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Soliman E, Mills J, Ju J, Kaloss AM, Basso EKG, Groot N, Kelly C, Kowalski EA, Elhassanny M, Chen M, Wang X, Theus MH. Conditional Deletion of EphA4 on Cx3cr1-Expressing Microglia Fails to Influence Histopathological Outcome and Blood Brain Barrier Disruption Following Brain Injury. Front Mol Neurosci 2021; 14:747770. [PMID: 34630039 PMCID: PMC8497746 DOI: 10.3389/fnmol.2021.747770] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 08/25/2021] [Indexed: 11/13/2022] Open
Abstract
Erythropoietin-producing human hepatocellular receptors play a major role in central nervous system injury. Preclinical and clinical studies revealed the upregulation of erythropoietin-producing human hepatocellular A4 (EphA4) receptors in the brain after acute traumatic brain injury. We have previously reported that Cx3cr1-expressing cells in the peri-lesion show high levels of EphA4 after the induction of controlled cortical impact (CCI) injury in mice. Cx3cr1 is a fractalkine receptor expressed on both resident microglia and peripheral-derived macrophages. The current study aimed to determine the role of microglial-specific EphA4 in CCI-induced damage. We used Cx3cr1 CreER/+ knock-in/knock-out mice, which express EYFP in Cx3cr1-positive cells to establish microglia, EphA4-deficient mice following 1-month tamoxifen injection. Consistent with our previous findings, induction of CCI in wild-type (WT) Cx3cr1 CreER/+ EphA4 +/+ mice increased EphA4 expression on EYFP-positive cells in the peri-lesion. To distinguish between peripheral-derived macrophages and resident microglia, we exploited GFP bone marrow-chimeric mice and found that CCI injury increased EphA4 expression in microglia (TMEM119+GFP-) using immunohistochemistry. Using Cx3cr1 CreER/+ EphA4 f/f (KO) mice, we observed that the EphA4 mRNA transcript was undetected in microglia but remained present in whole blood when compared to WT. Finally, we found no difference in lesion volume or blood-brain barrier (BBB) disruption between WT and KO mice at 3 dpi. Our data demonstrate a nonessential role of microglial EphA4 in the acute histopathological outcome in response to CCI.
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Affiliation(s)
- Eman Soliman
- Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA, United States.,Department of Pharmacology and Toxicology, Faculty of Pharmacy, Zagazig University, Zagazig, Egypt
| | - Jatia Mills
- Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA, United States
| | - Jing Ju
- Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA, United States
| | - Alexandra M Kaloss
- Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA, United States
| | | | - Nathalie Groot
- Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA, United States
| | - Colin Kelly
- Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA, United States
| | - Elizabeth A Kowalski
- Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA, United States
| | - Mohamed Elhassanny
- Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA, United States
| | - Michael Chen
- Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA, United States
| | - Xia Wang
- Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA, United States
| | - Michelle H Theus
- Department of Biomedical Sciences and Pathobiology, Virginia Tech, Blacksburg, VA, United States.,School of Neuroscience, Virginia Tech, Blacksburg, VA, United States.,Center for Engineered Health, Virginia Tech, Blacksburg, VA, United States
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2
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Poppe L, Rué L, Timmers M, Lenaerts A, Storm A, Callaerts-Vegh Z, Courtand G, de Boer A, Smolders S, Van Damme P, Van Den Bosch L, D'Hooge R, De Strooper B, Robberecht W, Lemmens R. EphA4 loss improves social memory performance and alters dendritic spine morphology without changes in amyloid pathology in a mouse model of Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2019; 11:102. [PMID: 31831046 PMCID: PMC6909519 DOI: 10.1186/s13195-019-0554-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 11/08/2019] [Indexed: 12/24/2022]
Abstract
Background EphA4 is a receptor of the ephrin system regulating spine morphology and plasticity in the brain. These processes are pivotal in the pathophysiology of Alzheimer’s disease (AD), characterized by synapse dysfunction and loss, and the progressive loss of memory and other cognitive functions. Reduced EphA4 signaling has been shown to rescue beta-amyloid-induced dendritic spine loss and long-term potentiation (LTP) deficits in cultured hippocampal slices and primary hippocampal cultures. In this study, we investigated whether EphA4 ablation might preserve synapse function and ameliorate cognitive performance in the APPPS1 transgenic mouse model of AD. Methods A postnatal genetic ablation of EphA4 in the forebrain was established in the APPPS1 mouse model of AD, followed by a battery of cognitive tests at 9 months of age to investigate cognitive function upon EphA4 loss. A Golgi-Cox staining was used to explore alterations in dendritic spine density and morphology in the CA1 region of the hippocampus. Results Upon EphA4 loss in APPPS1 mice, we observed improved social memory in the preference for social novelty test without affecting other cognitive functions. Dendritic spine analysis revealed altered synapse morphology as characterized by increased dendritic spine length and head width. These modifications were independent of hippocampal plaque load and beta-amyloid peptide levels since these were similar in mice with normal versus reduced levels of EphA4. Conclusion Loss of EphA4 improved social memory in a mouse model of Alzheimer’s disease in association with alterations in spine morphology.
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Affiliation(s)
- Lindsay Poppe
- Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute (LBI), KU Leuven - University of Leuven, Leuven, Belgium.,Laboratory of Neurobiology, Center for Brain and Disease Research, VIB, Leuven, Belgium
| | - Laura Rué
- Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute (LBI), KU Leuven - University of Leuven, Leuven, Belgium.,Laboratory of Neurobiology, Center for Brain and Disease Research, VIB, Leuven, Belgium
| | - Mieke Timmers
- Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute (LBI), KU Leuven - University of Leuven, Leuven, Belgium.,Laboratory of Neurobiology, Center for Brain and Disease Research, VIB, Leuven, Belgium
| | - Annette Lenaerts
- Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute (LBI), KU Leuven - University of Leuven, Leuven, Belgium.,Laboratory of Neurobiology, Center for Brain and Disease Research, VIB, Leuven, Belgium
| | - Annet Storm
- Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute (LBI), KU Leuven - University of Leuven, Leuven, Belgium.,Laboratory of Neurobiology, Center for Brain and Disease Research, VIB, Leuven, Belgium
| | - Zsuzsanna Callaerts-Vegh
- Laboratory of Biological Psychology, Faculty of Psychology and Educational Sciences, KU Leuven - University of Leuven, Leuven, Belgium.,mINT Animal Behavior Core Facility, Faculty of Psychology, KU Leuven, Leuven, Belgium
| | - Gilles Courtand
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, Unité Mixte de Recherche 5287, Centre National de la Recherche Scientifique, Université de Bordeaux, 33076, Bordeaux, France
| | - Antina de Boer
- Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute (LBI), KU Leuven - University of Leuven, Leuven, Belgium.,Laboratory of Neurobiology, Center for Brain and Disease Research, VIB, Leuven, Belgium
| | - Silke Smolders
- Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute (LBI), KU Leuven - University of Leuven, Leuven, Belgium.,Laboratory of Neurobiology, Center for Brain and Disease Research, VIB, Leuven, Belgium
| | - Philip Van Damme
- Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute (LBI), KU Leuven - University of Leuven, Leuven, Belgium.,Laboratory of Neurobiology, Center for Brain and Disease Research, VIB, Leuven, Belgium.,Department of Neurology, University Hospitals Leuven, Herestraat 49, B-3000, Leuven, Belgium
| | - Ludo Van Den Bosch
- Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute (LBI), KU Leuven - University of Leuven, Leuven, Belgium.,Laboratory of Neurobiology, Center for Brain and Disease Research, VIB, Leuven, Belgium
| | - Rudi D'Hooge
- Laboratory of Biological Psychology, Faculty of Psychology and Educational Sciences, KU Leuven - University of Leuven, Leuven, Belgium
| | - Bart De Strooper
- VIB Center for Brain and Disease Research, Leuven, Belgium.,Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium.,UK Dementia Research Institute at University College London, London, UK
| | - Wim Robberecht
- Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute (LBI), KU Leuven - University of Leuven, Leuven, Belgium.,Department of Neurology, University Hospitals Leuven, Herestraat 49, B-3000, Leuven, Belgium
| | - Robin Lemmens
- Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute (LBI), KU Leuven - University of Leuven, Leuven, Belgium. .,Laboratory of Neurobiology, Center for Brain and Disease Research, VIB, Leuven, Belgium. .,Department of Neurology, University Hospitals Leuven, Herestraat 49, B-3000, Leuven, Belgium.
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3
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Zhao J, Cooper LT, Boyd AW, Bartlett PF. Decreased signalling of EphA4 improves functional performance and motor neuron survival in the SOD1 G93A ALS mouse model. Sci Rep 2018; 8:11393. [PMID: 30061574 PMCID: PMC6065374 DOI: 10.1038/s41598-018-29845-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 07/17/2018] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is an untreatable, progressive, neurodegenerative disease specifically affecting motor neurons. Recently, the tyrosine kinase receptor EphA4 was directly implicated in ALS disease progression. We report that a long-lived mutated form of the EphA4 antagonist EphA4-Fc (mutEphA4-Fc), which blocks EphA4 binding to its ligands and inhibits its function, significantly improved functional performance in SOD1G93A ALS model mice, as assessed by rotarod and hind-limb grip strength tests. Further, heterozygous motor neuron-specific EphA4 gene deletion in SOD1G93A mice promoted significant improvement in functional performance during the disease course and a delay in disease onset relative to control mice. Importantly, mice in the heterozygous deletion group showed significantly improved survival of motor neurons and architecture of endplates of neuromuscular junctions compared with control and homozygous EphA4-deletion groups. Our novel results show that EphA4 signalling directly regulates motor neuron survival and that mutEphA4-Fc is a promising therapeutic candidate to slow disease progression in ALS.
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Affiliation(s)
- J Zhao
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
| | - L T Cooper
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
- Queensland Institute of Medical Research, Brisbane, Queensland, Australia
| | - A W Boyd
- Queensland Institute of Medical Research, Brisbane, Queensland, Australia
| | - P F Bartlett
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia.
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4
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Abdullah NL, Mohd-Zin SW, Ahmad-Annuar A, Abdul-Aziz NM. A Novel Occulta-Type Spina Bifida Mediated by Murine Double Heterozygotes EphA2 and EphA4 Receptor Tyrosine Kinases. Front Cell Dev Biol 2018; 5:105. [PMID: 29312933 PMCID: PMC5732981 DOI: 10.3389/fcell.2017.00105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 11/22/2017] [Indexed: 11/27/2022] Open
Abstract
Members of the Eph receptor tyrosine kinase have previously been implicated in cranial neural tube development. Failure of neural tube closure leads to the devastating conditions known as anencephaly and spina bifida. EphA2 and EphA4 are expressed at the tips of the closing spinal neural folds prior and during neural tube closure. We investigated the possible role of murine EphA2 and EphA4 during the last step of primary neural tube closure, which is adhesion and fusion. The individual mouse knockouts of EphA2 and EphA4 per se do not exhibit neural tube defects (NTDs). The embryos generated by the crossing of double heterozygotes Epha2tm1Jrui/+Epha4rb-2J/+ displayed NTDs with a wide degree of severity including close exencephaly and close spina bifida (spina bifida occulta). Interestingly, mutants displaying NTDs had skin covering the underlying lesion. The tissue sections revealed the elevated neural folds had not adhered and fused. The phenotypes seen in Epha2tm1Jrui/+Epha4rb-2J/+ double heterozygous embryos suggest both genes play a compensatory role with each other in the adhesion and fusion of the neural tube. In this study, there exists a >50% penetrance of NTDs in the mouse mutants, which genetically have a single allele each of EphA2 and EphA4 absent.
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Affiliation(s)
- Nor Linda Abdullah
- Faculty of Medicine, Department of Parasitology, University of Malaya, Kuala Lumpur, Malaysia
| | - Siti W Mohd-Zin
- Faculty of Medicine, Department of Parasitology, University of Malaya, Kuala Lumpur, Malaysia
| | - Azlina Ahmad-Annuar
- Faculty of Medicine, Department of Biomedical Science, University of Malaya, Kuala Lumpur, Malaysia
| | - Noraishah M Abdul-Aziz
- Faculty of Medicine, Department of Parasitology, University of Malaya, Kuala Lumpur, Malaysia
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5
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Nugent AA, Park JG, Wei Y, Tenney AP, Gilette NM, DeLisle MM, Chan WM, Cheng L, Engle EC. Mutant α2-chimaerin signals via bidirectional ephrin pathways in Duane retraction syndrome. J Clin Invest 2017; 127:1664-1682. [PMID: 28346224 DOI: 10.1172/jci88502] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 02/02/2017] [Indexed: 01/18/2023] Open
Abstract
Duane retraction syndrome (DRS) is the most common form of congenital paralytic strabismus in humans and can result from α2-chimaerin (CHN1) missense mutations. We report a knockin α2-chimaerin mouse (Chn1KI/KI) that models DRS. Whole embryo imaging of Chn1KI/KI mice revealed stalled abducens nerve growth and selective trochlear and first cervical spinal nerve guidance abnormalities. Stalled abducens nerve bundles did not reach the orbit, resulting in secondary aberrant misinnervation of the lateral rectus muscle by the oculomotor nerve. By contrast, Chn1KO/KO mice did not have DRS, and embryos displayed abducens nerve wandering distinct from the Chn1KI/KI phenotype. Murine embryos lacking EPH receptor A4 (Epha4KO/KO), which is upstream of α2-chimaerin in corticospinal neurons, exhibited similar abducens wandering that paralleled previously reported gait alterations in Chn1KO/KO and Epha4KO/KO adult mice. Findings from Chn1KI/KI Epha4KO/KO mice demonstrated that mutant α2-chimaerin and EphA4 have different genetic interactions in distinct motor neuron pools: abducens neurons use bidirectional ephrin signaling via mutant α2-chimaerin to direct growth, while cervical spinal neurons use only ephrin forward signaling, and trochlear neurons do not use ephrin signaling. These findings reveal a role for ephrin bidirectional signaling upstream of mutant α2-chimaerin in DRS, which may contribute to the selective vulnerability of abducens motor neurons in this disorder.
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6
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Okyere B, Giridhar K, Hazy A, Chen M, Keimig D, Bielitz RC, Xie H, He JQ, Huckle WR, Theus MH. Endothelial-Specific EphA4 Negatively Regulates Native Pial Collateral Formation and Re-Perfusion following Hindlimb Ischemia. PLoS One 2016; 11:e0159930. [PMID: 27467069 PMCID: PMC4965112 DOI: 10.1371/journal.pone.0159930] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 07/11/2016] [Indexed: 01/01/2023] Open
Abstract
Leptomeningeal anastomoses play a critical role in regulating vascular re-perfusion following obstruction, however, the mechanisms regulating their development remains under investingation. Our current findings indicate that EphA4 receptor is a novel negative regulator of collaterogenesis. We demonstrate that EphA4 is highly expressed on pial arteriole collaterals at post-natal day (P) 1 and 7, then significantly reduced by P21. Endothelial cell (EC)-specific loss of EphA4, EphA4f/f/Tie2::Cre (KO), resulted in an increase in the density but not diameter of pial collaterals compared to WT mice. ECs isolated from KO mice displayed a 3-fold increase in proliferation, enhanced migration, tube formation and elevated levels of phospho(p)-Akt compared to WT ECs. Attenuating p-Akt, using LY294002, reduced the proliferative and migration effects in the KO ECs. RNAseq analysis also revealed altered expression patterns for genes that regulate cell proliferation, vascular development, extracellular matrix and immune-mediate responses, namely MCP-1, MMP2 and angiopoietin-1. Lastly, we show that induction of hindlimb ischemia resulted in accelerated re-perfusion, collateral remodeling and reduced tissue necrosis in the absence of EC-specific EphA4 compared to WT mice. These findings demonstrate a novel role for EphA4 in the early development of the pial collateral network and suggests a role in regulating vascular remodeling after obstruction.
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Affiliation(s)
- Benjamin Okyere
- The Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Insititue and State University, 215 Duck Pond Drive, Blacksburg, Virginia, 24061, United States of America
| | - Kaavya Giridhar
- The Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Insititue and State University, 215 Duck Pond Drive, Blacksburg, Virginia, 24061, United States of America
| | - Amanda Hazy
- The Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Insititue and State University, 215 Duck Pond Drive, Blacksburg, Virginia, 24061, United States of America
| | - Miao Chen
- The Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Insititue and State University, 215 Duck Pond Drive, Blacksburg, Virginia, 24061, United States of America
| | - David Keimig
- Virginia BioComplexity Institute, Virginia Polytechnic Insititue and State University, 1015 Life Science Circle, Blacksburg, Virginia, 24061, United States of America
| | - Robert C. Bielitz
- The Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Insititue and State University, 215 Duck Pond Drive, Blacksburg, Virginia, 24061, United States of America
| | - Hehuang Xie
- Virginia BioComplexity Institute, Virginia Polytechnic Insititue and State University, 1015 Life Science Circle, Blacksburg, Virginia, 24061, United States of America
| | - Jia-Qiang He
- The Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Insititue and State University, 215 Duck Pond Drive, Blacksburg, Virginia, 24061, United States of America
| | - William R. Huckle
- The Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Insititue and State University, 215 Duck Pond Drive, Blacksburg, Virginia, 24061, United States of America
| | - Michelle H. Theus
- The Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Insititue and State University, 215 Duck Pond Drive, Blacksburg, Virginia, 24061, United States of America
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7
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Mohd-Zin SW, Abdullah NL, Abdullah A, Greene NDE, Cheah PS, Ling KH, Yusof H, Marwan AI, Williams SM, York KT, Ahmad-Annuar A, Abdul-Aziz NM. Identification of the genomic mutation in Epha4(rb-2J/rb-2J) mice. Genome 2016; 59:439-48. [PMID: 27373307 DOI: 10.1139/gen-2015-0142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
The EphA4 receptor tyrosine kinase is involved in numerous cell-signalling activities during embryonic development. EphA4 has the ability to bind to both types of ephrin ligands, the ephrinAs and ephrinBs. The C57BL/6J-Epha4rb-2J/GrsrJ strain, denoted Epha4(rb-2J/rb-2J), is a spontaneous mouse mutant that arose at The Jackson Laboratory. These mutants exhibited a synchronous hind limb locomotion defect or "hopping gait" phenotype, which is also characteristic of EphA4 null mice. Genetic complementation experiments suggested that Epha4(rb-2J) corresponds to an allele of EphA4, but details of the genomic defect in this mouse mutant are currently unavailable. We found a single base-pair deletion in exon 9 resulting in a frame shift mutation that subsequently resulted in a premature stop codon. Analysis of the predicted structure of the truncated protein suggests that both the kinase and sterile α motif (SAM) domains are absent. Definitive determination of genotype is needed for experimental studies of mice carrying the Epha4(rb-2J) allele, and we have also developed a method to ease detection of the mutation through RFLP. Eph-ephrin family members are reportedly expressed as numerous isoforms. Hence, delineation of the specific mutation in EphA4 in this strain is important for further functional studies, such as protein-protein interactions, immunostaining and gene compensatory studies, investigating the mechanism underlying the effects of altered function of Eph family of receptor tyrosine kinases on phenotype.
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Affiliation(s)
- Siti W Mohd-Zin
- a Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Nor-Linda Abdullah
- a Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Aminah Abdullah
- b School of Chemical Science and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, 43600 Selangor, Malaysia
| | - Nicholas D E Greene
- c Birth Defects Research Centre, Developmental Biology and Cancer Programme, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
| | - Pike-See Cheah
- d Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor DE, Malaysia
| | - King-Hwa Ling
- d Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor DE, Malaysia
- e Department of Obstetrics and Gynaecology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor DE, Malaysia
| | - Hadri Yusof
- d Genetics and Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor DE, Malaysia
| | - Ahmed I Marwan
- f Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, 12700 E 17th Ave., Aurora, CO 80045, USA
| | - Sarah M Williams
- f Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, 12700 E 17th Ave., Aurora, CO 80045, USA
| | - Kerri T York
- f Department of Surgery, University of Colorado Denver, Anschutz Medical Campus, 12700 E 17th Ave., Aurora, CO 80045, USA
| | - Azlina Ahmad-Annuar
- g Department of Biomedical Science, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Noraishah M Abdul-Aziz
- a Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
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8
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EphA4 Regulates the Balance between Self-Renewal and Differentiation of Radial Glial Cells and Intermediate Neuronal Precursors in Cooperation with FGF Signaling. PLoS One 2015; 10:e0126942. [PMID: 25978062 PMCID: PMC4433105 DOI: 10.1371/journal.pone.0126942] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 04/09/2015] [Indexed: 11/19/2022] Open
Abstract
In mouse cerebral corticogenesis, neurons are generated from radial glial cells (RGCs) or from their immediate progeny, intermediate neuronal precursors (INPs). The balance between self-renewal of these neuronal precursors and specification of cell fate is critical for proper cortical development, but the signaling mechanisms that regulate this progression are poorly understood. EphA4, a member of the receptor tyrosine kinase superfamily, is expressed in RGCs during embryogenesis. To illuminate the function of EphA4 in RGC cell fate determination during early corticogenesis, we deleted Epha4 in cortical cells at E11.5 or E13.5. Loss of EphA4 at both stages led to precocious in vivo RGC differentiation toward neurogenesis. Cortical cells isolated at E14.5 and E15.5 from both deletion mutants showed reduced capacity for neurosphere formation with greater differentiation toward neurons. They also exhibited lower phosphorylation of ERK and FRS2α in the presence of FGF. The size of the cerebral cortex at P0 was smaller than that of controls when Epha4 was deleted at E11.5 but not when it was deleted at E13.5, although the cortical layers were formed normally in both mutants. The number of PAX6-positive RGCs decreased at later developmental stages only in the E11.5 Epha4 deletion mutant. These results suggest that EphA4, in cooperation with an FGF signal, contributes to the maintenance of RGC self-renewal and repression of RGC differentiation through the neuronal lineage. This function of EphA4 is especially critical and uncompensated in early stages of corticogenesis, and thus deletion at E11.5 reduces the size of the neonatal cortex.
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9
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Agrawal P, Wang M, Kim S, Lewis AE, Bush JO. Embryonic expression of EphA receptor genes in mice supports their candidacy for involvement in cleft lip and palate. Dev Dyn 2014; 243:1470-6. [PMID: 25073978 DOI: 10.1002/dvdy.24170] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 07/24/2014] [Accepted: 07/25/2014] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Eph receptors, comprising the A- and B-subfamilies, are the largest family of receptor tyrosine kinases in the mammalian genome, and their function is critical for morphogenesis in a variety of contexts. Whereas signaling through B-type Ephs has been demonstrated to play a role in cleft lip and palate (CL/P), the involvement of A-type Ephs has not been examined in this context notwithstanding a recent genome-wide association study that identified the EPHA3 locus as a candidate for non-syndromic CL/P. RESULTS Here, we present a systematic analysis of the gene expression patterns for the nine EphA receptors at progressive stages of mouse development and find that EphA3, EphA4, and EphA7 exhibit restricted overlapping patterns of expression during palate development. We find that homozygous mutation of EphA3 or compound homozygous mutation of EphA3 and EphA4 in mice does not result in defective midfacial development, supporting the possibility of redundant function with EphA7. We also document previously undescribed expression patterns in other tissues of the craniofacial complex including the lacrimal duct and salivary glands. CONCLUSIONS Together, these results are consistent with the hypothesis that mutations in EPHA family genes may cause CL/P and also suggest that functional redundancy between family members may be at play.
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Affiliation(s)
- Puja Agrawal
- Department of Cell and Tissue Biology, Program in Craniofacial and Mesenchymal Biology and Institute for Human Genetics, University of California, San Francisco, California; Department of Molecular and Cell Biology, University of California, Berkeley, California
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10
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EphA4-mediated ipsilateral corticospinal tract misprojections are necessary for bilateral voluntary movements but not bilateral stereotypic locomotion. J Neurosci 2014; 34:5211-21. [PMID: 24719100 DOI: 10.1523/jneurosci.4848-13.2014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
In this study, we took advantage of the reported role of EphA4 in determining the contralateral spinal projection of the corticospinal tract (CST) to investigate the effects of ipsilateral misprojections on voluntary movements and stereotypic locomotion. Null EphA4 mutations produce robust ipsilateral CST misprojections, resulting in bilateral corticospinal tracts. We hypothesize that a unilateral voluntary limb movement, not a stereotypic locomotor movement, will become a bilateral movement in EphA4 knock-out mice with a bilateral CST. However, in EphA4 full knock-outs, spinal interneurons also develop bilateral misprojections. Aberrant bilateral spinal circuits could thus transform unilateral corticospinal control signals into bilateral movements. We therefore studied mice with conditional forebrain deletion of the EphA4 gene under control by Emx1, a gene expressed in the forebrain that affects the developing CST but spares brainstem motor pathways and spinal motor circuits. We examined two conditional knock-outs targeting forebrain EphA4 during performance of stereotypic locomotion and voluntary movement: adaptive locomotion over obstacles and exploratory reaching. We found that the conditional knock-outs used alternate stepping, not hopping, during overground locomotion, suggesting normal central pattern generator function and supporting our hypothesis of minimal CST involvement in the moment-to-moment control of stereotypic locomotion. In contrast, the conditional knock-outs showed bilateral voluntary movements under conditions when single limb movements are normally produced and, as a basis for this aberrant control, developed a bilateral motor map in motor cortex that is driven by the aberrant ipsilateral CST misprojections. Therefore, a specific change in CST connectivity is associated with and explains a change in voluntary movement.
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Spinal glutamatergic neurons defined by EphA4 signaling are essential components of normal locomotor circuits. J Neurosci 2014; 34:3841-53. [PMID: 24623763 DOI: 10.1523/jneurosci.4992-13.2014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
EphA4 signaling is essential for the spatiotemporal organization of neuronal circuit formation. In mice, deletion of this signaling pathway causes aberrant midline crossing of axons from both brain and spinal neurons and the complete knock-outs (KOs) exhibit a pronounced change in motor behavior, where alternating gaits are replaced by a rabbit-like hopping gait. The neuronal mechanism that is responsible for the gait switch in these KO mice is not known. Here, using intersectional genetics, we demonstrate that a spinal cord-specific deletion of EphA4 signaling is sufficient to generate the overground hopping gait. In contrast, selective deletion of EphA4 signaling in forebrain neurons, including the corticospinal tract neurons, did not result in a change in locomotor pattern. The gait switch was attributed to the loss of EphA4 signaling in excitatory Vglut2+ neurons, which is accompanied by an increased midline crossing of Vglut2+ neurons in the ventral spinal cord. Our findings functionally define spinal EphA4 signaling in excitatory Vglut2+ neurons as required for proper organization of the spinal locomotor circuitry, and place these cells as essential components of the mammalian locomotor network.
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Paixão S, Balijepalli A, Serradj N, Niu J, Luo W, Martin JH, Klein R. EphrinB3/EphA4-mediated guidance of ascending and descending spinal tracts. Neuron 2014; 80:1407-20. [PMID: 24360544 DOI: 10.1016/j.neuron.2013.10.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/10/2013] [Indexed: 11/27/2022]
Abstract
The spinal cord contains many descending and ascending longitudinal tracts whose development appears to be controlled by distinct guidance systems. We identified a population of dorsal spinal neurons marked by coexpression of the transcription factor Zic2 and the guidance receptor EphA4. Zic2+;EphA4+ neurons are surrounded by mechanosensory terminals, suggesting innervation by mechanoreceptor afferents. Their axons form an ipsilateral ascending pathway that develops during embryogenesis and projects within the ventral aspect of the dorsal funiculus, the same location as the descending corticospinal tract (CST), which develops postnatally. Interestingly, the same guidance mechanism, namely, ephrinB3-induced EphA4 forward signaling, is required for the guidance of both ascending and descending axon tracts. Our analysis of conditional EphA4 mutant mice also revealed that the development of the dorsal funiculus occurs independently of EphA4 expression in descending CST axons and is linked to the distribution of Zic2+;EphA4+ spinal neurons and the formation of the ascending pathway.
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Affiliation(s)
- Sónia Paixão
- Department 'Molecules - Signals - Development,' Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Aarathi Balijepalli
- Department 'Molecules - Signals - Development,' Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Najet Serradj
- Department of Physiology, Pharmacology, and Neuroscience, City College of the City University of New York, New York, NY 10031, USA
| | - Jingwen Niu
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Wenqin Luo
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - John H Martin
- Department of Physiology, Pharmacology, and Neuroscience, City College of the City University of New York, New York, NY 10031, USA
| | - Rüdiger Klein
- Department 'Molecules - Signals - Development,' Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany; Munich Cluster for Systems Neurology (Synergy), 80336 Munich, Germany.
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Genetic evidence for a contribution of EphA:ephrinA reverse signaling to motor axon guidance. J Neurosci 2012; 32:5209-15. [PMID: 22496566 DOI: 10.1523/jneurosci.5707-11.2012] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Repulsive Eph forward signaling from limb-derived ephrins guides the axons of lateral motor column (LMC) motor neurons. LMC axons also express ephrinAs, while their EphA receptors are expressed in the limb mesenchyme. In vitro studies have suggested that reverse signaling from limb-derived EphA4 to axonal ephrinAs might result in attraction of LMC axons. However, genetic evidence for this function is lacking. Here we use the Dunn chamber turning assay to show that EphA proteins are chemoattractants and elicit fast turning responses in LMC neurons in vitro. Moreover, ectopic expression of EphA4 in chick hindlimb changes the limb trajectory of LMC axons. Nervous system-specific deletion of EphA4 in mice resulted in fewer LMC axon projection errors than the ubiquitous deletion of EphA4. Additionally, a signaling-incompetent EphA4 mutant partially rescued guidance errors in the hindlimb, suggesting that limb-derived EphA4 contributes to the establishment of LMC projections. In summary, we provide evidence for a role of EphA:ephrinA attractive reverse signaling in motor axon guidance and in vivo evidence of in-parallel forward Eph and reverse ephrin signaling function in the same neuronal population.
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Dabrowski A, Umemori H. Orchestrating the synaptic network by tyrosine phosphorylation signalling. J Biochem 2011; 149:641-53. [PMID: 21508038 PMCID: PMC3143439 DOI: 10.1093/jb/mvr047] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Accepted: 04/08/2011] [Indexed: 01/07/2023] Open
Abstract
The establishment of a functional brain requires coordinated and stereotyped formation of synapses between neurons. For this, trans-synaptic molecular cues (synaptic organizers) are exchanged between a neuron and its target to organize appropriate synapses. The understanding of signalling mechanisms by which such synaptic organizers lead to synapse formation is just being elucidated. However, recent studies revealed that some of these cues act through receptor protein tyrosine kinases (RPTKs) or phosphatases (RPTPs). Synaptogenic RPTKs and RPTPs pattern synaptic network through affecting local protein-protein binding dynamics, changing the phosphorylation state of signalling cascades, or promoting gene expression. Each RPTK or RPTP has distinct roles in synapse formation, serving at different synapses or showing differential synaptogenic effects. Thus, tyrosine phosphorylation signalling plays critical roles in building the orchestrated synaptic circuitry in the brain.
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Affiliation(s)
- Ania Dabrowski
- Molecular & Behavioral Neuroscience Institute, Medical Scientist Training Program, Neuroscience Graduate Program and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Hisashi Umemori
- Molecular & Behavioral Neuroscience Institute, Medical Scientist Training Program, Neuroscience Graduate Program and Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
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EphA4 deficient mice maintain astroglial-fibrotic scar formation after spinal cord injury. Exp Neurol 2010; 223:582-98. [PMID: 20170651 DOI: 10.1016/j.expneurol.2010.02.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 02/04/2010] [Accepted: 02/09/2010] [Indexed: 11/21/2022]
Abstract
One important aspect of recovery and repair after spinal cord injury (SCI) lies in the complex cellular interactions at the injury site that leads to the formation of a lesion scar. EphA4, a promiscuous member of the EphA family of repulsive axon guidance receptors, is expressed by multiple cell types in the injured spinal cord, including astrocytes and neurons. We hypothesized that EphA4 contributes to aspects of cell-cell interactions at the injury site after SCI, thus modulating the formation of the astroglial-fibrotic scar. To test this hypothesis, we studied tissue responses to a thoracic dorsal hemisection SCI in an EphA4 mutant mouse line. We found that EphA4 expression, as assessed by beta-galactosidase reporter gene activity, is associated primarily with astrocytes in the spinal cord, neurons in the cerebral cortex and, to a lesser extent, spinal neurons, before and after SCI. However, we did not observe any overt reduction of glial fibrillary acidic protein (GFAP) expression in the injured area of EphA4 mutants in comparison with controls following SCI. Furthermore, there was no evident disruption of the fibrotic scar, and the boundary between reactive astrocytes and meningeal fibroblasts appeared unaltered in the mutants, as were lesion size, neuronal survival and inflammation marker expression. Thus, genetic deletion of EphA4 does not significantly alter the astroglial response or the formation of the astroglial-fibrotic scar following a dorsal hemisection SCI in mice. In contrast to what has been proposed, these data do not support a major role for EphA4 in reactive astrogliosis following SCI.
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