology, Medical College of Chifeng University
| | - Xin Li
- Department of Pathology, Medical College of Chifeng University
| | - En-Min Li
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
| | - Li-Yan Xu
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College
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8
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Yates N, Robertson D, Martin-Iverson M, Rodger J. Auditory brainstem responses of ephrin-A2, ephrin-A5(-/-) and ephrin-A2A5(-/-) mice. Audiol Neurootol 2014; 19:115-26. [PMID: 24457350 DOI: 10.1159/000357029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 10/30/2013] [Indexed: 01/04/2023] Open
Abstract
Eph receptors and ephrin ligands are large families of cell surface proteins which have established roles in axonal growth and guidance. These are well characterized in the visual and somatosensory systems but are less well documented in the auditory pathway. We examined the possible functional role of two ephrin genes (ephrin-A2 and ephrin-A5) in the auditory system by measuring auditory brainstem responses (ABR) to tone bursts from 6 to 30 kHz in ephrin-A2(-/-), ephrin-A5(-/-) and ephrin-A2A5(-/-) (knockout) mice. At high frequencies, the ephrin-A2A5(-/-) mice exhibited thresholds that were significantly lower than in wild-type mice by approximately 20 dB, suggesting ephrin-A2 and ephrin-A5 may have frequency-specific effects on the auditory system. There were also alterations in ABR wave peak amplitudes that were specific to each mouse strain which suggested both peripheral and central involvement of EphA-ephrin-A signalling in auditory function.
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Affiliation(s)
- Nathanael Yates
- School of Animal Biology, University of Western Australia, Crawley, W.A., Australia
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Dong Y, Lan W, Wu W, Huang Z, Zhao J, Peng L, Wang J. Increased expression of EphA7 in inflamed human dental pulp. J Endod 2014; 39:223-7. [PMID: 23321235 DOI: 10.1016/j.joen.2012.11.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 10/29/2012] [Accepted: 11/06/2012] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Pulpitis has been associated with abundant inflammatory cells, dilated blood vessels, and thickening nerve fibers histopathologically with or without severe pain clinically. On the basis of EphA7 receptor expression in inflammatory cells, the developing mouse dental pulp, and trigeminal nerve system, EphA7 may possibly be involved in local inflammatory response and sensory innervation of adult dental pulp as well as odontogenic pain conducted through the trigeminal system. The purpose of the study was to analyze the expression of EphA7 gene in healthy and inflamed human dental pulps and to elucidate the roles of EphA7 gene in dental pulp inflammation response and odontogenic pain. METHODS Twelve healthy controls, 5 acute pulpitis from dental trauma, 21 symptomatic, and 20 asymptomatic irreversible pulpitis human dental pulps were involved in the study. The protein expression, subcellular localization, and mRNA level of EphA7 gene were detected by immunohistochemistry and real-time reverse transcriptase-polymerase chain reaction, respectively. RESULTS In healthy samples, immunohistochemical staining showed positive EphA7 expression only in vascular endothelial cells and odontoblasts with cytoplasm staining. Under inflammatory conditions, in addition to the above cells, EphA7 staining began to occur in fibroblasts, nerve fiber tissues, and inflammatory cells. Compared with healthy samples, EphA7 expressions at both mRNA and protein levels increased significantly in acute and irreversible pulpitis samples. In asymptomatic irreversible pulpitis samples, EphA7 expressions were significantly lower than those in symptomatic ones but still higher than those in healthy ones. There was no significant difference between acute and symptomatic irreversible pulpitis groups. CONCLUSIONS The results suggest that EphA7 gene may be a marker reflecting inflammatory activity and pain state for human dental pulp.
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Affiliation(s)
- Yingchun Dong
- Department of Anesthesiology, Institute and Hospital of Stomatology, Nanjing University Medical School, Nanjing, PR China
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10
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Hoyo-Becerra C, López-Ávalos MD, Cifuentes M, Visser R, Fernández-Llebrez P, Grondona JM. The subcommissural organ and the development of the posterior commissure in chick embryos. Cell Tissue Res 2009; 339:383-95. [DOI: 10.1007/s00441-009-0899-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Accepted: 10/09/2009] [Indexed: 11/25/2022]
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11
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Deschamps C, Faideau M, Jaber M, Gaillard A, Prestoz L. Expression of ephrinA5 during development and potential involvement in the guidance of the mesostriatal pathway. Exp Neurol 2009; 219:466-80. [DOI: 10.1016/j.expneurol.2009.06.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Revised: 06/18/2009] [Accepted: 06/24/2009] [Indexed: 01/12/2023]
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12
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Canty A, Murphy M. Molecular mechanisms of axon guidance in the developing corticospinal tract. Prog Neurobiol 2008; 85:214-35. [DOI: 10.1016/j.pneurobio.2008.02.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 12/11/2007] [Accepted: 02/08/2008] [Indexed: 02/04/2023]
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13
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Wang LF, Fokas E, Juricko J, You A, Rose F, Pagenstecher A, Engenhart-Cabillic R, An HX. Increased expression of EphA7 correlates with adverse outcome in primary and recurrent glioblastoma multiforme patients. BMC Cancer 2008; 8:79. [PMID: 18366728 PMCID: PMC2292196 DOI: 10.1186/1471-2407-8-79] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Accepted: 03/25/2008] [Indexed: 12/19/2022] Open
Abstract
Background Malignant gliomas are lethal cancers, highly dependent on angiogenesis and treatment options and prognosis still remain poor for patients with recurrent glioblastoma multiforme (GBM). Ephs and ephrins have many well-defined functions during embryonic development of central nervous system such as axon mapping, neural crest cell migration, hindbrain segmentation and synapse formation as well as physiological and abnormal angiogenesis. Accumulating evidence indicates that Eph and ephrins are frequently overexpressed in different tumor types including GBM. However, their role in tumorigenesis remains controversial, as both tumor growth promoter and suppressor potential have been ascribed to Eph and ephrins while the function of EphA7 in GBM pathogenesis remains largely unknown. Methods In this study, we investigated the immunohistochemical expression of EphA7 in a series of 32 primary and recurrent GBM and correlated it with clinical pathological parameters and patient outcome. In addition, intratumor microvascular density (MVD) was quantified by immunostaining for endothelial cell marker von Willebrand factor (vWF). Results Overexpression of EphA7 protein was predictive of the adverse outcome in GBM patients, independent of MVD expression (p = 0.02). Moreover, high density of MVD as well as higher EphA7 expression predicted the disease outcome more accurately than EphA7 variable alone (p = 0.01). There was no correlation between MVD and overall survival or recurrence-free survival (p > 0.05). However, a statistically significant correlation between lower MVD and tumor recurrence was observed (p = 0.003). Conclusion The immunohistochemical assessment of tissue EphA7 provides important prognostic information in GBM and would justify its use as surrogate marker to screen patients for tyrosine kinase inhibitor therapy.
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Affiliation(s)
- Lin-Fang Wang
- Department of Radiotherapy and Radiation Oncology, Philipps-University Marburg, Baldingerstr, D-35043 Marburg, Germany.
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14
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Figueroa JD, Benton RL, Velazquez I, Torrado AI, Ortiz CM, Hernandez CM, Diaz JJ, Magnuson DS, Whittemore SR, Miranda JD. Inhibition of EphA7 up-regulation after spinal cord injury reduces apoptosis and promotes locomotor recovery. J Neurosci Res 2007; 84:1438-51. [PMID: 16983667 DOI: 10.1002/jnr.21048] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Functional impairment after spinal cord injury (SCI) is partially attributed to neuronal cell death, with further degeneration caused by the accompanying apoptosis of myelin-forming oligodendrocytes. The Eph receptor protein tyrosine kinase family and its cognate ligands, the ephrins, have been identified to be involved in axonal outgrowth, synapse formation, and target recognition, mainly mediated by repulsive activity. Recent reports suggest that ephrin/Eph signaling might also play a role as a physiological trigger for apoptosis during embryonic development. Here, we investigated the expression profile of EphA7, after SCI, by using a combination of quantitative real-time PCR (QRT-PCR) and immunohistochemical techniques. QRT-PCR analysis showed an increase in the expression of full-length EphA7 at 7 days postinjury (DPI). Receptor immunoreactivity was shown mostly in astrocytes of the white matter at the injury epicenter. In control animals, EphA7 expression was observed predominantly in motor neurons of the ventral gray matter, although some immunoreactivity was seen in white matter. Furthermore, blocking the expression of EphA7 after SCI using antisense oligonucleotides resulted in significant acceleration of hindlimb locomotor recovery at 1 week. This was a transient effect; by 2 weeks postinjury, treated animals were not different from controls. Antisense treatment also produced a return of nerve conduction, with shorter latencies than in control treated animals after transcranial magnetic stimulation. We identified EphA7 receptors as putative regulators of apoptosis in the acute phase after SCI. These results suggest a functional role for EphA7 receptors in the early stages of SCI pathophysiology.
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Affiliation(s)
- Johnny D Figueroa
- Department of Physiology, University of Puerto Rico Medical Science Campus, San Juan, Puerto Rico
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15
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Miko IJ, Nakamura PA, Henkemeyer M, Cramer KS. Auditory brainstem neural activation patterns are altered in EphA4- and ephrin-B2-deficient mice. J Comp Neurol 2007; 505:669-81. [DOI: 10.1002/cne.21530] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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16
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Miller K, Kolk SM, Donoghue MJ. EphA7-ephrin-A5 signaling in mouse somatosensory cortex: developmental restriction of molecular domains and postnatal maintenance of functional compartments. J Comp Neurol 2006; 496:627-42. [PMID: 16615124 DOI: 10.1002/cne.20926] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Members of the Eph family of receptor tyrosine kinases and their ligands, the ephrins, are expressed in distinct patterns in the forming cortex. EphA7 is expressed early in cortical development, becoming concentrated in anterior and posterior domains, whereas ephrin-A5 is expressed later in corticogenesis, highest in the middle region that has low levels of EphA7. The EphA7 gene produces full-length and truncated isoforms, which are repulsive and adhesive, respectively. Analysis of cortical RNA expression demonstrates that proportions of these isoforms change with time, from a more repulsive mix during embryogenesis to a more permissive mix postnatally. To examine how EphA7 and ephrin-A5 influence the formation of cortical regions, EphA7-/- mice were analyzed. Within the cortex of EphA7-/- mice, the distribution of ephrin-A5 was more extensive, encompassing its usual medial domain but also extending more posteriorly toward the occipital pole. Moreover, relative levels of ephrin-A5 along the cortex's anatomical axes changed in EphA7-/- animals, creating less striking shifts in ligand abundance. Furthermore, in vivo functional studies revealed that EphA7 exerts a repulsive influence on ephrin-A5-expressing cells during corticogenesis. In contrast, EphA7 appears to mediate permissive interactions in the postnatal cortex: the area of somatosensory cortex was significantly reduced in EphA7-/- mice. A similar reduction was present in ephrin-A5-/- animals and a more pronounced decrease was observed in EphA7/ephrin-A5-/- cortex. Taken together, this study supports a role for EphA7 and ephrin-A5 in the establishment and maintenance of certain cortical domains and suggests that the nature of their interactions changes with cortical maturity.
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Affiliation(s)
- Katherine Miller
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06520, USA
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Abstract
The sensory and motor components of nervous systems are connected topographically and contain neural maps of the external world. The paradigm for such maps is the precisely ordered wiring of the output cells of the eye to their synaptic targets in the tectum of the midbrain. The retinotectal map is organized in development through the graded activity of Eph receptor tyrosine kinases and their ephrin ligands. These signaling proteins are arrayed in complementary expression gradients along the orthogonal axes of the retina and tectum, and provide both input and recipient cells with Cartesian coordinates that specify their location. Molecular genetic studies in the mouse indicate that these coordinates are interpreted in the context of neuronal competition for termination sites in the tectum. They further suggest that order in the retinotectal map is determined by ratiometric rather than absolute difference comparisons in Eph signaling along the temporal-nasal and dorsal-ventral axes of the eye.
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Affiliation(s)
- Greg Lemke
- Molecular Neurobiology Laboratory, The Salk Institute, La Jolla, California 92037, USA.
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18
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Abstract
Many kinds of information are carried in the acoustic signal that reaches auditory receptor cells in the cochlea. The analysis of this information is possible in large part because of the neuronal architecture of the auditory system. The mechanisms that establish the precise circuitry that underlies auditory processing have not yet been identified. The Eph receptor tyrosine kinases and their ligands are proteins that regulate axon guidance and have been shown to contribute to the establishment of topographic projections in several areas of the nervous system. Several studies have begun to investigate whether these proteins are involved in the formation of auditory system connections. Studies of gene expression show that Eph proteins are extensively expressed in structures of the inner ear as well as in neurons in the peripheral and central components of the auditory system. Functional studies have demonstrated that Eph signaling influences the assembly of auditory pathways. These studies suggest that Eph protein signaling has a significant role in the formation of auditory circuitry.
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Affiliation(s)
- Karina S Cramer
- Department of Neurobiology and Behavior, University of California, 2205 McGaugh Hall, Irvine, CA 92697-4550, USA.
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Holmberg J, Armulik A, Senti KA, Edoff K, Spalding K, Momma S, Cassidy R, Flanagan JG, Frisén J. Ephrin-A2 reverse signaling negatively regulates neural progenitor proliferation and neurogenesis. Genes Dev 2005; 19:462-71. [PMID: 15713841 PMCID: PMC548947 DOI: 10.1101/gad.326905] [Citation(s) in RCA: 167] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The number of cells in an organ is regulated by mitogens and trophic factors that impinge on intrinsic determinants of proliferation and apoptosis. We here report the identification of an additional mechanism to control cell number in the brain: EphA7 induces ephrin-A2 reverse signaling, which negatively regulates neural progenitor cell proliferation. Cells in the neural stem cell niche in the adult brain proliferate more and have a shorter cell cycle in mice lacking ephrin-A2. The increased progenitor proliferation is accompanied by a higher number of cells in the olfactory bulb. Disrupting the interaction between ephrin-A2 and EphA7 in the adult brain of wild-type mice disinhibits proliferation and results in increased neurogenesis. The identification of ephrin-A2 and EphA7 as negative regulators of progenitor cell proliferation reveals a novel mechanism to control cell numbers in the brain.
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Affiliation(s)
- Johan Holmberg
- Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institute, SE-171 77 Stockholm, Sweden
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Luukko K, Løes S, Kvinnsland IH, Kettunen P. Expression of ephrin-A ligands and EphA receptors in the developing mouse tooth and its supporting tissues. Cell Tissue Res 2004; 319:143-52. [PMID: 15517401 DOI: 10.1007/s00441-004-0951-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2003] [Accepted: 06/22/2004] [Indexed: 10/26/2022]
Abstract
Ephrins are cell-membrane-bound ligands for Eph receptor tyrosine kinases and regulate a variety of developmental processes. In order to investigate the potential roles of the ephrin-Eph system in tooth formation, we studied the cellular mRNA expression of Ephrin-A1-A5 and EphA2, EphA3, EphA4, EphA7, and EphA8 receptors during embryonic histomorphogenesis of the mouse first molar (embryonic days 11.5-18.5). Ephrin-A1, ephrin-A5, EphA2, EphA3, EphA4, and EphA7 were expressed in the tooth germ at the epithelial thickening stage, and later, ephrin-A1, ephrin-A5, EphA2, EphA4, and EphA7 showed distinct expression patterns in the enamel organ undergoing epithelial folding morphogenesis. Prior to birth, ephrin-A1, ephrin-A5, EphA2, and EphA4 transcripts were present in the cuspal area of the dental papilla including the preodontoblasts. In addition, ephrin-A1 and ephrin-A5 were seen in the forming blood vessels and alveolar bone, respectively. In contrast, ephrin-A2, ephrin-A3, and ephrin-A4 showed ubiquitous expression during odontogenesis, whereas EphA8 transcripts were not observed. During dental trigeminal axon pathfinding (embryonic days 12.5-13.5), ephrin-A2, ephrin-A4, and ephrin-A5 were evenly distributed in the trigeminal ganglion, whereas EphA7 was expressed in a subset of ganglion cells. These results suggest regulatory roles for ephrin-A/EphA signaling in the formation of the tooth organ proper and its supporting tissues.
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Affiliation(s)
- Keijo Luukko
- Section of Anatomy and Cell Biology, Department of Biomedicine, University of Bergen, Jonas Lies Vei 91, 5009 Bergen, Norway
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21
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Abstract
The A-class of the erythropoietin-producing hepatocellular carcinoma cell-derived (EphA) tyrosine kinase receptors and their ligands, the A-ephrins, play critical roles in the specification of topographic axon projection maps during development. In this study, the role of the EphA subfamily in callosal projections was investigated using transgenic mice expressing a kinase deletion mutant of EphA5. In approximately half of these transgenic mice, cerebral cortical neurons in various cortical regions (primary and secondary somatosensory cortices and frontal as well as visual areas) failed to project to the contralateral cortex. When commissural axons were examined with DiI labeling, few callosal fibers were found to traverse the midline in both the adult and neonatal transgenic mice. This defect in callosal development correlates with the expression of the transgene, because neurons in the superficial layers of the motor cortex, where transgene expression is low, show normal contralateral projection through the corpus callosum. In addition, multiple EphA receptors are expressed in callosal neurons and ephrin-A5 stimulates neurite outgrowth of callosal neurons in vitro. The midline glia structures important for callosal axon midline crossing appear normal in the transgenic mice, suggesting that the defects are unrelated to defective guidance structures at the midline. These observations suggest critical functions for EphA receptor in establishing callosal connections during brain development.
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22
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Kiernan AE, Erven A, Voegeling S, Peters J, Nolan P, Hunter J, Bacon Y, Steel KP, Brown SDM, Guénet JL. ENU mutagenesis reveals a highly mutable locus on mouse Chromosome 4 that affects ear morphogenesis. Mamm Genome 2002; 13:142-8. [PMID: 11919684 DOI: 10.1007/bf02684018] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2001] [Accepted: 11/01/2001] [Indexed: 12/22/2022]
Abstract
Chemical mutagenesis followed by screening for abnormal phenotypes in the mouse holds much promise as a method for revealing gene function. This method is particularly well-suited for discovering genes involved in hearing or balance function, as these defects are relatively easy to screen for in the mouse. We report here the inner ear abnormalities and genetic localization of seven new dominant mutations created by ENU mutagenesis. All seven mutant stocks were identified because of circling and/or head-weaving behavior, which is an indication of balance dysfunction. Investigation of the inner ears of the seven mutant stocks revealed very similar lateral and posterior semicircular canal defects. Studies of the development of the canals in one mutant stock revealed that the affected canals showed reduced outgrowth and delayed canal fusion. Physiological studies performed in one mutant stock showed raised average compound-action-potential thresholds of approximately 10-20 dB sound pressure level (SPL) (depending on frequency), indicating a mild hearing impairment, although scanning electron microscopy performed in several of the mutant stocks revealed no obvious structural defects in the organ of Corti. All seven mutations mapped to the proximal portion of Chromosome (Chr) 4, near the centromere. On the basis of their similar phenotype and map location, we suggest that the seven mutant genes may be allelic and represent a highly mutable locus on Chr 4 that may be particularly susceptible to ENU-induced mutation on the BALB/c genetic background.
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Affiliation(s)
- Amy E Kiernan
- MRC Institute of Hearing Research, University Park, Nottingham, NG7 2RD, UK
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23
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Marín O, Blanco MJ, Nieto MA. Differential expression of Eph receptors and ephrins correlates with the formation of topographic projections in primary and secondary visual circuits of the embryonic chick forebrain. Dev Biol 2001; 234:289-303. [PMID: 11397000 DOI: 10.1006/dbio.2001.0268] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Repulsion plays a fundamental role in the establishment of a topographic map of the chick retinotectal projections. This has been highlighted by studies demonstrating the role of opposing gradients of the EphA3 receptor tyrosine kinase on retinal axons and two of its ligands, ephrin-A2 and ephrin-A5, in the tectum. We have analyzed the distribution of these two ephrins in other retinorecipient structures in the chick diencephalon and mesencephalon during the period when visual connections are being established. We have found that both ephrin-A2 and ephrin-A5 and their receptors EphA4 and EphA7 are expressed in gradients whose orientation is consistent with the topography of the nasotemporal axis of the respective retinofugal projections. In addition, their distribution suggests that receptor-ligand interactions may be involved in the organization of connections between the different primary visual centers and, thus, in the topographic organization of secondary visual projections. Interestingly, where projections lack a clear topographic representation, a uniform expression of the Eph-ephrin molecules was observed. Finally, we also show that a similar patterning mechanism may be implicated in the transfer of visual information to the telencephalon. These results suggest a conserved function for EphA receptors and their ligands in the elaboration of topographic maps at multiple levels of the visual pathway.
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Affiliation(s)
- O Marín
- Instituto Cajal, CSIC, Doctor Arce 37, Madrid, 28002, Spain
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Coonan JR, Greferath U, Messenger J, Hartley L, Murphy M, Boyd AW, Dottori M, Galea MP, Bartlett PF. Development and reorganization of corticospinal projections in EphA4 deficient mice. J Comp Neurol 2001. [DOI: 10.1002/cne.1064] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Ciossek T, Ullrich A, West E, Rogers JH. Segregation of the receptor EphA7 from its tyrosine kinase-negative isoform on neurons in adult mouse brain. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 74:231-6. [PMID: 10640696 DOI: 10.1016/s0169-328x(99)00285-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The EphA7 gene encodes not only a typical receptor tyrosine kinase (TK+) but also an isoform lacking the tyrosine kinase domain (TK-). We have made antibodies to localise EphA7 TK+ and TK- isoforms in mouse brain. The TK- isoform was not detectable prenatally, despite reported expression of the TK- mRNA in the embryo. However, both TK+ and TK- isoforms showed striking distributions in adult brain. TK+ receptor immunoreactivity was strong in neuropil throughout most of the telencephalon, probably on fine arborisations from neurons which expressed EphA7 during development (in cerebral cortex, hippocampus, and striatum). In contrast, TK- receptor immunoreactivity was conspicuous on cell bodies and proximal dendrites of a limited number of neuronal types, some of which carried EphA7 TK+ receptor on their axons. This suggests that the TK- receptor, acting as a dominant negative antagonist, may ensure that the TK+ receptor only responds to signals encountered by the growing extremities of axons or dendrites.
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Affiliation(s)
- T Ciossek
- Max-Planck-Institut for Biochemistry, 82152 Martinsried, Germany.
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Rogers JH, Ciossek T, Menzel P, Pasquale EB. Eph receptors and ephrins demarcate cerebellar lobules before and during their formation. Mech Dev 1999; 87:119-28. [PMID: 10495276 DOI: 10.1016/s0925-4773(99)00154-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The formation of the ten cerebellar lobules is an unsolved problem in brain development. We report a screen for the four subfamilies of Eph receptors and their ligands (ephrins) in developing mouse cerebellum, using soluble receptor-immunoglobulin and ligand-immunoglobulin fusion proteins, and antibodies against EphA and ephrin-B proteins. Our results identify Eph receptors and ephrins as the first molecules known to demarcate individual lobules during development. Staining for ephrin-A ligands is in lobule VIII as it forms, across the whole width of the cerebellum. Staining for three EphA receptors approximately coincides with presumptive lobules VI and/or VII before and just after birth, whereas a fourth EphA receptor (EphA4, which binds ligands of both subfamilies) has more widespread expression. Staining for EphB receptors is in lobules VII, VIII, and IX. Staining for ephrin-B ligands is much weaker, becomes detectable only after birth, and does not appear to be lobule-specific. Staining for all subfamilies spreads to at least some adjacent lobules as maturation proceeds. The lobule-specific patterns appear before the lobules form, and initially extend across the width of the cerebellum, in spite of the lesser conservation of the lateral extensions of the lobules. These expression patterns define previously unknown developmental units and suggest that Eph family proteins may contribute to cerebellar morphogenesis.
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Affiliation(s)
- J H Rogers
- Department of Physiology, University of Cambridge, Downing St., Cambridge, UK.
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