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Di Bonito M, Studer M. Cellular and Molecular Underpinnings of Neuronal Assembly in the Central Auditory System during Mouse Development. Front Neural Circuits 2017; 11:18. [PMID: 28469562 PMCID: PMC5395578 DOI: 10.3389/fncir.2017.00018] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/01/2017] [Indexed: 11/13/2022] Open
Abstract
During development, the organization of the auditory system into distinct functional subcircuits depends on the spatially and temporally ordered sequence of neuronal specification, differentiation, migration and connectivity. Regional patterning along the antero-posterior axis and neuronal subtype specification along the dorso-ventral axis intersect to determine proper neuronal fate and assembly of rhombomere-specific auditory subcircuits. By taking advantage of the increasing number of transgenic mouse lines, recent studies have expanded the knowledge of developmental mechanisms involved in the formation and refinement of the auditory system. Here, we summarize several findings dealing with the molecular and cellular mechanisms that underlie the assembly of central auditory subcircuits during mouse development, focusing primarily on the rhombomeric and dorso-ventral origin of auditory nuclei and their associated molecular genetic pathways.
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Huettl RE, Huber AB. Characterizing Semaphorin-Mediated Effects on Sensory and Motor Axon Pathfinding and Connectivity During Embryonic Development. Methods Mol Biol 2017; 1493:443-466. [PMID: 27787870 DOI: 10.1007/978-1-4939-6448-2_32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
How are precise connectivity to peripheral targets and corresponding sensory-motor networks established during developmental innervation of the vertebrate extremities? The formation of functional sensory-motor circuits requires highly appropriate temporal and spatial regulation of axon growth which is achieved through the combination of different molecular mechanisms such as communication between heterotypic fiber systems, axon-environment, or axon-glia interactions that ensure proper fasciculation and accurate pathfinding to distal targets. Family members of the class 3 semaphorins and their cognate receptors, the neuropilins, were shown to govern various events during wiring of central and peripheral circuits, with mice lacking Sema3-Npn signaling showing deficits in timing of growth, selective fasciculation, guidance fidelity, and coupling of sensory axon growth to motor axons at developmental time points. Given the accuracy with which these processes have to interact in a stepwise manner, deficiency of the smallest cog in the wheel may impact severely on the faithful establishment and functionality of peripheral circuitries, ultimately leading to behavioral impairments or even cause the death of the animal. Reliable quantitative analyses of sensory-motor fasciculation, extension, and guidance of axons to their cognate target muscles and the skin during development, but also assessment of physiological and behavioral consequences at adult age, are therefore a necessity to extend our understanding of the molecular mechanisms of peripheral circuit formation. In this chapter we provide a detailed methodology to characterize class 3 semaphorin-mediated effects on peripheral sensory and motor axon pathfinding and connectivity during embryonic development.
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Affiliation(s)
- Rosa Eva Huettl
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Developmental Genetics, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
| | - Andrea B Huber
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Developmental Genetics, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.
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ISL1-based LIM complexes control Slit2 transcription in developing cranial motor neurons. Sci Rep 2016; 6:36491. [PMID: 27819291 PMCID: PMC5098159 DOI: 10.1038/srep36491] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 10/17/2016] [Indexed: 01/02/2023] Open
Abstract
LIM-homeodomain (HD) transcription factors form a multimeric complex and assign neuronal subtype identities, as demonstrated by the hexameric ISL1-LHX3 complex which gives rise to somatic motor (SM) neurons. However, the roles of combinatorial LIM code in motor neuron diversification and their subsequent differentiation is much less well understood. In the present study, we demonstrate that the ISL1 controls postmitotic cranial branchiomotor (BM) neurons including the positioning of the cell bodies and peripheral axon pathfinding. Unlike SM neurons, which transform into interneurons, BM neurons are normal in number and in marker expression in Isl1 mutant mice. Nevertheless, the movement of trigeminal and facial BM somata is stalled, and their peripheral axons are fewer or misrouted, with ectopic branches. Among genes whose expression level changes in previous ChIP-seq and microarray analyses in Isl1-deficient cell lines, we found that Slit2 transcript was almost absent from BM neurons of Isl1 mutants. Both ISL1-LHX3 and ISL1-LHX4 bound to the Slit2 enhancer and drove endogenous Slit2 expression in SM and BM neurons. Our findings suggest that combinations of ISL1 and LHX factors establish cell-type specificity and functional diversity in terms of motor neuron identities and/or axon development.
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Knight MJ, Kauppinen RA. Diffusion-mediated nuclear spin phase decoherence in cylindrically porous materials. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 269:1-12. [PMID: 27208416 PMCID: PMC4965358 DOI: 10.1016/j.jmr.2016.05.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 05/09/2016] [Accepted: 05/10/2016] [Indexed: 05/30/2023]
Abstract
In NMR or MRI of complex materials, including biological tissues and porous materials, magnetic susceptibility differences within the material result in local magnetic field inhomogeneities, even if the applied magnetic field is homogeneous. Mobile nuclear spins move though the inhomogeneous field, by translational diffusion and other mechanisms, resulting in decoherence of nuclear spin phase more rapidly than transverse relaxation alone. The objective of this paper is to simulate this diffusion-mediated decoherence and demonstrate that it may substantially reduce coherence lifetimes of nuclear spin phase, in an anisotropic fashion. We do so using a model of cylindrical pores within an otherwise homogeneous material, and calculate the resulting magnetic field inhomogeneities. Our simulations show that diffusion-mediated decoherence in a system of parallel cylindrical pores is anisotropic, with coherence lifetime minimised when the array of cylindrical pores is perpendicular to B0. We also show that this anisotropy of coherence lifetime is reduced if the orientations of cylindrical pores are disordered within the system. In addition we characterise the dependence on B0, the magnetic susceptibility of the cylindrical pores relative to the surroundings, the diffusion coefficient and cylinder wall thickness. Our findings may aid in the interpretation of NMR and MRI relaxation data.
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Affiliation(s)
- Michael J Knight
- School of Experimental Psychology, University of Bristol, 12A Priory Road, Bristol BS8 1TU, United Kingdom.
| | - Risto A Kauppinen
- School of Experimental Psychology, University of Bristol, 12A Priory Road, Bristol BS8 1TU, United Kingdom; Clinical Research and Imaging Centre, University of Bristol, 60 St Michael's Hill, Bristol BS2 8DX, United Kingdom
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55
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Peretz Y, Eren N, Kohl A, Hen G, Yaniv K, Weisinger K, Cinnamon Y, Sela-Donenfeld D. A new role of hindbrain boundaries as pools of neural stem/progenitor cells regulated by Sox2. BMC Biol 2016; 14:57. [PMID: 27392568 PMCID: PMC4938926 DOI: 10.1186/s12915-016-0277-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 06/21/2016] [Indexed: 01/28/2023] Open
Abstract
Background Compartment boundaries are an essential developmental mechanism throughout evolution, designated to act as organizing centers and to regulate and localize differently fated cells. The hindbrain serves as a fascinating example for this phenomenon as its early development is devoted to the formation of repetitive rhombomeres and their well-defined boundaries in all vertebrates. Yet, the actual role of hindbrain boundaries remains unresolved, especially in amniotes. Results Here, we report that hindbrain boundaries in the chick embryo consist of a subset of cells expressing the key neural stem cell (NSC) gene Sox2. These cells co-express other neural progenitor markers such as Transitin (the avian Nestin), GFAP, Pax6 and chondroitin sulfate proteoglycan. The majority of the Sox2+ cells that reside within the boundary core are slow-dividing, whereas nearer to and within rhombomeres Sox2+ cells are largely proliferating. In vivo analyses and cell tracing experiments revealed the contribution of boundary Sox2+ cells to neurons in a ventricular-to-mantle manner within the boundaries, as well as their lateral contribution to proliferating Sox2+ cells in rhombomeres. The generation of boundary-derived neurospheres from hindbrain cultures confirmed the typical NSC behavior of boundary cells as a multipotent and self-renewing Sox2+ cell population. Inhibition of Sox2 in boundaries led to enhanced and aberrant neural differentiation together with inhibition in cell-proliferation, whereas Sox2 mis-expression attenuated neurogenesis, confirming its significant function in hindbrain neuronal organization. Conclusions Data obtained in this study deciphers a novel role of hindbrain boundaries as repetitive pools of neural stem/progenitor cells, which provide proliferating progenitors and differentiating neurons in a Sox2-dependent regulation. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0277-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yuval Peretz
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Noa Eren
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Ayelet Kohl
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Gideon Hen
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Karina Yaniv
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Karen Weisinger
- Department of Stem Cell and Regenerative Biology, Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA
| | - Yuval Cinnamon
- Institute of Animal Sciences, Department of Poultry and Aquaculture Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
| | - Dalit Sela-Donenfeld
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel.
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56
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Knight MJ, McCann B, Tsivos D, Dillon S, Coulthard E, Kauppinen RA. Quantitative T2 mapping of white matter: applications for ageing and cognitive decline. Phys Med Biol 2016; 61:5587-605. [PMID: 27384985 PMCID: PMC5390949 DOI: 10.1088/0031-9155/61/15/5587] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In MRI, the coherence lifetime T2 is sensitive to the magnetic environment imposed by tissue microstructure and biochemistry in vivo. Here we explore the possibility that the use of T2 relaxometry may provide information complementary to that provided by diffusion tensor imaging (DTI) in ageing of healthy controls (HC), Alzheimer’s disease (AD) and mild cognitive impairment (MCI). T2 and diffusion MRI metrics were quantified in HC and patients with MCI and mild AD using multi-echo MRI and DTI. We used tract-based spatial statistics (TBSS) to evaluate quantitative MRI parameters in white matter (WM). A prolonged T2 in WM was associated with AD, and able to distinguish AD from MCI, and AD from HC. Shorter WM T2 was associated with better cognition and younger age in general. In no case was a reduction in T2 associated with poorer cognition. We also applied principal component analysis, showing that WM volume changes independently of T2, MRI diffusion indices and cognitive performance indices. Our data add to the evidence that age-related and AD-related decline in cognition is in part attributable to WM tissue state, and much less to WM quantity. These observations suggest that WM is involved in AD pathology, and that T2 relaxometry is a potential imaging modality for detecting and characterising WM in cognitive decline and dementia.
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Affiliation(s)
- Michael J Knight
- School of Experimental Psychology, 12a Priory Road, University of Bristol, Bristol, BS8 1TU, UK
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57
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The atypical cadherin Celsr1 functions non-cell autonomously to block rostral migration of facial branchiomotor neurons in mice. Dev Biol 2016; 417:40-9. [PMID: 27395006 DOI: 10.1016/j.ydbio.2016.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 07/05/2016] [Accepted: 07/05/2016] [Indexed: 11/23/2022]
Abstract
The caudal migration of facial branchiomotor (FBM) neurons from rhombomere (r) 4 to r6 in the hindbrain is an excellent model to study neuronal migration mechanisms. Although several Wnt/Planar Cell Polarity (PCP) components are required for FBM neuron migration, only Celsr1, an atypical cadherin, regulates the direction of migration in mice. In Celsr1 mutants, a subset of FBM neurons migrates rostrally instead of caudally. Interestingly, Celsr1 is not expressed in the migrating FBM neurons, but rather in the adjacent floor plate and adjoining ventricular zone. To evaluate the contribution of different expression domains to neuronal migration, we conditionally inactivated Celsr1 in specific cell types. Intriguingly, inactivation of Celsr1 in the ventricular zone of r3-r5, but not in the floor plate, leads to rostral migration of FBM neurons, greatly resembling the migration defect of Celsr1 mutants. Dye fill experiments indicate that the rostrally-migrated FBM neurons in Celsr1 mutants originate from the anterior margin of r4. These data suggest strongly that Celsr1 ensures that FBM neurons migrate caudally by suppressing molecular cues in the rostral hindbrain that can attract FBM neurons.
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58
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Abstract
Cells of a given type maintain a characteristic cell size to function efficiently in their ecological or organismal context. They achieve this through the regulation of growth rates or by actively sensing size and coupling this signal to cell division. We focus this review on potential size-sensing mechanisms, including geometric, external cue, and titration mechanisms. Mechanisms that titrate proteins against DNA are of particular interest because they are consistent with the robust correlation of DNA content and cell size. We review the literature, which suggests that titration mechanisms may underlie cell-size sensing in Xenopus embryos, budding yeast, and Escherichia coli, whereas alternative mechanisms may function in fission yeast.
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Affiliation(s)
- Amanda A Amodeo
- Department of Biology, Stanford University, Stanford, California 94305
| | - Jan M Skotheim
- Department of Biology, Stanford University, Stanford, California 94305
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59
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Davey CF, Mathewson AW, Moens CB. PCP Signaling between Migrating Neurons and their Planar-Polarized Neuroepithelial Environment Controls Filopodial Dynamics and Directional Migration. PLoS Genet 2016; 12:e1005934. [PMID: 26990447 PMCID: PMC4798406 DOI: 10.1371/journal.pgen.1005934] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 02/24/2016] [Indexed: 11/18/2022] Open
Abstract
The planar cell polarity (PCP) pathway is a cell-contact mediated mechanism for transmitting polarity information between neighboring cells. PCP “core components” (Vangl, Fz, Pk, Dsh, and Celsr) are essential for a number of cell migratory events including the posterior migration of facial branchiomotor neurons (FBMNs) in the plane of the hindbrain neuroepithelium in zebrafish and mice. While the mechanism by which PCP signaling polarizes static epithelial cells is well understood, how PCP signaling controls highly dynamic processes like neuronal migration remains an important outstanding question given that PCP components have been implicated in a range of directed cell movements, particularly during vertebrate development. Here, by systematically disrupting PCP signaling in a rhombomere-restricted manner we show that PCP signaling is required both within FBMNs and the hindbrain rhombomere 4 environment at the time when they initiate their migration. Correspondingly, we demonstrate planar polarized localization of PCP core components Vangl2 and Fzd3a in the hindbrain neuroepithelium, and transient localization of Vangl2 at the tips of retracting FBMN filopodia. Using high-resolution timelapse imaging of FBMNs in genetic chimeras we uncover opposing cell-autonomous and non-cell-autonomous functions for Fzd3a and Vangl2 in regulating FBMN protrusive activity. Within FBMNs, Fzd3a is required to stabilize filopodia while Vangl2 has an antagonistic, destabilizing role. However, in the migratory environment Fzd3a acts to destabilize FBMN filopodia while Vangl2 has a stabilizing role. Together, our findings suggest a model in which PCP signaling between the planar polarized neuroepithelial environment and FBMNs directs migration by the selective stabilization of FBMN filopodia. Planar cell polarity (PCP) is a common feature of many animal tissues. This type of polarity is most obvious in cells that are organized into epithelial sheets, where PCP signaling components act to orient cells in the plane of the tissue. Although, PCP is best understood for its function in polarizing stable epithelia, PCP is also required for the dynamic process of cell migration in animal development and disease. The goal of this study was to determine how PCP functions to control cell migration. We used the migration of facial branchiomotor neurons in the zebrafish hindbrain, which requires almost the entire suite of PCP core components, to address this question. We present evidence that PCP signaling within migrating neurons, and between migrating neurons and cells of their migratory environment promote migration by regulating filopodial dynamics. Our results suggest that broadly conserved interactions between PCP components control the cytoskeleton in motile cells and non-motile epithelia alike.
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Affiliation(s)
- Crystal F. Davey
- Division of Basic Science, Fred Hutchinson Cancer Research Center, and University of Washington Molecular and Cellular Biology Graduate Program, Seattle, Washington, United States of America
| | - Andrew W. Mathewson
- Division of Basic Science, Fred Hutchinson Cancer Research Center, and University of Washington Molecular and Cellular Biology Graduate Program, Seattle, Washington, United States of America
| | - Cecilia B. Moens
- Division of Basic Science, Fred Hutchinson Cancer Research Center, and University of Washington Molecular and Cellular Biology Graduate Program, Seattle, Washington, United States of America
- * E-mail:
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60
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Vaswani AR, Blaess S. Reelin Signaling in the Migration of Ventral Brain Stem and Spinal Cord Neurons. Front Cell Neurosci 2016; 10:62. [PMID: 27013975 PMCID: PMC4786562 DOI: 10.3389/fncel.2016.00062] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Accepted: 02/26/2016] [Indexed: 12/03/2022] Open
Abstract
The extracellular matrix protein Reelin is an important orchestrator of neuronal migration during the development of the central nervous system. While its role and mechanism of action have been extensively studied and reviewed in the formation of dorsal laminar brain structures like the cerebral cortex, hippocampus, and cerebellum, its functions during the neuronal migration events that result in the nuclear organization of the ventral central nervous system are less well understood. In an attempt to delineate an underlying pattern of Reelin action in the formation of neuronal cell clusters, this review highlights the role of Reelin signaling in the migration of neuronal populations that originate in the ventral brain stem and the spinal cord.
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Affiliation(s)
- Ankita R Vaswani
- Neurodevelopmental Genetics, Institute of Reconstructive Neurobiology, Life and Brain Center, University of Bonn Bonn, Germany
| | - Sandra Blaess
- Neurodevelopmental Genetics, Institute of Reconstructive Neurobiology, Life and Brain Center, University of Bonn Bonn, Germany
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61
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Bai Z, Pu Q, Haque Z, Wang J, Huang R. The unique axon trajectory of the accessory nerve is determined by intrinsic properties of the neural tube in the avian embryo. Ann Anat 2016; 205:85-9. [PMID: 26955910 DOI: 10.1016/j.aanat.2016.02.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 02/10/2016] [Accepted: 02/20/2016] [Indexed: 11/26/2022]
Abstract
The accessory nerve is a cranial nerve, composed of only motor axons, which control neck muscles. Its axons ascend many segments along the lateral surface of the cervical spinal cord and hindbrain. At the level of the first somite, they pass ventrally through the somitic mesoderm into the periphery. The factors governing the unique root trajectory are unknown. Ablation experiments at the accessory nerve outlet points have shown that somites do not regulate the trajectory of the accessory nerve fibres. Factors from the neural tube that may control the longitudinal pathfinding of the accessory nerve fibres were tested by heterotopic transplantations of an occipital neural tube to the cervical and thoracic level. These transplantations resulted in a typical accessory nerve trajectory in the cervical and thoracic spinal cord. In contrast, cervical neural tube grafts were unable to give rise to the typical accessory nerve root pattern when transplanted to occipital level. Our results show that the formation of the unique axon root pattern of the accessory nerve is an intrinsic property of the neural tube.
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Affiliation(s)
- Zhongtian Bai
- The 2nd Department of General Surgery, the First Hospital of Lanzhou University, Key Laboratory of Biotherapy and Regenerative Medicine, Gansu Province, China; Department of Neuroanatomy, Institute of Anatomy, University of Bonn, Nussallee 10 53115, Bonn, Germany; Institute of Zoology, School of Life Science, Lanzhou University, China
| | - Qin Pu
- Department of Neuroanatomy, Institute of Anatomy, University of Bonn, Nussallee 10 53115, Bonn, Germany; Institute of Anatomy, Department of Anatomy and Molecular Embryology, Ruhr-University of Bochum, Bochum, Germany
| | - Ziaul Haque
- Department of Neuroanatomy, Institute of Anatomy, University of Bonn, Nussallee 10 53115, Bonn, Germany; Department of Anatomy and Histology, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | - Jianlin Wang
- Institute of Zoology, School of Life Science, Lanzhou University, China
| | - Ruijin Huang
- Department of Neuroanatomy, Institute of Anatomy, University of Bonn, Nussallee 10 53115, Bonn, Germany; Department of Molecular Embryology, Institute of Anatomy and Cell Biology, University of Freiburg, Germany.
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62
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Hox Function Is Required for the Development and Maintenance of the Drosophila Feeding Motor Unit. Cell Rep 2016; 14:850-860. [DOI: 10.1016/j.celrep.2015.12.077] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 11/18/2015] [Accepted: 12/15/2015] [Indexed: 11/24/2022] Open
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63
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Generation of serotonin neurons from human pluripotent stem cells. Nat Biotechnol 2015; 34:89-94. [PMID: 26655496 DOI: 10.1038/nbt.3435] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 11/20/2015] [Indexed: 01/06/2023]
Abstract
Serotonin neurons located in the raphe nucleus of the hindbrain have crucial roles in regulating brain functions and have been implicated in various psychiatric disorders. Yet functional human serotonin neurons are not available for in vitro studies. Through manipulation of the WNT pathway, we demonstrate efficient differentiation of human pluripotent stem cells (hPSCs) to cells resembling central serotonin neurons, primarily those located in the rhombomeric segments 2-3 of the rostral raphe, which participate in high-order brain functions. The serotonin neurons express a series of molecules essential for serotonergic development, including tryptophan hydroxylase 2, exhibit typical electrophysiological properties and release serotonin in an activity-dependent manner. When treated with the FDA-approved drugs tramadol and escitalopram oxalate, they release or uptake serotonin in a dose- and time-dependent manner, suggesting the utility of these cells for the evaluation of drug candidates.
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64
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LaMantia AS, Moody SA, Maynard TM, Karpinski BA, Zohn IE, Mendelowitz D, Lee NH, Popratiloff A. Hard to swallow: Developmental biological insights into pediatric dysphagia. Dev Biol 2015; 409:329-42. [PMID: 26554723 DOI: 10.1016/j.ydbio.2015.09.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 09/10/2015] [Accepted: 09/15/2015] [Indexed: 12/16/2022]
Abstract
Pediatric dysphagia-feeding and swallowing difficulties that begin at birth, last throughout childhood, and continue into maturity--is one of the most common, least understood complications in children with developmental disorders. We argue that a major cause of pediatric dysphagia is altered hindbrain patterning during pre-natal development. Such changes can compromise craniofacial structures including oropharyngeal muscles and skeletal elements as well as motor and sensory circuits necessary for normal feeding and swallowing. Animal models of developmental disorders that include pediatric dysphagia in their phenotypic spectrum can provide mechanistic insight into pathogenesis of feeding and swallowing difficulties. A fairly common human genetic developmental disorder, DiGeorge/22q11.2 Deletion Syndrome (22q11DS) includes a substantial incidence of pediatric dysphagia in its phenotypic spectrum. Infant mice carrying a parallel deletion to 22q11DS patients have feeding and swallowing difficulties that approximate those seen in pediatric dysphagia. Altered hindbrain patterning, craniofacial malformations, and changes in cranial nerve growth prefigure these difficulties. Thus, in addition to craniofacial and pharyngeal anomalies that arise independently of altered neural development, pediatric dysphagia may result from disrupted hindbrain patterning and its impact on peripheral and central neural circuit development critical for feeding and swallowing. The mechanisms that disrupt hindbrain patterning and circuitry may provide a foundation to develop novel therapeutic approaches for improved clinical management of pediatric dysphagia.
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Affiliation(s)
- Anthony-Samuel LaMantia
- Institute for Neuroscience, The George Washington University School of Medicine and Health Sciences, Washington D.C., USA; Department of Pharmacology and Physiology, George Washington University, School of Medicine and Health Sciences, Washington D.C., USA
| | - Sally A Moody
- Institute for Neuroscience, The George Washington University School of Medicine and Health Sciences, Washington D.C., USA; Department of Anatomy and Regenerative Biology, George Washington University, School of Medicine and Health Sciences, Washington D.C., USA
| | - Thomas M Maynard
- Institute for Neuroscience, The George Washington University School of Medicine and Health Sciences, Washington D.C., USA; Department of Pharmacology and Physiology, George Washington University, School of Medicine and Health Sciences, Washington D.C., USA
| | - Beverly A Karpinski
- Institute for Neuroscience, The George Washington University School of Medicine and Health Sciences, Washington D.C., USA; Department of Pharmacology and Physiology, George Washington University, School of Medicine and Health Sciences, Washington D.C., USA
| | - Irene E Zohn
- Institute for Neuroscience, The George Washington University School of Medicine and Health Sciences, Washington D.C., USA; Center for Neuroscience Research, Children's National Health System, Washington D.C., USA
| | - David Mendelowitz
- Institute for Neuroscience, The George Washington University School of Medicine and Health Sciences, Washington D.C., USA; Department of Pharmacology and Physiology, George Washington University, School of Medicine and Health Sciences, Washington D.C., USA
| | - Norman H Lee
- Institute for Neuroscience, The George Washington University School of Medicine and Health Sciences, Washington D.C., USA; Department of Pharmacology and Physiology, George Washington University, School of Medicine and Health Sciences, Washington D.C., USA
| | - Anastas Popratiloff
- Institute for Neuroscience, The George Washington University School of Medicine and Health Sciences, Washington D.C., USA; Department of Anatomy and Regenerative Biology, George Washington University, School of Medicine and Health Sciences, Washington D.C., USA
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65
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Wysiadecki G, Polguj M, Topol M. An unusual variant of the abducens nerve duplication with two nerve trunks merging within the orbit: a case report with comments on developmental background. Surg Radiol Anat 2015; 38:625-9. [PMID: 26501961 PMCID: PMC4911371 DOI: 10.1007/s00276-015-1573-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 10/12/2015] [Indexed: 11/27/2022]
Abstract
This study reports the first case of abducens nerve duplication along its entire intracranial course, ending within the orbit. A distinct abducens nerve duplication reaching the common tendinous ring (annulus of Zinn), as well as another split within the intraconal segment of the nerve have been revealed. Additionally, two groups (superior and inferior) of abducens nerve sub-branches to the lateral rectus muscle were visualised using Sihler's stain. The analysed anatomical variation has never been reported before and it seems to be in the middle of the spectrum between the cases of duplication occurring only within the intracranial segments of the abducens nerve found in the literature and those continuing throughout the whole course of the nerve. Abducens nerve duplication may be treated as a relic of early stages of ontogenesis. Such a variant might result from alternative developmental pathways in which axons of the abducens nerve, specific for a given segment of the lateral rectus muscle, run separately at some stage, instead of forming a single stem.
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Affiliation(s)
- Grzegorz Wysiadecki
- Department of Normal and Clinical Anatomy, Interfaculty Chair of Anatomy and Histology, Medical University of Lodz, ul. Narutowicza 60, 90-136, Łódź, Poland.
| | - Michał Polguj
- Department of Angiology, Interfaculty Chair of Anatomy and Histology, Medical University of Lodz, ul. Narutowicza 60, 90-136 Łódź, Poland
| | - Mirosław Topol
- Department of Normal and Clinical Anatomy, Interfaculty Chair of Anatomy and Histology, Medical University of Lodz, ul. Narutowicza 60, 90-136, Łódź, Poland
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Nixon JN, Dempsey JC, Doherty D, Ishak GE. Temporal bone and cranial nerve findings in pontine tegmental cap dysplasia. Neuroradiology 2015; 58:179-87. [DOI: 10.1007/s00234-015-1604-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 09/29/2015] [Indexed: 11/28/2022]
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67
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Terriente J, Pujades C. Cell segregation in the vertebrate hindbrain: a matter of boundaries. Cell Mol Life Sci 2015; 72:3721-30. [PMID: 26089248 PMCID: PMC11113478 DOI: 10.1007/s00018-015-1953-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 05/06/2015] [Accepted: 06/08/2015] [Indexed: 02/07/2023]
Abstract
Segregating cells into compartments during embryonic development is essential for growth and pattern formation. In the developing hindbrain, boundaries separate molecularly, physically and neuroanatomically distinct segments called rhombomeres. After rhombomeric cells have acquired their identity, interhombomeric boundaries restrict cell intermingling between adjacent rhombomeres and act as signaling centers to pattern the surrounding tissue. Several works have stressed the relevance of Eph/ephrin signaling in rhombomeric cell sorting. Recent data have unveiled the role of this pathway in the assembly of actomyosin cables as an important mechanism for keeping cells from different rhombomeres segregated. In this Review, we will provide a short summary of recent evidences gathered in different systems suggesting that physical actomyosin barriers can be a general mechanism for tissue separation. We will discuss current evidences supporting a model where cell-cell signaling pathways, such as Eph/ephrin, govern compartmental cell sorting through modulation of the actomyosin cytoskeleton and cell adhesive properties to prevent cell intermingling.
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Affiliation(s)
- Javier Terriente
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, PRBB, Dr Aiguader 88, 08003, Barcelona, Spain.
| | - Cristina Pujades
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, PRBB, Dr Aiguader 88, 08003, Barcelona, Spain.
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68
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Diving into the mammalian swamp of respiratory rhythm generation with the bullfrog. Respir Physiol Neurobiol 2015; 224:37-51. [PMID: 26384027 DOI: 10.1016/j.resp.2015.09.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 11/20/2022]
Abstract
All vertebrates produce some form of respiratory rhythm, whether to pump water over gills or ventilate lungs. Yet despite the critical importance of ventilation for survival, the architecture of the respiratory central pattern generator has not been resolved. In frogs and mammals, there is increasing evidence for multiple burst-generating regions in the ventral respiratory group. These regions work together to produce the respiratory rhythm. However, each region appears to be pivotally important to a different phase of the motor act. Regions also exhibit differing rhythmogenic capabilities when isolated and have different CO2 sensitivity and pharmacological profiles. Interestingly, in both frogs and rats the regions with the most robust rhythmogenic capabilities when isolated are located in rhombomeres 7/8. In addition, rhombomeres 4/5 in both clades are critical for controlling phases of the motor pattern most strongly modulated by CO2 (expiration in mammals, and recruitment of lung bursts in frogs). These key signatures may indicate that these cell clusters arose in a common ancestor at least 400 million years ago.
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69
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Huettl RE, Eckstein S, Stahl T, Petricca S, Ninkovic J, Götz M, Huber AB. Functional dissection of the Pax6 paired domain: Roles in neural tube patterning and peripheral nervous system development. Dev Biol 2015; 413:86-103. [PMID: 26187199 DOI: 10.1016/j.ydbio.2015.07.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 06/21/2015] [Accepted: 07/11/2015] [Indexed: 10/23/2022]
Abstract
During development of the CNS, stem and progenitor cell proliferation, cell fate designation, and patterning decisions are tightly regulated by interdependent networks of key transcriptional regulators. In a genetic approach we analyzed divergent functionality of the PAI and RED sub-domains of the Pax6 Paired domain (PD) during progenitor zone formation, motor and interneuron development, and peripheral connectivity at distinct levels within the neural tube: within the hindbrain, mutation of the PAI sub-domain severely affected patterning of the p3 and pMN domains and establishment of the corresponding motor neurons. Exit point designation of hypoglossal axons was disturbed in embryos harboring either mutations in the PD sub-domains or containing a functional Pax6 Null allele. At brachial spinal levels, we propose a selective involvement of the PAI sub-domain during patterning of ventral p2 and pMN domains, critically disturbing generation of specific motor neuron subtypes and increasing V2 interneuron numbers. Our findings present a novel aspect of how Pax6 not only utilizes its modular structure to perform distinct functions via its paired and homeodomain. Individual sub-domains can exert distinct functions, generating a new level of complexity for transcriptional regulation by one single transcription factor not only in dorso-ventral, but also rostro-caudal neural tube patterning.
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Affiliation(s)
- Rosa-Eva Huettl
- Institute of Developmental Genetics, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Simone Eckstein
- Institute of Developmental Genetics, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Tessa Stahl
- Institute of Stem Cell Research, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Stefania Petricca
- Institute of Stem Cell Research, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Jovica Ninkovic
- Institute of Stem Cell Research, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Magdalena Götz
- Institute of Stem Cell Research, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Andrea B Huber
- Institute of Developmental Genetics, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Ingolstädter Landstraße 1, 85764 Neuherberg, Germany.
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70
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Jarrar W, Dias JM, Ericson J, Arnold HH, Holz A. Nkx2.2 and Nkx2.9 are the key regulators to determine cell fate of branchial and visceral motor neurons in caudal hindbrain. PLoS One 2015; 10:e0124408. [PMID: 25919494 PMCID: PMC4412715 DOI: 10.1371/journal.pone.0124408] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 03/05/2015] [Indexed: 12/12/2022] Open
Abstract
Cranial motor nerves in vertebrates are comprised of the three principal subtypes of branchial, visceral, and somatic motor neurons, which develop in typical patterns along the anteroposterior and dorsoventral axes of hindbrain. Here we demonstrate that the formation of branchial and visceral motor neurons critically depends on the transcription factors Nkx2.2 and Nkx2.9, which together determine the cell fate of neuronal progenitor cells. Disruption of both genes in mouse embryos results in complete loss of the vagal and spinal accessory motor nerves, and partial loss of the facial and glossopharyngeal motor nerves, while the purely somatic hypoglossal and abducens motor nerves are not diminished. Cell lineage analysis in a genetically marked mouse line reveals that alterations of cranial nerves in Nkx2.2; Nkx2.9 double-deficient mouse embryos result from changes of cell fate in neuronal progenitor cells. As a consequence progenitors of branchiovisceral motor neurons in the ventral p3 domain of hindbrain are transformed to somatic motor neurons, which use ventral exit points to send axon trajectories to their targets. Cell fate transformation is limited to the caudal hindbrain, as the trigeminal nerve is not affected in double-mutant embryos suggesting that Nkx2.2 and Nkx2.9 proteins play no role in the development of branchiovisceral motor neurons in hindbrain rostral to rhombomere 4.
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Affiliation(s)
- Wassan Jarrar
- Cell and Molecular Biology, Zoological Institute, University of Braunschweig, Braunschweig, Germany
| | - Jose M. Dias
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden
| | - Johan Ericson
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden
| | - Hans-Henning Arnold
- Cell and Molecular Biology, Zoological Institute, University of Braunschweig, Braunschweig, Germany
- * E-mail: (AH); (HHA)
| | - Andreas Holz
- Cell and Molecular Biology, Zoological Institute, University of Braunschweig, Braunschweig, Germany
- * E-mail: (AH); (HHA)
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71
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Control of axon guidance and neurotransmitter phenotype of dB1 hindbrain interneurons by Lim-HD code. J Neurosci 2015; 35:2596-611. [PMID: 25673852 DOI: 10.1523/jneurosci.2699-14.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Hindbrain dorsal interneurons (HDIs) are implicated in receiving, processing, integrating, and transmitting sensory inputs from the periphery and spinal cord, including the vestibular, auditory, and proprioceptive systems. During development, multiple molecularly defined HDI types are set in columns along the dorsoventral axis, before migrating along well-defined trajectories to generate various brainstem nuclei. Major brainstem functions rely on the precise assembly of different interneuron groups and higher brain domains into common circuitries. Yet, knowledge regarding interneuron axonal patterns, synaptic targets, and the transcriptional control that govern their connectivity is sparse. The dB1 class of HDIs is formed in a district dorsomedial position along the hindbrain and gives rise to the inferior olive nuclei, dorsal cochlear nuclei, and vestibular nuclei. dB1 interneurons express various transcription factors (TFs): the pancreatic transcription factor 1a (Ptf1a), the homeobox TF-Lbx1 and the Lim-homeodomain (Lim-HD), and TF Lhx1 and Lhx5. To decipher the axonal and synaptic connectivity of dB1 cells, we have used advanced enhancer tools combined with conditional expression systems and the PiggyBac-mediated DNA transposition system in avian embryos. Multiple ipsilateral and contralateral axonal projections were identified ascending toward higher brain centers, where they formed synapses in the Purkinje cerebellar layer as well as at discrete midbrain auditory and vestibular centers. Decoding the mechanisms that instruct dB1 circuit formation revealed a fundamental role for Lim-HD proteins in regulating their axonal patterns, synaptic targets, and neurotransmitter choice. Together, this study provides new insights into the assembly and heterogeneity of HDIs connectivity and its establishment through the central action of Lim-HD governed programs.
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72
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Meechan DW, Maynard TM, Tucker ES, Fernandez A, Karpinski BA, Rothblat LA, LaMantia AS. Modeling a model: Mouse genetics, 22q11.2 Deletion Syndrome, and disorders of cortical circuit development. Prog Neurobiol 2015; 130:1-28. [PMID: 25866365 DOI: 10.1016/j.pneurobio.2015.03.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 03/24/2015] [Accepted: 03/29/2015] [Indexed: 12/21/2022]
Abstract
Understanding the developmental etiology of autistic spectrum disorders, attention deficit/hyperactivity disorder and schizophrenia remains a major challenge for establishing new diagnostic and therapeutic approaches to these common, difficult-to-treat diseases that compromise neural circuits in the cerebral cortex. One aspect of this challenge is the breadth and overlap of ASD, ADHD, and SCZ deficits; another is the complexity of mutations associated with each, and a third is the difficulty of analyzing disrupted development in at-risk or affected human fetuses. The identification of distinct genetic syndromes that include behavioral deficits similar to those in ASD, ADHC and SCZ provides a critical starting point for meeting this challenge. We summarize clinical and behavioral impairments in children and adults with one such genetic syndrome, the 22q11.2 Deletion Syndrome, routinely called 22q11DS, caused by micro-deletions of between 1.5 and 3.0 MB on human chromosome 22. Among many syndromic features, including cardiovascular and craniofacial anomalies, 22q11DS patients have a high incidence of brain structural, functional, and behavioral deficits that reflect cerebral cortical dysfunction and fall within the spectrum that defines ASD, ADHD, and SCZ. We show that developmental pathogenesis underlying this apparent genetic "model" syndrome in patients can be defined and analyzed mechanistically using genomically accurate mouse models of the deletion that causes 22q11DS. We conclude that "modeling a model", in this case 22q11DS as a model for idiopathic ASD, ADHD and SCZ, as well as other behavioral disorders like anxiety frequently seen in 22q11DS patients, in genetically engineered mice provides a foundation for understanding the causes and improving diagnosis and therapy for these disorders of cortical circuit development.
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Affiliation(s)
- Daniel W Meechan
- Institute for Neuroscience, Department of Pharmacology & Physiology, The George Washington University, Washington, DC, United States
| | - Thomas M Maynard
- Institute for Neuroscience, Department of Pharmacology & Physiology, The George Washington University, Washington, DC, United States
| | - Eric S Tucker
- Department of Neurobiology and Anatomy, Neuroscience Graduate Program, and Center for Neuroscience, West Virginia University School of Medicine, Morgantown, West Virginia
| | - Alejandra Fernandez
- Institute for Neuroscience, Department of Pharmacology & Physiology, The George Washington University, Washington, DC, United States
| | - Beverly A Karpinski
- Institute for Neuroscience, Department of Pharmacology & Physiology, The George Washington University, Washington, DC, United States
| | - Lawrence A Rothblat
- Institute for Neuroscience, Department of Pharmacology & Physiology, The George Washington University, Washington, DC, United States; Department of Psychology, The George Washington University, Washington, DC, United States
| | - Anthony-S LaMantia
- Institute for Neuroscience, Department of Pharmacology & Physiology, The George Washington University, Washington, DC, United States.
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73
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Menelaou E, Paul LT, Perera SN, Svoboda KR. Motoneuron axon pathfinding errors in zebrafish: differential effects related to concentration and timing of nicotine exposure. Toxicol Appl Pharmacol 2015; 284:65-78. [PMID: 25668718 PMCID: PMC4567840 DOI: 10.1016/j.taap.2015.01.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 01/27/2015] [Accepted: 01/28/2015] [Indexed: 12/12/2022]
Abstract
Nicotine exposure during embryonic stages of development can affect many neurodevelopmental processes. In the developing zebrafish, exposure to nicotine was reported to cause axonal pathfinding errors in the later born secondary motoneurons (SMNs). These alterations in SMN axon morphology coincided with muscle degeneration at high nicotine concentrations (15-30 μM). Previous work showed that the paralytic mutant zebrafish known as sofa potato exhibited nicotine-induced effects onto SMN axons at these high concentrations but in the absence of any muscle deficits, indicating that pathfinding errors could occur independent of muscle effects. In this study, we used varying concentrations of nicotine at different developmental windows of exposure to specifically isolate its effects onto subpopulations of motoneuron axons. We found that nicotine exposure can affect SMN axon morphology in a dose-dependent manner. At low concentrations of nicotine, SMN axons exhibited pathfinding errors, in the absence of any nicotine-induced muscle abnormalities. Moreover, the nicotine exposure paradigms used affected the 3 subpopulations of SMN axons differently, but the dorsal projecting SMN axons were primarily affected. We then identified morphologically distinct pathfinding errors that best described the nicotine-induced effects on dorsal projecting SMN axons. To test whether SMN pathfinding was potentially influenced by alterations in the early born primary motoneuron (PMN), we performed dual labeling studies, where both PMN and SMN axons were simultaneously labeled with antibodies. We show that only a subset of the SMN axon pathfinding errors coincided with abnormal PMN axonal targeting in nicotine-exposed zebrafish. We conclude that nicotine exposure can exert differential effects depending on the levels of nicotine and developmental exposure window.
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Affiliation(s)
- Evdokia Menelaou
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Latoya T Paul
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Surangi N Perera
- Joseph J. Zilber School of Public Health, University of Wisconsin - Milwaukee, Milwaukee, WI 53205, USA
| | - Kurt R Svoboda
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA; Joseph J. Zilber School of Public Health, University of Wisconsin - Milwaukee, Milwaukee, WI 53205, USA.
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74
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Tada MN, Kuratani S. Evolutionary and developmental understanding of the spinal accessory nerve. ZOOLOGICAL LETTERS 2015; 1:4. [PMID: 26605049 PMCID: PMC4604108 DOI: 10.1186/s40851-014-0006-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 05/27/2014] [Indexed: 05/11/2023]
Abstract
The vertebrate spinal accessory nerve (SAN) innervates the cucullaris muscle, the major muscle of the neck, and is recognized as a synapomorphy that defines living jawed vertebrates. Morphologically, the cucullaris muscle exists between the branchiomeric series of muscles innervated by special visceral efferent neurons and the rostral somitic muscles innervated by general somatic efferent neurons. The category to which the SAN belongs to both developmentally and evolutionarily has long been controversial. To clarify this, we assessed the innervation and cytoarchitecture of the spinal nerve plexus in the lamprey and reviewed studies of SAN in various species of vertebrates and their embryos. We then reconstructed an evolutionary sequence in which phylogenetic changes in developmental neuronal patterning led towards the gnathostome-specific SAN. We hypothesize that the SAN arose as part of a lamprey-like spinal nerve plexus that innervates the cyclostome-type infraoptic muscle, a candidate cucullaris precursor.
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Affiliation(s)
- Motoki N Tada
- Evolutionary Morphology Laboratory, RIKEN, 2-2-3 Minatojima-minami, Chuo-ku, Kobe, Hyogo 650-0047 Japan
| | - Shigeru Kuratani
- Evolutionary Morphology Laboratory, RIKEN, 2-2-3 Minatojima-minami, Chuo-ku, Kobe, Hyogo 650-0047 Japan
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75
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Hutlet B, Theys N, Coste C, Ahn MT, Doshishti-Agolli K, Lizen B, Gofflot F. Systematic expression analysis of Hox genes at adulthood reveals novel patterns in the central nervous system. Brain Struct Funct 2014; 221:1223-43. [PMID: 25527350 DOI: 10.1007/s00429-014-0965-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 12/10/2014] [Indexed: 12/30/2022]
Abstract
Hox proteins are key regulators of animal development, providing positional identity and patterning information to cells along the rostrocaudal axis of the embryo. Although their embryonic expression and function are well characterized, their presence and biological importance in adulthood remains poorly investigated. We provide here the first detailed quantitative and neuroanatomical characterization of the expression of the 39 Hox genes in the adult mouse brain. Using RT-qPCR we determined the expression of 24 Hox genes mainly in the brainstem of the adult brain, with low expression of a few genes in the cerebellum and the forebrain. Using in situ hybridization (ISH) we have demonstrated that expression of Hox genes is maintained in territories derived from the early segmental Hox expression domains in the hindbrain. Indeed, we show that expression of genes belonging to paralogy groups PG2-8 is maintained in the hindbrain derivatives at adulthood. The spatial colinearity, which characterizes the early embryonic expression of Hox genes, is still observed in sequential antero-posterior boundaries of expression. Moreover, the main mossy and climbing fibres precerebellar nuclei express PG2-8 Hox genes according to their migration origins. Second, ISH confirms the presence of Hox gene transcripts in territories where they are not detected during development, suggesting neo-expression in these territories in adulthood. Within the forebrain, we have mapped Hoxb1, Hoxb3, Hoxb4, Hoxd3 and Hoxa5 expression in restricted areas of the sensory cerebral cortices as well as in specific thalamic relay nuclei. Our data thus suggest a requirement of Hox genes beyond their role of patterning genes, providing a new dimension to their functional relevance in the central nervous system.
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Affiliation(s)
- Bertrand Hutlet
- Institut des Sciences de la Vie, Université catholique de Louvain, 1348, Louvain-La-Neuve, Belgium
| | - Nicolas Theys
- Institut des Sciences de la Vie, Université catholique de Louvain, 1348, Louvain-La-Neuve, Belgium
| | - Cécile Coste
- Institut des Sciences de la Vie, Université catholique de Louvain, 1348, Louvain-La-Neuve, Belgium.,Laboratory of Developmental Neurobiology, GIGA-Neurosciences Research Center, University of Liège, 4000, Liège, Belgium
| | - Marie-Thérèse Ahn
- Institut des Sciences de la Vie, Université catholique de Louvain, 1348, Louvain-La-Neuve, Belgium
| | | | - Benoît Lizen
- Institut des Sciences de la Vie, Université catholique de Louvain, 1348, Louvain-La-Neuve, Belgium
| | - Françoise Gofflot
- Institut des Sciences de la Vie, Université catholique de Louvain, 1348, Louvain-La-Neuve, Belgium.
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76
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Ratié L, Ware M, Jagline H, David V, Dupé V. Dynamic expression of Notch-dependent neurogenic markers in the chick embryonic nervous system. Front Neuroanat 2014; 8:158. [PMID: 25565981 PMCID: PMC4270182 DOI: 10.3389/fnana.2014.00158] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 12/04/2014] [Indexed: 11/13/2022] Open
Abstract
The establishment of a functional nervous system requires a highly orchestrated process of neural proliferation and differentiation. The evolutionary conserved Notch signaling pathway is a key regulator of this process, regulating basic helix-loop-helix (bHLH) transcriptional repressors and proneural genes. However, little is known about downstream Notch targets and subsequently genes required for neuronal specification. In this report, the expression pattern of Transgelin 3 (Tagln3), Chromogranin A (Chga) and Contactin 2 (Cntn2) was described in detail during early chick embryogenesis. Expression of these genes was largely restricted to the nervous system including the early axon scaffold populations, cranial ganglia and spinal motor neurons. Their temporal and spatial expression were compared with the neuronal markers Nescient Helix-Loop-Helix 1 (Nhlh1), Stathmin 2 (Stmn2) and HuC/D. We show that Tagln3 is an early marker for post-mitotic neurons whereas Chga and Cntn2 are expressed in mature neurons. We demonstrate that inhibition of Notch signaling during spinal cord neurogenesis enhances expression of these markers. This data demonstrates that Tagln3, Chga and Cntn2 represent strong new candidates to contribute to the sequential progression of vertebrate neurogenesis.
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Affiliation(s)
- Leslie Ratié
- CNRS UMR6290, Faculté de Médecine, Institut de Génétique et Développement de Rennes, Université de Rennes 1 Rennes, France
| | - Michelle Ware
- CNRS UMR6290, Faculté de Médecine, Institut de Génétique et Développement de Rennes, Université de Rennes 1 Rennes, France
| | - Hélène Jagline
- CNRS UMR6290, Faculté de Médecine, Institut de Génétique et Développement de Rennes, Université de Rennes 1 Rennes, France
| | - Véronique David
- CNRS UMR6290, Faculté de Médecine, Institut de Génétique et Développement de Rennes, Université de Rennes 1 Rennes, France ; Laboratoire de Génétique Moléculaire, CHU Pontchaillou Rennes Cedex, France
| | - Valérie Dupé
- CNRS UMR6290, Faculté de Médecine, Institut de Génétique et Développement de Rennes, Université de Rennes 1 Rennes, France
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77
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Abstract
Hindbrain cranial motor neurons are organized into discrete functional clusters. A new study demonstrates that coalescence of these nuclei is driven by the expression of distinct combinations of cadherin adhesion molecules by each motor neuron group.
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Affiliation(s)
- Caroline A Pearson
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Samantha J Butler
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
| | - Bennett G Novitch
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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78
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Maury Y, Côme J, Piskorowski RA, Salah-Mohellibi N, Chevaleyre V, Peschanski M, Martinat C, Nedelec S. Combinatorial analysis of developmental cues efficiently converts human pluripotent stem cells into multiple neuronal subtypes. Nat Biotechnol 2014; 33:89-96. [PMID: 25383599 DOI: 10.1038/nbt.3049] [Citation(s) in RCA: 257] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 09/19/2014] [Indexed: 12/19/2022]
Abstract
Specification of cell identity during development depends on exposure of cells to sequences of extrinsic cues delivered at precise times and concentrations. Identification of combinations of patterning molecules that control cell fate is essential for the effective use of human pluripotent stem cells (hPSCs) for basic and translational studies. Here we describe a scalable, automated approach to systematically test the combinatorial actions of small molecules for the targeted differentiation of hPSCs. Applied to the generation of neuronal subtypes, this analysis revealed an unappreciated role for canonical Wnt signaling in specifying motor neuron diversity from hPSCs and allowed us to define rapid (14 days), efficient procedures to generate spinal and cranial motor neurons as well as spinal interneurons and sensory neurons. Our systematic approach to improving hPSC-targeted differentiation should facilitate disease modeling studies and drug screening assays.
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Affiliation(s)
- Yves Maury
- CECS, I-STEM (Institute for Stem Cell Therapy and Exploration of Monogenic Diseases), AFM, Evry, France
| | - Julien Côme
- CECS, I-STEM (Institute for Stem Cell Therapy and Exploration of Monogenic Diseases), AFM, Evry, France
| | | | | | - Vivien Chevaleyre
- CNRS UMR 8118, Université Paris Descartes Sorbonne Paris Cité, Paris, France
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79
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Central topography of cranial motor nuclei controlled by differential cadherin expression. Curr Biol 2014; 24:2541-7. [PMID: 25308074 PMCID: PMC4228048 DOI: 10.1016/j.cub.2014.08.067] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 08/04/2014] [Accepted: 08/29/2014] [Indexed: 11/23/2022]
Abstract
Neuronal nuclei are prominent, evolutionarily conserved features of vertebrate central nervous system (CNS) organization [1]. Nuclei are clusters of soma of functionally related neurons and are located in highly stereotyped positions. Establishment of this CNS topography is critical to neural circuit assembly. However, little is known of either the cellular or molecular mechanisms that drive nucleus formation during development, a process termed nucleogenesis [2, 3, 4, 5]. Brainstem motor neurons, which contribute axons to distinct cranial nerves and whose functions are essential to vertebrate survival, are organized exclusively as nuclei. Cranial motor nuclei are composed of two main classes, termed branchiomotor/visceromotor and somatomotor [6]. Each of these classes innervates evolutionarily distinct structures, for example, the branchial arches and eyes, respectively. Additionally, each class is generated by distinct progenitor cell populations and is defined by differential transcription factor expression [7, 8]; for example, Hb9 distinguishes somatomotor from branchiomotor neurons. We characterized the time course of cranial motornucleogenesis, finding that despite differences in cellular origin, segregation of branchiomotor and somatomotor nuclei occurs actively, passing through a phase of each being intermingled. We also found that differential expression of cadherin cell adhesion family members uniquely defines each motor nucleus. We show that cadherin expression is critical to nucleogenesis as its perturbation degrades nucleus topography predictably. Cranial motor nucleogenesis occurs through an active process of segregation Differential cadherin expression defines cranial motor nuclei Cadherin expression drives specificity of cranial motor nucleus segregation Cadherin expression does not affect cranial motor neuron migration
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Sweeney LB, Kelley DB. Harnessing vocal patterns for social communication. Curr Opin Neurobiol 2014; 28:34-41. [PMID: 24995669 PMCID: PMC4177452 DOI: 10.1016/j.conb.2014.06.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 04/23/2014] [Accepted: 06/04/2014] [Indexed: 12/16/2022]
Abstract
Work on vocal communication, influenced by a drive to understand the evolution of language, has focused on auditory processing and forebrain control of learned vocalizations. The actual hindbrain neural mechanisms used to create communication signals are understudied, in part because of the difficulty of experimental studies in species that rely on respiration for vocalization. In these experimental systems-including those that embody vocal learning-vocal behaviors have rhythmic qualities. Recent studies using molecular markers and 'fictive' patterns produced by isolated brains are beginning to reveal how hindbrain circuits generate vocal patterns. Insights from central pattern generators for respiration and locomotion are illuminating common neural and developmental mechanisms. Choice of vocal patterns is responsive to socially salient input. Studies of the vertebrate social brain network suggest mechanisms used to integrate socially salient information and produce an appropriate vocal response.
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Affiliation(s)
- Lora B Sweeney
- Molecular Neurobiology Laboratory, Salk Institute, 10010 N Torrey Pines Rd, La Jolla, CA 92037, United States
| | - Darcy B Kelley
- Dept. of Biological Sciences, Columbia University, 1616 Amsterdam Avenue, New York, NY 10027, United States.
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81
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Kuert PA, Hartenstein V, Bello BC, Lovick JK, Reichert H. Neuroblast lineage identification and lineage-specific Hox gene action during postembryonic development of the subesophageal ganglion in the Drosophila central brain. Dev Biol 2014; 390:102-15. [DOI: 10.1016/j.ydbio.2014.03.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 03/23/2014] [Accepted: 03/29/2014] [Indexed: 11/16/2022]
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82
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Tillo M, Schwarz Q, Ruhrberg C. Mouse hindbrain ex vivo culture to study facial branchiomotor neuron migration. J Vis Exp 2014. [PMID: 24686480 PMCID: PMC4032788 DOI: 10.3791/51397] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Embryonic neurons are born in the ventricular zone of the brain, but subsequently migrate to new destinations to reach appropriate targets. Deciphering the molecular signals that cooperatively guide neuronal migration in the embryonic brain is therefore important to understand how the complex neural networks form which later support postnatal life. Facial branchiomotor (FBM) neurons in the mouse embryo hindbrain migrate from rhombomere (r) 4 caudally to form the paired facial nuclei in the r6-derived region of the hindbrain. Here we provide a detailed protocol for wholemount ex vivo culture of mouse embryo hindbrains suitable to investigate the signaling pathways that regulate FBM migration. In this method, hindbrains of E11.5 mouse embryos are dissected and cultured in an open book preparation on cell culture inserts for 24 hr. During this time, FBM neurons migrate caudally towards r6 and can be exposed to function-blocking antibodies and small molecules in the culture media or heparin beads loaded with recombinant proteins to examine roles for signaling pathways implicated in guiding neuronal migration.
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Affiliation(s)
- Miguel Tillo
- UCL Institute of Ophthalmology, University College London
| | - Quenten Schwarz
- UCL Institute of Ophthalmology, University College London; Department of Human Immunology, Centre for Cancer Biology, South Australia
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83
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Abstract
The Hox genes are an evolutionarily conserved family of genes, which encode a class of important transcription factors that function in numerous developmental processes. Following their initial discovery, a substantial amount of information has been gained regarding the roles Hox genes play in various physiologic and pathologic processes. These processes range from a central role in anterior-posterior patterning of the developing embryo to roles in oncogenesis that are yet to be fully elucidated. In vertebrates there are a total of 39 Hox genes divided into 4 separate clusters. Of these, mutations in 10 Hox genes have been found to cause human disorders with significant variation in their inheritance patterns, penetrance, expressivity and mechanism of pathogenesis. This review aims to describe the various phenotypes caused by germline mutation in these 10 Hox genes that cause a human phenotype, with specific emphasis paid to the genotypic and phenotypic differences between allelic disorders. As clinical whole exome and genome sequencing is increasingly utilized in the future, we predict that additional Hox gene mutations will likely be identified to cause distinct human phenotypes. As the known human phenotypes closely resemble gene-specific murine models, we also review the homozygous loss-of-function mouse phenotypes for the 29 Hox genes without a known human disease. This review will aid clinicians in identifying and caring for patients affected with a known Hox gene disorder and help recognize the potential for novel mutations in patients with phenotypes informed by mouse knockout studies.
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Affiliation(s)
- Shane C Quinonez
- University of Michigan, Department of Pediatrics, Division of Pediatric Genetics, 1500 East Medical Center Drive, D5240 MPB/Box 5718, Ann Arbor, MI 48109-5718, USA.
| | - Jeffrey W Innis
- University of Michigan, Department of Pediatrics, Division of Pediatric Genetics, 1500 East Medical Center Drive, D5240 MPB/Box 5718, Ann Arbor, MI 48109-5718, USA; University of Michigan, Department of Human Genetics, 1241 E. Catherine, 4909 Buhl Building, Ann Arbor, MI 48109-5618, USA.
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84
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Hua ZL, Smallwood PM, Nathans J. Frizzled3 controls axonal development in distinct populations of cranial and spinal motor neurons. eLife 2013; 2:e01482. [PMID: 24347548 PMCID: PMC3865743 DOI: 10.7554/elife.01482] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Disruption of the Frizzled3 (Fz3) gene leads to defects in axonal growth in the VIIth and XIIth cranial motor nerves, the phrenic nerve, and the dorsal motor nerve in fore- and hindlimbs. In Fz3−/− limbs, dorsal axons stall at a precise location in the nerve plexus, and, in contrast to the phenotypes of several other axon path-finding mutants, Fz3−/− dorsal axons do not reroute to other trajectories. Affected motor neurons undergo cell death 2 days prior to the normal wave of developmental cell death that coincides with innervation of muscle targets, providing in vivo evidence for the idea that developing neurons with long-range axons are programmed to die unless their axons arrive at intermediate targets on schedule. These experiments implicate planar cell polarity (PCP) signaling in motor axon growth and they highlight the question of how PCP proteins, which form cell–cell complexes in epithelia, function in the dynamic context of axonal growth. DOI:http://dx.doi.org/10.7554/eLife.01482.001 For the nervous system to become wired up correctly, neurons within the developing embryo must project over long distances to form connections with remote targets. They do this by lengthening their axons—the ‘cables’ along which electrical signals flow—and some axons in adult humans can grow to be more than 1 metre long. This type of long-range pathfinding activity is particularly common for neurons that control movement, as many of these neurons must establish connections with muscles that are some distance away from the brain. For example, motor neurons in the brainstem form connections with muscles in the face to control facial expressions, while motor neurons in parts of the spinal cord project to muscles in the limbs. Multiple signaling pathways tell the developing axons which direction to grow en route to their final targets. Now, Hua et al. have shown that an evolutionarily conserved protein called Frizzled3 is also involved in this process. In mouse embryos that lacked Frizzled3, the motor nerves that control breathing and limb movements were thinner than those in normal mice. In the mutant animals, many motor axons failed to form connections with their targets. Instead, these axons came to an abrupt halt midway along their intended paths and the neurons from which they originated died soon afterwards. These experiments support the idea that developing neurons are programmed to die unless their axons progress on the appropriate schedule. As well as increasing our knowledge of the networks of connections that form within the developing mammalian nervous system, the work of Hua et al. provides new insights into some of the molecular mechanisms by which these connections are established. DOI:http://dx.doi.org/10.7554/eLife.01482.002
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Affiliation(s)
- Zhong L Hua
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, United States
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85
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α2-Chimaerin regulates a key axon guidance transition during development of the oculomotor projection. J Neurosci 2013; 33:16540-51. [PMID: 24133258 DOI: 10.1523/jneurosci.1869-13.2013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The ocular motor system consists of three nerves which innervate six muscles to control eye movements. In humans, defective development of this system leads to eye movement disorders, such as Duane Retraction Syndrome, which can result from mutations in the α2-chimaerin signaling molecule. We have used the zebrafish to model the role of α2-chimaerin during development of the ocular motor system. We first mapped ocular motor spatiotemporal development, which occurs between 24 and 72 h postfertilization (hpf), with the oculomotor nerve following an invariant sequence of growth and branching to its muscle targets. We identified 52 hpf as a key axon guidance "transition," when oculomotor axons reach the orbit and select their muscle targets. Live imaging and quantitation showed that, at 52 hpf, axons undergo a switch in behavior, with striking changes in the dynamics of filopodia. We tested the role of α2-chimaerin in this guidance process and found that axons expressing gain-of-function α2-chimaerin isoforms failed to undergo the 52 hpf transition in filopodial dynamics, leading to axon stalling. α2-chimaerin loss of function led to ecotopic and misguided branching and hypoplasia of oculomotor axons; embryos had defective eye movements as measured by the optokinetic reflex. Manipulation of chimaerin signaling in oculomotor neurons in vitro led to changes in microtubule stability. These findings demonstrate that a correct level of α2-chimaerin signaling is required for key oculomotor axon guidance decisions, and provide a zebrafish model for Duane Retraction Syndrome.
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86
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Tokita M, Nakayama T. Development of the trigeminal motor neurons in parrots: implications for the role of nervous tissue in the evolution of jaw muscle morphology. J Morphol 2013; 275:191-205. [PMID: 24123304 DOI: 10.1002/jmor.20208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 08/23/2013] [Accepted: 09/04/2013] [Indexed: 11/12/2022]
Abstract
Vertebrates have succeeded to inhabit almost every ecological niche due in large part to the anatomical diversification of their jaw complex. As a component of the feeding apparatus, jaw muscles carry a vital role for determining the mode of feeding. Early patterning of the jaw muscles has been attributed to cranial neural crest-derived mesenchyme, however, much remains to be understood about the role of nonneural crest tissues in the evolution and diversification of jaw muscle morphology. In this study, we describe the development of trigeminal motor neurons in a parrot species with the uniquely shaped jaw muscles and compare its developmental pattern to that in the quail with the standard jaw muscles to uncover potential roles of nervous tissue in the evolution of vertebrate jaw muscles. In parrot embryogenesis, the motor axon bundles are detectable within the muscular tissue only after the basic shape of the muscular tissue has been established. This supports the view that nervous tissue does not primarily determine the spatial pattern of jaw muscles. In contrast, the trigeminal motor nucleus, which is composed of somata of neurons that innervate major jaw muscles, of parrot is more developed compared to quail, even in embryonic stage where no remarkable interspecific difference in both jaw muscle morphology and motor nerve branching pattern is recognized. Our data suggest that although nervous tissue may not have a large influence on initial patterning of jaw muscles, it may play an important role in subsequent growth and maintenance of muscular tissue and alterations in cranial nervous tissue development may underlie diversification of jaw muscle morphology.
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Affiliation(s)
- Masayoshi Tokita
- Program in Biological Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tenno-dai 1-1-1, Tsukuba, Ibaraki, 305-8572, Japan
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87
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Philippidou P, Dasen JS. Hox genes: choreographers in neural development, architects of circuit organization. Neuron 2013; 80:12-34. [PMID: 24094100 DOI: 10.1016/j.neuron.2013.09.020] [Citation(s) in RCA: 284] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The neural circuits governing vital behaviors, such as respiration and locomotion, are comprised of discrete neuronal populations residing within the brainstem and spinal cord. Work over the past decade has provided a fairly comprehensive understanding of the developmental pathways that determine the identity of major neuronal classes within the neural tube. However, the steps through which neurons acquire the subtype diversities necessary for their incorporation into a particular circuit are still poorly defined. Studies on the specification of motor neurons indicate that the large family of Hox transcription factors has a key role in generating the subtypes required for selective muscle innervation. There is also emerging evidence that Hox genes function in multiple neuronal classes to shape synaptic specificity during development, suggesting a broader role in circuit assembly. This Review highlights the functions and mechanisms of Hox gene networks and their multifaceted roles during neuronal specification and connectivity.
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Affiliation(s)
- Polyxeni Philippidou
- Howard Hughes Medical Institute, NYU Neuroscience Institute, Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA.
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88
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Wanner SJ, Saeger I, Guthrie S, Prince VE. Facial motor neuron migration advances. Curr Opin Neurobiol 2013; 23:943-50. [PMID: 24090878 DOI: 10.1016/j.conb.2013.09.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 09/03/2013] [Indexed: 11/19/2022]
Abstract
During development, the migration of specific neuronal subtypes is required for the correct establishment of neural circuits. In mice and zebrafish, facial branchiomotor (FBM) neurons undergo a tangential migration from rhombomere 4 caudally through the hindbrain. Recent advances in the field have capitalized on genetic studies in zebrafish and mouse, and high-resolution time-lapse imaging in zebrafish. Planar cell polarity signaling has emerged as a critical conserved factor in FBM neuron migration, functioning both within the neurons and their environment. In zebrafish, migration depends on specialized 'pioneer' neurons to lead follower FBM neurons through the hindbrain, and on interactions with structural components including pre-laid axon tracts and the basement membrane. Despite fundamental conservation, species-specific differences in migration mechanisms are being uncovered.
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Affiliation(s)
- Sarah J Wanner
- Department of Organismal Biology and Anatomy, The University of Chicago, 1027 E 57th Street, Chicago, IL 60637, United States
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89
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Alli O, Berzofsky C, Sharma S, Pitman MJ. Development of the rat larynx: a histological study. Laryngoscope 2013; 123:3093-8. [PMID: 23918405 DOI: 10.1002/lary.24145] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 02/11/2013] [Accepted: 03/18/2013] [Indexed: 11/09/2022]
Abstract
OBJECTIVES/HYPOTHESIS To evaluate and describe the cartilaginous and muscular development of the rat larynx. STUDY DESIGN Histologic evaluation. METHODS The larynges of Sprague Dawley rats of embryonic day (E) 13, 15, 17, 19, 21, postnatal day 0, 14, and adult of 250 gm were collected. Four larynges of each age were harvested, cut into 15-μm serial sections, stained with hematoxylin and eosin, and evaluated under light microscopy. Representative digital images were recorded and evaluated at the preglottic (supraglottic in humans), glottic, and postglottic (subglottic in humans) levels. RESULTS Brachial arches were observed at E13. At E17, immature structures of the larynx, including skeletal muscle, cartilage, and the lumen were identifiable. Chondrification and muscle formation were clearly seen by E19. The muscular and cartilagenous components of the larynx were well established by E21. During the span between birth and adult maturation, the size of the larynx increased from a height of 1.10 mm to 2.90 mm, and from a width of 1.80 mm to 5.40 mm, and from a length of 1.38 mm to 4.77 mm in the stained section. Although developed at E21, the laryngeal structures continued to grow by approximately 30%. CONCLUSION Rat laryngeal development parallels that in mice and humans. In the rat, at E17 immature structures of the larynx are identifiable, they are well developed at birth and grow by approximately 30% into adulthood. Understanding the chronology and morphology of the embryogenesis of the rat laryngeal musculature is essential and will allow for further evaluation of the embryologic innervation of these muscles.
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Affiliation(s)
- Opeyemi Alli
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York, U.S.A
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90
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Tissir F, Goffinet AM. Shaping the nervous system: role of the core planar cell polarity genes. Nat Rev Neurosci 2013; 14:525-35. [PMID: 23839596 DOI: 10.1038/nrn3525] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Planar cell polarity (PCP) is complementary to the intrinsic polarization of single cells and refers to the global coordination of cell behaviour in the plane of a tissue and, by extension, to the signalling pathways that control it. PCP is most evident in cell sheets, and research into PCP was for years confined to studies in Drosophila melanogaster. However, PCP has more recently emerged as an important phenomenon in vertebrates, in which it regulates various developmental processes and is associated with multiple disorders. In particular, core PCP genes are crucial for the development and function of the nervous system. They are involved in neural tube closure, ependymal polarity, neuronal migration, dendritic growth and axon guidance.
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Affiliation(s)
- Fadel Tissir
- University of Louvain, Institute of Neuroscience, Developmental Neurobiology Group, Avenue Mounier 73, Box B1.73.16, 1200 Brussels, Belgium
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91
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Pitman MJ, Berzofsky CE, Alli O, Sharma S. Embryologic innervation of the rat laryngeal musculature-a model for investigation of recurrent laryngeal nerve reinnervation. Laryngoscope 2013; 123:3117-26. [DOI: 10.1002/lary.24216] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 04/19/2013] [Accepted: 04/19/2013] [Indexed: 11/07/2022]
Affiliation(s)
- Michael J. Pitman
- New York Eye and Ear Infirmary, Department of Otolaryngology; Voice and Swallowing Institute; New York New York
| | - Craig E. Berzofsky
- Division of Laryngology; New York Eye and Ear Infirmary, Department of Otolaryngology; New York New York
| | - Opeyemi Alli
- New York Medical College, School of Medicine; Valhalla New York New York U.S.A
| | - Sansar Sharma
- Department of Cell Biology; New York Medical College; Valhalla New York
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92
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Nomaksteinsky M, Kassabov S, Chettouh Z, Stoeklé HC, Bonnaud L, Fortin G, Kandel ER, Brunet JF. Ancient origin of somatic and visceral neurons. BMC Biol 2013; 11:53. [PMID: 23631531 PMCID: PMC3660236 DOI: 10.1186/1741-7007-11-53] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 03/22/2013] [Indexed: 12/30/2022] Open
Abstract
Background A key to understanding the evolution of the nervous system on a large phylogenetic scale is the identification of homologous neuronal types. Here, we focus this search on the sensory and motor neurons of bilaterians, exploiting their well-defined molecular signatures in vertebrates. Sensorimotor circuits in vertebrates are of two types: somatic (that sense the environment and respond by shaping bodily motions) and visceral (that sense the interior milieu and respond by regulating vital functions). These circuits differ by a small set of largely dedicated transcriptional determinants: Brn3 is expressed in many somatic sensory neurons, first and second order (among which mechanoreceptors are uniquely marked by the Brn3+/Islet1+/Drgx+ signature), somatic motoneurons uniquely co-express Lhx3/4 and Mnx1, while the vast majority of neurons, sensory and motor, involved in respiration, blood circulation or digestion are molecularly defined by their expression and dependence on the pan-visceral determinant Phox2b. Results We explore the status of the sensorimotor transcriptional code of vertebrates in mollusks, a lophotrochozoa clade that provides a rich repertoire of physiologically identified neurons. In the gastropods Lymnaea stagnalis and Aplysia californica, we show that homologues of Brn3, Drgx, Islet1, Mnx1, Lhx3/4 and Phox2b differentially mark neurons with mechanoreceptive, locomotory and cardiorespiratory functions. Moreover, in the cephalopod Sepia officinalis, we show that Phox2 marks the stellate ganglion (in line with the respiratory — that is, visceral— ancestral role of the mantle, its target organ), while the anterior pedal ganglion, which controls the prehensile and locomotory arms, expresses Mnx. Conclusions Despite considerable divergence in overall neural architecture, a molecular underpinning for the functional allocation of neurons to interactions with the environment or to homeostasis was inherited from the urbilaterian ancestor by contemporary protostomes and deuterostomes.
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Affiliation(s)
- Marc Nomaksteinsky
- Institut de Biologie de l'École Normale Supérieure-IBENS, CNRS UMR8197, INSERM U1024, Paris, France
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93
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Pu Q, Bai Z, Haque Z, Wang J, Huang R. Occipital somites guide motor axons of the accessory nerve in the avian embryo. Neuroscience 2013; 246:22-7. [PMID: 23632169 DOI: 10.1016/j.neuroscience.2013.04.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 04/04/2013] [Accepted: 04/18/2013] [Indexed: 10/26/2022]
Abstract
The accessory nerve (nervus accessorius) displays a unique organization in that its axons ascend along the rostrocaudal axis after exiting the cervical spinal cord and medulla oblongata and thereafter project ventrally into the periphery at the first somite level. Little is known about how this organization is achieved. We have investigated the role of somites in the guidance of motor axons of the accessory nerve using heterotopic transplantations of somites in avian embryos. The formation of not only accessory nerve but also the vagal nerve was affected, when a more caudal occipital somite (somites 2-4) was grafted to the position of the first occipital somite. Our study reveals that only the first occipital somite permits the development of ventral projection of accessory axons, a process that is inhibited by more caudal occipital somites.
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Affiliation(s)
- Q Pu
- Department of Neuroanatomy, Institute of Anatomy, University of Bonn, Germany
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94
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Misra M, Sours E, Lance-Jones C. Hox transcription factors influence motoneuron identity through the integrated actions of both homeodomain and non-homeodomain regions. Dev Dyn 2013; 241:718-31. [PMID: 22411553 DOI: 10.1002/dvdy.23763] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Hox transcription factors play a critical role in the specification of motoneuron subtypes within the spinal cord. Our previous work showed that two orthologous members of this family, Hoxd10 and Hoxd11, exert opposing effects on motoneuron development in the lumbosacral (LS) spinal cord of the embryonic chick: Hoxd10 promotes the development of lateral motoneuron subtypes that project to dorsal limb muscles, while Hoxd11 represses the development of lateral subtypes in favor of medial subtypes that innervate ventral limb muscles and axial muscles. The striking degree of homology between the DNA-binding homeodomains of Hoxd10 and Hoxd11 suggested that non-homeodomain regions mediate their divergent effects. In the present study, we investigate the relative contributions of homeodomain and non-homeodomain regions of Hoxd10 and Hoxd11 to motoneuron specification. RESULTS Using in ovo electroporation to express chimeric and mutant constructs in LS motoneurons, we find that both the homeodomain and non-homeodomain regions of Hoxd10 are necessary to specify lateral motoneurons. In contrast, non-homeodomain regions of Hoxd11 are sufficient to repress lateral motoneuron fates in favor of medial fates. CONCLUSIONS Together, our data demonstrate that even closely related Hox orthologues rely on distinct combinations of homeodomain-dependent and -independent mechanisms to specify motoneuron identity.
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Affiliation(s)
- Mala Misra
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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95
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The histone demethylase Jarid1b ensures faithful mouse development by protecting developmental genes from aberrant H3K4me3. PLoS Genet 2013; 9:e1003461. [PMID: 23637629 PMCID: PMC3630093 DOI: 10.1371/journal.pgen.1003461] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 03/04/2013] [Indexed: 12/12/2022] Open
Abstract
Embryonic development is tightly regulated by transcription factors and chromatin-associated proteins. H3K4me3 is associated with active transcription and H3K27me3 with gene repression, while the combination of both keeps genes required for development in a plastic state. Here we show that deletion of the H3K4me2/3 histone demethylase Jarid1b (Kdm5b/Plu1) results in major neonatal lethality due to respiratory failure. Jarid1b knockout embryos have several neural defects including disorganized cranial nerves, defects in eye development, and increased incidences of exencephaly. Moreover, in line with an overlap of Jarid1b and Polycomb target genes, Jarid1b knockout embryos display homeotic skeletal transformations typical for Polycomb mutants, supporting a functional interplay between Polycomb proteins and Jarid1b. To understand how Jarid1b regulates mouse development, we performed a genome-wide analysis of histone modifications, which demonstrated that normally inactive genes encoding developmental regulators acquire aberrant H3K4me3 during early embryogenesis in Jarid1b knockout embryos. H3K4me3 accumulates as embryonic development proceeds, leading to increased expression of neural master regulators like Pax6 and Otx2 in Jarid1b knockout brains. Taken together, these results suggest that Jarid1b regulates mouse development by protecting developmental genes from inappropriate acquisition of active histone modifications.
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96
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Coppola E, D'autréaux F, Nomaksteinsky M, Brunet JF. Phox2b expression in the taste centers of fish. J Comp Neurol 2013; 520:3633-49. [PMID: 22473338 DOI: 10.1002/cne.23117] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The homeodomain transcription factor Phox2b controls the formation of the sensory-motor reflex circuits of the viscera in vertebrates. Among Phox2b-dependent structures characterized in rodents is the nucleus of the solitary tract, the first relay for visceral sensory input, including taste. Here we show that Phox2b is expressed throughout the primary taste centers of two cyprinid fish, Danio rerio and Carassius auratus, i.e., in their vagal, glossopharyngeal, and facial lobes, providing the first molecular evidence for their homology with the nucleus of the solitary tract of mammals and suggesting that a single ancestral Phox2b-positive neuronal type evolved to give rise to both fish and mammalian structures. In zebrafish larvae, the distribution of Phox2b²⁺ neurons, combined with the expression pattern of Olig4 (a homologue of Olig3, determinant of the nucleus of the solitary tract in mice), reveals that the superficial position and sheet-like architecture of the viscerosensory column in cyprinid fish, ideally suited for the somatotopic representation of oropharyngeal and bodily surfaces, arise by radial migration from a dorsal progenitor domain, in contrast to the tangential migration observed in amniotes.
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Affiliation(s)
- Eva Coppola
- École Normale Supérieure, Institut de Biologie de l'École Normale Supérieure, Paris F-75005, France
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97
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Tissir F, Goffinet AM. Atypical Cadherins Celsr1–3 and Planar Cell Polarity in Vertebrates. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 116:193-214. [DOI: 10.1016/b978-0-12-394311-8.00009-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Brockington A, Ning K, Heath PR, Wood E, Kirby J, Fusi N, Lawrence N, Wharton SB, Ince PG, Shaw PJ. Unravelling the enigma of selective vulnerability in neurodegeneration: motor neurons resistant to degeneration in ALS show distinct gene expression characteristics and decreased susceptibility to excitotoxicity. Acta Neuropathol 2013; 125:95-109. [PMID: 23143228 PMCID: PMC3535376 DOI: 10.1007/s00401-012-1058-5] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 10/16/2012] [Accepted: 10/19/2012] [Indexed: 12/11/2022]
Abstract
A consistent clinical feature of amyotrophic lateral sclerosis (ALS) is the sparing of eye movements and the function of external sphincters, with corresponding preservation of motor neurons in the brainstem oculomotor nuclei, and of Onuf’s nucleus in the sacral spinal cord. Studying the differences in properties of neurons that are vulnerable and resistant to the disease process in ALS may provide insights into the mechanisms of neuronal degeneration, and identify targets for therapeutic manipulation. We used microarray analysis to determine the differences in gene expression between oculomotor and spinal motor neurons, isolated by laser capture microdissection from the midbrain and spinal cord of neurologically normal human controls. We compared these to transcriptional profiles of oculomotor nuclei and spinal cord from rat and mouse, obtained from the GEO omnibus database. We show that oculomotor neurons have a distinct transcriptional profile, with significant differential expression of 1,757 named genes (q < 0.001). Differentially expressed genes are enriched for the functional categories of synaptic transmission, ubiquitin-dependent proteolysis, mitochondrial function, transcriptional regulation, immune system functions, and the extracellular matrix. Marked differences are seen, across the three species, in genes with a function in synaptic transmission, including several glutamate and GABA receptor subunits. Using patch clamp recording in acute spinal and brainstem slices, we show that resistant oculomotor neurons show a reduced AMPA-mediated inward calcium current, and a higher GABA-mediated chloride current, than vulnerable spinal motor neurons. The findings suggest that reduced susceptibility to excitotoxicity, mediated in part through enhanced GABAergic transmission, is an important determinant of the relative resistance of oculomotor neurons to degeneration in ALS.
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Affiliation(s)
- Alice Brockington
- Academic Neurology Unit, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Ke Ning
- Academic Neurology Unit, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Paul R. Heath
- Academic Neurology Unit, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Elizabeth Wood
- Academic Neurology Unit, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Janine Kirby
- Academic Neurology Unit, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Nicolò Fusi
- Computational Biology Unit, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Neil Lawrence
- Computational Biology Unit, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Stephen B. Wharton
- Academic Neuropathology Unit, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Paul G. Ince
- Academic Neuropathology Unit, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
| | - Pamela J. Shaw
- Academic Neurology Unit, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, 385A Glossop Road, Sheffield, S10 2HQ UK
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99
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Garland CB, Pomerantz JH. Regenerative strategies for craniofacial disorders. Front Physiol 2012; 3:453. [PMID: 23248598 PMCID: PMC3521957 DOI: 10.3389/fphys.2012.00453] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 11/12/2012] [Indexed: 01/26/2023] Open
Abstract
Craniofacial disorders present markedly complicated problems in reconstruction because of the complex interactions of the multiple, simultaneously affected tissues. Regenerative medicine holds promise for new strategies to improve treatment of these disorders. This review addresses current areas of unmet need in craniofacial reconstruction and emphasizes how craniofacial tissues differ from their analogs elsewhere in the body. We present a problem-based approach to illustrate current treatment strategies for various craniofacial disorders, to highlight areas of need, and to suggest regenerative strategies for craniofacial bone, fat, muscle, nerve, and skin. For some tissues, current approaches offer excellent reconstructive solutions using autologous tissue or prosthetic materials. Thus, new “regenerative” approaches would need to offer major advantages in order to be adopted. In other tissues, the unmet need is great, and we suggest the greatest regenerative need is for muscle, skin, and nerve. The advent of composite facial tissue transplantation and the development of regenerative medicine are each likely to add important new paradigms to our treatment of craniofacial disorders.
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Affiliation(s)
- Catharine B Garland
- Department of Surgery, Division of Plastic and Reconstructive Surgery, University of California San Francisco San Francisco, CA, USA ; Craniofacial and Mesenchymal Biology Program, University of California San Francisco San Francisco, CA, USA
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100
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Lin S, Kao CF, Yu HH, Huang Y, Lee T. Lineage analysis of Drosophila lateral antennal lobe neurons reveals notch-dependent binary temporal fate decisions. PLoS Biol 2012. [PMID: 23185131 PMCID: PMC3502534 DOI: 10.1371/journal.pbio.1001425] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
A high-resolution neuronal lineage analysis in the Drosophila antennal lobe reveals the complexity of lineage development and Notch signaling in cell fate specification. Binary cell fate decisions allow the production of distinct sister neurons from an intermediate precursor. Neurons are further diversified based on the birth order of intermediate precursors. Here we examined the interplay between binary cell fate and birth-order-dependent temporal fate in the Drosophila lateral antennal lobe (lAL) neuronal lineage. Single-cell mapping of the lAL lineage by twin-spot mosaic analysis with repressible cell markers (ts-MARCM) revealed that projection neurons (PNs) and local interneurons (LNs) are made in pairs through binary fate decisions. Forty-five types of PNs innervating distinct brain regions arise in a stereotyped sequence; however, the PNs with similar morphologies are not necessarily born in a contiguous window. The LNs are morphologically less diverse than the PNs, and the sequential morphogenetic changes in the two pairs occur independently. Sanpodo-dependent Notch activity promotes and patterns the LN fates. By contrast, Notch diversifies PN temporal fates in a Sanpodo-dispensable manner. These pleiotropic Notch actions underlie the differential temporal fate specification of twin neurons produced by common precursors within a lineage, possibly by modulating postmitotic neurons' responses to Notch-independent transcriptional cascades. The Drosophila brain develops from a limited number of neural stem cells that produce a series of ganglion mother cells (GMCs) that divide once to produce a pair of neurons in a defined order, termed a neuronal lineage. Here, we provide a detailed lineage map for the neurons derived from the Drosophila lateral antennal lobe (lAL) neuroblast. The lAL lineage consists of two distinct hemilineages, generated through differential Notch signaling in the two GMC daughters, to produce one projection neuron (PN) paired with a local interneuron (LN). Both hemilineages yield distinct cell types in the same sequence, although the temporal identity (birth-order-dependent fate) changes are regulated independently between projection neurons and local interneurons, such that a series of analogous local interneurons may co-derive with different projection neurons and vice versa. We also find that Notch signaling can transform a class of nonantennal lobe projection neurons into antennal lobe projection neurons. These findings suggest that Notch signaling not only modulates temporal fate but itself plays a role in the distinction of antennal lobe versus nonantennal lobe neurons.
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Affiliation(s)
- Suewei Lin
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Chih-Fei Kao
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Hung-Hsiang Yu
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America
| | - Yaling Huang
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America
| | - Tzumin Lee
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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