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Rodríguez-Pérez LM, López-de-San-Sebastián J, de Diego I, Smith A, Roales-Buján R, Jiménez AJ, Paez-Gonzalez P. A selective defect in the glial wedge as part of the neuroepithelium disruption in hydrocephalus development in the mouse hyh model is associated with complete corpus callosum dysgenesis. Front Cell Neurosci 2024; 18:1330412. [PMID: 38450283 PMCID: PMC10915275 DOI: 10.3389/fncel.2024.1330412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 02/08/2024] [Indexed: 03/08/2024] Open
Abstract
Introduction Dysgenesis of the corpus callosum is present in neurodevelopmental disorders and coexists with hydrocephalus in several human congenital syndromes. The mechanisms that underlie the etiology of congenital hydrocephalus and agenesis of the corpus callosum when they coappear during neurodevelopment persist unclear. In this work, the mechanistic relationship between both disorders is investigated in the hyh mouse model for congenital hydrocephalus, which also develops agenesis of the corpus callosum. In this model, hydrocephalus is generated by a defective program in the development of neuroepithelium during its differentiation into radial glial cells. Methods In this work, the populations implicated in the development of the corpus callosum (callosal neurons, pioneering axons, glial wedge cells, subcallosal sling and indusium griseum glial cells) were studied in wild-type and hyh mutant mice. Immunohistochemistry, mRNA in situ hybridization, axonal tracing experiments, and organotypic cultures from normal and hyh mouse embryos were used. Results Our results show that the defective program in the neuroepithelium/radial glial cell development in the hyh mutant mouse selectively affects the glial wedge cells. The glial wedge cells are necessary to guide the pioneering axons as they approach the corticoseptal boundary. Our results show that the pioneering callosal axons arising from neurons in the cingulate cortex can extend projections to the interhemispheric midline in normal and hyh mice. However, pioneering axons in the hyh mutant mouse, when approaching the area corresponding to the damaged glial wedge cell population, turned toward the ipsilateral lateral ventricle. This defect occurred before the appearance of ventriculomegaly. Discussion In conclusion, the abnormal development of the ventricular zone, which appears to be inherent to the etiology of several forms of congenital hydrocephalus, can explain, in some cases, the common association between hydrocephalus and corpus callosum dysgenesis. These results imply that further studies may be needed to understand the corpus callosum dysgenesis etiology when it concurs with hydrocephalus.
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Affiliation(s)
- Luis-Manuel Rodríguez-Pérez
- Departamento de Fisiología Humana, Histología Humana, Anatomía Patológica y Educación Física y Deportiva, Universidad de Málaga, Malaga, Spain
- Instituto de Investigación Biomédica de Málaga (IBIMA), Malaga, Spain
| | | | - Isabel de Diego
- Departamento de Anatomía y Medicina Legal e Historia de la Ciencia, Universidad de Málaga, Malaga, Spain
| | - Aníbal Smith
- Departamento de Anatomía y Medicina Legal e Historia de la Ciencia, Universidad de Málaga, Malaga, Spain
| | - Ruth Roales-Buján
- Departamento de Biología Celular, Genética y Fisiología, Universidad de Málaga, Malaga, Spain
| | - Antonio J. Jiménez
- Instituto de Investigación Biomédica de Málaga (IBIMA), Malaga, Spain
- Departamento de Biología Celular, Genética y Fisiología, Universidad de Málaga, Malaga, Spain
| | - Patricia Paez-Gonzalez
- Instituto de Investigación Biomédica de Málaga (IBIMA), Malaga, Spain
- Departamento de Biología Celular, Genética y Fisiología, Universidad de Málaga, Malaga, Spain
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Bartkowska K, Koguc-Sobolewska P, Djavadian R, Turlejski K. Astrocytes of the Anterior Commissure Regulate the Axon Guidance Pathways of Newly Generated Neocortical Neurons in the Opossum Monodelphis domestica. Int J Mol Sci 2024; 25:1476. [PMID: 38338755 PMCID: PMC10855434 DOI: 10.3390/ijms25031476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/17/2024] [Accepted: 01/22/2024] [Indexed: 02/12/2024] Open
Abstract
In marsupials, upper-layer cortical neurons derived from the progenitors of the subventricular zone of the lateral ventricle (SVZ) mature morphologically and send their axons to form interhemispheric connections through the anterior commissure. In contrast, eutherians have evolved a new extra callosal pathway, the corpus callosum, that interconnects both hemispheres. In this study, we aimed to examine neurogenesis during the formation of cortical upper layers, including their morphological maturation in a marsupial species, namely the opossum (Monodelphis domestica). Furthermore, we studied how the axons of upper layers neurons pass through the anterior commissure of the opossum, which connects neocortical areas. We showed that upper-layer II/III neurons were generated within at least seven days in the opossum neocortex. Surprisingly, these neurons expressed special AT-rich sequence binding protein 2 (Satb2) and neuropilin 1 interacting protein (Nrp1), which are proteins known to be essential for the formation of the corpus callosum in eutherians. This indicates that extrinsic, but not intrinsic, cues could be key players in guiding the axons of newly generated cortical neurons in the opossum. Although oligodendrocyte precursor cells were present in the neocortex and anterior commissure, newly generated upper-layer neurons sent unmyelinated axons to the anterior commissure. We also found numerous GFAP-expressing progenitor cells in both brain structures, the neocortex and the anterior commissure. However, at P12-P17 in the opossums, a small population of astrocytes was observed only in the midline area of the anterior commissure. We postulate that in the opossum, midline astrocytes allow neocortical axons to be guided to cross the midline, as this structure resembles the glial wedge required by fibers to cross the midline area of the corpus callosum in the rodent.
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Affiliation(s)
- Katarzyna Bartkowska
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (K.B.); (P.K.-S.); (R.D.)
| | - Paulina Koguc-Sobolewska
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (K.B.); (P.K.-S.); (R.D.)
| | - Ruzanna Djavadian
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (K.B.); (P.K.-S.); (R.D.)
| | - Krzysztof Turlejski
- Faculty of Biology and Environmental Sciences, Cardinal Stefan Wyszynski University in Warsaw, 01-938 Warsaw, Poland
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3
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Rapti G. Regulation of axon pathfinding by astroglia across genetic model organisms. Front Cell Neurosci 2023; 17:1241957. [PMID: 37941606 PMCID: PMC10628440 DOI: 10.3389/fncel.2023.1241957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 09/07/2023] [Indexed: 11/10/2023] Open
Abstract
Glia and neurons are intimately associated throughout bilaterian nervous systems, and were early proposed to interact for patterning circuit assembly. The investigations of circuit formation progressed from early hypotheses of intermediate guideposts and a "glia blueprint", to recent genetic and cell manipulations, and visualizations in vivo. An array of molecular factors are implicated in axon pathfinding but their number appears small relatively to circuit complexity. Comprehending this circuit complexity requires to identify unknown factors and dissect molecular topographies. Glia contribute to both aspects and certain studies provide molecular and functional insights into these contributions. Here, I survey glial roles in guiding axon navigation in vivo, emphasizing analogies, differences and open questions across major genetic models. I highlight studies pioneering the topic, and dissect recent findings that further advance our current molecular understanding. Circuits of the vertebrate forebrain, visual system and neural tube in zebrafish, mouse and chick, the Drosophila ventral cord and the C. elegans brain-like neuropil emerge as major contexts to study glial cell functions in axon navigation. I present astroglial cell types in these models, and their molecular and cellular interactions that drive axon guidance. I underline shared principles across models, conceptual or technical complications, and open questions that await investigation. Glia of the radial-astrocyte lineage, emerge as regulators of axon pathfinding, often employing common molecular factors across models. Yet this survey also highlights different involvements of glia in embryonic navigation or pioneer axon pathfinding, and unknowns in the molecular underpinnings of glial cell functions. Future cellular and molecular investigations should complete the comprehensive view of glial roles in circuit assembly.
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Affiliation(s)
- Georgia Rapti
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Epigenetics and Neurobiology Unit, European Molecular Biology Laboratory, Rome, Italy
- Interdisciplinary Center of Neurosciences, Heidelberg University, Heidelberg, Germany
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4
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Hemati-Gourabi M, Cao T, Romprey MK, Chen M. Capacity of astrocytes to promote axon growth in the injured mammalian central nervous system. Front Neurosci 2022; 16:955598. [PMID: 36203815 PMCID: PMC9530187 DOI: 10.3389/fnins.2022.955598] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/15/2022] [Indexed: 01/02/2023] Open
Abstract
Understanding the regulation of axon growth after injury to the adult central nervous system (CNS) is crucial to improve neural repair. Following acute focal CNS injury, astrocytes are one cellular component of the scar tissue at the primary lesion that is traditionally associated with inhibition of axon regeneration. Advances in genetic models and experimental approaches have broadened knowledge of the capacity of astrocytes to facilitate injury-induced axon growth. This review summarizes findings that support a positive role of astrocytes in axon regeneration and axon sprouting in the mature mammalian CNS, along with potential underlying mechanisms. It is important to recognize that astrocytic functions, including modulation of axon growth, are context-dependent. Evidence suggests that the local injury environment, neuron-intrinsic regenerative potential, and astrocytes’ reactive states determine the astrocytic capacity to support axon growth. An integrated understanding of these factors will optimize therapeutic potential of astrocyte-targeted strategies for neural repair.
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Affiliation(s)
| | - Tuoxin Cao
- Spinal Cord and Brain Injury Research Center, Lexington, KY, United States
| | - Megan K. Romprey
- Spinal Cord and Brain Injury Research Center, Lexington, KY, United States
- Department of Neuroscience, University of Kentucky, Lexington, KY, United States
| | - Meifan Chen
- Spinal Cord and Brain Injury Research Center, Lexington, KY, United States
- Department of Neuroscience, University of Kentucky, Lexington, KY, United States
- *Correspondence: Meifan Chen,
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5
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Morcom L, Edwards TJ, Rider E, Jones-Davis D, Lim JW, Chen KS, Dean RJ, Bunt J, Ye Y, Gobius I, Suárez R, Mandelstam S, Sherr EH, Richards LJ. DRAXIN regulates interhemispheric fissure remodelling to influence the extent of corpus callosum formation. eLife 2021; 10:61618. [PMID: 33945466 PMCID: PMC8137145 DOI: 10.7554/elife.61618] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 05/01/2021] [Indexed: 12/14/2022] Open
Abstract
Corpus callosum dysgenesis (CCD) is a congenital disorder that incorporates either partial or complete absence of the largest cerebral commissure. Remodelling of the interhemispheric fissure (IHF) provides a substrate for callosal axons to cross between hemispheres, and its failure is the main cause of complete CCD. However, it is unclear whether defects in this process could give rise to the heterogeneity of expressivity and phenotypes seen in human cases of CCD. We identify incomplete IHF remodelling as the key structural correlate for the range of callosal abnormalities in inbred and outcrossed BTBR mouse strains, as well as in humans with partial CCD. We identify an eight base-pair deletion in Draxin and misregulated astroglial and leptomeningeal proliferation as genetic and cellular factors for variable IHF remodelling and CCD in BTBR strains. These findings support a model where genetic events determine corpus callosum structure by influencing leptomeningeal-astroglial interactions at the IHF.
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Affiliation(s)
- Laura Morcom
- The University of Queensland, Queensland Brain Institute, Brisbane, Australia
| | - Timothy J Edwards
- The University of Queensland, Queensland Brain Institute, Brisbane, Australia.,Faculty of Medicine, Brisbane, Australia
| | - Eric Rider
- Departments of Neurology and Pediatrics, Institute of Human Genetics and Weill Institute of Neurosciences, University of California, San Francisco, San Francisco, United States
| | - Dorothy Jones-Davis
- Departments of Neurology and Pediatrics, Institute of Human Genetics and Weill Institute of Neurosciences, University of California, San Francisco, San Francisco, United States
| | - Jonathan Wc Lim
- The University of Queensland, Queensland Brain Institute, Brisbane, Australia
| | - Kok-Siong Chen
- The University of Queensland, Queensland Brain Institute, Brisbane, Australia
| | - Ryan J Dean
- The University of Queensland, Queensland Brain Institute, Brisbane, Australia
| | - Jens Bunt
- The University of Queensland, Queensland Brain Institute, Brisbane, Australia
| | - Yunan Ye
- The University of Queensland, Queensland Brain Institute, Brisbane, Australia
| | - Ilan Gobius
- The University of Queensland, Queensland Brain Institute, Brisbane, Australia
| | - Rodrigo Suárez
- The University of Queensland, Queensland Brain Institute, Brisbane, Australia
| | - Simone Mandelstam
- Department of Radiology, University of Melbourne, Royal Children's Hospital, Parkville, Australia
| | - Elliott H Sherr
- Departments of Neurology and Pediatrics, Institute of Human Genetics and Weill Institute of Neurosciences, University of California, San Francisco, San Francisco, United States
| | - Linda J Richards
- The University of Queensland, Queensland Brain Institute, Brisbane, Australia.,School of Biomedical Sciences, Brisbane, Australia
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6
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Fenlon LR, Suarez R, Lynton Z, Richards LJ. The evolution, formation and connectivity of the anterior commissure. Semin Cell Dev Biol 2021; 118:50-59. [PMID: 33958283 DOI: 10.1016/j.semcdb.2021.04.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 04/08/2021] [Accepted: 04/10/2021] [Indexed: 10/21/2022]
Abstract
The anterior commissure is the most ancient of the forebrain interhemispheric connections among all vertebrates. Indeed, it is the predominant pallial commissure in all non-eutherian vertebrates, universally subserving basic functions related to olfaction and survival. A key feature of the anterior commissure is its ability to convey connections from diverse brain areas, such as most of the neocortex in non-eutherian mammals, thereby mediating the bilateral integration of diverse functions. Shared developmental mechanisms between the anterior commissure and more evolutionarily recent commissures, such as the corpus callosum in eutherians, have led to the hypothesis that the former may have been a precursor for additional expansion of commissural circuits. However, differences between the formation of the anterior commissure and other telencephalic commissures suggest that independent developmental mechanisms underlie the emergence of these connections in extant species. Here, we review the developmental mechanisms and connectivity of the anterior commissure across evolutionarily distant species, and highlight its potential functional importance in humans, both in the course of normal neurodevelopment, and as a site of plastic axonal rerouting in the absence or damage of other connections.
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Affiliation(s)
- Laura R Fenlon
- The University of Queensland, The Queensland Brain Institute, Brisbane, Australia.
| | - Rodrigo Suarez
- The University of Queensland, The Queensland Brain Institute, Brisbane, Australia
| | - Zorana Lynton
- The University of Queensland, The Queensland Brain Institute, Brisbane, Australia; The Faculty of Medicine, Brisbane, Australia
| | - Linda J Richards
- The University of Queensland, The Queensland Brain Institute, Brisbane, Australia; The School of Biomedical Sciences, Brisbane, Australia.
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7
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Morcom L, Gobius I, Marsh APL, Suárez R, Lim JWC, Bridges C, Ye Y, Fenlon LR, Zagar Y, Douglass AM, Donahoo ALS, Fothergill T, Shaikh S, Kozulin P, Edwards TJ, Cooper HM, Sherr EH, Chédotal A, Leventer RJ, Lockhart PJ, Richards LJ. DCC regulates astroglial development essential for telencephalic morphogenesis and corpus callosum formation. eLife 2021; 10:e61769. [PMID: 33871356 PMCID: PMC8116049 DOI: 10.7554/elife.61769] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 04/18/2021] [Indexed: 02/04/2023] Open
Abstract
The forebrain hemispheres are predominantly separated during embryogenesis by the interhemispheric fissure (IHF). Radial astroglia remodel the IHF to form a continuous substrate between the hemispheres for midline crossing of the corpus callosum (CC) and hippocampal commissure (HC). Deleted in colorectal carcinoma (DCC) and netrin 1 (NTN1) are molecules that have an evolutionarily conserved function in commissural axon guidance. The CC and HC are absent in Dcc and Ntn1 knockout mice, while other commissures are only partially affected, suggesting an additional aetiology in forebrain commissure formation. Here, we find that these molecules play a critical role in regulating astroglial development and IHF remodelling during CC and HC formation. Human subjects with DCC mutations display disrupted IHF remodelling associated with CC and HC malformations. Thus, axon guidance molecules such as DCC and NTN1 first regulate the formation of a midline substrate for dorsal commissures prior to their role in regulating axonal growth and guidance across it.
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Affiliation(s)
- Laura Morcom
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
| | - Ilan Gobius
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
| | - Ashley PL Marsh
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children’s Research Institute, Royal Children’s HospitalParkvilleAustralia
- Department of Paediatrics, University of MelbourneParkvilleAustralia
| | - Rodrigo Suárez
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
| | - Jonathan WC Lim
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
| | - Caitlin Bridges
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
| | - Yunan Ye
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
| | - Laura R Fenlon
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
| | - Yvrick Zagar
- Sorbonne Université, INSERM, CNRS, Institut de la VisionParisFrance
| | - Amelia M Douglass
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
| | | | - Thomas Fothergill
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
| | - Samreen Shaikh
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
| | - Peter Kozulin
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
| | - Timothy J Edwards
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
- The University of Queensland, Faculty of MedicineBrisbaneAustralia
| | - Helen M Cooper
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
| | - IRC5 Consortium
- Members and Affiliates of the International Research Consortium for the Corpus Callosum and Cerebral Connectivity (IRC5)Los AngelesUnited States
| | - Elliott H Sherr
- Departments of Neurology and Pediatrics, Institute of Human Genetics and Weill Institute of Neurosciences, University of California, San FranciscoSan FranciscoUnited States
| | - Alain Chédotal
- Sorbonne Université, INSERM, CNRS, Institut de la VisionParisFrance
| | - Richard J Leventer
- Department of Paediatrics, University of MelbourneParkvilleAustralia
- Neuroscience Research Group, Murdoch Children’s Research InstituteParkvilleAustralia
- Department of Neurology, University of Melbourne, Royal Children’s HospitalParkvilleAustralia
| | - Paul J Lockhart
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children’s Research Institute, Royal Children’s HospitalParkvilleAustralia
- Department of Paediatrics, University of MelbourneParkvilleAustralia
| | - Linda J Richards
- The University of Queensland, Queensland Brain InstituteBrisbaneAustralia
- The University of Queensland, School of Biomedical SciencesBrisbaneAustralia
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8
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Schnabl J, Litz MPH, Schneider C, PenkoffLidbeck N, Bashiruddin S, Schwartz MS, Alligood K, Devoto SH, Barresi MJF. Characterizing the diverse cells that associate with the developing commissures of the zebrafish forebrain. Dev Neurobiol 2021; 81:671-695. [PMID: 33314626 DOI: 10.1002/dneu.22801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 10/20/2020] [Accepted: 12/08/2020] [Indexed: 01/02/2023]
Abstract
During embryonic development of bilaterally symmetrical organisms, neurons send axons across the midline at specific points to connect the two halves of the nervous system with a commissure. Little is known about the cells at the midline that facilitate this tightly regulated process. We exploit the conserved process of vertebrate embryonic development in the zebrafish model system to elucidate the identity of cells at the midline that may facilitate postoptic (POC) and anterior commissure (AC) development. We have discovered that three different gfap+ astroglial cell morphologies persist in contact with pathfinding axons throughout commissure formation. Similarly, olig2+ progenitor cells occupy delineated portions of the postoptic and anterior commissures where they act as multipotent, neural progenitors. Moreover, we conclude that both gfap+ and olig2+ progenitor cells give rise to neuronal populations in both the telencephalon and diencephalon; however, these varied cell populations showed significant developmental timing differences between the telencephalon and diencephalon. Lastly, we also showed that fli1a+ mesenchymal cells migrate along the presumptive commissure regions before and during midline axon crossing. Furthermore, following commissure maturation, specific blood vessels formed at the midline of the POC and immediately ventral and parallel to the AC. This comprehensive account of the cellular populations that correlate with the timing and position of commissural axon pathfinding has supported the conceptual modeling and identification of the early forebrain architecture that may be necessary for proper commissure development.
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Affiliation(s)
- Jake Schnabl
- Department of Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, USA
| | - Mackenzie P H Litz
- Department of Biological Sciences, Smith College, Northampton, MA, USA.,Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Caitlin Schneider
- Department of Biological Sciences, Smith College, Northampton, MA, USA.,McGill University, Montreal, QC, Canada
| | | | - Sarah Bashiruddin
- Department of Biological Sciences, Smith College, Northampton, MA, USA.,Family Medicine Assoc, Westfield, MA, USA
| | - Morgan S Schwartz
- Department of Biological Sciences, Smith College, Northampton, MA, USA.,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Kristin Alligood
- Department of Biological Sciences, Smith College, Northampton, MA, USA.,Farmers Conservation Alliance, Hood River, OR, USA
| | | | - Michael J F Barresi
- Department of Molecular and Cellular Biology, University of Massachusetts, Amherst, MA, USA.,Department of Biological Sciences, Smith College, Northampton, MA, USA
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9
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Ku RY, Torii M. New Molecular Players in the Development of Callosal Projections. Cells 2020; 10:cells10010029. [PMID: 33375263 PMCID: PMC7824101 DOI: 10.3390/cells10010029] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 12/18/2020] [Accepted: 12/23/2020] [Indexed: 12/28/2022] Open
Abstract
Cortical development in humans is a long and ongoing process that continuously modifies the neural circuitry into adolescence. This is well represented by the dynamic maturation of the corpus callosum, the largest white matter tract in the brain. Callosal projection neurons whose long-range axons form the main component of the corpus callosum are evolved relatively recently with a substantial, disproportionate increase in numbers in humans. Though the anatomy of the corpus callosum and cellular processes in its development have been intensively studied by experts in a variety of fields over several decades, the whole picture of its development, in particular, the molecular controls over the development of callosal projections, still has many missing pieces. This review highlights the most recent progress on the understanding of corpus callosum formation with a special emphasis on the novel molecular players in the development of axonal projections in the corpus callosum.
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Affiliation(s)
- Ray Yueh Ku
- Center for Neuroscience Research, Children’s Research Institute, Children’s National Hospital, Washington, DC 20010, USA
| | - Masaaki Torii
- Center for Neuroscience Research, Children’s Research Institute, Children’s National Hospital, Washington, DC 20010, USA
- Department of Pediatrics, Pharmacology and Physiology, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20052, USA
- Correspondence:
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10
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Huang KL, Hsiao IT, Ho MY, Hsu JL, Chang YJ, Chang TY, Liu CH, Chang CH, Wu YM, Wu KY, Wey SP, Yen TC, Okamura N, Lee TH, Lin KJ. Investigation of reactive astrogliosis effect on post-stroke cognitive impairment. J Neuroinflammation 2020; 17:308. [PMID: 33069238 PMCID: PMC7568828 DOI: 10.1186/s12974-020-01985-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/05/2020] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND The aim of this study is to investigate the associations between post-stroke cognitive impairment (PSCI) severity and reactive astrogliosis (RA) extent on normalized 18F-THK-5351 positron-emission tomography (PET) imaging in amyloid-negative patients with first-ever stroke. METHODS We prospectively enrolled 63 amyloid-negative patients with first-ever stroke. Neurocognitive evaluation, MRI, 18F-THK-5351, and 18F-florbetapir PET were performed around 3 months after stroke. The 18F-THK-5351 uptake intensity was normalized using a signal distribution template to obtain the Z-SUM scores as the RA extent in the whole brain and cerebral hemisphere ipsilateral to stroke lesion. We evaluated stroke volume, leukoaraiosis, and brain atrophy on MRI. We used a comprehensive neurocognitive battery to obtain composite cognitive scores, and defined PSCI as a general cognitive function score < - 1. We analyzed the influence of Z-SUM scores on PSCI severity after adjusting for demographic, vascular, and neurodegenerative variables. RESULTS Twenty-five of 63 stroke patients had PSCI. Patients with PSCI had older age, lower education, and more severe cortical atrophy and total Z-SUM scores. Total Z-SUM scores were significantly associated with general cognitive and executive functions at multiple regression models. Path analyses showed that stroke can exert cognitive influence directly by stroke itself as well as indirectly through RA, including total and ipsilateral Z-SUM scores, in patients with either right or left hemisphere stroke. CONCLUSION The patterns and intensity of 18F-THK-5351 uptake in amyloid-negative patients with first-ever stroke were associated with PSCI manifestations, which suggests that RA presents a modulating effect in PSCI development.
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Affiliation(s)
- Kuo-Lun Huang
- Department of Neurology, Linkou Chang Gung Memorial Hospital, and College of Medicine, Chang Gung University, No. 5, Fuxing St., Guishan, Taoyuan, Taiwan
| | - Ing-Tsung Hsiao
- Department of Nuclear Medicine and Molecular Imaging Center, Linkou Chang Gung Memorial Hospital, No. 5, Fuxing St., Guishan, Taoyuan, Taiwan
- Healthy Aging Research Center and Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Meng-Yang Ho
- Department of Neurology, Linkou Chang Gung Memorial Hospital, and College of Medicine, Chang Gung University, No. 5, Fuxing St., Guishan, Taoyuan, Taiwan
- Graduate Institute of Behavioral Sciences, Chang Gung University, Taoyuan, Taiwan
| | - Jung-Lung Hsu
- Department of Neurology, New Taipei Municipal TuCheng Hospital, Chang Gung Memorial Hospital, Chang Gung University, New Taipei City, Taiwan
- Taipei Medical University, College of Humanities and Social Sciences, Graduate Institute of Humanities in Medicine and Research Center for Brain and Consciousness, Shuang Ho Hospital, Taipei, Taiwan
| | - Yeu-Jhy Chang
- Department of Neurology, Linkou Chang Gung Memorial Hospital, and College of Medicine, Chang Gung University, No. 5, Fuxing St., Guishan, Taoyuan, Taiwan
| | - Ting-Yu Chang
- Department of Neurology, Linkou Chang Gung Memorial Hospital, and College of Medicine, Chang Gung University, No. 5, Fuxing St., Guishan, Taoyuan, Taiwan
| | - Chi-Hung Liu
- Department of Neurology, Linkou Chang Gung Memorial Hospital, and College of Medicine, Chang Gung University, No. 5, Fuxing St., Guishan, Taoyuan, Taiwan
| | - Chien-Hung Chang
- Department of Neurology, Linkou Chang Gung Memorial Hospital, and College of Medicine, Chang Gung University, No. 5, Fuxing St., Guishan, Taoyuan, Taiwan
| | - Yi-Ming Wu
- Department of Radiology, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Kuan-Yi Wu
- Department of Psychiatry, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Shiaw-Pyng Wey
- Department of Nuclear Medicine and Molecular Imaging Center, Linkou Chang Gung Memorial Hospital, No. 5, Fuxing St., Guishan, Taoyuan, Taiwan
- Healthy Aging Research Center and Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Tzu-Chen Yen
- Department of Nuclear Medicine and Molecular Imaging Center, Linkou Chang Gung Memorial Hospital, No. 5, Fuxing St., Guishan, Taoyuan, Taiwan
- Healthy Aging Research Center and Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Nobuyuki Okamura
- Division of Neuro-imaging, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
- Division of Pharmacology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Tsong-Hai Lee
- Department of Neurology, Linkou Chang Gung Memorial Hospital, and College of Medicine, Chang Gung University, No. 5, Fuxing St., Guishan, Taoyuan, Taiwan.
| | - Kun-Ju Lin
- Department of Nuclear Medicine and Molecular Imaging Center, Linkou Chang Gung Memorial Hospital, No. 5, Fuxing St., Guishan, Taoyuan, Taiwan.
- Healthy Aging Research Center and Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
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11
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Gottipati MK, Zuidema JM, Gilbert RJ. Biomaterial strategies for creating in vitro astrocyte cultures resembling in vivo astrocyte morphologies and phenotypes. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2020; 14:67-74. [PMID: 34296048 DOI: 10.1016/j.cobme.2020.06.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Astrocytes are dynamic cells residing in the central nervous system exhibiting many diverse functions. Astrocytes quickly change and present unique phenotypes in response to injury or disease. Here, we briefly summarize recent information regarding astrocyte morphology and function and provide brief insight into their phenotypic changes following injury or disease. We also present the utility of in vitro astrocyte cultures and present recent advances in biomaterial development that enable better recapitulation of their in vivo behavior and morphology.
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Affiliation(s)
- Manoj K Gottipati
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, 110 8 Street, Troy, NY. 12180.,Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8 Street, Troy, NY. 12180.,Center for Brain and Spinal Cord Repair, Department of Neuroscience, The Ohio State University, 460 W. 12 Avenue, Columbus, OH. 43210
| | - Jonathan M Zuidema
- Department of Neurosciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA. 92093
| | - Ryan J Gilbert
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, 110 8 Street, Troy, NY. 12180.,Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8 Street, Troy, NY. 12180
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12
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Hossain MM, Tsuzuki T, Sakakibara K, Imaizumi F, Ikegaya A, Inagaki M, Takahashi I, Ito T, Takamatsu H, Kumanogoh A, Negishi T, Yukawa K. PlexinA1 is crucial for the midline crossing of callosal axons during corpus callosum development in BALB/cAJ mice. PLoS One 2019; 14:e0221440. [PMID: 31430342 PMCID: PMC6701775 DOI: 10.1371/journal.pone.0221440] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 08/06/2019] [Indexed: 12/04/2022] Open
Abstract
The corpus callosum (CC) is the biggest commissure that links cerebral hemispheres. Guidepost structures develop in the cortical midline during CC development and express axon guidance molecules that instruct neurons regarding the proper direction of axonal elongation toward and across the cortical midline. Neuropilin-1 (Npn1), a high affinity receptor for class 3 semaphorins (Sema3s) localized on cingulate pioneering axons, plays a crucial role in axon guidance to the midline through interactions with Sema3s. However, it remains unclear which type of Plexin is a component of Sema3 holoreceptors with Npn1 during the guidance of cingulate pioneering axons. To address the role of PlexinA1 in CC development, we examined with immunohistochemistry the localization of PlexinA1, Npn1, and Sema3s using embryonic brains from wild-type (WT) and PlexinA1-deficient (PlexinA1 knock-out (KO)) mice with a BALB/cAJ background. The immunohistochemistry confirmed the expression of PlexinA1 in callosal axons derived from the cingulate and neocortex of the WT mice on embryonic day 17.5 (E17.5) but not in the PlexinA1 KO mice. To examine the role of PlexinA1 in the navigation of callosal axons, the extension of callosal axons toward and across the midline was traced in brains of WT and PlexinA1 KO mice at E17.5. As a result, callosal axons in the PlexinA1 KO brains had a significantly lower incidence of midline crossing at E17.5 compared with the WT brains. To further examine the role of PlexinA1 in CC development, the CC phenotype was examined in PlexinA1 KO mice at postnatal day 0.5 (P0.5). Most of the PlexinA1 KO mice at P0.5 showed agenesis of the CC. These results indicate the crucial involvement of PlexinA1 in the midline crossing of callosal axons during CC development in BALB/cAJ mice.
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Affiliation(s)
| | - Takamasa Tsuzuki
- Department of Physiology, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Kazuki Sakakibara
- Department of Physiology, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Fumitaka Imaizumi
- Department of Physiology, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Akihiro Ikegaya
- Department of Physiology, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Mami Inagaki
- Department of Physiology, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Ikuko Takahashi
- Radioisotope Center, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Takuji Ito
- Department of Physiology, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Hyota Takamatsu
- Department of Immunopathology, Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Atsushi Kumanogoh
- Department of Immunopathology, Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Takayuki Negishi
- Department of Physiology, Faculty of Pharmacy, Meijo University, Nagoya, Japan
| | - Kazunori Yukawa
- Department of Physiology, Faculty of Pharmacy, Meijo University, Nagoya, Japan
- * E-mail:
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13
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Calloni SF, Caschera L, Triulzi FM. Disorders of Ventral Induction/Spectrum of Holoprosencephaly. Neuroimaging Clin N Am 2019; 29:411-421. [DOI: 10.1016/j.nic.2019.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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14
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Quadri SA, Farooqui M, Ikram A, Zafar A, Khan MA, Suriya SS, Claus CF, Fiani B, Rahman M, Ramachandran A, Armstrong IIT, Taqi MA, Mortazavi MM. Recent update on basic mechanisms of spinal cord injury. Neurosurg Rev 2018; 43:425-441. [PMID: 29998371 DOI: 10.1007/s10143-018-1008-3] [Citation(s) in RCA: 125] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 06/20/2018] [Accepted: 07/06/2018] [Indexed: 12/20/2022]
Abstract
Spinal cord injury (SCI) is a life-shattering neurological condition that affects between 250,000 and 500,000 individuals each year with an estimated two to three million people worldwide living with an SCI-related disability. The incidence in the USA and Canada is more than that in other countries with motor vehicle accidents being the most common cause, while violence being most common in the developing nations. Its incidence is two- to fivefold higher in males, with a peak in younger adults. Apart from the economic burden associated with medical care costs, SCI predominantly affects a younger adult population. Therefore, the psychological impact of adaptation of an average healthy individual as a paraplegic or quadriplegic with bladder, bowel, or sexual dysfunction in their early life can be devastating. People with SCI are two to five times more likely to die prematurely, with worse survival rates in low- and middle-income countries. This devastating disorder has a complex and multifaceted mechanism. Recently, a lot of research has been published on the restoration of locomotor activity and the therapeutic strategies. Therefore, it is imperative for the treating physicians to understand the complex underlying pathophysiological mechanisms of SCI.
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Affiliation(s)
- Syed A Quadri
- California Institute of Neuroscience, 2100 Lynn Road, Suite 120, Thousand Oaks, CA, 91360, USA. .,National Skull Base Center, Thousand Oaks, CA, USA.
| | - Mudassir Farooqui
- Department of Neurology, University of New Mexico, Albuquerque, NM, USA
| | - Asad Ikram
- Department of Neurology, University of New Mexico, Albuquerque, NM, USA
| | - Atif Zafar
- Department of Neurology, University of New Mexico, Albuquerque, NM, USA
| | - Muhammad Adnan Khan
- California Institute of Neuroscience, 2100 Lynn Road, Suite 120, Thousand Oaks, CA, 91360, USA.,National Skull Base Center, Thousand Oaks, CA, USA
| | - Sajid S Suriya
- California Institute of Neuroscience, 2100 Lynn Road, Suite 120, Thousand Oaks, CA, 91360, USA.,National Skull Base Center, Thousand Oaks, CA, USA
| | - Chad F Claus
- Department of Neurosurgery, St. John Providence Hospital and Medical Centers, Michigan State University, Southfield, MI, USA
| | - Brian Fiani
- Department of Neurosurgery, Desert Regional Medical Center, Palm Springs, CA, USA
| | - Mohammed Rahman
- Department of Neurology, Desert Regional Medical Center, Palm Springs, CA, USA
| | - Anirudh Ramachandran
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, USA
| | - Ian I T Armstrong
- California Institute of Neuroscience, 2100 Lynn Road, Suite 120, Thousand Oaks, CA, 91360, USA.,National Skull Base Center, Thousand Oaks, CA, USA
| | - Muhammad A Taqi
- California Institute of Neuroscience, 2100 Lynn Road, Suite 120, Thousand Oaks, CA, 91360, USA.,National Skull Base Center, Thousand Oaks, CA, USA
| | - Martin M Mortazavi
- California Institute of Neuroscience, 2100 Lynn Road, Suite 120, Thousand Oaks, CA, 91360, USA.,National Skull Base Center, Thousand Oaks, CA, USA
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15
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Gobius I, Morcom L, Suárez R, Bunt J, Bukshpun P, Reardon W, Dobyns WB, Rubenstein JLR, Barkovich AJ, Sherr EH, Richards LJ. Astroglial-Mediated Remodeling of the Interhemispheric Midline Is Required for the Formation of the Corpus Callosum. Cell Rep 2017; 17:735-747. [PMID: 27732850 DOI: 10.1016/j.celrep.2016.09.033] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 08/18/2016] [Accepted: 09/12/2016] [Indexed: 11/29/2022] Open
Abstract
The corpus callosum is the major axon tract that connects and integrates neural activity between the two cerebral hemispheres. Although ∼1:4,000 children are born with developmental absence of the corpus callosum, the primary etiology of this condition remains unknown. Here, we demonstrate that midline crossing of callosal axons is dependent upon the prior remodeling and degradation of the intervening interhemispheric fissure. This remodeling event is initiated by astroglia on either side of the interhemispheric fissure, which intercalate with one another and degrade the intervening leptomeninges. Callosal axons then preferentially extend over these specialized astroglial cells to cross the midline. A key regulatory step in interhemispheric remodeling is the differentiation of these astroglia from radial glia, which is initiated by Fgf8 signaling to downstream Nfi transcription factors. Crucially, our findings from human neuroimaging studies reveal that developmental defects in interhemispheric remodeling are likely to be a primary etiology underlying human callosal agenesis.
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Affiliation(s)
- Ilan Gobius
- Queensland Brain Institute, The University of Queensland, St. Lucia, QLD 4072, Australia.
| | - Laura Morcom
- Queensland Brain Institute, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Rodrigo Suárez
- Queensland Brain Institute, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Jens Bunt
- Queensland Brain Institute, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Polina Bukshpun
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - William Reardon
- National Centre for Medical Genetics, Our Lady's Hospital for Sick Children, Crumlin, Dublin 12, Ireland
| | - William B Dobyns
- Center for Integrative Brain Research, Seattle Children's Research Institute, University of Washington, Seattle, WA 98101, USA; Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98101, USA
| | - John L R Rubenstein
- Department of Psychiatry, Neuroscience Program and Nina Ireland Laboratory of Developmental Neurobiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - A James Barkovich
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94143-0628, USA
| | - Elliott H Sherr
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Linda J Richards
- Queensland Brain Institute, The University of Queensland, St. Lucia, QLD 4072, Australia; The School of Biomedical Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia.
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16
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Balasubramanian S, Packard JA, Leach JB, Powell EM. Three-Dimensional Environment Sustains Morphological Heterogeneity and Promotes Phenotypic Progression During Astrocyte Development. Tissue Eng Part A 2017; 22:885-98. [PMID: 27193766 DOI: 10.1089/ten.tea.2016.0103] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Astrocytes are critical for coordinating normal brain function by regulating brain metabolic homeostasis, synaptogenesis and neurotransmission, and blood-brain barrier permeability and maintenance. Dysregulation of normal astrocyte ontogeny contributes to neurodevelopmental and neurodegenerative disorders, epilepsies, and adverse responses to injury. To achieve these multiple essential roles, astrocyte phenotypes are regionally, morphologically, and functionally heterogeneous. Therefore, the best regenerative medicine strategies may require selective production of distinct astrocyte subpopulations at defined maturation levels. However, little is known about the mechanisms that direct astrocyte diversity or whether heterogeneity is represented in biomaterials. In vitro studies report lack of normal morphologies and overrepresentation of the glial scar type of reactive astrocyte morphology and expression of markers, questioning how well the in vitro astrocytes represent glia in vivo and whether in vitro tissue engineering methods are suitable for regenerative medicine applications. Our previous work with neurons suggests that the three-dimensional (3D) environment, when compared with standard two-dimensional (2D) substrate, yields cellular and molecular behaviors that more closely approximately normal ontogeny. To specifically study the effects of dimensionality, we used purified glial fibrillary acidic protein (GFAP)-expressing primary cerebral cortical astrocyte cultures from single pups and characterized the cellular maturation profiles in 2D and 3D milieu. We identified four morphological groups in vitro: round, bipolar, stellate, and putative perivascular. In the 3D hydrogel culture environment, postnatal astrocytes transitioned from a population of nearly all round cells and very few bipolar cells toward a population with significant fractions of round, stellate, and putative perivascular cells within a few days, following the in vivo ontogeny. In 2D, however, the population shift from round and bipolar to stellate and perivascular was rarely observed. The transition to distinct cellular morphologies in 3D corresponded to the in vivo expression of phenotypic markers, supporting the generation of mature heterogeneous glial populations in vitro. This study presents quantitative data supporting that 3D culture is critical for sustaining the heterogeneity of astrocytes in vitro and for generating a representation of the in vivo portfolio of heterogeneous populations of astrocytes required for therapeutic interventions in neurodevelopmental disorders, epilepsy, and brain injury.
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Affiliation(s)
| | - John A Packard
- 1 Department of Chemical, Biochemical and Environmental Engineering, UMBC , Baltimore, Maryland
| | - Jennie B Leach
- 1 Department of Chemical, Biochemical and Environmental Engineering, UMBC , Baltimore, Maryland
| | - Elizabeth M Powell
- 2 Departments of Anatomy and Neurobiology, Psychiatry, and Bioengineering, University of Maryland School of Medicine , Baltimore, Maryland
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17
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Collette JC, Choubey L, Smith KM. -Glial and stem cell expression of murine Fibroblast Growth Factor Receptor 1 in the embryonic and perinatal nervous system. PeerJ 2017; 5:e3519. [PMID: 28674667 PMCID: PMC5493973 DOI: 10.7717/peerj.3519] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 06/08/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Fibroblast growth factors (FGFs) and their receptors (FGFRs) are involved in the development and function of multiple organs and organ systems, including the central nervous system (CNS). FGF signaling via FGFR1, one of the three FGFRs expressed in the CNS, stimulates proliferation of stem cells during prenatal and postnatal neurogenesis and participates in regulating cell-type ratios in many developing regions of the brain. Anomalies in FGFR1 signaling have been implicated in certain neuropsychiatric disorders. Fgfr1 expression has been shown, via in situ hybridization, to vary spatially and temporally throughout embryonic and postnatal development of the brain. However, in situ hybridization lacks sufficient resolution to identify which cell-types directly participate in FGF signaling. Furthermore, because antibodies raised against FGFR1 commonly cross-react with other members of the FGFR family, immunocytochemistry is not alone sufficient to accurately document Fgfr1 expression. Here, we elucidate the identity of Fgfr1 expressing cells in both the embryonic and perinatal mouse brain. METHODS To do this, we utilized a tgFGFR1-EGFPGP338Gsat BAC line (tgFgfr1-EGFP+) obtained from the GENSAT project. The tgFgfr1-EGFP+ line expresses EGFP under the control of a Fgfr1 promoter, thereby causing cells endogenously expressing Fgfr1 to also present a positive GFP signal. Through simple immunostaining using GFP antibodies and cell-type specific antibodies, we were able to accurately determine the cell-type of Fgfr1 expressing cells. RESULTS This technique revealed Fgfr1 expression in proliferative zones containing BLBP+ radial glial stem cells, such as the cortical and hippocampal ventricular zones, and cerebellar anlage of E14.5 mice, in addition to DCX+ neuroblasts. Furthermore, our data reveal Fgfr1 expression in proliferative zones containing BLBP+ cells of the anterior midline, hippocampus, cortex, hypothalamus, and cerebellum of P0.5 mice, in addition to the early-formed GFAP+ astrocytes of the anterior midline. DISCUSSION Understanding when during development and where Fgfr1 is expressed is critical to improving our understanding of its function during neurodevelopment as well as in the mature CNS. This information may one day provide an avenue of discovery towards understanding the involvement of aberrant FGF signaling in neuropsychiatric disorders.
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Affiliation(s)
- Jantzen C Collette
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, United States of America
| | - Lisha Choubey
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, United States of America
| | - Karen Müller Smith
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, United States of America
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18
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Wegiel J, Flory M, Kaczmarski W, Brown WT, Chadman K, Wisniewski T, Nowicki K, Kuchna I, Ma SY, Wegiel J. Partial Agenesis and Hypoplasia of the Corpus Callosum in Idiopathic Autism. J Neuropathol Exp Neurol 2017; 76:225-237. [PMID: 28395085 DOI: 10.1093/jnen/nlx003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To test the hypothesis that developmental anomalies of the corpus callosum (CC), contribute to the pathogenesis of autism, we characterized the type, topography, and severity of CC pathology corresponding to reduced CC areas that are detected by magnetic resonance imaging in the brains of 11 individuals with autism and 11 controls. In the brains of 3 autistic subjects, partial CC agenesis resulted in complete or partial lack of interhemispheric axonal connections in CC segments III-V. In these cases, a combination of focal agenesis and uniform axonal deficit caused reduction of CC areas by 37%, of axon numbers by 62%, and of the numerical density of axons by 39%. In the CC of 8 autistic subjects without agenesis, there was an 18% deficit of the midsagittal CC area, 48.4% deficit of axon numbers, and 37% reduction of the numerical density of axons. The significantly thinner CC, reduced CC area, and uniform axonal deficit in all autistic subjects were classified as CC hypoplasia. Thus, the byproduct of partial CC agenesis and hypoplasia is reduction of axonal connections between cortical areas known to be involved in behavioral alterations observed in people with autism.
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Affiliation(s)
- Jarek Wegiel
- Departments of Developmental Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
| | - Michael Flory
- Research Design and Analysis Services, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
| | - Wojciech Kaczmarski
- Departments of Developmental Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
| | - W Ted Brown
- Human Genetics, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
| | - Kathryn Chadman
- Behavioral Pharmacology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
| | - Thomas Wisniewski
- Departments of Neurology, Pathology and Psychiatry, NYU Langone Medical Center, New York, New York, USA
| | - Krzysztof Nowicki
- Departments of Developmental Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
| | - Izabela Kuchna
- Departments of Developmental Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
| | - Shuang Yong Ma
- Departments of Developmental Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
| | - Jerzy Wegiel
- Departments of Developmental Neurobiology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA
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19
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Garcia AR, Deacon TW, Dinsmore J, Isacson O. Extensive Axonal and Glial Fiber Growth from Fetal Porcine Cortical Xenografts in the Adult Rat Cortex. Cell Transplant 2017; 4:515-27. [PMID: 8520835 DOI: 10.1177/096368979500400512] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Axonal growth from cortically placed fetal neural transplants to subcortical targets in adult hosts has been difficult to demonstrate and is assumed to be minimal; however, experiments using xenogeneic neural grafts of either human or porcine fetal tissues into the adult rat striatum, mesencephalon, and spinal cord have demonstrated the capability for long-distance axonal growth. This study reports similar results for porcine cortical xenografts placed in the adult rat cerebral cortex and compares these findings with results from cortical allografts. Adult rats that previously received unilateral cortical lesions by an oblique intracortical stereotaxic injection of quinolinic acid, were implanted with suspensions of either E14 rat or E38 xenogeneic porcine fetal cortical cells. Xenografted rats were immunosuppressed by cyclosporin A. The corpus callosum was intact in all cases and grafts were confined to the overlying cortex. After a 31-34 wk posttransplant survival period, acetylcholinesterase (AChE) staining and tyrosine hydroxylase (TH) immunocytochemistry revealed that both allo- and xenografts received host afferents. Retrograde tracer injections into the ipsilateral striatum and cerebral peduncle in allografted animals failed to show any axonal growth to either subcortical target. Using a porcine-specific axonal marker in xenografted animals, we found graft axons in white matter tracts (corpus callosum, internal capsule, cingulum bundle, and medial forebrain bundle) and within the caudate-putamen and both the ipsilateral and contralateral cerebral cortex. Graft axons were not found in the thalamus, midbrain, or spinal cord. In addition, using an antibody to porcine glial fibers, we observed more extensive graft glial fiber growth into the same host fiber tracts, as far caudally as the cerebral peduncle, but not into gray matter targets outside the cortex. These results demonstrate that porcine cortical xenograft axons and glia can extend from lesioned cerebral cortex to cortical and subcortical targets in the adult rat brain. These findings are relevant for prospects of repairing cortical damage and obtaining functional recovery.
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Affiliation(s)
- A R Garcia
- Neuroregeneration Laboratory, McLean Hospital, Belmont, MA 02178, USA
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20
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Filous AR, Silver J. "Targeting astrocytes in CNS injury and disease: A translational research approach". Prog Neurobiol 2016; 144:173-87. [PMID: 27026202 PMCID: PMC5035184 DOI: 10.1016/j.pneurobio.2016.03.009] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 02/03/2016] [Accepted: 03/03/2016] [Indexed: 12/31/2022]
Abstract
Astrocytes are a major constituent of the central nervous system. These glia play a major role in regulating blood-brain barrier function, the formation and maintenance of synapses, glutamate uptake, and trophic support for surrounding neurons and glia. Therefore, maintaining the proper functioning of these cells is crucial to survival. Astrocyte defects are associated with a wide variety of neuropathological insults, ranging from neurodegenerative diseases to gliomas. Additionally, injury to the CNS causes drastic changes to astrocytes, often leading to a phenomenon known as reactive astrogliosis. This process is important for protecting the surrounding healthy tissue from the spread of injury, while it also inhibits axonal regeneration and plasticity. Here, we discuss the important roles of astrocytes after injury and in disease, as well as potential therapeutic approaches to restore proper astrocyte functioning.
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Affiliation(s)
- Angela R Filous
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 216-368-4615, United States.
| | - Jerry Silver
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 216-368-4615, United States.
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21
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Thomas LB, Steindler DA. Review : Glial Boundaries and Scars: Programs for Normal Development and Wound Healing in the Brain. Neuroscientist 2016. [DOI: 10.1177/107385849500100305] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Early studies of glial boundaries, which are composed of immature astrocytes and extracellular matrix mol ecules (which they express), initially offered insight into the partitioning that occurs in the developing nervous system. More recently, however, it has been suggested that similar "boundaries" may have important roles in other processes occurring in the brain, including repair after traumatic brain injury. As more is understood about the expression and function of boundary molecules and glia, their potential importance is becoming apparent in numerous neuropathological conditions, including neurodegeneration and neuroregeneration in Alzheimer's and Huntington's diseases as well as in brain neoplasms. Furthermore, before we can hope to fully understand and facilitate regeneration in the compromised brain, our knowledge of the glial boundary, both during development and in the adult, must be more complete. The Neuroscientist 1:142-154, 1995
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Affiliation(s)
- L. Brannon Thomas
- Department of Anatomy and Neurobiology Department of Neurosurgery The University of Tennessee Memphis, Tennessee
| | - Dennis A. Steindler
- Department of Anatomy and Neurobiology Department of Neurosurgery The University of Tennessee Memphis, Tennessee
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22
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Stewart CE, Corella KM, Samberg BD, Jones PT, Linscott ML, Chung WCJ. Perinatal midline astrocyte development is impaired in fibroblast growth factor 8 hypomorphic mice. Brain Res 2016; 1646:287-296. [PMID: 27291295 DOI: 10.1016/j.brainres.2016.06.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 05/27/2016] [Accepted: 06/09/2016] [Indexed: 12/31/2022]
Abstract
Our previous studies showed that Fgf8 mutations can cause Kallmann syndrome (KS), a form of congenital hypogonadotropic hypogonadism, in which patients do not undergo puberty and are infertile. Interestingly, some KS patients also have agenesis of the corpus callosum (ACC) suggesting that KS pathology is not limited to reproductive function. Here, we asked whether FGF8 dysfunction is the underlying cause of ACC in some KS patients. Indeed, early studies in transgenic mice with Fgf8 mutations reported the presence of failed or incomplete corpus callosum formation. Additional studies in transgenic mice showed that FGF8 function most likely prevents the prenatal elimination of glial fibrillary acidic protein (GFAP)-immunoreactive (IR) glial cells in the indusium griseum (IG) and midline zipper (MZ), two anterior-dorsal midline regions required for corpus callosum formation (i.e., between embryonic days (E) 15.5-18.5). Here, we tested the hypothesis that FGF8 function is critical for the survival of the GFAP-IR midline glial cells. First, we measured the incidence of apoptosis in the anterior-dorsal midline region in Fgf8 hypomorphic mice during embryonic corpus callosum formation. Second, we quantified the GFAP expression in the anterior-dorsal midbrain region during pre- and postnatal development, in order to study: 1) how Fgf8 hypomorphy disrupts prenatal GFAP-IR midline glial cell development, and 2) whether Fgf8 hypomorphy continues to disrupt postnatal GFAP-IR midline glial cell development. Our results indicate that perinatal FGF8 signaling is important for the timing of the onset of anterior-dorsal Gfap expression in midline glial cells suggesting that FGF8 function regulates midline GFAP-IR glial cell development, which when disrupted by Fgf8 deficiency prevents the formation of the corpus callosum. These studies provide an experimentally-based mechanistic explanation as to why corpus callosum formation may fail in KS patients with deficits in FGF signaling.
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Affiliation(s)
- Courtney E Stewart
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA
| | - Kristina M Corella
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA
| | - Brittany D Samberg
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Paula T Jones
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Megan L Linscott
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
| | - Wilson C J Chung
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA; Department of Biological Sciences, Kent State University, Kent, OH 44242, USA.
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Nulty J, Alsaffar M, Barry D. Radial glial cells organize the central nervous system via microtubule dependant processes. Brain Res 2015; 1625:171-9. [DOI: 10.1016/j.brainres.2015.08.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 08/21/2015] [Accepted: 08/22/2015] [Indexed: 11/16/2022]
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Hakanen J, Salminen M. Defects in neural guidepost structures and failure to remove leptomeningeal cells from the septal midline behind the interhemispheric fusion defects in Netrin1 deficient mice. Int J Dev Neurosci 2015; 47:206-15. [PMID: 26397040 DOI: 10.1016/j.ijdevneu.2015.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 08/19/2015] [Accepted: 08/19/2015] [Indexed: 11/18/2022] Open
Abstract
Corpus callosum (CC) is the largest commissural tract in mammalian brain and it acts to coordinate information between the two cerebral hemispheres. During brain development CC forms at the boundary area between the cortex and the septum and special transient neural and glial guidepost structures in this area are thought to be critical for CC formation. In addition, it is thought that the fusion of the two hemispheres in the septum area is a prerequisite for CC formation. However, very little is known of the molecular mechanisms behind the fusion of the two hemispheres. Netrin1 (NTN1) acts as an axon guidance molecule in the developing central nervous system and Ntn1 deficiency leads to the agenesis of CC in mouse. Here we have analyzed Ntn1 deficient mice to better understand the reasons behind the observed lack of CC. We show that Ntn1 deficiency leads to defects in neural, but not in glial guidepost structures that may contribute to the agenesis of CC. In addition, Nnt1 was expressed by the leptomeningeal cells bordering the two septal walls prior to fusion. Normally these cells are removed when the septal fusion occurs. At the same time, the Laminin containing basal lamina produced by the leptomeningeal cells is disrupted in the midline area to allow the cells to mix and the callosal axons to cross. In Ntn1 deficient embryos however, the leptomeninges and the basal lamina were not removed properly from the midline area and the septal fusion did not occur. Thus, NTN1 contributes to the formation of the CC by promoting the preceding removal of the midline leptomeningeal cells and interhemispheric fusion.
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Affiliation(s)
- Janne Hakanen
- Department of Veterinary Biosciences, University of Helsinki, Finland.
| | - Marjo Salminen
- Department of Veterinary Biosciences, University of Helsinki, Finland.
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Panza P, Sitko AA, Maischein HM, Koch I, Flötenmeyer M, Wright GJ, Mandai K, Mason CA, Söllner C. The LRR receptor Islr2 is required for retinal axon routing at the vertebrate optic chiasm. Neural Dev 2015; 10:23. [PMID: 26492970 PMCID: PMC4618557 DOI: 10.1186/s13064-015-0050-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 10/01/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the visual system of most binocular vertebrates, the axons of retinal ganglion cells (RGCs) diverge at the diencephalic midline and extend to targets on both ipsi- and contralateral sides of the brain. While a molecular mechanism explaining ipsilateral guidance decisions has been characterized, less is known of how RGC axons cross the midline. RESULTS Here, we took advantage of the zebrafish, in which all RGC axons project contralaterally at the optic chiasm, to characterize Islr2 as an RGC receptor required for complete retinal axon midline crossing. We used a systematic extracellular protein-protein interaction screening assay to identify two Vasorin paralogs, Vasna and Vasnb, as specific Islr2 ligands. Antibodies against Vasna and Vasnb reveal cellular populations surrounding the retinal axon pathway, suggesting the involvement of these proteins in guidance decisions made by axons of the optic nerve. Specifically, Vasnb marks the membranes of a cellular barricade located anteriorly to the optic chiasm, a structure termed the "glial knot" in higher vertebrates. Loss of function mutations in either vasorin paralog, individually or combined, however, do not exhibit an overt retinal axon projection phenotype, suggesting that additional midline factors, acting either independently or redundantly, compensate for their loss. Analysis of Islr2 knockout mice supports a scenario in which Islr2 controls the coherence of RGC axons through the ventral midline and optic tract. CONCLUSIONS Although stereotypic guidance of RGC axons at the vertebrate optic chiasm is controlled by multiple, redundant mechanisms, and despite the differences in ventral diencephalic tissue architecture, we identify a novel role for the LRR receptor Islr2 in ensuring proper axon navigation at the optic chiasm of both zebrafish and mouse.
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Affiliation(s)
- Paolo Panza
- Max-Planck-Institut für Entwicklungsbiologie, Abteilung Genetik, Spemannstraße 35, 72076, Tübingen, Germany.
| | - Austen A Sitko
- Department of Neuroscience, Columbia University, College of Physicians and Surgeons, 630 West 168th Street, New York, NY, 10032, USA
| | - Hans-Martin Maischein
- Max-Planck-Institut für Entwicklungsbiologie, Abteilung Genetik, Spemannstraße 35, 72076, Tübingen, Germany.,Present address: Max-Planck-Institut für Herz- und Lungenforschung, Abteilung Genetik der Entwicklung, Ludwigstraße 43, 61231, Bad Nauheim, Germany
| | - Iris Koch
- Max-Planck-Institut für Entwicklungsbiologie, Elektronenmikroskopie, Spemannstraße 35, 72076, Tübingen, Germany
| | - Matthias Flötenmeyer
- Max-Planck-Institut für Entwicklungsbiologie, Elektronenmikroskopie, Spemannstraße 35, 72076, Tübingen, Germany
| | - Gavin J Wright
- Wellcome Trust Sanger Institute, Cell Surface Signalling Laboratory, Hinxton, Cambridge, CB10 1HH, UK
| | - Kenji Mandai
- Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo, 650-0017, Japan
| | - Carol A Mason
- Department of Pathology & Cell Biology, Columbia University, College of Physicians and Surgeons, 630 West 168th Street, New York, NY, 10032, USA.,Department of Neuroscience, Columbia University, College of Physicians and Surgeons, 630 West 168th Street, New York, NY, 10032, USA
| | - Christian Söllner
- Max-Planck-Institut für Entwicklungsbiologie, Abteilung Genetik, Spemannstraße 35, 72076, Tübingen, Germany
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Squarzoni P, Thion MS, Garel S. Neuronal and microglial regulators of cortical wiring: usual and novel guideposts. Front Neurosci 2015; 9:248. [PMID: 26236185 PMCID: PMC4505395 DOI: 10.3389/fnins.2015.00248] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 06/30/2015] [Indexed: 12/17/2022] Open
Abstract
Neocortex functioning relies on the formation of complex networks that begin to be assembled during embryogenesis by highly stereotyped processes of cell migration and axonal navigation. The guidance of cells and axons is driven by extracellular cues, released along by final targets or intermediate targets located along specific pathways. In particular, guidepost cells, originally described in the grasshopper, are considered discrete, specialized cell populations located at crucial decision points along axonal trajectories that regulate tract formation. These cells are usually early-born, transient and act at short-range or via cell-cell contact. The vast majority of guidepost cells initially identified were glial cells, which play a role in the formation of important axonal tracts in the forebrain, such as the corpus callosum, anterior, and post-optic commissures as well as optic chiasm. In the last decades, tangential migrating neurons have also been found to participate in the guidance of principal axonal tracts in the forebrain. This is the case for several examples such as guideposts for the lateral olfactory tract (LOT), corridor cells, which open an internal path for thalamo-cortical axons and Cajal-Retzius cells that have been involved in the formation of the entorhino-hippocampal connections. More recently, microglia, the resident macrophages of the brain, were specifically observed at the crossroads of important neuronal migratory routes and axonal tract pathways during forebrain development. We furthermore found that microglia participate to the shaping of prenatal forebrain circuits, thereby opening novel perspectives on forebrain development and wiring. Here we will review the last findings on already known guidepost cell populations and will discuss the role of microglia as a potentially new class of atypical guidepost cells.
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Affiliation(s)
- Paola Squarzoni
- Centre National de la Recherche Scientifique UMR8197, Ecole Normale Supérieure, Institut de Biologie, Institut National de la Santé et de la Recherche Médicale U1024 Paris, France
| | - Morgane S Thion
- Centre National de la Recherche Scientifique UMR8197, Ecole Normale Supérieure, Institut de Biologie, Institut National de la Santé et de la Recherche Médicale U1024 Paris, France
| | - Sonia Garel
- Centre National de la Recherche Scientifique UMR8197, Ecole Normale Supérieure, Institut de Biologie, Institut National de la Santé et de la Recherche Médicale U1024 Paris, France
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Laclef C, Anselme I, Besse L, Catala M, Palmyre A, Baas D, Paschaki M, Pedraza M, Métin C, Durand B, Schneider-Maunoury S. The role of primary cilia in corpus callosum formation is mediated by production of the Gli3 repressor. Hum Mol Genet 2015; 24:4997-5014. [PMID: 26071364 DOI: 10.1093/hmg/ddv221] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 06/09/2015] [Indexed: 12/13/2022] Open
Abstract
Agenesis of the corpus callosum (AgCC) is a frequent brain disorder found in over 80 human congenital syndromes including ciliopathies. Here, we report a severe AgCC in Ftm/Rpgrip1l knockout mouse, which provides a valuable model for Meckel-Grüber syndrome. Rpgrip1l encodes a protein of the ciliary transition zone, which is essential for ciliogenesis in several cell types in mouse including neuroepithelial cells in the developing forebrain. We show that AgCC in Rpgrip1l(-/-) mouse is associated with a disturbed location of guidepost cells in the dorsomedial telencephalon. This mislocalization results from early patterning defects and abnormal cortico-septal boundary (CSB) formation in the medial telencephalon. We demonstrate that all these defects primarily result from altered GLI3 processing. Indeed, AgCC, together with patterning defects and mispositioning of guidepost cells, is rescued by overexpressing in Rpgrip1l(-/-) embryos, the short repressor form of the GLI3 transcription factor (GLI3R), provided by the Gli3(Δ699) allele. Furthermore, Gli3(Δ699) also rescues AgCC in Rfx3(-/-) embryos deficient for the ciliogenic RFX3 transcription factor that regulates the expression of several ciliary genes. These data demonstrate that GLI3 processing is a major outcome of primary cilia function in dorsal telencephalon morphogenesis. Rescuing CC formation in two independent ciliary mutants by GLI3(Δ699) highlights the crucial role of primary cilia in maintaining the proper level of GLI3R required for morphogenesis of the CC.
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Affiliation(s)
- Christine Laclef
- Sorbonne Universités, UPMC Univ Paris 06, UMR7622, CNRS, Institut de Biologie Paris Seine (IBPS)-Developmental Biology Laboratory, UMR7622, INSERM, ERL1156 and
| | - Isabelle Anselme
- Sorbonne Universités, UPMC Univ Paris 06, UMR7622, CNRS, Institut de Biologie Paris Seine (IBPS)-Developmental Biology Laboratory, UMR7622, INSERM, ERL1156 and
| | - Laurianne Besse
- Sorbonne Universités, UPMC Univ Paris 06, UMR7622, CNRS, Institut de Biologie Paris Seine (IBPS)-Developmental Biology Laboratory, UMR7622, INSERM, ERL1156 and
| | - Martin Catala
- Sorbonne Universités, UPMC Univ Paris 06, UMR7622, CNRS, Institut de Biologie Paris Seine (IBPS)-Developmental Biology Laboratory, UMR7622, INSERM, ERL1156 and Fédération de Neurologie, Groupe hospitalier Pitié-Salpêtrière-APHP, F-75013 Paris, France
| | - Aurélien Palmyre
- Sorbonne Universités, UPMC Univ Paris 06, UMR7622, CNRS, Institut de Biologie Paris Seine (IBPS)-Developmental Biology Laboratory, UMR7622, INSERM, ERL1156 and
| | - Dominique Baas
- Université Claude Bernard Lyon 1 and CNRS, CGPhiMC-UMR5534, F-69622 Villeurbanne, France and
| | - Marie Paschaki
- Université Claude Bernard Lyon 1 and CNRS, CGPhiMC-UMR5534, F-69622 Villeurbanne, France and
| | - Maria Pedraza
- Institut du Fer à Moulin, INSERM S839, F-75005 Paris, France, Sorbonne Université, UPMC Univ Paris 06, S839, Paris, France
| | - Christine Métin
- Institut du Fer à Moulin, INSERM S839, F-75005 Paris, France, Sorbonne Université, UPMC Univ Paris 06, S839, Paris, France
| | - Bénédicte Durand
- Université Claude Bernard Lyon 1 and CNRS, CGPhiMC-UMR5534, F-69622 Villeurbanne, France and
| | - Sylvie Schneider-Maunoury
- Sorbonne Universités, UPMC Univ Paris 06, UMR7622, CNRS, Institut de Biologie Paris Seine (IBPS)-Developmental Biology Laboratory, UMR7622, INSERM, ERL1156 and
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Guo JH, Ma W, Yang JW, Gao Y, Liang Z, Liu J, Wang DY, Luo T, Cheng JR, Li LY. Expression pattern of NeuN and GFAP during human fetal spinal cord development. Childs Nerv Syst 2015; 31:863-72. [PMID: 25904356 DOI: 10.1007/s00381-015-2713-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 04/12/2015] [Indexed: 02/06/2023]
Abstract
PURPOSE The development of the human embryonic spinal cord is very complicated, and many cell types are involved in the process. However, the morphological characteristics of neuronal and glial cells during the development of the human fetal spinal cord have not been described. We investigated the systemic distributions and expression pattern of the cell type-specific markers Neuron-specific nuclear protein (NeuN) and glial fibrillary acidic protein (GFAP) during the development of the human fetal spinal cord, in order to clarify the detailed developmental changes of neuronal and glial cells in chronological and spatial aspects. METHODS A total of 35 fetuses, aged 3 weeks to 8 months of gestation (E3W-E8M), were studied. The markers used for immunohistochemical study were NeuN and GFAP. RESULTS The intracellular makers NeuN and GFAP were widely detected expression in different structures and cells during the development of the human fetal spinal cord, including the following: central canal, neuroepithelial layer, internal limiting membrane, mantle layer, marginal layer, basal plate, alar plate, ependymal layer, gray matter, white matter, neuron, astrocytes, and nerve fibers. However, there was an absence of GFAP in astrocytes during early fetal spinal cord development until E9W, and the appearance of GFAP-positive reactivity was later than that of neurons. CONCLUSIONS We consider that NeuN and GFAP can be used to identify neuronal and glial cells during the development of the human fetal spinal cord, and their distribution differs both chronologically and spatially. These characteristic expression patterns would give us a clue to better understand the developmental characteristics of the human spinal cord.
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Affiliation(s)
- Jian-Hui Guo
- Second Department of General Surgery, First People's Hospital of Yunnan Province, Kunming, 650032, Yunnan, China,
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Nkx2.1-derived astrocytes and neurons together with Slit2 are indispensable for anterior commissure formation. Nat Commun 2015; 6:6887. [PMID: 25904499 PMCID: PMC4423212 DOI: 10.1038/ncomms7887] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 02/19/2015] [Indexed: 12/16/2022] Open
Abstract
Guidepost cells present at and surrounding the midline provide guidance cues that orient the growing axons through commissures. Here we show that the transcription factor Nkx2.1 known to control the specification of GABAergic interneurons also regulates the differentiation of astroglia and polydendrocytes within the mouse anterior commissure (AC). Nkx2.1-positive glia were found to originate from three germinal regions of the ventral telencephalon. Nkx2.1-derived glia were observed in and around the AC region by E14.5. Thereafter, a selective cell ablation strategy showed a synergistic role of Nkx2.1-derived cells, both GABAergic interneurons and astroglia, towards the proper formation of the AC. Finally, our results reveal that the Nkx2.1-regulated cells mediate AC axon guidance through the expression of the repellent cue, Slit2. These results bring forth interesting insights about the spatial and temporal origin of midline telencephalic glia, and highlight the importance of neurons and astroglia towards the formation of midline commissures. Guidepost cells provide guidance cues that orient growing axons in the brain but little is known about the midline guidepost cells that populate the mouse anterior commissure (AC). Here, the authors show that the transcription factor Nkx2.1 regulates the differentiation of astroglia and neurons that cooperate to guide AC axons through the expression of Slit2.
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Functional synergy between cholecystokinin receptors CCKAR and CCKBR in mammalian brain development. PLoS One 2015; 10:e0124295. [PMID: 25875176 PMCID: PMC4398320 DOI: 10.1371/journal.pone.0124295] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 03/11/2015] [Indexed: 12/11/2022] Open
Abstract
Cholecystokinin (CCK), a peptide hormone and one of the most abundant neuropeptides in vertebrate brain, mediates its actions via two G-protein coupled receptors, CCKAR and CCKBR, respectively active in peripheral organs and the central nervous system. Here, we demonstrate that the CCK receptors have a dynamic and largely reciprocal expression in embryonic and postnatal brain. Using compound homozygous mutant mice lacking the activity of both CCK receptors, we uncover their additive, functionally synergistic effects in brain development and demonstrate that CCK receptor loss leads to abnormalities of cortical development, including defects in the formation of the midline and corpus callosum, and cortical interneuron migration. Using comparative transcriptome analysis of embryonic neocortex, we define the molecular mechanisms underlying these defects. Thus we demonstrate a developmental, hitherto unappreciated, role of the two CCK receptors in mammalian neocortical development.
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Expression of hyaluronidase-4 in a rat spinal cord hemisection model. Asian Spine J 2015; 9:7-13. [PMID: 25705329 PMCID: PMC4330222 DOI: 10.4184/asj.2015.9.1.7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/24/2014] [Accepted: 04/28/2014] [Indexed: 12/04/2022] Open
Abstract
Study Design Examination of hyaluronidase-4 (Hyal-4) expression in a rat spinal cord hemisection model. Purpose To determine the status of Hyal-4 expression after hemisection of the spinal cord, and the relationship between its expression and that of chondroitin sulfate proteoglycans (CSPGs). Overview of Literature CSPGs are expressed at the site of spinal cord injury and inhibit axon regeneration. Administration of exogenous chrondroitinase ABC (ChABC), derived from bacteria, digested CSPGs and promoted axonal regrowth. Using a rat hemisection model, we have demonstrated peak CSPGs levels at by 3 weeks after injury but then decreased spontaneously. Could there be an endogenous enzyme similar to ChABC in the spinal cord? It has been suggested that Hyal-4 is involved in CSPG degradation. Methods A rat hemisection model was prepared and spinal cord frozen sections were prepared at 4 days and 1, 2, 3, 4, 5, and 6 weeks post-cordotomy and stained for CSPGs and Hyal-4 and subjected to Western blotting. Results CSPGs appeared at the injury site at 4 days after hemisection, reached a peak after 3 weeks, and then decreased. Hyal-4 was observed around the injury site from 4 days after cordotomy and increased until after 5-6 weeks. Double staining showed Hyal-4 around CSPGs. Western blotting identified a band corresponding to Hyal-4 from 4 days after hemisection. Conclusions Hyal-4 was expressed in a rat hemisection model in areas surrounding CSPGs, and as its peak was delayed compared with that of CSPGs. These results suggest the involvement of Hyal-4 in the digestion of CSPGs.
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Lavado A, Ware M, Paré J, Cao X. The tumor suppressor Nf2 regulates corpus callosum development by inhibiting the transcriptional coactivator Yap. Development 2014; 141:4182-93. [PMID: 25336744 DOI: 10.1242/dev.111260] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The corpus callosum connects cerebral hemispheres and is the largest axon tract in the mammalian brain. Callosal malformations are among the most common congenital brain anomalies and are associated with a wide range of neuropsychological deficits. Crossing of the midline by callosal axons relies on a proper midline environment that harbors guidepost cells emitting guidance cues to instruct callosal axon navigation. Little is known about what controls the formation of the midline environment. We find that two components of the Hippo pathway, the tumor suppressor Nf2 (Merlin) and the transcriptional coactivator Yap (Yap1), regulate guidepost development and expression of the guidance cue Slit2 in mouse. During normal brain development, Nf2 suppresses Yap activity in neural progenitor cells to promote guidepost cell differentiation and prevent ectopic Slit2 expression. Loss of Nf2 causes malformation of midline guideposts and Slit2 upregulation, resulting in callosal agenesis. Slit2 heterozygosity and Yap deletion both restore callosal formation in Nf2 mutants. Furthermore, selectively elevating Yap activity in midline neural progenitors is sufficient to disrupt guidepost formation, upregulate Slit2 and prevent midline crossing. The Hippo pathway is known for its role in controlling organ growth and tumorigenesis. Our study identifies a novel role of this pathway in axon guidance. Moreover, by linking axon pathfinding and neural progenitor behaviors, our results provide an example of the intricate coordination between growth and wiring during brain development.
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Affiliation(s)
- Alfonso Lavado
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Michelle Ware
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Joshua Paré
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Xinwei Cao
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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Silver J, Schwab ME, Popovich PG. Central nervous system regenerative failure: role of oligodendrocytes, astrocytes, and microglia. Cold Spring Harb Perspect Biol 2014; 7:a020602. [PMID: 25475091 DOI: 10.1101/cshperspect.a020602] [Citation(s) in RCA: 219] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Animal studies are now showing the exciting potential to achieve significant functional recovery following central nervous system (CNS) injury by manipulating both the inefficient intracellular growth machinery in neurons, as well as the extracellular barriers, which further limit their regenerative potential. In this review, we have focused on the three major glial cell types: oligodendrocytes, astrocytes, and microglia/macrophages, in addition to some of their precursors, which form major extrinsic barriers to regrowth in the injured CNS. Although axotomized neurons in the CNS have, at best, a limited capacity to regenerate or sprout, there is accumulating evidence that even in the adult and, especially after boosting their growth motor, neurons possess the capacity for considerable circuit reorganization and even lengthy regeneration when these glial obstacles to neuronal regrowth are modified, eliminated, or overcome.
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Affiliation(s)
- Jerry Silver
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44140
| | - Martin E Schwab
- Brain Research Institute, University of Zurich and Department of Health Sciences and Technology, ETH Zurich, 8057 Zurich, Switzerland
| | - Phillip G Popovich
- Center for Brain and Spinal Cord Repair, Ohio State University, Columbus, Ohio 43210
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Suárez R, Gobius I, Richards LJ. Evolution and development of interhemispheric connections in the vertebrate forebrain. Front Hum Neurosci 2014; 8:497. [PMID: 25071525 PMCID: PMC4094842 DOI: 10.3389/fnhum.2014.00497] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 06/19/2014] [Indexed: 12/20/2022] Open
Abstract
Axonal connections between the left and right sides of the brain are crucial for bilateral integration of lateralized sensory, motor, and associative functions. Throughout vertebrate species, forebrain commissures share a conserved developmental plan, a similar position relative to each other within the brain and similar patterns of connectivity. However, major events in the evolution of the vertebrate brain, such as the expansion of the telencephalon in tetrapods and the origin of the six-layered isocortex in mammals, resulted in the emergence and diversification of new commissural routes. These new interhemispheric connections include the pallial commissure, which appeared in the ancestors of tetrapods and connects the left and right sides of the medial pallium (hippocampus in mammals), and the corpus callosum, which is exclusive to eutherian (placental) mammals and connects both isocortical hemispheres. A comparative analysis of commissural systems in vertebrates reveals that the emergence of new commissural routes may have involved co-option of developmental mechanisms and anatomical substrates of preexistent commissural pathways. One of the embryonic regions of interest for studying these processes is the commissural plate, a portion of the early telencephalic midline that provides molecular specification and a cellular scaffold for the development of commissural axons. Further investigations into these embryonic processes in carefully selected species will provide insights not only into the mechanisms driving commissural evolution, but also regarding more general biological problems such as the role of developmental plasticity in evolutionary change.
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Affiliation(s)
- Rodrigo Suárez
- Queensland Brain Institute, The University of QueenslandBrisbane, QLD, Australia
| | - Ilan Gobius
- Queensland Brain Institute, The University of QueenslandBrisbane, QLD, Australia
| | - Linda J. Richards
- Queensland Brain Institute, The University of QueenslandBrisbane, QLD, Australia
- School of Biomedical Sciences, The University of QueenslandBrisbane, QLD, Australia
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Chinn GA, Hirokawa KE, Chuang TM, Urbina C, Patel F, Fong J, Funatsu N, Monuki ES. Agenesis of the Corpus Callosum Due to Defective Glial Wedge Formation in Lhx2 Mutant Mice. Cereb Cortex 2014; 25:2707-18. [PMID: 24781987 DOI: 10.1093/cercor/bhu067] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Establishment of the corpus callosum involves coordination between callosal projection neurons and multiple midline structures, including the glial wedge (GW) rostrally and hippocampal commissure caudally. GW defects have been associated with agenesis of the corpus callosum (ACC). Here we show that conditional Lhx2 inactivation in cortical radial glia using Emx1-Cre or Nestin-Cre drivers results in ACC. The ACC phenotype was characterized by aberrant ventrally projecting callosal axons rather than Probst bundles, and was 100% penetrant on 2 different mouse strain backgrounds. Lhx2 inactivation in postmitotic cortical neurons using Nex-Cre mice did not result in ACC, suggesting that the mutant phenotype was not autonomous to the callosal projection neurons. Instead, ACC was associated with an absent hippocampal commissure and a markedly reduced to absent GW. Expression studies demonstrated strong Lhx2 expression in the normal GW and in its radial glial progenitors, with absence of Lhx2 resulting in normal Emx1 and Sox2 expression, but premature exit from the cell cycle based on EdU-Ki67 double labeling. These studies define essential roles for Lhx2 in GW, hippocampal commissure, and corpus callosum formation, and suggest that defects in radial GW progenitors can give rise to ACC.
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Affiliation(s)
- Gregory A Chinn
- Department of Developmental and Cell Biology, School of Biological Sciences, University of California Irvine, Irvine, CA, USA Department of Pathology and Laboratory Medicine, School of Medicine, University of California Irvine, Irvine, CA, USA
| | - Karla E Hirokawa
- Department of Developmental and Cell Biology, School of Biological Sciences, University of California Irvine, Irvine, CA, USA Department of Pathology and Laboratory Medicine, School of Medicine, University of California Irvine, Irvine, CA, USA
| | - Tony M Chuang
- Department of Pathology and Laboratory Medicine, School of Medicine, University of California Irvine, Irvine, CA, USA
| | - Cecilia Urbina
- Department of Pathology and Laboratory Medicine, School of Medicine, University of California Irvine, Irvine, CA, USA
| | - Fenil Patel
- Department of Developmental and Cell Biology, School of Biological Sciences, University of California Irvine, Irvine, CA, USA
| | - Jeanette Fong
- Department of Developmental and Cell Biology, School of Biological Sciences, University of California Irvine, Irvine, CA, USA
| | - Nobuo Funatsu
- Department of Pathology and Laboratory Medicine, School of Medicine, University of California Irvine, Irvine, CA, USA
| | - Edwin S Monuki
- Department of Developmental and Cell Biology, School of Biological Sciences, University of California Irvine, Irvine, CA, USA Department of Pathology and Laboratory Medicine, School of Medicine, University of California Irvine, Irvine, CA, USA Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA, USA
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36
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Burda JE, Sofroniew MV. Reactive gliosis and the multicellular response to CNS damage and disease. Neuron 2014; 81:229-48. [PMID: 24462092 DOI: 10.1016/j.neuron.2013.12.034] [Citation(s) in RCA: 973] [Impact Index Per Article: 97.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2013] [Indexed: 02/07/2023]
Abstract
The CNS is prone to heterogeneous insults of diverse etiologies that elicit multifaceted responses. Acute and focal injuries trigger wound repair with tissue replacement. Diffuse and chronic diseases provoke gradually escalating tissue changes. The responses to CNS insults involve complex interactions among cells of numerous lineages and functions, including CNS intrinsic neural cells, CNS intrinsic nonneural cells, and CNS extrinsic cells that enter from the circulation. The contributions of diverse nonneuronal cell types to outcome after acute injury, or to the progression of chronic disease, are of increasing interest as the push toward understanding and ameliorating CNS afflictions accelerates. In some cases, considerable information is available, in others, comparatively little, as examined and reviewed here.
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Affiliation(s)
- Joshua E Burda
- Department of Neurobiology and Brain Research Institute, University of California Los Angeles, Los Angeles, CA 90095-1763, USA
| | - Michael V Sofroniew
- Department of Neurobiology and Brain Research Institute, University of California Los Angeles, Los Angeles, CA 90095-1763, USA.
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37
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Glial scar borders are formed by newly proliferated, elongated astrocytes that interact to corral inflammatory and fibrotic cells via STAT3-dependent mechanisms after spinal cord injury. J Neurosci 2013; 33:12870-86. [PMID: 23904622 DOI: 10.1523/jneurosci.2121-13.2013] [Citation(s) in RCA: 558] [Impact Index Per Article: 50.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Astroglial scars surround damaged tissue after trauma, stroke, infection, or autoimmune inflammation in the CNS. They are essential for wound repair, but also interfere with axonal regrowth. A better understanding of the cellular mechanisms, regulation, and functions of astroglial scar formation is fundamental to developing safe interventions for many CNS disorders. We used wild-type and transgenic mice to quantify and dissect these parameters. Adjacent to crush spinal cord injury (SCI), reactive astrocytes exhibited heterogeneous phenotypes as regards proliferation, morphology, and chemistry, which all varied with distance from lesions. Mature scar borders at 14 d after SCI consisted primarily of newly proliferated astroglia with elongated cell processes that surrounded large and small clusters of inflammatory, fibrotic, and other cells. During scar formation from 5 to 14 d after SCI, cell processes deriving from different astroglia associated into overlapping bundles that quantifiably reoriented and organized into dense mesh-like arrangements. Selective deletion of STAT3 from astroglia quantifiably disrupted the organization of elongated astroglia into scar borders, and caused a failure of astroglia to surround inflammatory cells, resulting in increased spread of these cells and neuronal loss. In cocultures, wild-type astroglia spontaneously corralled inflammatory or fibromeningeal cells into segregated clusters, whereas STAT3-deficient astroglia failed to do so. These findings demonstrate heterogeneity of reactive astroglia and show that scar borders are formed by newly proliferated, elongated astroglia, which organize via STAT3-dependent mechanisms to corral inflammatory and fibrotic cells into discrete areas separated from adjacent tissue that contains viable neurons.
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Leyva-Díaz E, López-Bendito G. In and out from the cortex: development of major forebrain connections. Neuroscience 2013; 254:26-44. [PMID: 24042037 DOI: 10.1016/j.neuroscience.2013.08.070] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/27/2013] [Accepted: 08/28/2013] [Indexed: 12/21/2022]
Abstract
In this review we discuss recent advances in the understanding of the development of forebrain projections attending to their origin, fate determination, and axon guidance. Major forebrain connections include callosal, corticospinal, corticothalamic and thalamocortical projections. Although distinct transcriptional programs specify these subpopulations of projecting neurons, the mechanisms involved in their axonal development are similar. Guidance by short- and long-range molecular cues, interaction with intermediate target populations and activity-dependent mechanisms contribute to their development. Moreover, some of these connections interact with each other showing that the development of these axonal tracts is a well-orchestrated event. Finally, we will recapitulate recent discoveries that challenge the field of neural wiring that show that these forebrain connections can be changed once formed. The field of reprogramming has arrived to postmitotic cortical neurons and has showed us that forebrain connectivity is not immutable and might be changed by manipulations in the transcriptional program of matured cells.
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Affiliation(s)
- E Leyva-Díaz
- Instituto de Neurociencias de Alicante, CSIC & Universidad Miguel Hernández, 03550 Sant Joan d'Alacant, Spain.
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Niquille M, Minocha S, Hornung JP, Rufer N, Valloton D, Kessaris N, Alfonsi F, Vitalis T, Yanagawa Y, Devenoges C, Dayer A, Lebrand C. Two specific populations of GABAergic neurons originating from the medial and the caudal ganglionic eminences aid in proper navigation of callosal axons. Dev Neurobiol 2013; 73:647-72. [PMID: 23420573 DOI: 10.1002/dneu.22075] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 02/10/2013] [Accepted: 02/11/2013] [Indexed: 12/22/2022]
Abstract
The corpus callosum (CC) plays a crucial role in interhemispheric communication. It has been shown that CC formation relies on the guidepost cells located in the midline region that include glutamatergic and GABAergic neurons as well as glial cells. However, the origin of these guidepost GABAergic neurons and their precise function in callosal axon pathfinding remain to be investigated. Here, we show that two distinct GABAergic neuronal subpopulations converge toward the midline prior to the arrival of callosal axons. Using in vivo and ex vivo fate mapping we show that CC GABAergic neurons originate in the caudal and medial ganglionic eminences (CGE and MGE) but not in the lateral ganglionic eminence (LGE). Time lapse imaging on organotypic slices and in vivo analyses further revealed that CC GABAergic neurons contribute to the normal navigation of callosal axons. The use of Nkx2.1 knockout (KO) mice confirmed a role of these neurons in the maintenance of proper behavior of callosal axons while growing through the CC. Indeed, using in vitro transplantation assays, we demonstrated that both MGE- and CGE-derived GABAergic neurons exert an attractive activity on callosal axons. Furthermore, by combining a sensitive RT-PCR technique with in situ hybridization, we demonstrate that CC neurons express multiple short and long range guidance cues. This study strongly suggests that MGE- and CGE-derived interneurons may guide CC axons by multiple guidance mechanisms and signaling pathways.
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Affiliation(s)
- Mathieu Niquille
- Département des neurosciences fondamentales, University of Lausanne, Rue du Bugnon 9, CH-1005 Lausanne, Switzerland
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40
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Axon guidance mechanisms for establishment of callosal connections. Neural Plast 2013; 2013:149060. [PMID: 23533817 PMCID: PMC3595665 DOI: 10.1155/2013/149060] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 12/30/2012] [Accepted: 01/21/2013] [Indexed: 01/03/2023] Open
Abstract
Numerous studies have investigated the formation of interhemispheric connections which are involved in high-ordered functions of the cerebral cortex in eutherian animals, including humans. The development of callosal axons, which transfer and integrate information between the right/left hemispheres and represent the most prominent commissural system, must be strictly regulated. From the beginning of their growth, until reaching their targets in the contralateral cortex, the callosal axons are guided mainly by two environmental cues: (1) the midline structures and (2) neighboring? axons. Recent studies have shown the importance of axona guidance by such cues and the underlying molecular mechanisms. In this paper, we review these guidance mechanisms during the development of the callosal neurons. Midline populations express and secrete guidance molecules, and "pioneer" axons as well as interactions between the medial and lateral axons are also involved in the axon pathfinding of the callosal neurons. Finally, we describe callosal dysgenesis in humans and mice, that results from a disruption of these navigational mechanisms.
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41
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Liu CH, Yang J, Ren JQ, Liu CM, You Z, Liu PK. MRI reveals differential effects of amphetamine exposure on neuroglia in vivo. FASEB J 2012; 27:712-24. [PMID: 23150521 DOI: 10.1096/fj.12-220061] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
How amphetamine affects the neuroglia in living brains is not well understood. In an effort to elucidate this effect, we investigated neuroglia in response to amphetamine exposure using antisense (AS) or sense (S) phosphorothioate-modified oligodeoxynucleotide (sODN) sequences that correspond to glial fibrillary acidic protein (GFAP) mRNA (AS-gfap or S-gfap, respectively) expression. The control is a random-sequence sODN (Ran). Using cyanine 5.5-superparamagnetic iron oxide nanoparticle (Cy5.5-SPION) labeling and fluorescent microscopy, we demonstrated that living neural progenitor cells (PC-12.1), as well as the cells in fresh brain slices and intact brains of male C57BL6 mice, exhibited universal uptake of all of the sODNs but rapidly excluded all sODN-Ran and most S-gfap. Moreover, transmission electron microscopy revealed electron-dense nanoparticles only in the neuroglia of normal or transgenic mice [B6;DBA-Tg(Fos-tTA, Fos-EGFP*)1MmayTg(tetO-lacZ,tTA*)1Mmay/J] that had been administered AS-gfap or Cy5.5-SPION-gfap. Subtraction R2* maps from mice with acute and chronic amphetamine exposure demonstrated, validated by postmortem immunohistochemistry, a reduction in striatal neuroglia, with gliogenesis in the subventricular zone and the somatosensory cortex in vivo. The sensitivity of our unique gene transcript targeted MRI was illustrated by a positive linear correlation (r(2)=1.0) between in vivo MRI signal changes and GFAP mRNA copy numbers determined by ex vivo quantitative RT-PCR. The study provides direct evidence for targeting neuroglia by antisense DNA-based SPION-gfap that enables in vivo MRI of inaccessible tissue with PCR sensitivity. The results enable us to conclude that amphetamine induces toxicity to neuroglia in vivo, which may cause remodeling or reconnectivity of neuroglia.
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Affiliation(s)
- Christina H Liu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
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42
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Barry DS, Pakan JMP, O'Keeffe GW, McDermott KW. The spatial and temporal arrangement of the radial glial scaffold suggests a role in axon tract formation in the developing spinal cord. J Anat 2012; 222:203-13. [PMID: 23121514 DOI: 10.1111/joa.12006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2012] [Indexed: 01/14/2023] Open
Abstract
Radial glial cells serve diverse roles during the development of the central nervous system (CNS). In the embryonic brain, they are recognised as guidance conduits for migrating neuroblasts and as multipotent stem cells, generating both neurons and glia. While their stem cell capacities in the developing spinal cord are as yet not fully clarified, they are classically seen as a population of astrocytes precursors, before gradually disappearing as the spinal cord matures. Although the origins and lineages of CNS radial glial cells are being more clearly understood, the relationships between radial glial cells and growing white matter (WM) tracts are largely unknown. Here, we provide an in-depth description of the distribution and organisation of radial glial cell processes during the peak periods of axonogenesis in the rat spinal cord. We show that radial glial cell distribution is highly ordered in the WM from E14 to E18, when the initial patterning of axon tracts is taking place. We report that the density of radial glial cell processes is tightly conserved throughout development in the dorsal, lateral and ventral WM funiculi along the rostrocaudal axis of the spinal cord. We provide evidence that from E16 the dorsal funiculi grow within and are segregated by fascicles of processes emanating from the dorsomedial septum. The density of radial glial cells declines with the maturation of axon tracts and coincides with the onset of the radial glial cell-astrocyte transformation. As such, we propose that radial glial cells act as structural scaffolds by compartmentalising and supporting WM patterning in the spinal cord during embryonic development.
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Affiliation(s)
- Denis S Barry
- Department of Anatomy and Neuroscience, University College Cork, Ireland
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43
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Grondona JM, Hoyo-Becerra C, Visser R, Fernández-Llebrez P, López-Ávalos MD. The subcommissural organ and the development of the posterior commissure. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 296:63-137. [PMID: 22559938 DOI: 10.1016/b978-0-12-394307-1.00002-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Growing axons navigate through the developing brain by means of axon guidance molecules. Intermediate targets producing such signal molecules are used as guideposts to find distal targets. Glial, and sometimes neuronal, midline structures represent intermediate targets when axons cross the midline to reach the contralateral hemisphere. The subcommissural organ (SCO), a specialized neuroepithelium located at the dorsal midline underneath the posterior commissure, releases SCO-spondin, a large glycoprotein belonging to the thrombospondin superfamily that shares molecular domains with axonal pathfinding molecules. Several evidences suggest that the SCO could be involved in the development of the PC. First, both structures display a close spatiotemporal relationship. Second, certain mutants lacking an SCO present an abnormal PC. Third, some axonal guidance molecules are expressed by SCO cells. Finally, SCO cells, the Reissner's fiber (the aggregated form of SCO-spondin), or synthetic peptides from SCO-spondin affect the neurite outgrowth or neuronal aggregation in vitro.
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Affiliation(s)
- Jesús M Grondona
- Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, Spain.
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Magnani D, Hasenpusch-Theil K, Benadiba C, Yu T, Basson MA, Price DJ, Lebrand C, Theil T. Gli3 controls corpus callosum formation by positioning midline guideposts during telencephalic patterning. ACTA ACUST UNITED AC 2012; 24:186-98. [PMID: 23042737 DOI: 10.1093/cercor/bhs303] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The corpus callosum (CC) represents the major forebrain commissure connecting the 2 cerebral hemispheres. Midline crossing of callosal axons is controlled by several glial and neuronal guideposts specifically located along the callosal path, but it remains unknown how these cells acquire their position. Here, we show that the Gli3 hypomorphic mouse mutant Polydactyly Nagoya (Pdn) displays agenesis of the CC and mislocation of the glial and neuronal guidepost cells. Using transplantation experiments, we demonstrate that agenesis of the CC is primarily caused by midline defects. These defects originate during telencephalic patterning and involve an up-regulation of Slit2 expression and altered Fgf and Wnt/β-catenin signaling. Mutations in sprouty1/2 which mimic the changes in these signaling pathways cause a disorganization of midline guideposts and CC agenesis. Moreover, a partial recovery of midline abnormalities in Pdn/Pdn;Slit2(-/-) embryos mutants confirms the functional importance of correct Slit2 expression levels for callosal development. Hence, Gli3 controlled restriction of Fgf and Wnt/β-catenin signaling and of Slit2 expression is crucial for positioning midline guideposts and callosal development.
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Affiliation(s)
- Dario Magnani
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
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45
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Unni DK, Piper M, Moldrich RX, Gobius I, Liu S, Fothergill T, Donahoo ALS, Baisden JM, Cooper HM, Richards LJ. Multiple Slits regulate the development of midline glial populations and the corpus callosum. Dev Biol 2012; 365:36-49. [PMID: 22349628 DOI: 10.1016/j.ydbio.2012.02.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 01/20/2012] [Accepted: 02/03/2012] [Indexed: 11/28/2022]
Abstract
The Slit molecules are chemorepulsive ligands that regulate axon guidance at the midline of both vertebrates and invertebrates. In mammals, there are three Slit genes, but only Slit2 has been studied in any detail with regard to mammalian brain commissure formation. Here, we sought to understand the relative contributions that Slit proteins make to the formation of the largest brain commissure, the corpus callosum. Slit ligands bind Robo receptors, and previous studies have shown that Robo1(-/-) mice have defects in corpus callosum development. However, whether the Slit genes signal exclusively through Robo1 during callosal formation is unclear. To investigate this, we compared the development of the corpus callosum in both Slit2(-/-) and Robo1(-/-) mice using diffusion magnetic resonance imaging. This analysis demonstrated similarities in the phenotypes of these mice, but crucially also highlighted subtle differences, particularly with regard to the guidance of post-crossing axons. Analysis of single mutations in Slit family members revealed corpus callosum defects (but not complete agenesis) in 100% of Slit2(-/-) mice and 30% of Slit3(-/-) mice, whereas 100% of Slit1(-/-); Slit2(-/-) mice displayed complete agenesis of the corpus callosum. These results revealed a role for Slit1 in corpus callosum development, and demonstrated that Slit2 was necessary but not sufficient for midline crossing in vivo. However, co-culture experiments utilising Robo1(-/-) tissue versus Slit2 expressing cell blocks demonstrated that Slit2 was sufficient for the guidance activity mediated by Robo1 in pre-crossing neocortical axons. This suggested that Slit1 and Slit3 might also be involved in regulating other mechanisms that allow the corpus callosum to form, such as the establishment of midline glial populations. Investigation of this revealed defects in the development and dorso-ventral positioning of the indusium griseum glia in multiple Slit mutants. These findings indicate that Slits regulate callosal development via both classical chemorepulsive mechanisms, and via a novel role in mediating the correct positioning of midline glial populations. Finally, our data also indicate that some of the roles of Slit proteins at the midline may be independent of Robo signalling, suggestive of additional receptors regulating Slit signalling during development.
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Affiliation(s)
- Divya K Unni
- The Queensland Brain Institute, The University of Queensland, Brisbane 4072, Australia.
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Nandi S, Gokhan S, Dai XM, Wei S, Enikolopov G, Lin H, Mehler MF, Stanley ER. The CSF-1 receptor ligands IL-34 and CSF-1 exhibit distinct developmental brain expression patterns and regulate neural progenitor cell maintenance and maturation. Dev Biol 2012; 367:100-13. [PMID: 22542597 DOI: 10.1016/j.ydbio.2012.03.026] [Citation(s) in RCA: 241] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 03/21/2012] [Accepted: 03/22/2012] [Indexed: 01/11/2023]
Abstract
The CSF-1 receptor (CSF-1R) regulates CNS microglial development. However, the localization and developmental roles of this receptor and its ligands, IL-34 and CSF-1, in the brain are poorly understood. Here we show that compared to wild type mice, CSF-1R-deficient (Csf1r-/-) mice have smaller brains of greater mass. They further exhibit an expansion of lateral ventricle size, an atrophy of the olfactory bulb and a failure of midline crossing of callosal axons. In brain, IL-34 exhibited a broader regional expression than CSF-1, mostly without overlap. Expression of IL-34, CSF-1 and the CSF-1R were maximal during early postnatal development. However, in contrast to the expression of its ligands, CSF-1R expression was very low in adult brain. Postnatal neocortical expression showed that CSF-1 was expressed in layer VI, whereas IL-34 was expressed in the meninges and layers II-V. The broader expression of IL-34 is consistent with its previously implicated role in microglial development. The differential expression of CSF-1R ligands, with respect to CSF-1R expression, could reflect their CSF-1R-independent signaling. Csf1r-/- mice displayed increased proliferation and apoptosis of neocortical progenitors and reduced differentiation of specific excitatory neuronal subtypes. Indeed, addition of CSF-1 or IL-34 to microglia-free, CSF-1R-expressing dorsal forebrain clonal cultures, suppressed progenitor self-renewal and enhanced neuronal differentiation. Consistent with a neural developmental role for the CSF-1R, ablation of the Csf1r gene in Nestin-positive neural progenitors led to a smaller brain size, an expanded neural progenitor pool and elevated cellular apoptosis in cortical forebrain. Thus our results also indicate novel roles for the CSF-1R in the regulation of corticogenesis.
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Affiliation(s)
- Sayan Nandi
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, New York, NY 10461, USA
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47
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Benadiba C, Magnani D, Niquille M, Morlé L, Valloton D, Nawabi H, Ait-Lounis A, Otsmane B, Reith W, Theil T, Hornung JP, Lebrand C, Durand B. The ciliogenic transcription factor RFX3 regulates early midline distribution of guidepost neurons required for corpus callosum development. PLoS Genet 2012; 8:e1002606. [PMID: 22479201 PMCID: PMC3315471 DOI: 10.1371/journal.pgen.1002606] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 02/03/2012] [Indexed: 01/28/2023] Open
Abstract
The corpus callosum (CC) is the major commissure that bridges the cerebral hemispheres. Agenesis of the CC is associated with human ciliopathies, but the origin of this default is unclear. Regulatory Factor X3 (RFX3) is a transcription factor involved in the control of ciliogenesis, and Rfx3-deficient mice show several hallmarks of ciliopathies including left-right asymmetry defects and hydrocephalus. Here we show that Rfx3-deficient mice suffer from CC agenesis associated with a marked disorganisation of guidepost neurons required for axon pathfinding across the midline. Using transplantation assays, we demonstrate that abnormalities of the mutant midline region are primarily responsible for the CC malformation. Conditional genetic inactivation shows that RFX3 is not required in guidepost cells for proper CC formation, but is required before E12.5 for proper patterning of the cortical septal boundary and hence accurate distribution of guidepost neurons at later stages. We observe focused but consistent ectopic expression of Fibroblast growth factor 8 (Fgf8) at the rostro commissural plate associated with a reduced ratio of GLIoma-associated oncogene family zinc finger 3 (GLI3) repressor to activator forms. We demonstrate on brain explant cultures that ectopic FGF8 reproduces the guidepost neuronal defects observed in Rfx3 mutants. This study unravels a crucial role of RFX3 during early brain development by indirectly regulating GLI3 activity, which leads to FGF8 upregulation and ultimately to disturbed distribution of guidepost neurons required for CC morphogenesis. Hence, the RFX3 mutant mouse model brings novel understandings of the mechanisms that underlie CC agenesis in ciliopathies.
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Affiliation(s)
- Carine Benadiba
- Département de Biologie Cellulaire et de Morphologie, University of Lausanne, Lausanne, Switzerland
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, CNRS UMR 5534, Université Claude Bernard Lyon 1, Lyon, France
| | - Dario Magnani
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Mathieu Niquille
- Département de Biologie Cellulaire et de Morphologie, University of Lausanne, Lausanne, Switzerland
| | - Laurette Morlé
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, CNRS UMR 5534, Université Claude Bernard Lyon 1, Lyon, France
| | - Delphine Valloton
- Département de Biologie Cellulaire et de Morphologie, University of Lausanne, Lausanne, Switzerland
| | - Homaira Nawabi
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, CNRS UMR 5534, Université Claude Bernard Lyon 1, Lyon, France
| | - Aouatef Ait-Lounis
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Centre Médical Universitaire, Geneva, Switzerland
| | - Belkacem Otsmane
- Département de Biologie Cellulaire et de Morphologie, University of Lausanne, Lausanne, Switzerland
| | - Walter Reith
- Department of Pathology and Immunology, Faculty of Medicine, University of Geneva, Centre Médical Universitaire, Geneva, Switzerland
| | - Thomas Theil
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Jean-Pierre Hornung
- Département de Biologie Cellulaire et de Morphologie, University of Lausanne, Lausanne, Switzerland
| | - Cécile Lebrand
- Département de Biologie Cellulaire et de Morphologie, University of Lausanne, Lausanne, Switzerland
- National Center of Competence in Research Robotics, Ecole Polytechnique Fédérale, Lausanne, Switzerland
| | - Bénédicte Durand
- Centre de Génétique et de Physiologie Moléculaire et Cellulaire, CNRS UMR 5534, Université Claude Bernard Lyon 1, Lyon, France
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48
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Meng F, Hlady V, Tresco PA. Inducing alignment in astrocyte tissue constructs by surface ligands patterned on biomaterials. Biomaterials 2011; 33:1323-35. [PMID: 22100982 DOI: 10.1016/j.biomaterials.2011.10.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 10/13/2011] [Indexed: 11/24/2022]
Abstract
Planar substrates with patterned ligands were used to induce astrocyte alignment whereas substrates with uniform fields of ligand were used to produce random cell orientation. DRG neurons plated on top of oriented astrocyte monolayers exhibited directional outgrowth along aligned astrocytes, demonstrating that purely biological cues provided by the oriented astrocytes were sufficient to provide guidance cues. Antibody blocking studies demonstrated that astrocyte associated FN played a major mechanistic role in directing engineered neurite extension. Our results show that nanometer level surface cues are sufficient to direct nerve outgrowth through an intervening organized astrocyte cell layer. In other studies, we showed that patterned ligands were able to transmit organization cues through multiple cell layers to control the overall alignment of an astrocyte tissue construct, demonstrating how natural scar tissue may develop in situ into potent barriers. In such constructs the spatial organization of astrocyte derived FN maintained its organizational anisotropy throughout the thickness of multilayered astrocyte constructs. These in vitro studies suggest possible roles for such constructs as bridging substrates for neuroregenerative applications.
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Affiliation(s)
- Fanwei Meng
- The Keck Center for Tissue Engineering, Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, USA
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49
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Sánchez-Camacho C, Ortega JA, Ocaña I, Alcántara S, Bovolenta P. Appropriate Bmp7 levels are required for the differentiation of midline guidepost cells involved in corpus callosum formation. Dev Neurobiol 2011; 71:337-50. [PMID: 21485009 DOI: 10.1002/dneu.20865] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Guidepost cells are essential structures for the establishment of major axonal tracts. How these structures are specified and acquire their axon guidance properties is still poorly understood. Here, we show that in mouse embryos appropriate levels of Bone Morphogenetic Protein 7 (Bmp7), a member of the TGF-β superfamily of secreted proteins, are required for the correct development of the glial wedge, the indusium griseum, and the subcallosal sling, three groups of cells that act as guidepost cells for growing callosal axons. Bmp7 is expressed in the region occupied by these structures and its genetic inactivation in mouse embryos caused a marked reduction and disorganization of these cell populations. On the contrary, infusion of recombinant Bmp7 in the developing forebrain induced their premature differentiation. In both cases, changes were associated with the disruption of callosal axon growth and, in most animals fibers did not cross the midline forming typical Probst bundles. Addition of Bmp7 to cortical explants did not modify the extent of their outgrowth nor their directionality, when explants were exposed to a focalized source of the protein. Together, these results indicate that Bmp7 is indirectly required for corpus callosum formation by controlling the timely differentiation of its guidepost cells.
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Affiliation(s)
- Cristina Sánchez-Camacho
- Departamento de Neurobiología Molecular, Celular y del Desarrollo, Instituto Cajal (CSIC) and CIBER de Enfermedades Raras (CIBERER), Madrid, Spain
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50
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Gobius I, Richards L. Creating Connections in the Developing Brain: Mechanisms Regulating Corpus Callosum Development. ACTA ACUST UNITED AC 2011. [DOI: 10.4199/c00038ed1v01y201107dbr002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Ilan Gobius
- Queensland Brain Institute, University of Queensland, Australia
| | - Linda Richards
- Queensland Brain Institute, University of Queensland, Australia
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