101
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Lim BK, Cho SJ, Sumbre G, Poo MM. Region-specific contribution of ephrin-B and Wnt signaling to receptive field plasticity in developing optic tectum. Neuron 2010; 65:899-911. [PMID: 20346764 DOI: 10.1016/j.neuron.2010.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/07/2010] [Indexed: 10/19/2022]
Abstract
Ephrin-B/EphB and Wnts are known to regulate synapse maturation and plasticity, besides serving as axon guidance molecules, but the relevance of such synaptic regulation to neural circuit functions in vivo remains unclear. In this study, we have examined the role of ephrin-B and Wnt signaling in regulating visual experience-dependent and developmental plasticity of receptive fields (RFs) of tectal cells in the developing Xenopus optic tectum. We found that repetitive exposure to unidirectional moving visual stimuli caused varying degrees of shift in the RFs in different regions of the tectum. By acute perfusion of exogenous antagonists and inducible transgene expression, we showed that ephrin-B signaling in presynaptic retinal ganglion cells and Wnt secretion from tectal cells are specifically responsible for the enhanced visual stimulation-induced changes in neuronal responses and RFs in the ventral and dorsal tectum, respectively. Thus, ephrin-B and Wnt signaling contribute to region-specific plasticity of visual circuit functions.
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Affiliation(s)
- Byung Kook Lim
- Division of Neurobiology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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102
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Andersson ER, Bryjova L, Biris K, Yamaguchi TP, Arenas E, Bryja V. Genetic interaction between Lrp6 and Wnt5a during mouse development. Dev Dyn 2010; 239:237-45. [PMID: 19795512 DOI: 10.1002/dvdy.22101] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lrp6 is generally described as a receptor required for signal transduction in the Wnt/beta-catenin pathway. Wnt5a, however, is a Wnt ligand that usually does not activate Wnt/beta-catenin but rather activates noncanonical Wnt signaling. We have previously shown that Lrp6 can inhibit noncanonical Wnt5a/Wnt11 signaling and that Lrp5/6 loss-of-function produces noncanonical gain-of function defects, which can be rescued by loss of Wnt5a. Here, we describe other phenotypes found in Wnt5a/Lrp6 compound mutant mice, including a worsening of individual Wnt5a or Lrp6 loss of function phenotypes. Lrp6 haploinsufficiency in a Wnt5a-/- background caused spina bifida and exacerbated posterior truncation. Wnt5a-/-Lrp6-/- embryos displayed presomitic mesoderm morphogenesis, somitogenesis, and neurogenesis defects, which are much more severe than in either of the single mutants. Interestingly these results reveal a further level of complexity in processes in which Wnt5a and LRP6 cooperate, or oppose each other, during mouse development.
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Affiliation(s)
- Emma R Andersson
- Molecular Neurobiology, Department of Medical Biochemistry & Biophysics, Karolinska Institutet, Stockholm, Sweden
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103
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Warchol ME, Montcouquiol M. Maintained expression of the planar cell polarity molecule Vangl2 and reformation of hair cell orientation in the regenerating inner ear. J Assoc Res Otolaryngol 2010; 11:395-406. [PMID: 20177731 DOI: 10.1007/s10162-010-0209-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 01/18/2010] [Indexed: 12/27/2022] Open
Abstract
The avian inner ear possesses a remarkable ability to regenerate sensory hair cells after ototoxic injury. Regenerated hair cells possess phenotypes and innervation that are similar to those found in the undamaged ear, but little is known about the signaling pathways that guide hair cell differentiation during the regenerative process. The aim of the present study was to examine the factors that specify the orientation of hair cell stereocilia bundles during regeneration. Using organ cultures of the chick utricle, we show that hair cells are properly oriented after having regenerated entirely in vitro and that orientation is not affected by surgical removal of the striolar reversal zone. These results suggest that the orientation of regenerating stereocilia is not guided by the release of a diffusible morphogen from the striolar reversal zone but is specified locally within the regenerating sensory organ. In order to determine the nature of the reorientation cues, we examined the expression patterns of the core planar cell polarity molecule Vangl2 in the normal and regenerating utricle. We found that Vangl2 is asymmetrically expressed on cells within the sensory epithelium and that this expression pattern is maintained after ototoxic injury and throughout regeneration. Notably, treatment with a small molecule inhibitor of c-Jun-N-terminal kinase disrupted the orientation of regenerated hair cells. Both of these results are consistent with the hypothesis that noncanonical Wnt signaling guides hair cell orientation during regeneration.
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Affiliation(s)
- Mark E Warchol
- Fay and Carl Simons Center for the Biology of Hearing and Deafness, Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Ave., St. Louis, MO 63110, USA.
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104
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Koch S, Capaldo CT, Samarin S, Nava P, Neumaier I, Skerra A, Sacks DB, Parkos CA, Nusrat A. Dkk-1 inhibits intestinal epithelial cell migration by attenuating directional polarization of leading edge cells. Mol Biol Cell 2009; 20:4816-25. [PMID: 19776352 DOI: 10.1091/mbc.e09-05-0415] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Wnt signaling pathways regulate proliferation, motility, and survival in a variety of human cell types. Dickkopf-1 (Dkk-1) is a secreted Wnt antagonist that has been proposed to regulate tissue homeostasis in the intestine. In this report, we show that Dkk-1 is secreted by intestinal epithelial cells after wounding and that it inhibits cell migration by attenuating the directional orientation of migrating epithelial cells. Dkk-1 exposure induced mislocalized activation of Cdc42 in migrating cells, which coincided with a displacement of the polarity protein Par6 from the leading edge. Consequently, the relocation of the microtubule organizing center and the Golgi apparatus in the direction of migration was significantly and persistently inhibited in the presence of Dkk-1. Small interfering RNA-induced down-regulation of Dkk-1 confirmed that extracellular exposure to Dkk-1 was required for this effect. Together, these data demonstrate a novel role of Dkk-1 in the regulation of directional polarization of migrating intestinal epithelial cells, which contributes to the effect of Dkk-1 on wound closure in vivo.
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Affiliation(s)
- Stefan Koch
- Epithelial Pathobiology Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
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105
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Expression of Wnt receptors in adult spiral ganglion neurons: frizzled 9 localization at growth cones of regenerating neurites. Neuroscience 2009; 164:478-87. [PMID: 19716861 DOI: 10.1016/j.neuroscience.2009.08.049] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2009] [Revised: 08/21/2009] [Accepted: 08/22/2009] [Indexed: 01/10/2023]
Abstract
Little is known about signaling pathways, besides those of neurotrophic factors, that are operational in adult spiral ganglion neurons. In patients with sensorineural hearing loss, such pathways could eventually be targeted to stimulate and guide neurite outgrowth from the remnants of the spiral ganglion towards a cochlear implant, thereby improving the fidelity of sound transmission. To systematically identify neuronal receptors for guidance cues in the adult cochlea, we conducted a genome-wide cDNA microarray screen with 2-month-old CBA/CaJ mice. A meta-analysis of our data and those from older mice in two other studies revealed the presence of neuronal transmembrane receptors that represent all four established guidance pathways--ephrin, netrin, semaphorin, and slit--in the mature cochlea as late as 15 months. In addition, we observed the expression of all known receptors for the "wingless-related MMTV integration site" (Wnt) morphogens, whose neuronal guidance function has only recently been recognized. In situ hybridizations located the mRNAs of the Wnt receptors frizzled 1, 4, 6, 9, and 10 specifically in adult spiral ganglion neurons. Finally, frizzled 9 protein was found in the growth cones of adult spiral ganglion neurons that were regenerating neurites in culture. We conclude from our results that adult spiral ganglion neurons are poised to respond to neurite damage, owing to the constitutive expression of a large and diverse collection of guidance receptors. Wnt signaling, in particular, emerges as a candidate pathway for guiding neurite outgrowth towards a cochlear implant after sensorineural hearing loss.
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106
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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: 126] [Impact Index Per Article: 7.9] [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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107
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Wada H, Okamoto H. Roles of noncanonical Wnt/PCP pathway genes in neuronal migration and neurulation in zebrafish. Zebrafish 2009; 6:3-8. [PMID: 19250033 DOI: 10.1089/zeb.2008.0557] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Noncanonical Wnt/planar cell polarity (PCP) pathways regulate oriented cell movement during development in both Drosophila and vertebrates. Recent studies have revealed similarities and differences between these pathways in the tissues on which they act. In zebrafish, PCP pathway genes regulate the directional migration of a specific population of motor neurons in the hindbrain, as well as morphogenesis of the neuroepithelium. In the present review, neuronal and neuroepithelial defects in zebrafish PCP pathway mutants are compared, and the possible cellular and molecular mechanisms underlying these phenotypes are discussed. Future analyses of zebrafish PCP mutants will reveal the general mechanisms underlying the development of the neuroepithelium and provide novel insights into both conserved and diverse functions of PCP pathway genes in vertebrate development.
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Affiliation(s)
- Hironori Wada
- Center for Transdisciplinary Research, Niigata University , Niigata, Japan
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108
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Dawe HR, Adams M, Wheway G, Szymanska K, Logan CV, Noegel AA, Gull K, Johnson CA. Nesprin-2 interacts with meckelin and mediates ciliogenesis via remodelling of the actin cytoskeleton. J Cell Sci 2009; 122:2716-26. [PMID: 19596800 DOI: 10.1242/jcs.043794] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Meckel-Gruber syndrome (MKS) is a severe autosomal recessively inherited disorder caused by mutations in genes that encode components of the primary cilium and basal body. Here we show that two MKS proteins, MKS1 and meckelin, that are required for centrosome migration and ciliogenesis interact with actin-binding isoforms of nesprin-2 (nuclear envelope spectrin repeat protein 2, also known as Syne-2 and NUANCE). Nesprins are important scaffold proteins for maintenance of the actin cytoskeleton, nuclear positioning and nuclear-envelope architecture. However, in ciliated-cell models, meckelin and nesprin-2 isoforms colocalized at filopodia prior to the establishment of cell polarity and ciliogenesis. Loss of nesprin-2 and nesprin-1 shows that both mediate centrosome migration and are then essential for ciliogenesis, but do not otherwise affect apical-basal polarity. Loss of meckelin (by siRNA and in a patient cell-line) caused a dramatic remodelling of the actin cytoskeleton, aberrant localization of nesprin-2 isoforms to actin stress-fibres and activation of RhoA signalling. These findings further highlight the important roles of the nesprins during cellular and developmental processes, particularly in general organelle positioning, and suggest that a mechanistic link between centrosome positioning, cell polarity and the actin cytoskeleton is required for centrosomal migration and is essential for early ciliogenesis.
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Affiliation(s)
- Helen R Dawe
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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109
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A trophic role for Wnt-Ror kinase signaling during developmental pruning in Caenorhabditis elegans. Nat Neurosci 2009; 12:981-7. [PMID: 19561603 DOI: 10.1038/nn.2347] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Accepted: 05/05/2009] [Indexed: 11/09/2022]
Abstract
The molecular mechanism by which neurites are selected for elimination or incorporation into the mature circuit during developmental pruning remains unknown. The trophic theory postulates that local cues provided by target or surrounding cells act to inhibit neurite elimination. However, no widely conserved factor mediating this trophic function has been identified. We found that the developmental survival of specific neurites in Caenorhabditis elegans largely depends on detection of the morphogen Wnt by the Ror kinase CAM-1, which is a transmembrane tyrosine kinase with a Frizzled domain. Mutations in Wnt genes or in cam-1 enhanced neurite elimination, whereas overexpression of cam-1 inhibited neurite elimination in a Wnt-dependent manner. Moreover, mutations in these genes counteracted the effect of a mutation in mbr-1, which encodes a transcription factor that promotes neurite elimination. These results reveal the trophic role of an atypical Wnt pathway and reinforce the classical model of developmental pruning.
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110
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Vandenberg AL, Sassoon DA. Non-canonical Wnt signaling regulates cell polarity in female reproductive tract development via van gogh-like 2. Development 2009; 136:1559-70. [PMID: 19363157 DOI: 10.1242/dev.034066] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Wnt signaling effectors direct the development and adult remodeling of the female reproductive tract (FRT); however, the role of non-canonical Wnt signaling has not been explored in this tissue. The non-canonical Wnt signaling protein van gogh-like 2 is mutated in loop-tail (Lp) mutant mice (Vangl2(Lp)), which display defects in multiple tissues. We find that Vangl2(Lp) mutant uterine epithelium displays altered cell polarity, concommitant with changes in cytoskeletal actin and scribble (scribbled, Scrb1) localization. The postnatal mutant phenotype is an exacerbation of that seen at birth, exhibiting more smooth muscle and reduced stromal mesenchyme. These data suggest that early changes in cell polarity have lasting consequences for FRT development. Furthermore, Vangl2 is required to restrict Scrb1 protein to the basolateral epithelial membrane in the neonatal uterus, and an accumulation of fibrillar-like structures observed by electron microscopy in Vangl2(Lp) mutant epithelium suggests that mislocalization of Scrb1 in mutants alters the composition of the apical face of the epithelium. Heterozygous and homozygous Vangl2(Lp) mutant postnatal tissues exhibit similar phenotypes and polarity defects and display a 50% reduction in Wnt7a levels, suggesting that the Vangl2(Lp) mutation acts dominantly in the FRT. These studies demonstrate that the establishment and maintenance of cell polarity through non-canonical Wnt signaling are required for FRT development.
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111
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Bodmer D, Levine-Wilkinson S, Richmond A, Hirsh S, Kuruvilla R. Wnt5a mediates nerve growth factor-dependent axonal branching and growth in developing sympathetic neurons. J Neurosci 2009; 29:7569-81. [PMID: 19515925 PMCID: PMC2759712 DOI: 10.1523/jneurosci.1445-09.2009] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Accepted: 05/06/2009] [Indexed: 01/27/2023] Open
Abstract
Nerve growth factor (NGF) is a potent survival and axon growth factor for neuronal populations in the peripheral nervous system. Although the mechanisms by which target-derived NGF influences survival of innervating neurons have been extensively investigated, its regulation of axonal growth and target innervation are just being elucidated. Here, we identify Wnt5a, a member of the Wnt family of secreted growth factors, as a key downstream effector of NGF in mediating axonal branching and growth in developing sympathetic neurons. Wnt5a is robustly expressed in sympathetic neurons when their axons are innervating NGF-expressing targets. NGF:TrkA signaling enhances neuronal expression of Wnt5a. Wnt5a rapidly induces axon branching while it has a long-term effect on promoting axon extension. Loss of Wnt5a function revealed that it is necessary for NGF-dependent axonal branching and growth, but not survival, in vitro. Furthermore, Wnt5a(-/-) mice display reduced innervation of NGF-expressing target tissues, and a subsequent increase in neuronal apoptosis, in vivo. Wnt5a functions in developing sympathetic neurons by locally activating protein kinase C in axons. Together, our findings define a novel regulatory pathway in which Wnt5a, expressed in sympathetic neurons in response to target-derived NGF, regulates innervation of peripheral targets.
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Affiliation(s)
- Daniel Bodmer
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218
| | | | - Alissa Richmond
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218
| | - Sarah Hirsh
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218
| | - Rejji Kuruvilla
- Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218
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112
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Farías GG, Alfaro IE, Cerpa W, Grabowski CP, Godoy JA, Bonansco C, Inestrosa NC. Wnt-5a/JNK signaling promotes the clustering of PSD-95 in hippocampal neurons. J Biol Chem 2009; 284:15857-66. [PMID: 19332546 PMCID: PMC2708882 DOI: 10.1074/jbc.m808986200] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 03/06/2009] [Indexed: 01/22/2023] Open
Abstract
During the formation of synapses, specific regions of pre- and postsynaptic cells associate to form a single functional transmission unit. In this process, synaptogenic factors are necessary to modulate pre- and postsynaptic differentiation. In mammals, different Wnt ligands operate through canonical and non-canonical Wnt pathways, and their precise functions to coordinate synapse structure and function in the mature central nervous system are still largely unknown. Here, we studied the effect of different Wnt ligands on postsynaptic organization. We found that Wnt-5a induces short term changes in the clustering of PSD-95, without affecting its total levels. Wnt-5a promotes the recruitment of PSD-95 from a diffuse dendritic cytoplasmic pool to form new PSD-95 clusters in dendritic spines. Moreover, Wnt-5a acting as a non-canonical ligand regulates PSD-95 distribution through a JNK-dependent signaling pathway, as demonstrated by using the TAT-TI-JIP peptide in mature hippocampal neurons. Finally, using adult rat hippocampal slices, we found that Wnt-5a modulates glutamatergic synaptic transmission through a postsynaptic mechanism. Our studies indicate that the Wnt-5a/JNK pathway modulates the postsynaptic region of mammalian synapse directing the clustering and distribution of the physiologically relevant scaffold protein, PSD-95.
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Affiliation(s)
- Ginny G. Farías
- From the Centro de Envejecimiento y Regeneración, Centro de Regulación Celular y Patología “Joaquín V. Luco,” Instituto Milenio, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, P.O. Box 8331150, Santiago, Chile
| | - Iván E. Alfaro
- From the Centro de Envejecimiento y Regeneración, Centro de Regulación Celular y Patología “Joaquín V. Luco,” Instituto Milenio, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, P.O. Box 8331150, Santiago, Chile
| | - Waldo Cerpa
- From the Centro de Envejecimiento y Regeneración, Centro de Regulación Celular y Patología “Joaquín V. Luco,” Instituto Milenio, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, P.O. Box 8331150, Santiago, Chile
- Centro de Neurobiología y Plasticidad del Desarrollo, Departamento de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, P.O. Box 2360102, Valparaíso, Chile
| | - Catalina P. Grabowski
- From the Centro de Envejecimiento y Regeneración, Centro de Regulación Celular y Patología “Joaquín V. Luco,” Instituto Milenio, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, P.O. Box 8331150, Santiago, Chile
| | - Juan A. Godoy
- From the Centro de Envejecimiento y Regeneración, Centro de Regulación Celular y Patología “Joaquín V. Luco,” Instituto Milenio, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, P.O. Box 8331150, Santiago, Chile
| | - Christian Bonansco
- Centro de Neurobiología y Plasticidad del Desarrollo, Departamento de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, P.O. Box 2360102, Valparaíso, Chile
| | - Nibaldo C. Inestrosa
- From the Centro de Envejecimiento y Regeneración, Centro de Regulación Celular y Patología “Joaquín V. Luco,” Instituto Milenio, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, P.O. Box 8331150, Santiago, Chile
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113
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Hingwing K, Lee S, Nykilchuk L, Walston T, Hardin J, Hawkins N. CWN-1 functions with DSH-2 to regulate C. elegans asymmetric neuroblast division in a β-catenin independent Wnt pathway. Dev Biol 2009; 328:245-56. [DOI: 10.1016/j.ydbio.2009.01.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 01/14/2009] [Accepted: 01/17/2009] [Indexed: 12/30/2022]
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114
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Wada H, Okamoto H. Roles of planar cell polarity pathway genes for neural migration and differentiation. Dev Growth Differ 2009; 51:233-40. [DOI: 10.1111/j.1440-169x.2009.01092.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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115
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Abstract
The "core genes" were identified as a group of genes believed to function as a conserved signaling cassette for the specification of planar polarity in Drosophila Melanogaster, and includes frizzled (fz), van gogh (vang) or strabismus (stbm), prickle (Pk), dishevelled (dsh), flamingo (fmi), and diego. The mutation of each of these genes not only causes the disruption of planar polarity within the wing or the eye of the animal, but also affects the localization of all the other protein members of the core group. These properties emphasize the importance of the interrelations between the proteins of this group. All of these core genes have homologs in vertebrates. Studies in Danio Rerio (zebrafish) and Xenopus laevis (frog) have uncovered other roles for some of these molecules in gastrulation and neurulation, during which the shape of a given tissue will undergo major transformation through cell movements. A disruption in these processes can lead to severe neural tube defects in diverse organisms, including humans. In fact, a large body of evidence suggests that planar polarity proteins are not involved in one specific cascade but in many different ones and many different mechanisms such as, but not limited to, hair or cilia orientation, asymmetric division, cellular movements, or neuronal migration. In mice cochleae, mutations in planar polarity genes lead to defects in the orientation of the stereociliary bundles at the apex of each hair cell. This phenotype established the cochlea as one of the clearest examples of planar polarity in mammals. Although significant progress has been made toward understanding the molecular basis required for the development of planar polarity in invertebrates, similar advances in vertebrates are more recent and rely mainly on the identification of a group of mammalian mutants that affect hair cell stereociliary bundle orientation. These include mutation of vangl2, scrb1, celsr1, PTK-7, dvl1-2, and more recently fz3 and fz6. In this chapter, we describe how to use the mammalian cochlea, which represents one of the best systems to study planar polarity in mammals, to identify planar polarity mutants, study protein distribution, do in vitro analysis, and perform Western blots to analyze putative planar polarity proteins.
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116
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Davis EK, Zou Y, Ghosh A. Wnts acting through canonical and noncanonical signaling pathways exert opposite effects on hippocampal synapse formation. Neural Dev 2008; 3:32. [PMID: 18986540 PMCID: PMC2596118 DOI: 10.1186/1749-8104-3-32] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2008] [Accepted: 11/05/2008] [Indexed: 11/21/2022] Open
Abstract
Background Wnt proteins comprise a large class of signaling molecules that regulate a variety of developmental processes, including synapse formation. Previous studies have shown Wnts to be involved in both the induction and prevention of synapses in a number of different organisms. However, it is not clear whether the influence of Wnts on synapses is a result of Wnts' behavior in different organisms or differences in the activity of different Wnt ligands. Results We used in situ hybridization to show that several Wnt ligands (Wnt3, Wnt5a, Wnt7a, and Wnt7b) and their receptors, Frizzled, are expressed in the developing hippocampus during the period of synapse formation in rodents. We used recombinant Wnt protein or Wnt conditioned media to explore the effects of Wnts on synapses in hippocampal cultures. We found that Wnt7a and Wnt7b activate canonical signaling, whereas Wnt5a activates a noncanonical pathway. The activation of the canonical pathway, either through pathway manipulations or through Wnt stimulation, increases presynaptic inputs. In contrast, exposure to Wnt5a, which activates a noncanonical signaling pathway, decreases the number of presynaptic terminals. Conclusion Our observations suggest that the pro- and antisynaptogenic effects of Wnt proteins are associated with the activation of the canonical and noncanonical Wnt signaling pathways.
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Affiliation(s)
- Elizabeth K Davis
- Division of Biological Sciences, Neurobiology Section, UCSD, La Jolla, CA 92093-0366, USA.
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117
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Abstract
The Wnt signaling network, which is composed of Wnt ligands, receptors, antagonists, and intracellular signaling molecules, has emerged as a powerful regulator of cell fate, proliferation, and function in multicellular organisms. Over the past two decades, the critical role of Wnt signaling in embryonic cartilage and bone development has been well established, and much has been learnt regarding the role of Wnt signaling in chondrogenesis and cartilage development. However, relatively little is known about the role of Wnt signaling in adult articular cartilage and degenerative cartilage tissue. This review will briefly summarize recent advances in Wnt regulation of chondrogenesis and hypertrophic maturation of chondrocytes, and review data concerning the role of Wnt signaling in the maintenance and degeneration of articular chondrocytes and cartilage.
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Affiliation(s)
- Jang-Soo Chun
- Cell Dynamics Research Center, Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Korea.
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118
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Killeen MT, Sybingco SS. Netrin, Slit and Wnt receptors allow axons to choose the axis of migration. Dev Biol 2008; 323:143-51. [PMID: 18801355 DOI: 10.1016/j.ydbio.2008.08.027] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Revised: 08/15/2008] [Accepted: 08/26/2008] [Indexed: 01/25/2023]
Abstract
One of the challenges to understanding nervous system development has been to establish how a fairly limited number of axon guidance cues can set up the patterning of very complex nervous systems. Studies on organisms with relatively simple nervous systems such as Drosophila melanogaster and C. elegans have provided many insights into axon guidance mechanisms. The axons of many neurons migrate along both the dorsal-ventral (DV) and the anterior-posterior (AP) axes at different phases of development, and in addition they may also cross the midline. Axon migration in the dorsal-ventral (DV) direction is mainly controlled by Netrins with their receptors; UNC-40/DCC and UNC-5, and the Slits with their receptors; Robo/SAX-3. Axon guidance in the anterior-posterior (AP) axis is mainly controlled by Wnts with their receptors; the Frizzleds/Fz. An individual axon may be subjected to opposing attractive and repulsive forces coming from opposite sides in the same axis but there may also be opposing cues in the other axis of migration. All the information from the cues has to be integrated within the growth cone at the leading edge of the migrating axon to elicit a response. Recent studies have provided insight into how this is achieved. Evidence suggests that the axis of axon migration is determined by the manner in which Netrin, Slit and Wnt receptors are polarized (localized) within the neuron prior to axon outgrowth. The same molecules are involved in both axon outgrowth and axon guidance, for at least some neurons in C. elegans, whether the cue is the attractive cue UNC-6/Netrin working though UNC-40/DCC or the repulsive cue SLT-1/Slit working though the receptor SAX-3/Robo (Adler et al., 2006, Chang et al., 2006, Quinn et al., 2006, 2008). The molecules involved in cell signaling in this case are polarized within the cell body of the neuron before process outgrowth and direct the axon outgrowth. Expression of the Netrin receptor UNC-40/DCC or the Slit receptor SAX-3/Robo in axons that normally migrate in the AP direction causes neuronal polarity reversal in a Netrin and Slit independent manner (Levy-Strumpf and Culotti 2007, Watari-Goshima et al., 2007). Localization of the receptors in this case is caused by the kinesin-related VAB-8L which appears to govern the site of axon outgrowth in these neurons by causing receptor localization. Therefore, asymmetric localization of axon guidance receptors is followed by axon outgrowth in vivo using the receptor's normal cue, either attractive, repulsive or unknown cues.
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Affiliation(s)
- Marie T Killeen
- Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, Ontario, Canada M5B 2K3.
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119
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Wu J, Mlodzik M. The frizzled extracellular domain is a ligand for Van Gogh/Stbm during nonautonomous planar cell polarity signaling. Dev Cell 2008; 15:462-469. [PMID: 18804440 PMCID: PMC2814157 DOI: 10.1016/j.devcel.2008.08.004] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 06/25/2008] [Accepted: 08/18/2008] [Indexed: 01/19/2023]
Abstract
The Frizzled (Fz) receptor is required cell autonomously in Wnt/beta-catenin and planar cell polarity (PCP) signaling. In addition to these requirements, Fz acts nonautonomously during PCP establishment: wild-type cells surrounding fz(-) patches reorient toward the fz(-) cells. The molecular mechanism(s) of nonautonomous Fz signaling are unknown. Our in vivo studies identify the extracellular domain (ECD) of Fz, in particular its CRD (cysteine rich domain), as critical for nonautonomous Fz-PCP activity. Importantly, we demonstrate biochemical and physical interactions between the FzECD and the transmembrane protein Van Gogh/Strabismus (Vang/Stbm). We show that this function precedes cell-autonomous interactions and visible asymmetric PCP factor localization. Our data suggest that Vang/Stbm can act as a FzECD receptor, allowing cells to sense Fz activity/levels of their neighbors. Thus, direct Fz-Vang/Stbm interactions represent an intriguing mechanism that may account for the global orientation of cells within the plane of their epithelial field.
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Affiliation(s)
- Jun Wu
- Mount Sinai School of Medicine, Department of Developmental and Regenerative Biology, 1 Gustav L. Levy Place, New York, NY 10029, USA
| | - Marek Mlodzik
- Mount Sinai School of Medicine, Department of Developmental and Regenerative Biology, 1 Gustav L. Levy Place, New York, NY 10029, USA.
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120
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The multiple-wing-hairs gene encodes a novel GBD-FH3 domain-containing protein that functions both prior to and after wing hair initiation. Genetics 2008; 180:219-28. [PMID: 18723886 DOI: 10.1534/genetics.108.091314] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The frizzled signaling/signal transduction pathway controls planar cell polarity (PCP) in both vertebrates and invertebrates. Epistasis experiments argue that in the Drosophila epidermis multiple wing hairs (mwh) acts as a downstream component of the pathway. The PCP proteins accumulate asymmetrically in pupal wing cells where they are thought to form distinct protein complexes. One is located on the distal side of wing cells and a second on the proximal side. This asymmetric protein accumulation is thought to lead to the activation of the cytoskeleton on the distal side, which in turn leads to each cell forming a single distally pointing hair. We identified mwh as CG13913, which encodes a novel G protein binding domain-formin homology 3 (GBD-FH3) domain protein. The Mwh protein accumulated on the proximal side of wing cells prior to hair formation. Unlike planar polarity proteins such as Frizzled or Inturned, Mwh also accumulated in growing hairs. This suggested that mwh had two temporally separate functions in wing development. Evidence for these two functions also came from temperature-shift experiments with a temperature-sensitive allele. Overexpression of Mwh inhibited hair initiation, thus Mwh acts as a negative regulator of the cytoskeleton. Our data argued early proximal Mwh accumulation restricts hair initiation to the distal side of wing cells and the later hair accumulation of Mwh prevents the formation of ectopic secondary hairs. This later function appears to be a feedback mechanism that limits cytoskeleton activation to ensure a single hair is formed.
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121
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Caspi E, Rosin-Arbesfeld R. A novel functional screen in human cells identifies MOCA as a negative regulator of Wnt signaling. Mol Biol Cell 2008; 19:4660-74. [PMID: 18716063 DOI: 10.1091/mbc.e07-10-1046] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Aberrant Wnt signal transduction is involved in many human diseases such as cancer and neurodegenerative disorders. The key effector protein of the canonical Wnt pathway is beta-catenin, which functions with T-cell factor/lymphoid enhancer factor (TCF/LEF) to activate gene transcription that leads to expression of Wnt target genes. In this study we provide results obtained from a novel functional screen of a human brain cDNA library used to identify 63 genes that are putative negative Wnt regulators. These genes were divided into eight functional groups that include known canonical and noncanonical Wnt pathway components and genes that had not yet been assigned to the Wnt pathway. One of the groups, the presenilin-binding proteins, contains the modifier of cell adhesion (MOCA) gene. We show that MOCA is a novel inhibitor of Wnt/beta-catenin signaling. MOCA forms a complex with beta-catenin and inhibits transcription of known Wnt target genes. Epistasis experiments indicate that MOCA acts to reduce the levels of nuclear beta-catenin, increase the levels of membrane-bound beta-catenin, and enhances cell-cell adhesion. Therefore, our data indicate that MOCA is a novel Wnt negative regulator and demonstrate that this screening approach can be a rapid means for isolation of new Wnt regulators.
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Affiliation(s)
- Elanite Caspi
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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122
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Hardin J, King RS. The long and the short of Wnt signaling in C. elegans. Curr Opin Genet Dev 2008; 18:362-7. [PMID: 18625312 DOI: 10.1016/j.gde.2008.06.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 06/04/2008] [Accepted: 06/14/2008] [Indexed: 10/21/2022]
Abstract
The simplicity of C. elegans makes it an outstanding system to study the role of Wnt signaling in development. Many asymmetric cell divisions in C. elegans require the Wnt/beta-catenin asymmetry pathway. Recent studies confirm that SYS-1 is a structurally and functionally divergent beta-catenin, and implicate lipids and retrograde trafficking in maintenance of WRM-1/beta-catenin asymmetry. Wnts also regulate short-range events such as spindle rotation and gastrulation, and a PCP-like pathway regulates asymmetric divisions. Long-range, cell non-autonomous Wnt signals regulate vulval induction. Both short-range and long-range Wnt signal s are regulated by recycling of MIG-14/Wntless via the retromer complex. These studies indicate that C. elegans continues to be useful for identifying new, conserved mechanisms underlying Wnt signaling in metazoans.
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Affiliation(s)
- Jeff Hardin
- Graduate Program in Cellular and Molecular Biology, Department of Zoology, University of Wisconsin, 1117 W. Johnson Street, Madison, WI 53706, USA.
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123
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Endo Y, Beauchamp E, Woods D, Taylor WG, Toretsky JA, Uren A, Rubin JS. Wnt-3a and Dickkopf-1 stimulate neurite outgrowth in Ewing tumor cells via a Frizzled3- and c-Jun N-terminal kinase-dependent mechanism. Mol Cell Biol 2008; 28:2368-79. [PMID: 18212053 PMCID: PMC2268413 DOI: 10.1128/mcb.01780-07] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Revised: 10/23/2007] [Accepted: 01/09/2008] [Indexed: 11/20/2022] Open
Abstract
Recombinant Wnt-3a stimulated the rapid formation of elongated processes in Ewing sarcoma family tumor (ESFT) cells that were identified as neurites. The processes stained positively for polymerized actin and microtubules as well as synapsin I and growth-associated protein 43. Inhibition of the Wnt receptor, Frizzled3 (Fzd3), with antiserum or by short interfering RNA (siRNA) markedly reduced neurite extension. Knockdown of Dishevelled-2 (Dvl-2) and Dvl-3 also suppressed neurite outgrowth. Surprisingly, disruption of the Wnt/Fzd/lipoprotein receptor-related protein (LRP) complex and the associated beta-catenin signaling by treating cells either with the Wnt antagonist Dickkopf-1 (Dkk1) or LRP5/LRP6 siRNA enhanced neuritogenesis. Neurite outgrowth induced by Dkk1 or with LRP5/LRP6 siRNA was inhibited by secreted Fzd-related protein 1, a Wnt antagonist that binds directly to Wnt. Moreover, Dkk1 stimulation of neurite outgrowth was blocked by Fzd3 siRNA. These results suggested that Dkk1 shifted endogenous Wnt activity from the beta-catenin pathway to Fzd3-mediated, noncanonical signaling that is responsible for neurite formation. In particular, c-Jun amino-terminal kinase (JNK) was important for neurite outgrowth stimulated by both Wnt-3a and Dkk1. Our data demonstrate that Fzd3, Dvl, and JNK activity mediate Wnt-dependent neurite outgrowth and that ESFT cell lines will be useful experimental models for the study of Wnt-dependent neurite extension.
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Affiliation(s)
- Yoshimi Endo
- National Cancer Institute, Bldg. 37, Room 2042, 37 Convent Drive, MSC 4256, Bethesda, MD 20892-4256, USA
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124
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Issack PS, Helfet DL, Lane JM. Role of Wnt signaling in bone remodeling and repair. HSS J 2008; 4:66-70. [PMID: 18751865 PMCID: PMC2504275 DOI: 10.1007/s11420-007-9072-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Accepted: 11/16/2007] [Indexed: 02/07/2023]
Abstract
The Wnt genes encode a highly conserved class of signaling factors required for the development of several types of tissues including musculoskeletal and neural structures. There is increasing evidence that Wnt signaling is critical for bone mass accrual, bone remodeling, and fracture repair. Wnt proteins bind to cell-surface receptors and activate signaling pathways which control nuclear gene expression; this Wnt-regulated gene expression controls cell growth and differentiation. Many of the components of the Wnt pathway have recently been characterized, and specific loss-of-function or gain-of-function mutations in this pathway in mice and in humans have resulted in disorders of deficient or excess bone formation, respectively. Pharmacologically targeting components of the Wnt signaling pathway will allow for the manipulation of bone formation and remodeling and will have several orthopedic applications including enhancing bone formation in nonunion and osteoporosis and restricting pathologic bone formation in osteogenic tumors and heterotopic ossification.
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Affiliation(s)
- Paul S. Issack
- Orthopaedic Trauma, Adult Reconstructive Surgery, and Metabolic Bone Diseases, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021 USA
| | - David L. Helfet
- Orthopaedic Trauma Service, Hospital for Special Surgery and Weill-Cornell Medical Center, New York, NY USA
| | - Joseph M. Lane
- Metabolic Bone Disease Service, Hospital for Special Surgery, New York, NY USA
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125
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Abstract
Most, if not all, cell types and tissues display several aspects of polarization. In addition to the ubiquitous epithelial cell polarity along the apical-basolateral axis, many epithelial tissues and organs are also polarized within the plane of the epithelium. This is generally referred to as planar cell polarity (PCP; or historically, tissue polarity). Genetic screens in Drosophila pioneered the discovery of core PCP factors, and subsequent work in vertebrates has established that the respective pathways are evolutionarily conserved. PCP is not restricted only to epithelial tissues but is also found in mesenchymal cells, where it can regulate cell migration and cell intercalation. Moreover, particularly in vertebrates, the conserved core PCP signaling factors have recently been found to be associated with the orientation or formation of cilia. This review discusses new developments in the molecular understanding of PCP establishment in Drosophila and vertebrates; these developments are integrated with new evidence that links PCP signaling to human disease.
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Affiliation(s)
- Matias Simons
- Mount Sinai School of Medicine, Department of Developmental & Regenerative Biology, New York, NY 10029;
| | - Marek Mlodzik
- Mount Sinai School of Medicine, Department of Developmental & Regenerative Biology, New York, NY 10029;
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126
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Li S, Zhang SQ, Liu SW, Li BY, Zhu HL, Yu H, Zheng QY. Assessment criteria for rotated stereociliary bundles in the guinea pig cochlea. Otol Neurotol 2008; 29:86-92. [PMID: 18199962 PMCID: PMC2832703 DOI: 10.1097/mao.0b013e31815dbb5b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Our study examined the relationship between variant stereociliary bundles of cochlear outer hair cells (OHCs) and auditory function to analyze assessment criteria for rotated stereociliary bundles in the guinea pig cochlea. METHODS Auditory brainstem response and distortion product otoacoustic emission (DPOAE) were recorded on 100 guinea pigs. Variant hair cells were identified and counted by scanning electron and light microscopy. RESULTS The most common variation observed was rotation of stereociliary bundles in the first-row OHCs (OHC1), with most 13.3% variant OHC1 rotated 90 degrees and a few 2.5% rotated 180 degrees. Occasionally, the length and angle of the 2 arms of an OHC deviated from the norm. The auditory brainstem response threshold of affected animals increased only slightly, 20- to 30-dB sound pressure level. More importantly, amplitude of DPOAE increased significantly (40.5 dB sound pressure level). CONCLUSION Our study suggests that rotation of stereociliary bundles in the cochlear OHC was found to be prevalent in 28% of the animals. We established the assessment criteria for rotated stereociliary bundles that were more than 10% OHC1 rotated. This hair bundle seemed to be rotated by 90 degrees from the normal orientation and was accompanied with changes of auditory function. Increased amplitude of DPOAE is associated with the variation of rotated OHC that might result in hearing loss.
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MESH Headings
- Action Potentials/drug effects
- Action Potentials/physiology
- Animals
- Anti-Bacterial Agents/toxicity
- Cilia/drug effects
- Cilia/physiology
- Cochlea/drug effects
- Cochlea/physiology
- Cochlea/ultrastructure
- Evoked Potentials, Auditory, Brain Stem/drug effects
- Evoked Potentials, Auditory, Brain Stem/physiology
- Gentamicins/toxicity
- Guinea Pigs
- Hair Cells, Auditory, Outer/drug effects
- Hair Cells, Auditory, Outer/physiology
- Hair Cells, Auditory, Outer/ultrastructure
- Microscopy, Electron, Scanning
- Otoacoustic Emissions, Spontaneous/drug effects
- Otoacoustic Emissions, Spontaneous/physiology
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Affiliation(s)
- Shengli Li
- Department of Hearing Research, Center of Neuroscience and Otolaryngology of Second Hospital, Xi’an Jiaotong University of Medicine, Xi’an, China
- Department of Otolaryngology-HNS, Case Western Reserve University, Cleveland, Ohio, U.S.A
| | - Shao Qiang Zhang
- Department of Hearing Research, Center of Neuroscience and Otolaryngology of Second Hospital, Xi’an Jiaotong University of Medicine, Xi’an, China
| | - Si Wei Liu
- Department of Hearing Research, Center of Neuroscience and Otolaryngology of Second Hospital, Xi’an Jiaotong University of Medicine, Xi’an, China
| | - Bai Ya Li
- Department of Hearing Research, Center of Neuroscience and Otolaryngology of Second Hospital, Xi’an Jiaotong University of Medicine, Xi’an, China
| | - Hong Liang Zhu
- Department of Hearing Research, Center of Neuroscience and Otolaryngology of Second Hospital, Xi’an Jiaotong University of Medicine, Xi’an, China
| | - Heping Yu
- Department of Hearing Research, Center of Neuroscience and Otolaryngology of Second Hospital, Xi’an Jiaotong University of Medicine, Xi’an, China
| | - Qing Yin Zheng
- Department of Hearing Research, Center of Neuroscience and Otolaryngology of Second Hospital, Xi’an Jiaotong University of Medicine, Xi’an, China
- Department of Otolaryngology-HNS, Case Western Reserve University, Cleveland, Ohio, U.S.A
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127
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Christensen ST, Pedersen SF, Satir P, Veland IR, Schneider L. The primary cilium coordinates signaling pathways in cell cycle control and migration during development and tissue repair. Curr Top Dev Biol 2008; 85:261-301. [PMID: 19147009 DOI: 10.1016/s0070-2153(08)00810-7] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cell cycle control and migration are critical processes during development and maintenance of tissue functions. Recently, primary cilia were shown to take part in coordination of the signaling pathways that control these cellular processes in human health and disease. In this review, we present an overview of the function of primary cilia and the centrosome in the signaling pathways that regulate cell cycle control and migration with focus on ciliary signaling via platelet-derived growth factor receptor alpha (PDGFRalpha). We also consider how the primary cilium and the centrosome interact with the extracellular matrix, coordinate Wnt signaling, and modulate cytoskeletal changes that impinge on both cell cycle control and cell migration.
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Affiliation(s)
- Søren T Christensen
- Department of Biology, Section of Cell and Developmental Biology, The August Krogh Building, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen OE, Denmark
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128
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Jones C, Roper VC, Foucher I, Qian D, Banizs B, Petit C, Yoder BK, Chen P. Ciliary proteins link basal body polarization to planar cell polarity regulation. Nat Genet 2007; 40:69-77. [PMID: 18066062 DOI: 10.1038/ng.2007.54] [Citation(s) in RCA: 271] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 09/21/2007] [Indexed: 11/09/2022]
Abstract
Planar cell polarity (PCP) refers to coordinated polarization of cells within the plane of a cell sheet. A conserved signaling pathway is required for the establishment of PCP in epithelial tissues and for polarized cellular rearrangements known as convergent extension. During PCP signaling, core PCP proteins are sorted asymmetrically along the polarization axis; this sorting is thought to direct coordinated downstream morphogenetic changes across the entire tissue. Here, we show that a gene encoding a ciliary protein (a 'ciliary gene'), Ift88, also known as Polaris, is required for establishing epithelial PCP and for convergent extension of the cochlear duct of Mus musculus. We also show that the proper positioning of ciliary basal bodies and the formation of polarized cellular structures are disrupted in mice with mutant ciliary proteins ('ciliary mutants'), whereas core PCP proteins are partitioned normally along the polarization axis. Thus, our data uncover a distinct requirement for ciliary genes in basal body positioning and morphological polarization during PCP regulation.
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Affiliation(s)
- Chonnettia Jones
- Department of Cell Biology, Emory University School of Medicine, 615 Michael St., Atlanta, Georgia 30322, USA
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129
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Klassen MP, Shen K. Wnt signaling positions neuromuscular connectivity by inhibiting synapse formation in C. elegans. Cell 2007; 130:704-16. [PMID: 17719547 DOI: 10.1016/j.cell.2007.06.046] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 03/16/2007] [Accepted: 06/18/2007] [Indexed: 11/21/2022]
Abstract
Nervous system function is mediated by a precisely patterned network of synaptic connections. While several cell-adhesion and secreted molecules promote the assembly of synapses, the contribution of signals that negatively regulate synaptogenesis is not well understood. We examined synapse formation in the Caenorhabditis elegans motor neuron DA9, whose presynapses are restricted to a specific segment of its axon. We report that the Wnt lin-44 localizes the Wnt receptor lin-17/Frizzled (Fz) to a subdomain of the DA9 axon that is devoid of presynaptic specializations. When this signaling pathway, composed of the Wnts lin-44 and egl-20, lin-17/Frizzled and dsh-1/Dishevelled, is compromised, synapses develop ectopically in this subdomain. Conversely, overexpression of LIN-44 in cells adjacent to DA9 is sufficient to expand LIN-17 localization within the DA9 axon, thereby inhibiting presynaptic assembly. These results suggest that morphogenetic signals can spatially regulate the patterning of synaptic connections by subdividing an axon into discrete domains.
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Affiliation(s)
- Matthew P Klassen
- Department of Biological Sciences and Neurosciences Program, Stanford University, Stanford, CA 94305, USA
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130
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Van Raay TJ, Coffey RJ, Solnica-Krezel L. Zebrafish Naked1 and Naked2 antagonize both canonical and non-canonical Wnt signaling. Dev Biol 2007; 309:151-68. [PMID: 17689523 PMCID: PMC2729589 DOI: 10.1016/j.ydbio.2007.04.018] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2006] [Revised: 04/04/2007] [Accepted: 04/17/2007] [Indexed: 01/18/2023]
Abstract
Wnt signaling controls a wide range of developmental processes and its aberrant regulation can lead to disease. To better understand the regulation of this pathway, we identified zebrafish homologues of Naked Cuticle (Nkd), Nkd1 and Nkd2, which have previously been shown to inhibit canonical Wnt/beta-catenin signaling. Zebrafish nkd1 expression increases substantially after the mid-blastula transition in a pattern mirroring that of activated canonical Wnt/beta-catenin signaling, being expressed in both the ventrolateral blastoderm margin and also in the axial mesendoderm. In contrast, zebrafish nkd2 is maternally and ubiquitously expressed. Overexpression of Nkd1 or Nkd2a suppressed canonical Wnt/beta-catenin signaling at multiple stages of early zebrafish development and also exacerbated the cyclopia and axial mesendoderm convergence and extension (C&E) defect in the non-canonical Wnt/PCP mutant silberblick (slb/wnt11). Thus, Nkds are sufficient to antagonize both canonical and non-canonical Wnt signaling. Reducing Nkd function using antisense morpholino oligonucleotides resulted in increased expression of canonical Wnt/beta-catenin target genes. Finally, reducing Nkd1 function in slb mutants suppressed the axial mesendoderm C&E defect. These data indicate that zebrafish Nkd1 and Nkd2 function to limit both canonical and non-canonical Wnt signaling.
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Affiliation(s)
| | - Robert J. Coffey
- Department of Medicine, Vanderbilt University Medical Center, USA
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, USA
- Department of Veterans Affairs Medical Center, Nashville, TN 37232-2279, USA
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131
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Zhang Y, Liu K, Gao Y, Li S. Modulation of Dishevelled and Vangl2 by all-trans-retinoic acid in the developing mouse central nervous system and its relationship to teratogenesis. Acta Biochim Biophys Sin (Shanghai) 2007; 39:684-92. [PMID: 17805463 DOI: 10.1111/j.1745-7270.2007.00325.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The response to exposure to all-trans-retinoic acid (RA) during embryogenesis varies from physiologic to severe teratogenic effects and is dependent upon the dose and the stage of development in all species. Vangl2 and Dishevelled genes play key roles in establishing planar cell polarity and regulating convergent extension movements during the neurula period. The effects of RA-mediated teratogenesis might be due to its misregulation of Vangl2 and Dishevelled genes. The aim of this study is to monitor the modulation of Vangl2 and Dishevelled in Kunming mouse embryos following maternal treatment with a single oral dose of 30 mg/(kg body weight) of RA during the neurula period. Exposure of 7.75 d embryos to RA induced characteristic morphological changes. The most obvious external effect was the failure of neural tube closure in the midbrain and forebrain regions in 10 d embryos, resulting in exencephaly in later embryos. RA treatment also led to a pronounced decrease of Vangl2 mRNA at 4 and 18 h and a pronounced increase at 66 h after maternal treatment, as detected by reverse transcription-polymerase chain reaction. Western blot analysis showed a marked decrease of Vangl2 protein at 18 and 42 h and a marked increase at 66 and 90 h after maternal treatment. Dishevelled1/2/3 mRNA was significantly down-regulated at 4 and 18 h and up-regulated at 42 h in the fetus after RA treatment, except for an up-regulation of Dishevelled3 at 66 h. The Dishevelled2 mRNA and its protein matched each other. These results hinted that Vangl2 and Dishevelled genes might take part in RA teratogenesis of mouse embryos.
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Affiliation(s)
- Yanping Zhang
- Department of Histology and Embryology, Medical College of Shandong University, Jinan 250012, China
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132
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Abstract
Neural tube defects (NTDs) represent a common group of severe congenital malformations that result from failure of neural tube closure during early development. Their etiology is quite complex involving environmental and genetic factors and their underlying molecular and cellular pathogenic mechanisms remain poorly understood. Animal studies have recently demonstrated an essential role for the planar cell polarity pathway (PCP) in mediating a morphogenetic process called convergent extension during neural tube formation. Alterations in members of this pathway lead to NTDs in vertebrate models, representing novel and exciting candidates for human NTDs. Genetic studies in NTDs have focused mainly on folate-related genes based on the finding that perinatal folic acid supplementation reduces the risk of NTDs by 60-70%. A few variants in these genes have been found to be significantly associated with an increased risk for NTDs. The candidate gene approach investigating genes involved in neurulation has failed to identify major causative genes in the etiology of NTDs. Despite this history of generally negative findings, we are achieving a rapid and impressive progress in understanding the genetic basis of NTDs, based mainly on the powerful tool of animal models.
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Affiliation(s)
- Z Kibar
- CHU Sainte-Justine Research Center and Department of Obstetrics and Gynecology, University of Montreal, Montreal, QC, Canada.
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133
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Wang Y, Nathans J. Tissue/planar cell polarity in vertebrates: new insights and new questions. Development 2007; 134:647-58. [PMID: 17259302 DOI: 10.1242/dev.02772] [Citation(s) in RCA: 348] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This review focuses on the tissue/planar cell polarity (PCP) pathway and its role in generating spatial patterns in vertebrates. Current evidence suggests that PCP integrates both global and local signals to orient diverse structures with respect to the body axes. Interestingly, the system acts on both subcellular structures, such as hair bundles in auditory and vestibular sensory neurons, and multicellular structures, such as hair follicles. Recent work has shown that intriguing connections exist between the PCP-based orienting system and left-right asymmetry, as well as between the oriented cell movements required for neural tube closure and tubulogenesis. Studies in mice, frogs and zebrafish have revealed that similarities, as well as differences, exist between PCP in Drosophila and vertebrates.
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Affiliation(s)
- Yanshu Wang
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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134
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Pan J, You Y, Huang T, Brody SL. RhoA-mediated apical actin enrichment is required for ciliogenesis and promoted by Foxj1. J Cell Sci 2007; 120:1868-76. [PMID: 17488776 DOI: 10.1242/jcs.005306] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Programs that direct cellular differentiation are dependent on the strict temporal expression of regulatory factors that can be provided by Rho GTPases. Ciliogenesis is a complex sequence of events involving the generation and docking of basal bodies at the apical membrane, followed by ciliary axoneme generation. Although a cilia proteome has been assembled, programs that direct ciliated cell differentiation are not well established, particularly in mammalian systems. Using mouse primary culture airway epithelial cells, we identified a critical stage of ciliogenesis requiring the temporal establishment of an apical web-like structure of actin for basal body docking and subsequent axoneme growth. Apical web formation and basal body docking were prevented by interruption of actin remodeling and were dependent on RhoA activation. Additional evidence for this program was provided by analysis of Foxj1-null mice that failed to dock basal bodies and lacked apical actin. Foxj1 expression coincided with actin web formation, activated RhoA and RhoB, and persisted despite RhoA inhibition, suggesting that Foxj1 promoted RhoA during ciliogenesis. Apical ezrin localization was also dependent on Foxj1, actin remodeling, and RhoA, but was not critical for ciliogenesis. Thus, temporal Foxj1 and RhoA activity are essential regulatory events for cytoskeletal remodeling during mammalian ciliogenesis.
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Affiliation(s)
- Jiehong Pan
- Pulmonary and Critical Care Medicine, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
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135
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Arimura N, Kaibuchi K. Neuronal polarity: from extracellular signals to intracellular mechanisms. Nat Rev Neurosci 2007; 8:194-205. [PMID: 17311006 DOI: 10.1038/nrn2056] [Citation(s) in RCA: 501] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
After they are born and differentiate, neurons break their previous symmetry, dramatically change their shape, and establish two structurally and functionally distinct compartments - axons and dendrites - within one cell. How do neurons develop their morphologically and molecularly distinct compartments? Recent studies have implicated several signalling pathways evoked by extracellular signals as having essential roles in a number of aspects of neuronal polarization.
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Affiliation(s)
- Nariko Arimura
- Department of Cell Pharmacology, Graduate School of Medicine, Nagoya University, 65, Tsurumai, Showa, Nagoya, Aichi 466-8550, Japan
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136
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Schleiffarth JR, Person AD, Martinsen BJ, Sukovich DJ, Neumann A, Baker CVH, Lohr JL, Cornfield DN, Ekker SC, Petryk A. Wnt5a is required for cardiac outflow tract septation in mice. Pediatr Res 2007; 61:386-91. [PMID: 17515859 DOI: 10.1203/pdr.0b013e3180323810] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Lack of septation of the cardiac outflow tract (OFT) results in persistent truncus arteriosus (PTA), a form of congenital heart disease. The outflow myocardium expands through addition of cells originating from the pharyngeal mesoderm referred to as secondary/anterior heart field, whereas cardiac neural crest (CNC) cell-derived mesenchyme condenses to form an aortopulmonary septum. We show for the first time that a mutation in Wnt5a in mice leads to PTA. We provide evidence that Wnt5a is expressed in the pharyngeal mesoderm adjacent to CNC cells in both mouse and chicken embryos and in the myocardial cell layer of the conotruncus at the time when CNC cells begin to form the aortopulmonary septum in mice. Although expression domains of secondary heart field markers are not altered in Wnt5a mutant embryos, the expression of CNC cell marker PlexinA2 is significantly reduced. Stimulation of CNC cells with Wnt5a protein elicits Ca2+ transients, suggesting that CNC cells are capable of responding to Wnt5a. We propose a novel model in which Wnt5a produced in the OFT by cells originating from the pharyngeal mesoderm signals to adjacent CNC cells during formation of the aortopulmonary septum through a noncanonical pathway via localized intracellular increases in Ca2+.
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Affiliation(s)
- J Robert Schleiffarth
- Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota 55455, USA
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137
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Seifert JRK, Mlodzik M. Frizzled/PCP signalling: a conserved mechanism regulating cell polarity and directed motility. Nat Rev Genet 2007; 8:126-38. [PMID: 17230199 DOI: 10.1038/nrg2042] [Citation(s) in RCA: 394] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Signalling through Frizzled (Fz)/planar cell polarity (PCP) is a conserved mechanism that polarizes cells along specific axes in a tissue. Genetic screens in Drosophila melanogaster pioneered the discovery of core PCP factors, which regulate the orientation of hairs on wings and facets in eyes. Recent genetic evidence shows that the Fz/PCP pathway is conserved in vertebrates and is crucial for disparate processes as gastrulation and sensory cell orientation. Fz/PCP signalling depends on complex interactions between core components, leading to their asymmetric distribution and ultimately polarized activity in a cell. Whereas several mechanistic aspects of PCP have been uncovered, the global coordination of this polarization remains debated.
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Affiliation(s)
- Jessica R K Seifert
- Brookdale Department of Molecular, Cell and Developmental Biology, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA
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138
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Song MR, Shirasaki R, Cai CL, Ruiz EC, Evans SM, Lee SK, Pfaff SL. T-Box transcription factor Tbx20 regulates a genetic program for cranial motor neuron cell body migration. Development 2007; 133:4945-55. [PMID: 17119020 PMCID: PMC5851594 DOI: 10.1242/dev.02694] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Members of the T-box transcription factor family (Tbx) are associated with several human syndromes during embryogenesis. Nevertheless, their functions within the developing CNS remain poorly characterized. Tbx20 is expressed by migrating branchiomotor/visceromotor (BM/VM) neurons within the hindbrain during neuronal circuit formation. We examined Tbx20 function in BM/VM cells using conditional Tbx20-null mutant mice to delete the gene in neurons. Hindbrain rhombomere patterning and the initial generation of post-mitotic BM/VM neurons were normal in Tbx20 mutants. However, Tbx20 was required for the tangential (caudal) migration of facial neurons, the lateral migration of trigeminal cells and the trans-median movement of vestibuloacoustic neurons. Facial cell soma migration defects were associated with the coordinate downregulation of multiple components of the planar cell polarity pathway including Fzd7, Wnt11, Prickle1, Vang1 and Vang2. Our study suggests that Tbx20 programs a variety of hindbrain motor neurons for migration, independent of directionality, and in facial neurons is a positive regulator of the non-canonical Wnt signaling pathway.
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Affiliation(s)
- Mi-Ryoung Song
- Gene Expression Laboratory, The Salk Institute, La Jolla, CA 92037, USA
| | - Ryuichi Shirasaki
- Gene Expression Laboratory, The Salk Institute, La Jolla, CA 92037, USA
| | - Chen-Leng Cai
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Esmeralda C. Ruiz
- Gene Expression Laboratory, The Salk Institute, La Jolla, CA 92037, USA
| | - Sylvia M. Evans
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Soo-Kyung Lee
- Gene Expression Laboratory, The Salk Institute, La Jolla, CA 92037, USA
| | - Samuel L. Pfaff
- Gene Expression Laboratory, The Salk Institute, La Jolla, CA 92037, USA
- Author for correspondence ()
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139
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Abe K, Takeichi M. NMDA-Receptor Activation Induces Calpain-Mediated β-Catenin Cleavages for Triggering Gene Expression. Neuron 2007; 53:387-97. [PMID: 17270735 DOI: 10.1016/j.neuron.2007.01.016] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Revised: 10/03/2006] [Accepted: 01/17/2007] [Indexed: 11/28/2022]
Abstract
The canonical Wnt-beta-catenin signaling pathway is important for a variety of developmental phenomena as well as for carcinogenesis. Here, we show that, in hippocampal neurons, NMDA-receptor-dependent activation of calpain induced the cleavage of beta-catenin at the N terminus, generating stable, truncated forms. These beta-catenin fragments accumulated in the nucleus and induced Tcf/Lef-dependent gene transcription. We identified Fosl1, one of the immediate-early genes, as a target of this signaling pathway. In addition, exploratory behavior by mice resulted in a similar cleavage of beta-catenin, as well as activation of the Tcf signaling pathway, in hippocampal neurons. Both beta-catenin cleavage and Tcf-dependent gene transcription were suppressed by calpain inhibitors. These findings reveal another pathway for beta-catenin-dependent signaling, in addition to the canonical Wnt-beta-catenin pathway, and suggest that this other pathway could play an important role in activity-dependent gene expression.
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Affiliation(s)
- Kentaro Abe
- Graduate School of Biostudies, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan
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140
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Abstract
The sensory epithelia of the inner ear contain mechanosensory hair cells and non-sensory supporting cells. Both classes of cell are heterogeneous, with phenotypes varying both between and within epithelia. The specification of individual cells as distinct types of hair cell or supporting cell is regulated through intra- and extracellular signalling pathways that have been poorly understood. However, new methodologies have resulted in significant steps forward in our understanding of the molecular pathways that direct cells towards these cell fates.
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Affiliation(s)
- Matthew W Kelley
- Section on Developmental Neuroscience, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, 35 Convent Dr., Bethesda, Maryland 20892, USA.
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141
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Cai C, Grabel L. Directing the differentiation of embryonic stem cells to neural stem cells. Dev Dyn 2007; 236:3255-66. [PMID: 17823944 DOI: 10.1002/dvdy.21306] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Embryonic stem cells (ESCs) are a potential source of neural derivatives that can be used in stem cell-based therapies designed to treat neurological disorders. The derivation of specific neuronal or glial cell types from ESCs invariably includes the production of neural stem cells (NSCs). We describe the basic mechanisms of neural induction during vertebrate embryogenesis and how this information helped formulate several protocols used to generate NSCs from ESCs. We highlight the advantages and disadvantages of each approach and review what has been learned about the intermediate stages in the transition from ESC to NSC. Recent data describing how specific growth factors and signaling molecules regulate production of NSCs are described and a model synthesizing this information is presented.
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Affiliation(s)
- Chunyu Cai
- Biology Department, Wesleyan University, Middletown, Connecticut 06459-1070, USA
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