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Huang T, Xie Z, Wang J, Li M, Jing N, Li L. Nuclear factor of activated T cells (NFAT) proteins repress canonical Wnt signaling via its interaction with Dishevelled (Dvl) protein and participate in regulating neural progenitor cell proliferation and differentiation. J Biol Chem 2011; 286:37399-405. [PMID: 21880741 DOI: 10.1074/jbc.m111.251165] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Ca(2+) signaling pathway appears to regulate the processes of the early development through its antagonism of canonical Wnt/β-catenin signaling pathway. However, the underlying mechanism is still poorly understood. Here, we show that nuclear factor of activated T cells (NFAT), a component of Ca(2+) signaling, interacts directly with Dishevelled (Dvl) in a Ca(2+)-dependent manner. A dominant negative form of NFAT rescued the inhibition of the Wnt/β-catenin pathway triggered by the Ca(2+) signal. NFAT functioned downstream of β-catenin without interfering with its stability, but influencing the interaction of β-catenin with Dvl by its competitively binding to Dvl. Furthermore, we demonstrate that NFAT is a regulator in the proliferation and differentiation of neural progenitor cells by modulating canonical Wnt/β-catenin signaling pathway in the neural tube of chick embryo. Our findings suggest that NFAT negatively regulates canonical Wnt/β-catenin signaling by binding to Dvl, thereby participating in vertebrate neurogenesis.
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Affiliation(s)
- Tao Huang
- State Key Laboratory of Molecular Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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52
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Wang H, Lei Q, Oosterveen T, Ericson J, Matise MP. Tcf/Lef repressors differentially regulate Shh-Gli target gene activation thresholds to generate progenitor patterning in the developing CNS. Development 2011; 138:3711-21. [PMID: 21775418 DOI: 10.1242/dev.068270] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During neural tube development, Shh signaling through Gli transcription factors is necessary to establish five distinct ventral progenitor domains that give rise to unique classes of neurons and glia that arise in specific positions along the dorsoventral axis. These cells are generated from progenitors that display distinct transcription factor gene expression profiles in specific domains in the ventricular zone. However, the molecular genetic mechanisms that control the differential spatiotemporal transcriptional responses of progenitor target genes to graded Shh-Gli signaling remain unclear. The current study demonstrates a role for Tcf/Lef repressor activity in this process. We show that Tcf3 and Tcf7L2 (Tcf4) are required for proper ventral patterning and function by independently regulating two Shh-Gli target genes, Nkx2.2 and Olig2, which are initially induced in a common pool of progenitors that ultimately segregate into unique territories giving rise to distinct progeny. Genetic and functional studies in vivo show that Tcf transcriptional repressors selectively elevate the strength and duration of Gli activity necessary to induce Nkx2.2, but have no effect on Olig2, and thereby contribute to the establishment of their distinct expression domains in cooperation with graded Shh signaling. Together, our data reveal a Shh-Gli-independent transcriptional input that is required to shape the precise spatial and temporal response to extracellular morphogen signaling information during lineage segregation in the CNS.
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Affiliation(s)
- Hui Wang
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, 675 Hoes Lane, Piscataway, NJ 08854, USA
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Abstract
OLs (oligodendrocytes) are the myelinating cells of the CNS (central nervous system), wrapping axons in conductive sheathes to ensure effective transmission of neural signals. The regulation of OL development, from precursor to mature myelinating cell, is controlled by a variety of inhibitory and inductive signalling factors. The dorsal spinal cord contains signals that inhibit OL development, possibly to prevent premature and ectopic precursor differentiation. The Wnt and BMP (bone morphogenic protein) signalling pathways have been identified as dorsal spinal cord signals with overlapping temporal activity, and both have similar inhibitory effects on OL differentiation. Both these pathways feature prominently in many developmental processes and demyelinating events after injury, and they are known to interact in complex inductive, inhibitive and synergistic manners in many developing systems. The interaction between BMP and Wnt signalling in OL development, however, has not been extensively explored. In the present study, we examine the relationship between the canonical Wnt and BMP pathways. We use pharmacological and genetic paradigms to show that both Wnt3a and BMP4 will inhibit OL differentiation in vitro. We also show that when the canonical BMP signalling pathway is blocked, neither Wnt3a nor BMP4 have inhibitory effects on OL differentiation. In contrast, abrogating the Wnt signalling pathway does not alter the actions of BMP4 treatment. Our results indicate that the BMP signalling pathway is necessary for the canonical Wnt signalling pathway to exert its effects on OL development, but not vice versa, suggesting that Wnt signals upstream of BMP.
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54
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Zhang XY, Yang YJ, Xu PR, Zheng XR, Wang QH, Chen CF, Yao Y. The role of β-catenin signaling pathway on proliferation of rats neural stem cells after hyperbaric oxygen therapy in vitro. Cell Mol Neurobiol 2010; 31:101-9. [PMID: 20886368 DOI: 10.1007/s10571-010-9559-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Accepted: 08/17/2010] [Indexed: 11/26/2022]
Abstract
β-catenin, a protein that functions in both cell adhesion and Wnt signaling, plays a key role in mammalian neural development. To investigate the role of β-catenin in hyperbaric oxygen therapy (HBO)-induced neurogenesis after hypoxic ischemic brain damage (HIBD), we transfected β-catenin siRNA and negative control siRNA into neural stem cells (NSCs) after HIBD. We found that HBO promoted NSCs differentiate into neurons or oligodendrocytes, and inhibited NSCs differentiate into astrocytes; HIBD brain tissue extract conditioned cultures promoted NSCs differentiate into neurons; β-Catenin siRNA decreased the NSE-positive neurons and increased GFAP-positive astrocytes in the NSCs in vitro. Furthermore, the expression of Ngn1 protein and mRNA in NSCs was increased when HBO promoted NSCs differentiate into neurons after HIBD, and the expression of BMP-4 protein and mRNA was decreased when HBO depressed NSCs differentiate into astrocytes after HIBD. These results showed that β-catenin-mediated transcriptional activation functions in the decision of NSCs to proliferate neurogenesis during HBO-induced after HIBD, and suggested that HBO therapy promotes the proliferation of neural stem cells in vitro, an effect that may be correlated with β-catenin protein and HBO therapy could promote neurogenesis by β-catenin-induced activated Ngn1 gene and repress astrocytogenesis by β-catenin-induced down-regulated BMP-4 gene.
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Affiliation(s)
- Xiao-Ying Zhang
- Department of Pediatrics, XiangYa Hospital, Central South University, Changsha, People's Republic of China
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55
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Abstract
The Wnt/β-catenin pathway plays an important role in development and disease. Theoretical approaches have been used to describe this pathway and have provided intriguing insights into its signalling characteristics. In the present paper, we review mathematical models of the pathway. We focus on a quantitative kinetic model for canonical Wnt/β-catenin signalling describing the reactions of the pathway's core compounds [Lee, Salic, Krüger, Heinrich and Kirschner (2003) PLoS Biol. 1, 116–132]. Numerous modifications and further analyses with respect to signalling characteristics, transcriptional feedback and cross-talk were performed. In addition, the role of β-catenin in gene expression and cell–cell adhesion as well as spatial aspects of signalling are investigated in various theoretical models.
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56
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Xue XJ, Yuan XB. Nestin is essential for mitogen-stimulated proliferation of neural progenitor cells. Mol Cell Neurosci 2010; 45:26-36. [PMID: 20510364 DOI: 10.1016/j.mcn.2010.05.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 04/29/2010] [Accepted: 05/14/2010] [Indexed: 12/28/2022] Open
Abstract
The intermediate filament (IF) protein nestin is a widely accepted molecular marker for neural progenitor cells (NPCs), but its function during neurogenesis remains largely unknown. We found that in embryonic cortical NPCs down-regulation of the expression of nestin, but not its co-polymer IF protein vimentin, resulted in a G1 cell-cycle arrest and a severe reduction in the generation of neurons. Furthermore, down-regulating nestin expression in cultured cortical NPCs markedly suppressed their colony-formation ability and blocked the elevation of the cyclin D1/E protein level in response to the treatment with bFGF. Interestingly, nestin down-regulation caused a marked suppression in the activation of the phosphoinositide 3-kinase (PI3K) pathway but not the mitogen-activated protein kinase (MAPK) pathway in these NPCs. Moreover, defects in the proliferation of cortical NPCs caused by nestin down-regulation could be prevented by up-regulating PI3K activity. Thus, nestin is essential for the proliferation of NPCs by promoting the activation of PI3K in response to mitogenic growth factors.
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Affiliation(s)
- Xiao-Jing Xue
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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57
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CNS/PNS boundary transgression by central glia in the absence of Schwann cells or Krox20/Egr2 function. J Neurosci 2010; 30:5958-67. [PMID: 20427655 DOI: 10.1523/jneurosci.0017-10.2010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
CNS/PNS interfaces constitute cell boundaries, because they delimit territories with different neuronal and glial contents. Despite their potential interest in regenerative medicine, the mechanisms restricting oligodendrocytes and astrocytes to the CNS and Schwann cells to the PNS in mammals are not known. To investigate the involvement of peripheral glia and myelin in the maintenance of the CNS/PNS boundary, we have first made use of different mouse mutants. We show that depletion of Schwann cells and boundary cap cells or inactivation of Krox20/Egr2, a master regulatory gene for myelination in Schwann cells, results in transgression of the CNS/PNS boundary by astrocytes and oligodendrocytes and in myelination of nerve root axons by oligodendrocytes. In contrast, such migration does not occur with the Trembler(J) mutation, which prevents PNS myelination without affecting Krox20 expression. Altogether, these data suggest that maintenance of the CNS/PNS boundary requires a Krox20 function separable from myelination control. Finally, we have analyzed a human patient affected by a congenital amyelinating neuropathy, associated with the absence of the KROX20 protein in Schwann cells. In this case, the nerve roots were also invaded by oligodendrocytes and astrocytes. This indicates that transgression of the CNS/PNS boundary by central glia can occur in pathological situations in humans and suggests that the underlying mechanisms are common with the mouse.
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58
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Itasaki N, Hoppler S. Crosstalk between Wnt and bone morphogenic protein signaling: a turbulent relationship. Dev Dyn 2010; 239:16-33. [PMID: 19544585 DOI: 10.1002/dvdy.22009] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Wnt and the bone morphogenic protein (BMP) pathways are evolutionarily conserved and essentially independent signaling mechanisms, which, however, often regulate similar biological processes. Wnt and BMP signaling are functionally integrated in many biological processes, such as embryonic patterning in Drosophila and vertebrates, formation of kidney, limb, teeth and bones, maintenance of stem cells, and cancer progression. Detailed inspection of regulation in these and other tissues reveals that Wnt and BMP signaling are functionally integrated in four fundamentally different ways. The molecular mechanism evolved to mediate this integration can also be summarized in four different ways. However, a fundamental aspect of functional and mechanistic interaction between these pathways relies on tissue-specific mechanisms, which are often not conserved and cannot be extrapolated to other tissues. Integration of the two pathways contributes toward the sophisticated means necessary for creating the complexity of our bodies and the reliable and healthy function of its tissues and organs.
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Affiliation(s)
- Nobue Itasaki
- Division of Developmental Neurobiology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom.
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59
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Ulloa F, Martí E. Wnt won the war: antagonistic role of Wnt over Shh controls dorso-ventral patterning of the vertebrate neural tube. Dev Dyn 2010; 239:69-76. [PMID: 19681160 DOI: 10.1002/dvdy.22058] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The spinal cord has been used as a model to dissect the mechanisms that govern the patterning of tissues during animal development, since the principles that rule the dorso-ventral patterning of the neural tube are applicable to other systems. Signals that determine the dorso-ventral axis of the spinal cord include Sonic hedgehog (Shh), acting as a bona fide morphogenetic signal to determine ventral progenitor identities, and members of the Bmp and the Wnt families, acting in the dorsal neural tube. Although Wnts have been initially recognized as important in proliferation of neural progenitor cells, their role in the dorso-ventral patterning has been controversial. In this review, we discuss recent reports that show an important contribution of the Wnt canonical pathway in dorso-ventral pattern formation. These data allow building a model by which the ventralizing activity of Shh is antagonized by Wnt activity through the expression of Gli3, a potent inhibitor of the Shh pathway. Therefore, antagonistic interactions between canonical Wnt, promoting dorsal identities, and Shh pathways, inducing ventral ones, would define the dorso-ventral patterning of the developing central nervous system.
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Affiliation(s)
- Fausto Ulloa
- Institute for Research in Biomedicine, Parc Cientific de Barcelona; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Department of Cell Biology, University of Barcelona, Barcelona, Spain
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60
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Resende RR, da Costa JL, Kihara AH, Adhikari A, Lorençon E. Intracellular Ca2+ Regulation During Neuronal Differentiation of Murine Embryonal Carcinoma and Mesenchymal Stem Cells. Stem Cells Dev 2010; 19:379-94. [DOI: 10.1089/scd.2008.0289] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Rodrigo R. Resende
- Department of Physics, Institute of Exacts Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
- Instituto de Ensino e Pesquisa Santa Casa de BH (ISCM-BH), Belo Horizante, Brazil
| | - José L. da Costa
- Instrumental Analysis Laboratory, Criminalistic Institute of São Paulo, São Paulo, Brazil; Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Alexandre H. Kihara
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, Santo André, Brasil
| | - Avishek Adhikari
- Department of Biological Sciences, Columbia University, New York
| | - Eudes Lorençon
- Department of Physics, Institute of Exacts Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
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61
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Inoue A, Nagafuchi A, Kikuchi A. Retinoic acid induces discrete Wnt-signaling-dependent differentiation in F9 cells. Biochem Biophys Res Commun 2009; 390:564-9. [DOI: 10.1016/j.bbrc.2009.10.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 10/02/2009] [Indexed: 02/01/2023]
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62
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Khalfallah O, Ravassard P, Lagache CS, Fligny C, Serre A, Bayard E, Faucon-Biguet N, Mallet J, Meloni R, Nardelli J. Zinc finger protein 191 (ZNF191/Zfp191) is necessary to maintain neural cells as cycling progenitors. Stem Cells 2009; 27:1643-53. [PMID: 19544452 DOI: 10.1002/stem.88] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The identification of the factors that allow better monitoring of stem cell renewal and differentiation is of paramount importance for the implementation of new regenerative therapies, especially with regard to the nervous and hematopoietic systems. In this article, we present new information on the function of zinc finger protein 191 (ZNF/Zfp191), a factor isolated in hematopoietic cell lines, within progenitors of the central nervous system (CNS). ZNF/Zfp191 has been found to be principally expressed in progenitors of the developing CNS of humans and mice. Such an overlap of the expression patterns in addition to the high homology of the protein in mammals suggested that ZNF/Zfp191 exerts a conserved function within such progenitors. Indeed, ZNF191 knockdown in human neural progenitors inhibits proliferation and leads to the exit of the cell cycle. Conversely, ZNF191 misexpression maintains progenitors in cycle and exerts negative control on the Notch pathway, which prevents them from differentiating. The present data, together with the fact that the inactivation of Zfp191 leads to embryonic lethality, confirm ZNF191 as an essential factor acting for the promotion of the cell cycle and thus maintenance in the progenitor stage. On the bases of expression data, such a function can be extended to progenitor cells of other tissues such as the hematopoietic system, which emphasizes the important issue of further understanding the molecular events controlled by ZNF/Zfp191.
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Affiliation(s)
- Olfa Khalfallah
- CRICM UPMC/Inserm UMR_S 975;CNRS UMR 7225, Biotechnology and Biotherapy Laboratory F-75005, Paris, France
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63
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Stage- and area-specific control of stem cells in the developing nervous system. Curr Opin Genet Dev 2009; 19:454-60. [DOI: 10.1016/j.gde.2009.08.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 07/23/2009] [Accepted: 08/07/2009] [Indexed: 12/18/2022]
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64
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Henke RM, Savage TK, Meredith DM, Glasgow SM, Hori K, Dumas J, MacDonald RJ, Johnson JE. Neurog2 is a direct downstream target of the Ptf1a-Rbpj transcription complex in dorsal spinal cord. Development 2009; 136:2945-54. [PMID: 19641016 DOI: 10.1242/dev.035352] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PTF1-J is a trimeric transcription factor complex essential for generating the correct balance of GABAergic and glutamatergic interneurons in multiple regions of the nervous system, including the dorsal horn of the spinal cord and the cerebellum. Although the components of PTF1-J have been identified as the basic helix-loop-helix (bHLH) factor Ptf1a, its heterodimeric E-protein partner, and Rbpj, no neural targets are known for this transcription factor complex. Here we identify the neuronal differentiation gene Neurog2 (Ngn2, Math4A, neurogenin 2) as a direct target of PTF1-J. A Neurog2 dorsal neural tube enhancer localized 3' of the Neurog2 coding sequence was identified that requires a PTF1-J binding site for dorsal activity in mouse and chick neural tube. Gain and loss of Ptf1a function in vivo demonstrate its role in Neurog2 enhancer activity. Furthermore, chromatin immunoprecipitation from neural tube tissue demonstrates that Ptf1a is bound to the Neurog2 enhancer. Thus, Neurog2 expression is directly regulated by the PTF1-J complex, identifying Neurog2 as the first neural target of Ptf1a and revealing a bHLH transcription factor cascade functioning in the specification of GABAergic neurons in the dorsal spinal cord and cerebellum.
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Affiliation(s)
- R Michael Henke
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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65
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Feigenson K, Reid M, See J, Crenshaw EB, Grinspan JB. Wnt signaling is sufficient to perturb oligodendrocyte maturation. Mol Cell Neurosci 2009; 42:255-65. [PMID: 19619658 DOI: 10.1016/j.mcn.2009.07.010] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 06/24/2009] [Accepted: 07/09/2009] [Indexed: 01/06/2023] Open
Abstract
The development of oligodendrocytes, the myelinating cells of the central nervous system, is temporally and spatially controlled by local signaling factors acting as inducers or inhibitors. Dorsal spinal cord tissue has been shown to contain inhibitors of oligodendrogliogenesis, although their identity is not completely known. We have studied the actions of one family of dorsal signaling molecules, the Wnts, on oligodendrocyte development. Using tissue culture models, we have shown that canonical Wnt activity through beta-catenin activation inhibits oligodendrocyte maturation, independently of precursor proliferation, cell death, or diversion to an alternate cell fate. Mice in which Wnt/beta-catenin signaling was constitutively activated in cells of the oligodendrocyte lineage had equal numbers of oligodendrocyte precursors relative to control littermates, but delayed appearance of mature oligodendrocytes, myelin protein, and myelinated axons during development, although these differences largely disappeared by adulthood. These results indicate that activating the Wnt/beta-catenin pathway delays the development of myelinating oligodendrocytes.
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Affiliation(s)
- Keith Feigenson
- Department of Research Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
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66
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Eyckmans J, Roberts SJ, Schrooten J, Luyten FP. A clinically relevant model of osteoinduction: a process requiring calcium phosphate and BMP/Wnt signalling. J Cell Mol Med 2009; 14:1845-56. [PMID: 19538476 PMCID: PMC3829044 DOI: 10.1111/j.1582-4934.2009.00807.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
In this study, we investigated a clinically relevant model of in vivo ectopic bone formation utilizing human periosteum derived cells (HPDCs) seeded in a Collagraft™ carrier and explored the mechanisms by which this process is driven. Bone formation occurred after eight weeks when a minimum of one million HPDCs was loaded on Collagraft™ carriers and implanted subcutaneously in NMRI nu/nu mice. De novo bone matrix, mainly secreted by the HPDCs, was found juxta-proximal of the calcium phosphate (CaP) granules suggesting that CaP may have triggered the ‘osteoinductive program’. Indeed, removal of the CaP granules by ethylenediaminetetraacetic acid decalcification prior to cell seeding and implantation resulted in loss of bone formation. In addition, inhibition of endogenous bone morphogenetic protein and Wnt signalling by overexpression of the secreted antagonists Noggin and Frzb, respectively, also abrogated osteoinduction. Proliferation of the engrafted HPDCs was strongly reduced in the decalcified scaffolds or when seeded with adenovirus-Noggin/Frzb transduced HPDCs indicating that cell division of the engrafted HPDCs is required for the direct bone formation cascade. These data suggest that this model of bone formation is similar to that observed during physiological intramembranous bone development and may be of importance when investigating tissue engineering strategies.
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Affiliation(s)
- J Eyckmans
- Laboratory for Skeletal Development and Joint Disorders, Katholieke Universiteit Leuven, Herestraat, Leuven, Belgium
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67
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Pierani A, Wassef M. Cerebral cortex development: From progenitors patterning to neocortical size during evolution. Dev Growth Differ 2009; 51:325-42. [PMID: 19298550 DOI: 10.1111/j.1440-169x.2009.01095.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The central nervous system is composed of thousands of distinct neurons that are assembled in a highly organized structure. In order to form functional neuronal networks, distinct classes of cells have to be generated in a precise number, in a spatial and temporal hierarchy and to be positioned at specific coordinates. An exquisite coordination of appropriate growth of competent territories and their patterning is required for regionalization and neurogenesis along both the anterior-posterior and dorso-ventral axis of the developing nervous system. The neocortex represents the brain territory that has undergone a major increase in its relative size during the course of mammalian evolution. In this review we will discuss how the fine tuning of growth and cell fate patterning plays a crucial role in the achievement of the final size of central nervous system structures and how divergence might have contributed to the surface increase of the cerebral cortex in mammals. In particular, we will describe how lack of precision might have been instrumental to neocortical evolution.
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Affiliation(s)
- Alessandra Pierani
- Centre National de Recherche Scientifique (CNRS)-UMR 7592, Institut Jacques Monod, Université Paris Diderot et UPMC, 2 place Jussieu, 75005 Paris, France.
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68
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Gribble SL, Kim HS, Bonner J, Wang X, Dorsky RI. Tcf3 inhibits spinal cord neurogenesis by regulating sox4a expression. Development 2009; 136:781-9. [PMID: 19176587 DOI: 10.1242/dev.027995] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The Lef/Tcf factor Tcf3 is expressed throughout the developing vertebrate central nervous system (CNS), but its function and transcriptional targets are uncharacterized. Tcf3 is thought to mediate canonical Wnt signaling, which functions in CNS patterning, proliferation and neurogenesis. In this study, we examine Tcf3 function in the zebrafish spinal cord, and find that this factor does not play a general role in patterning, but is required for the proper expression of Dbx genes in intermediate progenitors. In addition, we show that Tcf3 is required to inhibit premature neurogenesis in spinal progenitors by repressing sox4a, a known mediator of spinal neurogenesis. Both of these functions are mediated by Tcf3 independently of canonical Wnt signaling. Together, our data indicate a novel mechanism for the regulation of neurogenesis by Tcf3-mediated repression.
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Affiliation(s)
- Suzanna L Gribble
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
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69
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Falk S, Wurdak H, Ittner LM, Ille F, Sumara G, Schmid MT, Draganova K, Lang KS, Paratore C, Leveen P, Suter U, Karlsson S, Born W, Ricci R, Götz M, Sommer L. Brain area-specific effect of TGF-beta signaling on Wnt-dependent neural stem cell expansion. Cell Stem Cell 2009; 2:472-83. [PMID: 18462697 DOI: 10.1016/j.stem.2008.03.006] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 02/07/2008] [Accepted: 03/11/2008] [Indexed: 12/18/2022]
Abstract
Regulating the choice between neural stem cell maintenance versus differentiation determines growth and size of the developing brain. Here we identify TGF-beta signaling as a crucial factor controlling these processes. At early developmental stages, TGF-beta signal activity is localized close to the ventricular surface of the neuroepithelium. In the midbrain, but not in the forebrain, Tgfbr2 ablation results in ectopic expression of Wnt1/beta-catenin and FGF8, activation of Wnt target genes, and increased proliferation and horizontal expansion of neuroepithelial cells due to shortened cell-cycle length and decreased cell-cycle exit. Consistent with this phenotype, self-renewal of mutant neuroepithelial stem cells is enhanced in the presence of FGF and requires Wnt signaling. Moreover, TGF-beta signal activation counteracts Wnt-induced proliferation of midbrain neuroepithelial cells. Thus, TGF-beta signaling controls the size of a specific brain area, the dorsal midbrain, by antagonizing canonical Wnt signaling and negatively regulating self-renewal of neuroepithelial stem cells.
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Affiliation(s)
- Sven Falk
- Institute of Cell Biology, ETH-Hönggerberg, CH-8093 Zurich, Switzerland
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70
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Civenni G, Sommer L. Chemokines in neuroectodermal development and their potential implication in cancer stem cell-driven metastasis. Semin Cancer Biol 2008; 19:68-75. [PMID: 19084599 DOI: 10.1016/j.semcancer.2008.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 11/17/2008] [Indexed: 12/19/2022]
Abstract
Chemokines regulate proliferation and migration of various types of normal stem and progenitor cells, including precursor cells of neuroectodermal origin. Based on this it is conceivable that the established role of chemokines in cancer cell proliferation and organ-specific metastasis might also be associated with stem cell-like cells present in the tumor. Such cancer stem cells (CSCs) represent a small subpopulation of tumor cells that are thought to initiate and sustain tumor formation. More recently, characteristics of stem cells have also been observed in metastatic cancer cells, and it has been suggested that CSCs might play a crucial role in the metastatic process as such. Intriguingly, first evidence has been provided that the metastatic spread of specific CSCs is driven by chemokine signaling. Thus it is possible that chemokine-mediated CSC regulation might be a general feature of metastasis formation.
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Affiliation(s)
- Gianluca Civenni
- Cell and Developmental Biology, Institute of Anatomy, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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71
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Veien ES, Rosenthal JS, Kruse-Bend RC, Chien CB, Dorsky RI. Canonical Wnt signaling is required for the maintenance of dorsal retinal identity. Development 2008; 135:4101-11. [PMID: 19004855 DOI: 10.1242/dev.027367] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Accurate retinotectal axon pathfinding depends upon the correct establishment of dorsal-ventral retinal polarity. We show that dorsal retinal gene expression is regulated by Wnt signaling in the dorsal retinal pigment epithelium (RPE). We find that a Wnt reporter transgene and Wnt pathway components are expressed in the dorsal RPE beginning at 14-16 hours post-fertilization. In the absence of Wnt signaling, tbx5 and Bmp genes initiate normal dorsal retinal expression but are not maintained. The expression of these genes is rescued by the downstream activation of Wnt signaling, and tbx5 is rescued by Bmp signaling. Furthermore, activation of Wnt signaling cannot rescue tbx5 in the absence of Bmp signaling, suggesting that Wnt signaling maintains dorsal retinal gene expression by regulating Bmp signaling. We present a model in which dorsal RPE-derived Wnt activity maintains the expression of Bmp ligands in the dorsal retina, thus coordinating the patterning of these two ocular tissues.
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Affiliation(s)
- Eric S Veien
- Department of Neurobiology and Anatomy, University of Utah, 401 MREB, 20 N. 1900 E., Salt Lake City, UT 84132, USA
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72
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Yu W, McDonnell K, Taketo MM, Bai CB. Wnt signaling determines ventral spinal cord cell fates in a time-dependent manner. Development 2008; 135:3687-96. [PMID: 18927156 DOI: 10.1242/dev.021899] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The identity of distinct cell types in the ventral neural tube is generally believed to be specified by sonic hedgehog (Shh) in a concentration-dependent manner. However, recent studies have questioned whether Shh is the sole signaling molecule determining ventral neuronal cell fates. Here we provide evidence that canonical Wnt signaling is involved in the generation of different cell types in the ventral spinal cord. We show that Wnt signaling is active in the mouse ventral spinal cord at the time when ventral cell types are specified. Furthermore, using an approach that stabilizes beta-catenin protein in small patches of ventral spinal cord cells at different stages, we show that Wnt signaling activates different subsets of target genes depending on the time when Wnt signaling is amplified. Moreover, disruption of Wnt signaling results in the expansion of ventrally located progenitors. Finally, we show genetically that Wnt signaling interacts with Hh signaling at least in part through regulating the transcription of Gli3. Our results reveal a novel mechanism by which ventral patterning is achieved through a coordination of Wnt and Shh signaling.
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Affiliation(s)
- Weiying Yu
- Department of Genetics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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73
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Grigoryan T, Wend P, Klaus A, Birchmeier W. Deciphering the function of canonical Wnt signals in development and disease: conditional loss- and gain-of-function mutations of beta-catenin in mice. Genes Dev 2008; 22:2308-41. [PMID: 18765787 PMCID: PMC2749675 DOI: 10.1101/gad.1686208] [Citation(s) in RCA: 453] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Wnt signaling is one of a handful of powerful signaling pathways that play crucial roles in the animal life by controlling the genetic programs of embryonic development and adult homeostasis. When disrupted, these signaling pathways cause developmental defects, or diseases, among them cancer. The gateway of the canonical Wnt pathway, which contains >100 genes, is an essential molecule called beta-catenin (Armadillo in Drosophila). Conditional loss- and gain-of-function mutations of beta-catenin in mice provided powerful tools for the functional analysis of canonical Wnt signaling in many tissues and organs. Such studies revealed roles of Wnt signaling that were previously not accessible to genetic analysis due to the early embryonic lethality of conventional beta-catenin knockout mice, as well as the redundancy of Wnt ligands, receptors, and transcription factors. Analysis of conditional beta-catenin loss- and gain-of-function mutant mice demonstrated that canonical Wnt signals control progenitor cell expansion and lineage decisions both in the early embryo and in many organs. Canonical Wnt signaling also plays important roles in the maintenance of various embryonic or adult stem cells, and as recent findings demonstrated, in cancer stem cell types. This has opened new opportunities to model numerous human diseases, which have been associated with deregulated Wnt signaling. Our review summarizes what has been learned from genetic studies of the Wnt pathway by the analysis of conditional beta-catenin loss- and gain-of-function mice.
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Affiliation(s)
- Tamara Grigoryan
- Max-Delbück Center for Molecular Medicine, 13125 Berlin, Germany
| | - Peter Wend
- Max-Delbück Center for Molecular Medicine, 13125 Berlin, Germany
| | - Alexandra Klaus
- Max-Delbück Center for Molecular Medicine, 13125 Berlin, Germany
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74
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Wang WH, McNatt LG, Pang IH, Millar JC, Hellberg PE, Hellberg MH, Steely HT, Rubin JS, Fingert JH, Sheffield VC, Stone EM, Clark AF. Increased expression of the WNT antagonist sFRP-1 in glaucoma elevates intraocular pressure. J Clin Invest 2008; 118:1056-64. [PMID: 18274669 DOI: 10.1172/jci33871] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2007] [Accepted: 12/19/2007] [Indexed: 12/19/2022] Open
Abstract
Elevated intraocular pressure (IOP) is the principal risk factor for glaucoma and results from excessive impedance of the fluid outflow from the eye. This abnormality likely originates from outflow pathway tissues such as the trabecular meshwork (TM), but the associated molecular etiology is poorly understood. We discovered what we believe to be a novel role for secreted frizzled-related protein-1 (sFRP-1), an antagonist of Wnt signaling, in regulating IOP. sFRP1 was overexpressed in human glaucomatous TM cells. Genes involved in the Wnt signaling pathway were expressed in cultured TM cells and human TM tissues. Addition of recombinant sFRP-1 to ex vivo perfusion-cultured human eyes decreased outflow facility, concomitant with reduced levels of beta-catenin, the Wnt signaling mediator, in the TM. Intravitreal injection of an adenoviral vector encoding sFRP1 in mice produced a titer-dependent increase in IOP. Five days after vector injection, IOP increased 2 fold, which was significantly reduced by topical ocular administration of an inhibitor of a downstream suppressor of Wnt signaling. Thus, these data indicate that increased expression of sFRP1 in the TM appears to be responsible for elevated IOP in glaucoma and restoring Wnt signaling in the TM may be a novel disease intervention strategy for treating glaucoma.
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75
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Gribble SL, Nikolaus OB, Dorsky RI. Regulation and function of Dbx genes in the zebrafish spinal cord. Dev Dyn 2008; 236:3472-83. [PMID: 17994542 DOI: 10.1002/dvdy.21367] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Dbx homeodomain proteins are important for spinal cord dorsal/ventral patterning and the production of multiple spinal cord cell types. We have examined the regulation and function of Dbx genes in the zebrafish. We report that Hedgehog signaling is not required for the induction or maintenance of these genes; in the absence of Hedgehog signaling, dbx1a/1b/2 are expanded ventrally with concomitant increases in postmitotic neurons that differentiate from this domain. Also, we find that retinoic acid signaling is not required for the induction of Dbx expression. Furthermore, we are the first to report that knockdown of Dbx1 function causes a dorsal expansion of nkx6.2, which is thought to be the cross-repressive partner of Dbx1 in mouse. Our data confirm that the dbx1a/1b/2 domain in zebrafish spinal cord development behaves similarly to amniotes, while extending knowledge of Dbx1 function in spinal cord patterning.
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Affiliation(s)
- Suzanna L Gribble
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah 84132-3401, USA
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76
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Alvarez-Medina R, Cayuso J, Okubo T, Takada S, Martí E. Wnt canonical pathway restricts graded Shh/Gli patterning activity through the regulation of Gli3 expression. Development 2007; 135:237-47. [PMID: 18057099 DOI: 10.1242/dev.012054] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Dorsoventral patterning of the vertebrate nervous system is achieved by the combined activity of morphogenetic signals secreted from dorsal and ventral signalling centres. The Shh/Gli pathway plays a major role in patterning the ventral neural tube; however, the molecular mechanisms that limit target gene responses to specific progenitor domains remain unclear. Here, we show that Wnt1/Wnt3a, by signalling through the canonical beta-catenin/Tcf pathway, control expression of dorsal genes and suppression of the ventral programme, and that this role in DV patterning depends on Gli activity. Additionally, we show that Gli3 expression is controlled by Wnt activity. Identification and characterization of highly conserved non-coding DNA regions around the human Gli3 gene revealed the presence of transcriptionally active Tcf-binding sequences. These indicated that dorsal Gli3 expression might be directly regulated by canonical Wnt activity. In turn, Gli3, by acting as a transcriptional repressor, restricted graded Shh/Gli ventral activity to properly pattern the spinal cord.
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Affiliation(s)
- Roberto Alvarez-Medina
- Instituto de Biología Molecular de Barcelona, CSIC, Parc Cientific de Barcelona, C/Josep Samitier 1-5, Barcelona 08028, Spain
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77
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Proliferation and patterning are mediated independently in the dorsal spinal cord downstream of canonical Wnt signaling. Dev Biol 2007; 313:398-407. [PMID: 18062957 DOI: 10.1016/j.ydbio.2007.10.041] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Revised: 10/23/2007] [Accepted: 10/25/2007] [Indexed: 01/16/2023]
Abstract
Canonical Wnt signaling can regulate proliferation and patterning in the developing spinal cord, but the relationship between these functions has remained elusive. It has been difficult to separate the distinct activities of Wnts because localized changes in proliferation could conceivably alter patterning, and gain and loss of function experiments have resulted in both types of defects. To resolve this issue we have investigated canonical Wnt signaling in the zebrafish spinal cord using multiple approaches. We demonstrate that Wnt signaling is required initially for proliferation throughout the entire spinal cord, and later for patterning dorsal progenitor domains. Furthermore, we find that spinal cord patterning is normal in embryos after cell division has been pharmacologically blocked. Finally, we determine the transcriptional mediators of Wnt signaling that are responsible for patterning and proliferation. We show that tcf7 gene knockdown results in dorsal patterning defects without decreasing the mitotic index in dorsal domains. In contrast, tcf3 gene knockdown results in a reduced mitotic index without affecting dorsal patterning. Together, our work demonstrates that proliferation and patterning in the developing spinal cord are separable events that are regulated independently by Wnt signaling.
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78
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Michaelidis TM, Lie DC. Wnt signaling and neural stem cells: caught in the Wnt web. Cell Tissue Res 2007; 331:193-210. [PMID: 17828608 DOI: 10.1007/s00441-007-0476-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Accepted: 07/13/2007] [Indexed: 12/22/2022]
Abstract
Wnt proteins have now been identified as major physiological regulators of multiple aspects of stem cell biology, from self-renewal and pluripotency to precursor cell competence and terminal differentiation. Neural stem cells are the cellular building blocks of the developing nervous system and provide the basis for continued neurogenesis in the adult mammalian central nervous system. Here, we outline the most recent advances in the field about the critical factors and regulatory networks involved in Wnt signaling and discuss recent findings on how this increasingly intricate pathway contributes to the shaping of the developing and adult nervous system on the level of the neural stem cell.
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Affiliation(s)
- Theologos M Michaelidis
- GSF-National Research Center for Environment and Health, Institute of Developmental Genetics, Ingolstädter Landstrasse 1, 85764, Munich-Neuherberg, Germany
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79
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Li N, Volff JN, Wizenmann A. Rab23 GTPase is expressed asymmetrically in Hensen's node and plays a role in the dorsoventral patterning of the chick neural tube. Dev Dyn 2007; 236:2993-3006. [DOI: 10.1002/dvdy.21331] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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