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Nixon-Abell J, Berwick DC, Grannó S, Spain VA, Blackstone C, Harvey K. Protective LRRK2 R1398H Variant Enhances GTPase and Wnt Signaling Activity. Front Mol Neurosci 2016; 9:18. [PMID: 27013965 PMCID: PMC4781896 DOI: 10.3389/fnmol.2016.00018] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 02/22/2016] [Indexed: 12/04/2022] Open
Abstract
Mutations in LRRK2 are a common cause of familial and idiopathic Parkinson’s disease (PD). Recently, the LRRK2 GTPase domain R1398H variant was suggested in genetic studies to confer protection against PD but mechanistic data supporting this is lacking. Here, we present evidence that R1398H affects GTPase function, axon outgrowth, and Wnt signaling in a manner opposite to pathogenic LRRK2 mutations. LRRK2 R1398H GTPase domain dimerization and GTP hydrolysis were increased whereas GTP binding was reduced, leading to a decrease in active GTP-bound LRRK2. This protective variant also increased axon length of primary cortical neurones in comparison to wild-type LRRK2, whereas the R1441G LRRK2 pathogenic mutant decreased axon outgrowth. Importantly, R1398H enhanced the stimulatory effect of LRRK2 on canonical Wnt signaling whereas the G2385R risk variant, in accordance with all previously tested pathogenic LRRK2 mutants, had the opposite effect. Molecular modeling placed R1398H in close proximity to PD-causing mutations suggesting that this protective LRRK2 variant, like familial mutations, affects intramolecular RocCOR domain interactions. Thus, our data suggest that R1398H LRRK2 is a bona fide protective variant. The opposite effects of protective versus PD associated LRRK2 variants on GTPase function and canonical Wnt signaling activity also suggests that regulation of these two basic signaling mechanisms is important for neuronal function. We conclude that LRRK2 mediated Wnt signaling and GTPase function are fundamental in conferring disease susceptibility and have clear implications for therapeutic target identification.
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Affiliation(s)
- Jonathon Nixon-Abell
- Department of Pharmacology, UCL School of Pharmacy, University College LondonLondon, UK; Neurogenetics Branch, National Institute of Neurological Disorders and Stroke - National Institutes of Health, BethesdaMD, USA
| | - Daniel C Berwick
- Department of Pharmacology, UCL School of Pharmacy, University College LondonLondon, UK; Department of Life, Health and Chemical Sciences, The Open UniversityMilton Keynes, UK
| | - Simone Grannó
- Department of Pharmacology, UCL School of Pharmacy, University College London London, UK
| | - Victoria A Spain
- Department of Pharmacology, UCL School of Pharmacy, University College London London, UK
| | - Craig Blackstone
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke - National Institutes of Health, Bethesda MD, USA
| | - Kirsten Harvey
- Department of Pharmacology, UCL School of Pharmacy, University College London London, UK
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102
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Horigane SI, Ageta-Ishihara N, Kamijo S, Fujii H, Okamura M, Kinoshita M, Takemoto-Kimura S, Bito H. Facilitation of axon outgrowth via a Wnt5a-CaMKK-CaMKIα pathway during neuronal polarization. Mol Brain 2016; 9:8. [PMID: 26772170 PMCID: PMC4715351 DOI: 10.1186/s13041-016-0189-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 01/10/2016] [Indexed: 11/10/2022] Open
Abstract
Background Wnt5a, originally identified as a guidance cue for commissural axons, activates a non-canonical pathway critical for cortical axonal morphogenesis. The molecular signaling cascade underlying this event remains obscure. Results Through Ca2+ imaging in acute embryonic cortical slices, we tested if radially migrating cortical excitatory neurons that already bore primitive axons were sensitive to Wnt5a. While Wnt5a only evoked brief Ca2+ transients in immature neurons present in the intermediate zone (IZ), Wnt5a-induced Ca2+ oscillations were sustained in neurons that migrated out to the cortical plate (CP). We wondered whether this early Wnt5a-Ca2+ signaling during neuronal polarization has a morphogenetic consequence. During transition from round to polarized shape, Wnt5a administration to immature cultured cortical neurons specifically promoted axonal, but not dendritic, outgrowth. Pharmacological and genetic inhibition of the CaMKK-CaMKIα pathway abolished Wnt5a-induced axonal elongation, and rescue of CaMKIα in CaMKIα-knockdown neurons restored Wnt5a-mediated axon outgrowth. Conclusions This study suggests that Wnt5a activates Ca2+ signaling during a neuronal morphogenetic time window when axon outgrowth is critically facilitated. Furthermore, the CaMKK-CaMKIα cascade is required for the axonal growth effect of Wnt5a during neuronal polarization. Electronic supplementary material The online version of this article (doi:10.1186/s13041-016-0189-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shin-ichiro Horigane
- Department of Neurochemistry, Graduate School of Medicine, The University of Tokyo, Igakubu-3-gokan, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. .,Department of Neuroscience I, Research Institute of Environmental Medicine, Nagoya University, Nagoya, 464-8601, Japan.
| | - Natsumi Ageta-Ishihara
- Department of Neurochemistry, Graduate School of Medicine, The University of Tokyo, Igakubu-3-gokan, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. .,Department of Molecular Biology, Division of Biological Sciences, Nagoya University Graduate School of Science, Furo-cho, Chikusa, Nagoya, 464-8602, Japan.
| | - Satoshi Kamijo
- Department of Neurochemistry, Graduate School of Medicine, The University of Tokyo, Igakubu-3-gokan, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. .,CREST, Japan Agency for Medical Research and Development, Chiyoda-ku, Tokyo, 100-0004, Japan.
| | - Hajime Fujii
- Department of Neurochemistry, Graduate School of Medicine, The University of Tokyo, Igakubu-3-gokan, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. .,CREST, Japan Agency for Medical Research and Development, Chiyoda-ku, Tokyo, 100-0004, Japan.
| | - Michiko Okamura
- Department of Neurochemistry, Graduate School of Medicine, The University of Tokyo, Igakubu-3-gokan, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| | - Makoto Kinoshita
- Department of Molecular Biology, Division of Biological Sciences, Nagoya University Graduate School of Science, Furo-cho, Chikusa, Nagoya, 464-8602, Japan.
| | - Sayaka Takemoto-Kimura
- Department of Neurochemistry, Graduate School of Medicine, The University of Tokyo, Igakubu-3-gokan, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. .,Department of Neuroscience I, Research Institute of Environmental Medicine, Nagoya University, Nagoya, 464-8601, Japan. .,PRESTO, Japan Science and Technology Agency, Chiyoda-ku, Tokyo, 102-0076, Japan.
| | - Haruhiko Bito
- Department of Neurochemistry, Graduate School of Medicine, The University of Tokyo, Igakubu-3-gokan, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. .,CREST, Japan Agency for Medical Research and Development, Chiyoda-ku, Tokyo, 100-0004, Japan.
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103
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β-Catenin, a Transcription Factor Activated by Canonical Wnt Signaling, Is Expressed in Sensory Neurons of Calves Latently Infected with Bovine Herpesvirus 1. J Virol 2016; 90:3148-59. [PMID: 26739046 DOI: 10.1128/jvi.02971-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 12/30/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Like many Alphaherpesvirinae subfamily members, bovine herpesvirus 1 (BoHV-1) expresses an abundant transcript in latently infected sensory neurons, the latency-related (LR)-RNA. LR-RNA encodes a protein (ORF2) that inhibits apoptosis, interacts with Notch family members, interferes with Notch-mediated transcription, and stimulates neurite formation in cells expressing Notch. An LR mutant virus containing stop codons at the amino terminus of ORF2 does not reactivate from latency or replicate efficiently in certain tissues, indicating that LR gene products are important. In this study, β-catenin, a transcription factor activated by the canonical Wnt signaling pathway, was frequently detected in ORF2-positive trigeminal ganglionic neurons of latently infected, but not mock-infected, calves. Conversely, the lytic cycle regulatory protein (BoHV-1 infected cell protein 0, or bICP0) was not frequently detected in β-catenin-positive neurons in latently infected calves. During dexamethasone-induced reactivation from latency, mRNA expression levels of two Wnt antagonists, Dickkopf-1 (DKK-1) and secreted Frizzled-related protein 2 (SFRP2), were induced in bovine trigeminal ganglia (TG), which correlated with reduced β-catenin protein expression in TG neurons 6 h after dexamethasone treatment. ORF2 and a coactivator of β-catenin, mastermind-like protein 1 (MAML1), stabilized β-catenin protein levels and stimulated β-catenin-dependent transcription in mouse neuroblastoma cells more effectively than MAML1 or ORF2 alone. Neuroblastoma cells expressing ORF2, MAML1, and β-catenin were highly resistant to cell death following serum withdrawal, whereas most cells transfected with only one of these genes died. The Wnt signaling pathway interferes with neurodegeneration but promotes neuronal differentiation, suggesting that stabilization of β-catenin expression by ORF2 promotes neuronal survival and differentiation. IMPORTANCE Bovine herpesvirus 1 (BoHV-1) is an important pathogen of cattle, and like many Alphaherpesvirinae subfamily members establishes latency in sensory neurons. Lifelong latency and the ability to reactivate from latency are crucial for virus transmission. Maintaining the survival and normal functions of terminally differentiated neurons is also crucial for lifelong latency. Our studies revealed that BoHV-1 gene products expressed during latency stabilize expression of the transcription factor β-catenin and perhaps its cofactor, mastermind-like protein 1 (MAML1). In contrast to expression during latency, β-catenin expression in sensory neurons is not detectable following treatment of latently infected calves with the synthetic corticosteroid dexamethasone to initiate reactivation from latency. A viral protein (ORF2) expressed in a subset of latently infected neurons stabilized β-catenin and MAML1 in transfected cells. ORF2, β-catenin, and MAML1 also enhanced cell survival when growth factors were withdrawn, suggesting that these genes enhance survival of latently infected neurons.
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Venø MT, Hansen TB, Venø ST, Clausen BH, Grebing M, Finsen B, Holm IE, Kjems J. Spatio-temporal regulation of circular RNA expression during porcine embryonic brain development. Genome Biol 2015; 16:245. [PMID: 26541409 PMCID: PMC4635978 DOI: 10.1186/s13059-015-0801-3] [Citation(s) in RCA: 367] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 10/07/2015] [Indexed: 12/28/2022] Open
Abstract
Background Recently, thousands of circular RNAs (circRNAs) have been discovered in various tissues and cell types from human, mouse, fruit fly and nematodes. However, expression of circRNAs across mammalian brain development has never been examined. Results Here we profile the expression of circRNA in five brain tissues at up to six time-points during fetal porcine development, constituting the first report of circRNA in the brain development of a large animal. An unbiased analysis reveals a highly complex regulation pattern of thousands of circular RNAs, with a distinct spatio-temporal expression profile. The amount and complexity of circRNA expression was most pronounced in cortex at day 60 of gestation. At this time-point we find 4634 unique circRNAs expressed from 2195 genes out of a total of 13,854 expressed genes. Approximately 20 % of the porcine splice sites involved in circRNA production are functionally conserved between mouse and human. Furthermore, we observe that “hot-spot” genes produce multiple circRNA isoforms, which are often differentially expressed across porcine brain development. A global comparison of porcine circRNAs reveals that introns flanking circularized exons are longer than average and more frequently contain proximal complementary SINEs, which potentially can facilitate base pairing between the flanking introns. Finally, we report the first use of RNase R treatment in combination with in situ hybridization to show dynamic subcellular localization of circRNA during development. Conclusions These data demonstrate that circRNAs are highly abundant and dynamically expressed in a spatio-temporal manner in porcine fetal brain, suggesting important functions during mammalian brain development. Electronic supplementary material The online version of this article (doi:10.1186/s13059-015-0801-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Morten T Venø
- Department of Molecular Biology and Genetics, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Thomas B Hansen
- Department of Molecular Biology and Genetics, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Susanne T Venø
- Department of Molecular Biology and Genetics, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Bettina H Clausen
- Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Manuela Grebing
- Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Bente Finsen
- Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Ida E Holm
- Laboratory for Experimental Neuropathology, Department of Pathology, Randers Hospital, Randers, Denmark
| | - Jørgen Kjems
- Department of Molecular Biology and Genetics, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark.
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105
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Wnt signalling tunes neurotransmitter release by directly targeting Synaptotagmin-1. Nat Commun 2015; 6:8302. [PMID: 26400647 PMCID: PMC4667432 DOI: 10.1038/ncomms9302] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 08/07/2015] [Indexed: 01/22/2023] Open
Abstract
The functional assembly of the synaptic release machinery is well understood; however, how signalling factors modulate this process remains unknown. Recent studies suggest that Wnts play a role in presynaptic function. To examine the mechanisms involved, we investigated the interaction of release machinery proteins with Dishevelled-1 (Dvl1), a scaffold protein that determines the cellular locale of Wnt action. Here we show that Dvl1 directly interacts with Synaptotagmin-1 (Syt-1) and indirectly with the SNARE proteins SNAP25 and Syntaxin (Stx-1). Importantly, the interaction of Dvl1 with Syt-1, which is regulated by Wnts, modulates neurotransmitter release. Moreover, presynaptic terminals from Wnt signalling-deficient mice exhibit reduced release probability and are unable to sustain high-frequency release. Consistently, the readily releasable pool size and formation of SNARE complexes are reduced. Our studies demonstrate that Wnt signalling tunes neurotransmitter release and identify Syt-1 as a target for modulation by secreted signalling proteins.
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106
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Adenomatous Polyposis Coli Protein Deletion in Efferent Olivocochlear Neurons Perturbs Afferent Synaptic Maturation and Reduces the Dynamic Range of Hearing. J Neurosci 2015; 35:9236-45. [PMID: 26085645 DOI: 10.1523/jneurosci.4384-14.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
UNLABELLED Normal hearing requires proper differentiation of afferent ribbon synapses between inner hair cells (IHCs) and spiral ganglion neurons (SGNs) that carry acoustic information to the brain. Within individual IHCs, presynaptic ribbons show a size gradient with larger ribbons on the modiolar face and smaller ribbons on the pillar face. This structural gradient is associated with a gradient of spontaneous rates and threshold sensitivity, which is essential for a wide dynamic range of hearing. Despite their importance for hearing, mechanisms that direct ribbon differentiation are poorly defined. We recently identified adenomatous polyposis coli protein (APC) as a key regulator of interneuronal synapse maturation. Here, we show that APC is required for ribbon size heterogeneity and normal cochlear function. Compared with wild-type littermates, APC conditional knock-out (cKO) mice exhibit decreased auditory brainstem responses. The IHC ribbon size gradient is also perturbed. Whereas the normal-developing IHCs display ribbon size gradients before hearing onset, ribbon sizes are aberrant in APC cKOs from neonatal ages on. Reporter expression studies show that the CaMKII-Cre used to delete the floxed APC gene is present in efferent olivocochlear (OC) neurons, not IHCs or SGNs. APC loss led to increased volumes and numbers of OC inhibitory dopaminergic boutons on neonatal SGN fibers. Our findings identify APC in efferent OC neurons as essential for regulating ribbon heterogeneity, dopaminergic terminal differentiation, and cochlear sensitivity. This APC effect on auditory epithelial cell synapses resembles interneuronal and nerve-muscle synapses, thereby defining a global role for APC in synaptic maturation in diverse cell types. SIGNIFICANCE STATEMENT This study identifies novel molecules and cellular interactions that are essential for the proper maturation of afferent ribbon synapses in sensory cells of the inner ear, and for normal hearing.
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107
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Parodi J, Montecinos-Oliva C, Varas R, Alfaro IE, Serrano FG, Varas-Godoy M, Muñoz FJ, Cerpa W, Godoy JA, Inestrosa NC. Wnt5a inhibits K(+) currents in hippocampal synapses through nitric oxide production. Mol Cell Neurosci 2015; 68:314-22. [PMID: 26311509 DOI: 10.1016/j.mcn.2015.08.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 06/05/2015] [Accepted: 08/19/2015] [Indexed: 02/06/2023] Open
Abstract
Hippocampal synapses play a key role in memory and learning processes by inducing long-term potentiation and depression. Wnt signaling is essential in the development and maintenance of synapses via several mechanisms. We have previously found that Wnt5a induces the production of nitric oxide (NO), which modulates NMDA receptor expression in the postsynaptic regions of hippocampal neurons. Here, we report that Wnt5a selectively inhibits a voltage-gated K(+) current (Kv current) and increases synaptic activity in hippocampal slices. Further supporting a specific role for Wnt5a, the soluble Frizzled receptor protein (sFRP-2; a functional Wnt antagonist) fully inhibits the effects of Wnt5a. We additionally show that these responses to Wnt5a are mediated by activation of a ROR2 receptor and increased NO production because they are suppressed by the shRNA-mediated knockdown of ROR2 and by 7-nitroindazole, a specific inhibitor of neuronal NOS. Together, our results show that Wnt5a increases NO production by acting on ROR2 receptors, which in turn inhibit Kv currents. These results reveal a novel mechanism by which Wnt5a may regulate the excitability of hippocampal neurons.
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Affiliation(s)
- Jorge Parodi
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carla Montecinos-Oliva
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Rodrigo Varas
- Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Talca, Chile
| | - Iván E Alfaro
- Fundación Ciencia y Vida, Santiago, Chile; Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha, Valparaiso, Chile
| | - Felipe G Serrano
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | - Francisco J Muñoz
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Parc de Recerca Biomédica de Barcelonab, Spain
| | - Waldo Cerpa
- Laboratorio de Función y Patología Neuronal, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago, Chile
| | - Juan A Godoy
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Parc de Recerca Biomédica de Barcelonab, Spain
| | - Nibaldo C Inestrosa
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile; Centre for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, Australia; Centro UC Síndrome de Down, Pontificia Universidad Católica de Chile, Santiago, Chile; Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile.
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Stamatakou E, Hoyos-Flight M, Salinas PC. Wnt Signalling Promotes Actin Dynamics during Axon Remodelling through the Actin-Binding Protein Eps8. PLoS One 2015; 10:e0134976. [PMID: 26252776 PMCID: PMC4529215 DOI: 10.1371/journal.pone.0134976] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 07/07/2015] [Indexed: 11/26/2022] Open
Abstract
Upon arrival at their synaptic targets, axons slow down their growth and extensively remodel before the assembly of presynaptic boutons. Wnt proteins are target-derived secreted factors that promote axonal remodelling and synaptic assembly. In the developing spinal cord, Wnts secreted by motor neurons promote axonal remodelling of NT-3 responsive dorsal root ganglia neurons. Axon remodelling induced by Wnts is characterised by growth cone pausing and enlargement, processes that depend on the re-organisation of microtubules. However, the contribution of the actin cytoskeleton has remained unexplored. Here, we demonstrate that Wnt3a regulates the actin cytoskeleton by rapidly inducing F-actin accumulation in growth cones from rodent DRG neurons through the scaffold protein Dishevelled-1 (Dvl1) and the serine-threonine kinase Gsk3β. Importantly, these changes in actin cytoskeleton occurs before enlargement of the growth cones is evident. Time-lapse imaging shows that Wnt3a increases lamellar protrusion and filopodia velocity. In addition, pharmacological inhibition of actin assembly demonstrates that Wnt3a increases actin dynamics. Through a yeast-two hybrid screen, we identified the actin-binding protein Eps8 as a direct interactor of Dvl1, a scaffold protein crucial for the Wnt signalling pathway. Gain of function of Eps8 mimics Wnt-mediated axon remodelling, whereas Eps8 silencing blocks the axon remodelling activity of Wnt3a. Importantly, blockade of the Dvl1-Eps8 interaction completely abolishes Wnt3a-mediated axonal remodelling. These findings demonstrate a novel role for Wnt-Dvl1 signalling through Eps8 in the regulation of axonal remodeling.
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Affiliation(s)
- Eleanna Stamatakou
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, United Kingdom
| | - Monica Hoyos-Flight
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, United Kingdom
| | - Patricia C. Salinas
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, United Kingdom
- * E-mail:
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109
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Xu Z, Chen Y, Yu J, Yin D, Liu C, Chen X, Zhang D. TCF4 Mediates the Maintenance of Neuropathic Pain Through Wnt/β-Catenin Signaling Following Peripheral Nerve Injury in Rats. J Mol Neurosci 2015; 56:397-408. [PMID: 25963533 DOI: 10.1007/s12031-015-0565-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 04/14/2015] [Indexed: 01/20/2023]
Abstract
Neuropathic pain is elicited after a serious disorder of the nervous system and is along with the neural damage. It is usually chronic and challenging to treat. Transcription factor 4 (TCF4) is a key transcription factor of Wnt signaling system. Recent studies have shown that TCF4 interacts with β-catenin in the Wnt signaling pathway and coactivates downstream target genes in diverse systems. However, it is not well elucidated in the pathogenesis of neuropathic pain. In the present study, we investigated the role of TCF4 in the maintenance of neuropathic pain after chronic constriction injury (CCI) in rats. CCI induced persistent TCF4 upregulation in the dorsal root ganglion and spinal cord. Interestingly, TCF4 was mainly colocalized with neurons in the injured dorsal root ganglion and spinal cord on CCI day 7. Moreover, the expression patterns of β-catenin and glycogen synthase kinase-3β (GSK-3β) were parallel with that of TCF4 in vivo studies. Intrathecal injection of Wnt/β-catenin pathway inhibitor IWR-1-endo and TCF4 small interfering RNA (siRNA) significantly attenuated CCI-induced mechanical allodynia and heat hyperalgesia. The results suggest that TCF4 in the dorsal root ganglion and spinal cord is involved in the maintenance of CCI-induced neuropathic pain. Targeting TCF4 or Wnt/β-catenin signaling may be a potential treatment for chronic neuropathic pain.
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Affiliation(s)
- Zhongling Xu
- Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong, 226001, China
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The Secreted Protein C1QL1 and Its Receptor BAI3 Control the Synaptic Connectivity of Excitatory Inputs Converging on Cerebellar Purkinje Cells. Cell Rep 2015; 10:820-832. [DOI: 10.1016/j.celrep.2015.01.034] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 01/08/2015] [Accepted: 01/15/2015] [Indexed: 11/21/2022] Open
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Martinez E, Tran TS. Vertebrate spinal commissural neurons: a model system for studying axon guidance beyond the midline. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 4:283-97. [PMID: 25619385 DOI: 10.1002/wdev.173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 11/27/2014] [Accepted: 12/04/2014] [Indexed: 12/21/2022]
Abstract
For bilaterally symmetric organisms, the transfer of information between the left and right side of the nervous system is mediated by commissures formed by neurons that project their axons across the body midline to the contralateral side of the central nervous system (CNS). After crossing the midline, many of these axons must travel long distances to reach their targets, including those that extend from spinal commissural neurons. Owing to the highly stereotyped trajectories of spinal commissural neurons that can be divided into several segments as these axons project to their targets, it is an ideal system for investigators to ask fundamental questions related to mechanisms of short- and long-range axon guidance, fasciculation, and choice point decisions at the midline intermediate target. In addition, studies of patterning genes of the nervous system have revealed complex transcription factor codes that function in a combinatorial fashion to specify individual classes of spinal neurons including commissural neurons. Despite these advances and the functional importance of spinal commissural neurons in mediating the transfer of external sensory information from the peripheral nervous system (PNS) to the CNS, only a handful of studies have begun to elucidate the mechanistic logic underlying their long-range pathfinding and the characterization of their synaptic targets. Using in vitro assays, in vivo labeling methodologies, in combination with both loss- and gain-of-function experiments, several studies have revealed that the molecular mechanisms of long-range spinal commissural axon pathfinding involve an interplay between classical axon guidance cues, morphogens and cell adhesion molecules. For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Edward Martinez
- Department of Biological Sciences, Rutgers University, Newark, NJ, USA
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112
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Remodelling of spared proprioceptive circuit involving a small number of neurons supports functional recovery. Nat Commun 2015; 6:6079. [PMID: 25597627 DOI: 10.1038/ncomms7079] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 12/10/2014] [Indexed: 11/09/2022] Open
Abstract
Studies show that limited functional recovery can be achieved by plasticity and adaptation of the remaining circuitry in partial injuries in the central nervous system, although the new circuits that arise in these contexts have not been clearly identified or characterized. We show here that synaptic contacts from dorsal root ganglions to a small number of dorsal column neurons, a caudal extension of nucleus gracilis, whose connections to the thalamus are spared in a precise cervical level 1 lesion, underwent remodeling over time. These connections support proprioceptive functional recovery in a conditioning lesion paradigm, as silencing or eliminating the remodelled circuit completely abolishes the recovered proprioceptive function of the hindlimb. Furthermore, we show that blocking repulsive Wnt signalling increases axon plasticity and synaptic connections that drive greater functional recovery.
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113
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Galli S, Lopes DM, Ammari R, Kopra J, Millar SE, Gibb A, Salinas PC. Deficient Wnt signalling triggers striatal synaptic degeneration and impaired motor behaviour in adult mice. Nat Commun 2014; 5:4992. [PMID: 25318560 PMCID: PMC4218967 DOI: 10.1038/ncomms5992] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 08/15/2014] [Indexed: 12/31/2022] Open
Abstract
Synapse degeneration is an early and invariant feature of neurodegenerative diseases. Indeed, synapse loss occurs prior to neuronal degeneration and correlates with the symptom severity of these diseases. However, the molecular mechanisms that trigger synaptic loss remain poorly understood. Here we demonstrate that deficient Wnt signalling elicits synaptic degeneration in the adult striatum. Inducible expression of the secreted Wnt antagonist Dickkopf1 (Dkk1) in adult mice (iDkk1) decreases the number of cortico-striatal glutamatergic synapses and of D1 and D2 dopamine receptor clusters. Synapse loss occurs in the absence of axon retraction or cell death. The remaining excitatory terminals contain fewer synaptic vesicles and have a reduced probability of evoked transmitter release. IDkk1 mice show impaired motor coordination and are irresponsive to amphetamine. These studies identify Wnts as key endogenous regulators of synaptic maintenance and suggest that dysfunction in Wnt signalling contributes to synaptic degeneration at early stages in neurodegenerative diseases.
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Affiliation(s)
- Soledad Galli
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Douglas M. Lopes
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Rachida Ammari
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Jaakko Kopra
- Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, Helsinki 00014, Finland
| | - Sarah E. Millar
- Department of Dermatology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Alasdair Gibb
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Patricia C. Salinas
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
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114
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Adenomatous polyposis coli protein deletion leads to cognitive and autism-like disabilities. Mol Psychiatry 2014; 19:1133-42. [PMID: 24934177 PMCID: PMC4317257 DOI: 10.1038/mp.2014.61] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 04/16/2014] [Accepted: 04/25/2014] [Indexed: 12/14/2022]
Abstract
Intellectual disabilities (IDs) and autism spectrum disorders link to human APC inactivating gene mutations. However, little is known about adenomatous polyposis coli's (APC's) role in the mammalian brain. This study is the first direct test of the impact of APC loss on central synapses, cognition and behavior. Using our newly generated APC conditional knock-out (cKO) mouse, we show that deletion of this single gene in forebrain neurons leads to a multisyndromic neurodevelopmental disorder. APC cKO mice, compared with wild-type littermates, exhibit learning and memory impairments, and autistic-like behaviors (increased repetitive behaviors, reduced social interest). To begin to elucidate neuronal changes caused by APC loss, we focused on the hippocampus, a key brain region for cognitive function. APC cKO mice display increased synaptic spine density, and altered synaptic function (increased frequency of miniature excitatory synaptic currents, modestly enhanced long-term potentiation). In addition, we found excessive β-catenin levels and associated changes in canonical Wnt target gene expression and N-cadherin synaptic adhesion complexes, including reduced levels of presenilin1. Our findings identify some novel functional and molecular changes not observed previously in other genetic mutant mouse models of co-morbid cognitive and autistic-like disabilities. This work thereby has important implications for potential therapeutic targets and the impact of their modulation. We provide new insights into molecular perturbations and cell types that are relevant to human ID and autism. In addition, our data elucidate a novel role for APC in the mammalian brain as a hub that links to and regulates synaptic adhesion and signal transduction pathways critical for normal cognition and behavior.
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115
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Ackley BD. Wnt-signaling and planar cell polarity genes regulate axon guidance along the anteroposterior axis in C. elegans. Dev Neurobiol 2014; 74:781-96. [PMID: 24214205 PMCID: PMC4167394 DOI: 10.1002/dneu.22146] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 09/18/2013] [Accepted: 11/02/2013] [Indexed: 11/10/2022]
Abstract
During the development of the nervous system, neurons encounter signals that inform their outgrowth and polarization. Understanding how these signals combinatorially function to pattern the nervous system is of considerable interest to developmental neurobiologists. The Wnt ligands and their receptors have been well characterized in polarizing cells during asymmetric cell division. The planar cell polarity (PCP) pathway is also critical for cell polarization in the plane of an epithelium. The core set of PCP genes include members of the conserved Wnt-signaling pathway, such as Frizzled and Disheveled, but also the cadherin-domain protein Flamingo. In Drosophila, the Fat and Dachsous cadherins also function in PCP, but in parallel to the core PCP components. C. elegans also have two Fat-like and one Dachsous-like cadherins, at least one of which, cdh-4, contributes to neural development. In C. elegans Wnt ligands and the conserved PCP genes have been shown to regulate a number of different events, including embryonic cell polarity, vulval morphogenesis, and cell migration. As is also observed in vertebrates, the Wnt and PCP genes appear to function to primarily provide information about the anterior to posterior axis of development. Here, we review the recent work describing how mutations in the Wnt and core PCP genes affect axon guidance and synaptogenesis in C. elegans.
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Affiliation(s)
- Brian D Ackley
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, 66045
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116
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Testing models of the APC tumor suppressor/β-catenin interaction reshapes our view of the destruction complex in Wnt signaling. Genetics 2014; 197:1285-302. [PMID: 24931405 DOI: 10.1534/genetics.114.166496] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Wnt pathway is a conserved signal transduction pathway that contributes to normal development and adult homeostasis, but is also misregulated in human diseases such as cancer. The tumor suppressor adenomatous polyposis coli (APC) is an essential negative regulator of Wnt signaling inactivated in >80% of colorectal cancers. APC participates in a multiprotein "destruction complex" that targets the proto-oncogene β-catenin for ubiquitin-mediated proteolysis; however, the mechanistic role of APC in the destruction complex remains unknown. Several models of APC function have recently been proposed, many of which have emphasized the importance of phosphorylation of high-affinity β-catenin-binding sites [20-amino-acid repeats (20Rs)] on APC. Here we test these models by generating a Drosophila APC2 mutant lacking all β-catenin-binding 20Rs and performing functional studies in human colon cancer cell lines and Drosophila embryos. Our results are inconsistent with current models, as we find that β-catenin binding to the 20Rs of APC is not required for destruction complex activity. In addition, we generate an APC2 mutant lacking all β-catenin-binding sites (including the 15Rs) and find that a direct β-catenin/APC interaction is also not essential for β-catenin destruction, although it increases destruction complex efficiency in certain developmental contexts. Overall, our findings support a model whereby β-catenin-binding sites on APC do not provide a critical mechanistic function per se, but rather dock β-catenin in the destruction complex to increase the efficiency of β-catenin destruction. Furthermore, in Drosophila embryos expressing some APC2 mutant transgenes we observe a separation of β-catenin destruction and Wg/Wnt signaling outputs and suggest that cytoplasmic retention of β-catenin likely accounts for this difference.
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117
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Kim HJ, Ryu J, Woo HM, Cho SS, Sung MK, Kim SC, Park MH, Park T, Koo SK. Patterns of gene expression associated with Pten deficiency in the developing inner ear. PLoS One 2014; 9:e97544. [PMID: 24893171 PMCID: PMC4043736 DOI: 10.1371/journal.pone.0097544] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 04/19/2014] [Indexed: 12/26/2022] Open
Abstract
In inner ear development, phosphatase and tensin homolog (PTEN) is necessary for neuronal maintenance, such as neuronal survival and accurate nerve innervations of hair cells. We previously reported that Pten conditional knockout (cKO) mice exhibited disorganized fasciculus with neuronal apoptosis in spiral ganglion neurons (SGNs). To better understand the genes and signaling networks related to auditory neuron maintenance, we compared the profiles of differentially expressed genes (DEGs) using microarray analysis of the inner ear in E14.5 Pten cKO and wild-type mice. We identified 46 statistically significant transcripts using significance analysis of microarrays, with the false-discovery rate set at 0%. Among the DEGs, expression levels of candidate genes and expression domains were validated by quantitative real-time RT-PCR and in situ hybridization, respectively. Ingenuity pathway analysis using DEGs identified significant signaling networks associated with apoptosis, cellular movement, and axon guidance (i.e., secreted phosphoprotein 1 (Spp1)-mediated cellular movement and regulator of G-protein signaling 4 (Rgs4)-mediated axon guidance). This result was consistent with the phenotypic defects of SGNs in Pten cKO mice (e.g., neuronal apoptosis, abnormal migration, and irregular nerve fiber patterns of SGNs). From this study, we suggest two key regulatory signaling networks mediated by Spp1 and Rgs4, which may play potential roles in neuronal differentiation of developing auditory neurons.
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Affiliation(s)
- Hyung Jin Kim
- Division of Intractable Diseases, Center for Biomedical Sciences, National Institute of Health, Chungcheongbuk-do, South Korea
| | - Jihee Ryu
- Division of Intractable Diseases, Center for Biomedical Sciences, National Institute of Health, Chungcheongbuk-do, South Korea
| | - Hae-Mi Woo
- Division of Intractable Diseases, Center for Biomedical Sciences, National Institute of Health, Chungcheongbuk-do, South Korea
| | - Samuel Sunghwan Cho
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul, South Korea
| | - Min Kyung Sung
- Korean BioInformation Center (KOBIC), Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea
| | - Sang Cheol Kim
- Korean BioInformation Center (KOBIC), Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea
| | - Mi-Hyun Park
- Division of Intractable Diseases, Center for Biomedical Sciences, National Institute of Health, Chungcheongbuk-do, South Korea
| | - Taesung Park
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul, South Korea
- Department of Statistics, Seoul National University, Seoul, South Korea
| | - Soo Kyung Koo
- Division of Intractable Diseases, Center for Biomedical Sciences, National Institute of Health, Chungcheongbuk-do, South Korea
- * E-mail:
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118
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Developmental increase in ecto-5'-nucleotidase activity overlaps with appearance of two immunologically distinct enzyme isoforms in rat hippocampal synaptic plasma membranes. J Mol Neurosci 2014; 54:109-18. [PMID: 24563227 DOI: 10.1007/s12031-014-0256-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 02/04/2014] [Indexed: 12/24/2022]
Abstract
Ecto-5'-nucleotidase (e-5NT), a glycosylphosphatidylinositol-linked membrane protein, catalyzes a conversion of AMP to adenosine, which influences nearly every aspect of brain physiology, including embryonic and postnatal brain development. The present study aimed to investigate a pattern of expression, activity and kinetic properties of e-5NT in the hippocampal formation and synaptic plasma membrane (SPM) preparations in rats at postnatal days (PDs) 7, 15, 20, 30 and 90. By combining gene expression analysis and enzyme histochemistry, we observed that e-5NT mRNA reached the adult level at PD20, while the enzyme activity continued to increase beyond this age. Further analysis revealed that hippocampal layers rich in synapses expressed the highest levels of e-5NT activity, while in layers populated with neuronal cell bodies, the enzyme activity was weak or absent. Therefore, activity and expression of e-5NT were analyzed in SPM preparations isolated from rats at different ages. The presence of two protein bands of about 65 and 68 kDa was determined by immunoblot analysis. The 65-kDa band was present at all ages, and its abundance increased from PD7 to PD20. The 68-kDa band appeared at PD15 and increased until PD30, coinciding with the increase of e-5NT activity, substrate affinity and enzymatic efficiency. Since distinct e-5NT isoforms may derive from different patterns of the enzyme protein N-glycosylation, we speculate that long-term regulation of e-5NT activity in adulthood may be effectuated at posttranslational level and without overall change in the gene and protein expression.
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119
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Itokazu T, Hayano Y, Takahashi R, Yamashita T. Involvement of Wnt/β-catenin signaling in the development of neuropathic pain. Neurosci Res 2014; 79:34-40. [DOI: 10.1016/j.neures.2013.12.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 12/10/2013] [Accepted: 12/10/2013] [Indexed: 02/08/2023]
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120
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Clark CEJ, Richards LJ, Stacker SA, Cooper HM. Wnt5a induces Ryk-dependent and -independent effects on callosal axon and dendrite growth. Growth Factors 2014; 32:11-7. [PMID: 24471468 DOI: 10.3109/08977194.2013.875544] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The non-canonical Wnt receptor, Ryk, promotes chemorepulsive axon guidance in the developing mouse brain and spinal cord in response to Wnt5a. Ryk has also been identified as a major suppressor of axonal regrowth after spinal cord injury. Thus, a comprehensive understanding of how growing axons and dendrites respond to Wnt5a-mediated Ryk activation is required if we are to overcome this detrimental activity. Here we undertook a detailed analysis of the effect of Wnt5a/Ryk interactions on axonal and dendritic growth in dissociated embryonic mouse cortical neuron cultures, focusing on callosal neurons known to be responsive to Ryk-induced chemorepulsion. We show that Ryk inhibits axonal growth in response to Wnt5a. We also show that Wnt5a inhibits dendrite growth independently of Ryk. However, this inhibition is relieved when Ryk is present. Therefore, Wnt5a-mediated Ryk activation triggers divergent responses in callosal axons and dendrites in the in vitro context.
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Affiliation(s)
- Charlotte E J Clark
- Queensland Brain Institute, The University of Queensland, St Lucia , Queensland , Australia
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121
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Purro SA, Galli S, Salinas PC. Dysfunction of Wnt signaling and synaptic disassembly in neurodegenerative diseases. J Mol Cell Biol 2014; 6:75-80. [PMID: 24449494 PMCID: PMC4344549 DOI: 10.1093/jmcb/mjt049] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The molecular mechanisms that regulate synapse formation have been well documented. However, little is known about the factors that modulate synaptic stability. Synapse loss is an early and invariant feature of neurodegenerative diseases including Alzheimer's (AD) and Parkinson's disease. Notably, in AD the extent of synapse loss correlates with the severity of the disease. Hence, understanding the molecular mechanisms that underlie synaptic maintenance is crucial to reveal potential targets that will allow the development of therapies to protect synapses. Wnts play a central role in the formation and function of neuronal circuits. Moreover, Wnt signaling components are expressed in the adult brain suggesting their role in synaptic maintenance in the adult. Indeed, blockade of Wnts with the Wnt antagonist Dickkopf-1 (Dkk1) causes synapse disassembly in mature hippocampal cells. Dkk1 is elevated in brain biopsies from AD patients and animal models. Consistent with these findings, Amyloid-β (Aβ) oligomers induce the rapid expression of Dkk1. Importantly, Dkk1 neutralizing antibodies protect synapses against Aβ toxicity, indicating that Dkk1 is required for Aβ-mediated synapse loss. In this review, we discuss the role of Wnt signaling in synapse maintenance in the adult brain, particularly in relation to synaptic loss in neurodegenerative diseases.
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Affiliation(s)
- Silvia A Purro
- Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
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122
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L'Episcopo F, Tirolo C, Caniglia S, Testa N, Morale MC, Serapide MF, Pluchino S, Marchetti B. Targeting Wnt signaling at the neuroimmune interface for dopaminergic neuroprotection/repair in Parkinson's disease. J Mol Cell Biol 2014; 6:13-26. [PMID: 24431301 DOI: 10.1093/jmcb/mjt053] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
During the past three decades, the Wingless-type MMTV integration site (Wnt) signaling cascade has emerged as an essential system regulating multiple processes in developing and adult brain. Accumulating evidence points to a dysregulation of Wnt signaling in major neurodegenerative pathologies including Parkinson's disease (PD), a common neurodegenerative disorder characterized by the progressive loss of midbrain dopaminergic (mDA) neurons and deregulated activation of astrocytes and microglia. This review highlights the emerging link between Wnt signaling and key inflammatory pathways during mDA neuron damage/repair in PD progression. In particular, we summarize recent evidence documenting that aging and neurotoxicant exposure strongly antagonize Wnt/β-catenin signaling in mDA neurons and subventricular zone (SVZ) neuroprogenitors via astrocyte-microglial interactions. Dysregulation of the crosstalk between Wnt/β-catenin signaling and anti-oxidant/anti-inflammatory pathways delineate novel mechanisms driving the decline of SVZ plasticity with age and the limited nigrostriatal dopaminergic self-repair in PD. These findings hold a promise in developing therapies that target Wnt/β-catenin signaling to enhance endogenous restoration and neuronal outcome in age-dependent diseases, such as PD.
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Affiliation(s)
- Francesca L'Episcopo
- OASI Institute for Research and Care on Mental Retardation and Brain Aging (IRCCS), Neuropharmacology Section, Via Conte Ruggero 73, 94018 Troina, Italy
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123
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Ortiz-Matamoros A, Salcedo-Tello P, Avila-Muñoz E, Zepeda A, Arias C. Role of wnt signaling in the control of adult hippocampal functioning in health and disease: therapeutic implications. Curr Neuropharmacol 2014; 11:465-76. [PMID: 24403870 PMCID: PMC3763754 DOI: 10.2174/1570159x11311050001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 03/16/2013] [Accepted: 03/16/2013] [Indexed: 12/12/2022] Open
Abstract
It is well recognized the role of the Wnt pathway in many developmental processes such as neuronal maturation, migration, neuronal connectivity and synaptic formation. Growing evidence is also demonstrating its function in the mature brain where is associated with modulation of axonal remodeling, dendrite outgrowth, synaptic activity, neurogenesis and behavioral plasticity. Proteins involved in Wnt signaling have been found expressed in the adult hippocampus suggesting that Wnt pathway plays a role in the hippocampal function through life. Indeed, Wnt ligands act locally to regulate neurogenesis, neuronal cell shape and pre- and postsynaptic assembly, events that are thought to underlie changes in synaptic function associated with long-term potentiation and with cognitive tasks such as learning and memory. Recent data have demonstrated the increased expression of the Wnt antagonist Dickkopf-1 (DKK1) in brains of Alzheimer´s disease (AD) patients suggesting that dysfunction of Wnt signaling could also contribute to AD pathology. We review here evidence of Wnt-associated molecules expression linked to physiological and pathological hippocampal functioning in the adult brain. The basic aspects of Wnt related mechanisms underlying hippocampal plasticity as well as evidence of how hippocampal dysfunction may rely on Wnt dysregulation is analyzed. This information would provide some clues about the possible therapeutic targets for developing treatments for neurodegenerative diseases associated with aberrant brain plasticity.
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Affiliation(s)
- Abril Ortiz-Matamoros
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F
| | - Pamela Salcedo-Tello
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F
| | - Evangelina Avila-Muñoz
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F
| | - Angélica Zepeda
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F
| | - Clorinda Arias
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F
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Brauburger K, Akyildiz S, Ruppert JG, Graeb M, Bernkopf DB, Hadjihannas MV, Behrens J. Adenomatous polyposis coli (APC) membrane recruitment 3, a member of the APC membrane recruitment family of APC-binding proteins, is a positive regulator of Wnt-β-catenin signalling. FEBS J 2013; 281:787-801. [PMID: 24251807 DOI: 10.1111/febs.12624] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 11/18/2013] [Accepted: 11/19/2013] [Indexed: 12/18/2022]
Abstract
The adenomatous polyposis coli (APC) membrane recruitment (Amer) family proteins Amer1/Wilms tumour gene on the X chromosome and Amer2 are binding partners of the APC tumour suppressor protein, and act as negative regulators in the Wnt signalling cascade. So far, nothing has been known about the third member of the family, Amer3. Here we show that Amer3 binds to the armadillo repeat domain of APC, similarly to Amer1 and Amer2. Amer3 also binds to the Wnt pathway regulator conductin/axin2. Furthermore, we identified Amer1 as binding partner of Amer3. Whereas Amer1 and Amer2 are linked to the plasma membrane by an N-terminal membrane localization domain, Amer3 lacks this domain. Amer3 localizes to the cytoplasm and nucleus of epithelial cells, and this is dependent on specific nuclear import and export sequences. Functionally, exogenous Amer3 enhances the expression of a β-catenin/T-cell factor-dependent reporter gene, and knockdown of endogenous Amer3 reduces Wnt target gene expression in colorectal cancer cells. Thus, Amer3 acts as an activator of Wnt signalling, in contrast to Amer1 and Amer2, which are inhibitors, suggesting a nonredundant role of Amer proteins in the regulation of this pathway. Our data, together with those of previous studies, provide a comprehensive picture of similarities and differences within the Amer protein family.
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Affiliation(s)
- Katharina Brauburger
- Nikolaus Fiebiger Centre for Molecular Medicine, University Erlangen-Nuremberg, Erlangen, Germany
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125
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Abstract
Primary cilia are generally solitary organelles that emanate from the surface of almost all vertebrate cell types. Until recently, details regarding the function of these structures were lacking; however, extensive evidence now suggests that primary cilia have critical roles in sensing the extracellular environment, and in coordinating developmental and homeostatic signalling pathways. Furthermore, disruption of these functions seems to underlie a diverse spectrum of disorders, known as primary ciliopathies. These disorders are characterized by wide-ranging clinical and genetic heterogeneity, but with substantial overlap among distinct conditions. Indeed, ciliopathies are associated with a large variety of manifestations that often include distinctive neurological findings. Herein, we review neurological features associated with primary ciliopathies, highlight genotype-phenotype correlations, and discuss potential mechanisms underlying these findings.
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126
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Pinto C, Cárdenas P, Osses N, Henríquez JP. Characterization of Wnt/β-catenin and BMP/Smad signaling pathways in an in vitro model of amyotrophic lateral sclerosis. Front Cell Neurosci 2013; 7:239. [PMID: 24348333 PMCID: PMC3847560 DOI: 10.3389/fncel.2013.00239] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 11/13/2013] [Indexed: 12/11/2022] Open
Abstract
Different pathways activated by morphogens of the early embryonic development, such as the Wnt and the Bone Morphogenetic Protein (BMP) ligands, are involved in diverse physiological and pathological conditions of the nervous system, including neurodegeneration. In this work, we have analyzed the endogenous activity of the canonical Wnt/β-catenin and BMP/Smad-dependent pathways in an in vitro model of amyotrophic lateral sclerosis (ALS), given by motor neuron-like NSC34 cells stably expressing wild-type or G93A mutated forms of human Cu/Zn superoxide dismutase-1 (SOD1). As ALS-derived motor neurons, NSC34 cells expressing mutated hSOD1 show a decreased proliferation rate, are more susceptible to oxidation-induced cell death and display Golgi fragmentation. In addition, they display an impaired ability to induce the expression of the motor neuronal marker Hb9 and, consistently, to morphologically differentiate into a motor neuronal phenotype. Regarding signaling, our data show that the transcriptional activity associated to the Wnt/β-catenin pathway is decreased, a finding possibly associated to the cytosolic aggregation of β-catenin. In turn, the BMP-dependent phosphorylation of Smad1 and the transcriptional activation of the BMP/Smad pathway is increased in the pathologic model. Together, these findings suggest that Wnt/β-catenin and the BMP-dependent pathways could play relevant roles in the neurodegeneration of motor neurons in the context of ALS.
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Affiliation(s)
- Cristina Pinto
- Laboratory of Developmental Neurobiology, Department of Cell Biology, Faculty of Biological Sciences, Center for Advanced Microscopy, Universidad de ConcepciónConcepción, Chile
| | - Pilar Cárdenas
- Institute of Chemistry, Faculty of Sciences, Pontificia Universidad Católica de ValparaísoValparaiso, Chile
| | - Nelson Osses
- Institute of Chemistry, Faculty of Sciences, Pontificia Universidad Católica de ValparaísoValparaiso, Chile
| | - Juan P. Henríquez
- Laboratory of Developmental Neurobiology, Department of Cell Biology, Faculty of Biological Sciences, Center for Advanced Microscopy, Universidad de ConcepciónConcepción, Chile
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127
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Dickins EM, Salinas PC. Wnts in action: from synapse formation to synaptic maintenance. Front Cell Neurosci 2013; 7:162. [PMID: 24223536 PMCID: PMC3819050 DOI: 10.3389/fncel.2013.00162] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 08/04/2013] [Indexed: 11/13/2022] Open
Abstract
A proper balance between synapse assembly and disassembly is crucial for the formation of functional neuronal circuits and synaptic plasticity in the adult brain. During development, synaptogenesis generates a vast excess of synapses, which are subsequently eliminated. Importantly, aberrant synaptic disassembly during development underpins many neurological disorders. Wnt secreted proteins are robust synaptogenic factors that regulate synapse assembly and function in the developing and mature brain. Recent studies show that Wnt blockade with the antagonist Dickkopf-1 (Dkk1) induces the rapid disassembly of synapses in mature neurons. Importantly, Dkk1 mediates synaptic loss induced by Amyloid-ß, a key pathogenic molecule in Alzheimer's disease (AD). These findings provide new insights into the potential contribution of dysfunctional Wnt signaling to synaptic loss observed in neurodegenerative diseases. In this review, we discuss the role of Wnt signaling in vertebrate synaptic assembly, function and maintenance, and consider how dysfunction of Wnt signaling could contribute to synaptic disassembly in neurodegenerative diseases such as AD.
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Affiliation(s)
- Ellen M Dickins
- Department of Cell and Developmental Biology, University College London London, UK
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128
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Cavodeassi F. Integration of anterior neural plate patterning and morphogenesis by the Wnt signaling pathway. Dev Neurobiol 2013; 74:759-71. [PMID: 24115566 DOI: 10.1002/dneu.22135] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 09/13/2013] [Accepted: 09/23/2013] [Indexed: 01/08/2023]
Abstract
Wnts are essential for a multitude of processes during embryonic development and adult homeostasis. The molecular structure of the Wnt pathway is extremely complex, and it keeps growing as new molecular components and novel interactions are uncovered. Recent studies have advanced our understanding on how the diverse molecular outcomes of the Wnt pathway are integrated during organ development, an integration that is also essential, although mechanistically poorly understood, during the formation of the anterior part of the nervous system, the forebrain. In this article, the author has summarized these findings and discussed their implications for forebrain development. A special emphasis has been put forth on studies performed in the zebrafish as this model system has been instrumental for our current understanding of forebrain patterning.
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Affiliation(s)
- Florencia Cavodeassi
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Nicolás Cabrera 1, 28049, Madrid, Spain
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129
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Li L, Fothergill T, Hutchins BI, Dent EW, Kalil K. Wnt5a evokes cortical axon outgrowth and repulsive guidance by tau mediated reorganization of dynamic microtubules. Dev Neurobiol 2013; 74:797-817. [PMID: 23818454 PMCID: PMC4087151 DOI: 10.1002/dneu.22102] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 04/24/2013] [Accepted: 06/20/2013] [Indexed: 01/08/2023]
Abstract
Wnt5a guides cortical axons in vivo by repulsion and in vitro evokes cortical axon outgrowth and repulsion by calcium signaling pathways. Here we examined the role of microtubule (MT) reorganization and dynamics in mediating effects of Wnt5a. Inhibiting MT dynamics with nocodazole and taxol abolished Wnt5a evoked axon outgrowth and repulsion of cultured hamster cortical neurons. EGFP-EB3 labeled dynamic MTs visualized in live cell imaging revealed that growth cone MTs align with the nascent axon. Wnt5a increased axon outgrowth by reorganization of dynamic MTs from a splayed to a bundled array oriented in the direction of axon extension, and Wnt5a gradients induced asymmetric redistribution of dynamic MTs toward the far side of the growth cone. Wnt5a gradients also evoked calcium transients that were highest on the far side of the growth cone. Calcium signaling and the reorganization of dynamic MTs could be linked by tau, a MT associated protein that stabilizes MTs. Tau is phosphorylated at the Ser 262 MT binding site by CaMKII, and is required for Wnt5a induced axon outgrowth and repulsive turning. Phosphorylation of tau at Ser262 is known to detach tau from MTs to increase their dynamics. Using transfection with tau constructs mutated at Ser262, we found that this site is required for the growth and guidance effects of Wnt5a by mediating reorganization of dynamic MTs in cortical growth cones. Moreover, CaMKII inhibition also prevents MT reorganization required for Wnt5a induced axon outgrowth, thus linking Wnt/calcium signaling to tau mediated MT reorganization during growth cone behaviors. © 2013 The Authors. Developmental Neurobiology Published by Wiley Periodicals, Inc.Develop Neurobiol 74: 797–817, 2014
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Affiliation(s)
- Li Li
- Neuroscience Training Program, University of Wisconsin-Madison, Wisconsin, 53706
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130
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Poon VY, Choi S, Park M. Growth factors in synaptic function. Front Synaptic Neurosci 2013; 5:6. [PMID: 24065916 PMCID: PMC3776238 DOI: 10.3389/fnsyn.2013.00006] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 08/29/2013] [Indexed: 12/15/2022] Open
Abstract
Synapses are increasingly recognized as key structures that malfunction in disorders like schizophrenia, mental retardation, and neurodegenerative diseases. The importance and complexity of the synapse has fuelled research into the molecular mechanisms underlying synaptogenesis, synaptic transmission, and plasticity. In this regard, neurotrophic factors such as netrin, Wnt, transforming growth factor-β (TGF-β), tumor necrosis factor-α (TNF-α), and others have gained prominence for their ability to regulate synaptic function. Several of these factors were first implicated in neuroprotection, neuronal growth, and axon guidance. However, their roles in synaptic development and function have become increasingly clear, and the downstream signaling pathways employed by these factors have begun to be elucidated. In this review, we will address the role of these factors and their downstream effectors in synaptic function in vivo and in cultured neurons.
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Affiliation(s)
- Vivian Y Poon
- Neuroscience and Behavioral Disorders Program, Duke-NUS Graduate Medical School Singapore, Singapore
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131
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Wnt signaling through the Ror receptor in the nervous system. Mol Neurobiol 2013; 49:303-15. [PMID: 23990374 DOI: 10.1007/s12035-013-8520-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 07/18/2013] [Indexed: 01/04/2023]
Abstract
The receptor tyrosine kinase-like orphan receptor (Ror) proteins are conserved tyrosine kinase receptors that play roles in a variety of cellular processes that pattern tissues and organs during vertebrate and invertebrate development. Ror signaling is required for skeleton and neuronal development and modulates cell migration, cell polarity, and convergent extension. Ror has also been implicated in two human skeletal disorders, brachydactyly type B and Robinow syndrome. Rors are widely expressed during metazoan development including domains in the nervous system. Here, we review recent progress in understanding the roles of the Ror receptors in neuronal migration, axonal pruning, axon guidance, and synaptic plasticity. The processes by which Ror signaling execute these diverse roles are still largely unknown, but they likely converge on cytoskeletal remodeling. In multiple species, Rors have been shown to act as Wnt receptors signaling via novel non-canonical Wnt pathways mediated in some tissues by the adapter protein disheveled and the non-receptor tyrosine kinase Src. Rors can either activate or repress Wnt target expression depending on the cellular context and can also modulate signal transduction by sequestering Wnt ligands away from their signaling receptors. Future challenges include the identification of signaling components of the Ror pathways and bettering our understanding of the roles of these pleiotropic receptors in patterning the nervous system.
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132
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Homodimerization of the Wnt receptor DERAILED recruits the Src family kinase SRC64B. Mol Cell Biol 2013; 33:4116-27. [PMID: 23979591 DOI: 10.1128/mcb.00169-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Ryk pseudokinase receptors act as important transducers of Wnt signals, particularly in the nervous system. Little is known, however, of their interactions at the cell surface. Here, we show that a Drosophila Ryk family member, DERAILED (DRL), forms cell surface homodimers and can also heterodimerize with the two other fly Ryks, DERAILED-2 and DOUGHNUT ON 2. DERAILED homodimerization levels increase significantly in the presence of its ligand, WNT5. In addition, DERAILED displays ligand-independent dimerization mediated by a motif in its transmembrane domain. Increased dimerization of DRL upon WNT5 binding or upon the replacement of DERAILED's extracellular domain with the immunoglobulin Fc domain results in an increased recruitment of the Src family kinase SRC64B, a previously identified downstream pathway effector. Formation of the SRC64B/DERAILED complex requires SRC64B's SH2 domain and DERAILED's PDZ-binding motif. Mutations in DERAILED's inactive tyrosine kinase-homologous domain also disrupt the formation of DERAILED/SRC64B complexes, indicating that its conformation is likely important in facilitating its interaction with SRC64B. Finally, we show that DERAILED's function during embryonic axon guidance requires its Wnt-binding domain, a putative juxtamembrane extracellular tetrabasic cleavage site, and the PDZ-binding domain, indicating that DERAILED's activation involves a complex set of events including both dimerization and proteolytic processing.
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133
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Mulvaney JF, Yatteau A, Sun WW, Jacques B, Takubo K, Suda T, Yamada W, Dabdoub A. Secreted factor R-Spondin 2 is involved in refinement of patterning of the mammalian cochlea. Dev Dyn 2013. [PMID: 23192966 DOI: 10.1002/dvdy.23908] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND In the cochlea, patterning of the organ of Corti is tightly regulated to produce a single row of sound-detecting inner hair cells and three rows of outer hair cells, which amplify and refine the signal. The recently identified R-Spondin family of signaling molecules usually act as co-activators of Wnt signaling; it is thought that they regulate turnover of Wnt receptors at the membrane. We sought to test whether R-Spondins function in the developing cochlea. RESULTS Expression analysis of all four members of the R-Spondin family showed that only R-Spondin2 (Rspo2) is expressed in the cochlea during development of the sensory epithelium. Examination of an Rspo2(-/-) mouse showed that loss of Rspo2 results in an additional single row of outer hair cells and disruption of peripheral innervation pattern. Addition of Rspo2 recombinant protein to organotypic cochlear cultures resulted in a small but significant decrease in the number of outer hair cells. CONCLUSIONS Rspo2 is required to limit the number of outer hair cells to three rows and for optimal arrangement of peripheral nerve fibers. The Rspo2 gain- and loss-of-function studies show that in the ear, Rspo2 function is not consistent with its assigned role as a Wnt potentiator.
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Affiliation(s)
- J F Mulvaney
- Division of Otolaryngology, Department of Surgery, School of Medicine, University of California, San Diego, La Jolla, CA, USA.
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134
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Toyama R, Kim MH, Rebbert ML, Gonzales J, Burgess H, Dawid IB. Habenular commissure formation in zebrafish is regulated by the pineal gland-specific gene unc119c. Dev Dyn 2013; 242:1033-42. [PMID: 23749482 DOI: 10.1002/dvdy.23994] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Revised: 05/24/2013] [Accepted: 05/26/2013] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND The zebrafish pineal gland (epiphysis) is a site of melatonin production, contains photoreceptor cells, and functions as a circadian clock pacemaker. Since it is located on the surface of the forebrain, it is accessible for manipulation and, therefore, is a useful model system to analyze pineal gland function and development. We previously analyzed the pineal transcriptome during development and showed that many genes exhibit a highly dynamic expression pattern in the pineal gland. RESULTS Among genes preferentially expressed in the zebrafish pineal gland, we identified a tissue-specific form of the unc119 gene family, unc119c, which is highly preferentially expressed in the pineal gland during day and night at all stages examined from embryo to adult. When expression of unc119c was inhibited, the formation of the habenular commissure (HC) was specifically compromised. The Unc119c interacting factors Arl3l1 and Arl3l2 as well as Wnt4a also proved indispensible for HC formation. CONCLUSIONS We suggest that Unc119c, together with Arl3l1/2, plays an important role in modulating Wnt4a production and secretion during HC formation in the forebrain of the zebrafish embryo.
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Affiliation(s)
- Reiko Toyama
- Program in Genomics of Development, NICHD, NIH, Bethesda, Maryland, USA
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135
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Avilés EC, Wilson NH, Stoeckli ET. Sonic hedgehog and Wnt: antagonists in morphogenesis but collaborators in axon guidance. Front Cell Neurosci 2013; 7:86. [PMID: 23772206 PMCID: PMC3677135 DOI: 10.3389/fncel.2013.00086] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 05/21/2013] [Indexed: 12/31/2022] Open
Abstract
As indicated by their name, morphogens were first identified for their role in the formation of tissues early in development. Secreted from a source, they spread through the tissue to form gradients by which they affect the differentiation of precursor cells in a concentration-dependent manner. In this context, the antagonistic roles of the morphogens of the Wnt family and Sonic hedgehog (Shh) in the specification of cell types along the dorso-ventral axis of the neural tube have been studied in detail. However, more recently, morphogens have been demonstrated to act well beyond the early stages of nervous system development, as additional roles of morphogen gradients in vertebrate neural circuit formation have been identified. Both Wnt and Shh affect neural circuit formation at several stages by their influence on neurite extension, axon pathfinding and synapse formation. In this review, we will summarize the mechanisms of morphogen function during axon guidance in the vertebrate nervous system.
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Affiliation(s)
- Evelyn C Avilés
- Institute of Molecular Life Sciences, University of Zurich Zurich, Switzerland
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136
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Marchetti B, L'Episcopo F, Morale MC, Tirolo C, Testa N, Caniglia S, Serapide MF, Pluchino S. Uncovering novel actors in astrocyte-neuron crosstalk in Parkinson's disease: the Wnt/β-catenin signaling cascade as the common final pathway for neuroprotection and self-repair. Eur J Neurosci 2013; 37:1550-63. [PMID: 23461676 PMCID: PMC3660182 DOI: 10.1111/ejn.12166] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 01/21/2013] [Accepted: 01/25/2013] [Indexed: 12/31/2022]
Abstract
Parkinson's disease (PD) is a common neurodegenerative disorder characterized by progressive loss of dopaminergic (DAergic) neuronal cell bodies in the substantia nigra pars compacta and gliosis. The cause and mechanisms underlying the demise of nigrostriatal DAergic neurons are ill-defined, but interactions between genes and environmental factors are recognized to play a critical role in modulating the vulnerability to PD. Current evidence points to reactive glia as a pivotal factor in PD pathophysiology, playing both protective and destructive roles. Here, the contribution of reactive astrocytes and their ability to modulate DAergic neurodegeneration, neuroprotection and neurorepair in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) rodent model of PD will be discussed in the light of novel emerging evidence implicating wingless-type mouse mammary tumor virus integration site (Wnt)/β-catenin signaling as a strong candidate in MPTP-induced nigrostriatal DAergic plasticity. In this work, we highlight an intrinsic Wnt1/frizzled-1/β-catenin tone that critically contributes to the survival and protection of adult midbrain DAergic neurons, with potential implications for drug design or drug action in PD. The dynamic interplay between astrocyte-derived factors and neurogenic signals in MPTP-induced nigrostriatal DAergic neurotoxicity and repair will be summarized, together with recent findings showing a critical role of glia-neural stem/progenitor cell (NPC) interactions aimed at overcoming neurodegeneration and inducing neurorestoration. Understanding the intrinsic plasticity of nigrostriatal DAergic neurons and deciphering the signals facilitating the crosstalk between astrocytes, microglia, DAergic neurons and NPCs may have major implications for the role of stem cell technology in PD, and for identifying potential therapeutic targets to induce endogenous neurorepair.
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Affiliation(s)
- Bianca Marchetti
- Department of Clinical and Molecular Biomedicine, Pharmacology Section, Medical School, University of Catania, Catania, Italy.
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137
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Coate TM, Kelley MW. Making connections in the inner ear: recent insights into the development of spiral ganglion neurons and their connectivity with sensory hair cells. Semin Cell Dev Biol 2013; 24:460-9. [PMID: 23660234 PMCID: PMC3690159 DOI: 10.1016/j.semcdb.2013.04.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 04/15/2013] [Indexed: 01/18/2023]
Abstract
In mammals, auditory information is processed by the hair cells (HCs) located in the cochlea and then rapidly transmitted to the CNS via a specialized cluster of bipolar afferent connections known as the spiral ganglion neurons (SGNs). Although many anatomical aspects of SGNs are well described, the molecular and cellular mechanisms underlying their genesis, how they are precisely arranged along the cochlear duct, and the guidance mechanisms that promote the innervation of their hair cell targets are only now being understood. Building upon foundational studies of neurogenesis and neurotrophins, we review here new concepts and technologies that are helping to enrich our understanding of the development of the nervous system within the inner ear.
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Affiliation(s)
- Thomas M Coate
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA.
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138
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Halleskog C, Schulte G. WNT-3A and WNT-5A counteract lipopolysaccharide-induced pro-inflammatory changes in mouse primary microglia. J Neurochem 2013; 125:803-8. [DOI: 10.1111/jnc.12250] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 03/22/2013] [Accepted: 03/22/2013] [Indexed: 12/20/2022]
Affiliation(s)
- Carina Halleskog
- Department of Physiology & Pharmacology; Sec Receptor Biology & Signaling; Karolinska Institutet; Stockholm Sweden
| | - Gunnar Schulte
- Department of Physiology & Pharmacology; Sec Receptor Biology & Signaling; Karolinska Institutet; Stockholm Sweden
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139
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Marchetti B, Pluchino S. Wnt your brain be inflamed? Yes, it Wnt! Trends Mol Med 2013; 19:144-56. [PMID: 23312954 DOI: 10.1016/j.molmed.2012.12.001] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Revised: 12/06/2012] [Accepted: 12/06/2012] [Indexed: 12/15/2022]
Abstract
The roles of Wnts in neural development, synaptogenesis, and cancer are generally well characterized. Nonetheless, evidence exists that interactions between the immune and nervous systems control major brain regenerative processes ranging from physiological or pathological (reparative) regeneration to neurogenesis and synaptic plasticity. Recent studies describe deregulated Wnt-Fzd signaling in degenerative and inflammatory central nervous system (CNS) disorders, and the expression of Wnt signaling components in the immune system, and in immune-like cells of the mammalian CNS. This would suggest a likely involvement of Wnts in inflammation-driven brain damage and inflammation-directed brain repair. Here, we review how Wnts modulate neuroimmune interactions and offer a perspective on the most challenging therapeutic opportunities for those CNS diseases where injury-reactive Wnt-flavored inflammation precedes secondary neurodegeneration.
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Affiliation(s)
- Bianca Marchetti
- Department of Clinical and Molecular Biomedicine, Pharmacology Section, Medical School, University of Catania, 95125 Catania, Italy.
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140
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Park M, Shen K. WNTs in synapse formation and neuronal circuitry. EMBO J 2012; 31:2697-704. [PMID: 22617419 DOI: 10.1038/emboj.2012.145] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 04/20/2012] [Indexed: 11/09/2022] Open
Abstract
Wnt proteins play important roles in wiring neural circuits. Wnts regulate many aspects of neural circuit generation through their receptors and distinct signalling pathways. In this review, we discuss recent findings on the functions of Wnts in various aspects of neural circuit formation, including neuronal polarity, axon guidance, synapse formation, and synaptic plasticity in vertebrate and invertebrate nervous systems.
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Affiliation(s)
- Mikyoung Park
- Center for Functional Connectomics, Brain Science Institute, Seoul, Korea.
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