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Axonal pathfind

Sian Lewis
No abstract text is available yet for this article.
October 18, 2016: Nature Reviews. Neuroscience
Karen Stanic, Natalia Saldivia, Benjamín Förstera, Marcela Torrejón, Hernán Montecinos, Teresa Caprile
Extracellular matrix (ECM) molecules are pivotal for central nervous system (CNS) development, facilitating cell migration, axonal growth, myelination, dendritic spine formation, and synaptic plasticity, among other processes. During axon guidance, the ECM not only acts as a permissive or non-permissive substrate for navigating axons, but also modulates the effects of classical guidance cues, such as netrin or Eph/ephrin family members. Despite being highly important, little is known about the expression of ECM molecules during CNS development...
2016: Frontiers in Neuroanatomy
Lulu I T Korsak, Molly E Mitchell, Katherine A Shepard, Michael R Akins
RNA localization is a key mechanism in the regulation of protein expression. In neurons, this includes the axonal transport of select mRNAs based on the recognition of axonal localization motifs in these RNAs by RNA binding proteins. Bioinformatic analyses of axonal RNAs suggest that selective inclusion of such localization motifs in mature mRNAs is one mechanism controlling the composition of the axonal transcriptome. The subsequent translation of axonal transcripts in response to specific stimuli provides precise spatiotemporal control of the axonal proteome...
March 2016: Current Genetic Medicine Reports
David E Koser, Amelia J Thompson, Sarah K Foster, Asha Dwivedy, Eva K Pillai, Graham K Sheridan, Hanno Svoboda, Matheus Viana, Luciano da F Costa, Jochen Guck, Christine E Holt, Kristian Franze
During nervous system development, neurons extend axons along well-defined pathways. The current understanding of axon pathfinding is based mainly on chemical signaling. However, growing neurons interact not only chemically but also mechanically with their environment. Here we identify mechanical signals as important regulators of axon pathfinding. In vitro, substrate stiffness determined growth patterns of Xenopus retinal ganglion cell axons. In vivo atomic force microscopy revealed a noticeable pattern of stiffness gradients in the embryonic brain...
September 19, 2016: Nature Neuroscience
Seyun Roh, Da-Som Yang, Sangyun Jeong
Plexins (Plexs) are a large family of phylogenetically conserved guidance receptors that bind specifically to semaphorins (Semas), another large family of guidance molecules. In the Drosophila embryonic central nervous system (CNS), the secreted semaphorins Sema-2a and Sema-2b both act as ligands for PlexB, but mediate mutually independent and opposite functions (repulsive and attractive guidance, respectively). PlexB is also known to regulate motor axon guidance in the embryonic peripheral nervous system (PNS)...
September 13, 2016: International Journal of Developmental Neuroscience
Nitasha R Phatak, Dorota L Stankowska, Raghu R Krishnamoorthy
PURPOSE: Brn3b is a class IV POU domain transcription factor that plays an important role in the development of retinal ganglion cells (RGCs), RGC survival, and particularly axon growth and pathfinding. Our previous study demonstrated that recombinant adenoassociated virus serotype 2 (rAAV-2)-mediated overexpression of Brn3b in RGCs promoted neuroprotection in a rodent model of glaucoma. However, the mechanisms underlying neuroprotection of RGCs in rats overexpressing Brn3b in animal models of glaucoma remain largely unknown...
2016: Molecular Vision
J J Winters, L L Isom
Voltage-gated Na(+) channels (VGSCs) isolated from mammalian neurons are heterotrimeric complexes containing one pore-forming α subunit and two non-pore-forming β subunits. In excitable cells, VGSCs are responsible for the initiation of action potentials. VGSC β subunits are type I topology glycoproteins, containing an extracellular amino-terminal immunoglobulin (Ig) domain with homology to many neural cell adhesion molecules (CAMs), a single transmembrane segment, and an intracellular carboxyl-terminal domain...
2016: Current Topics in Membranes
Bryan Black, Vivek Vishwakarma, Kamal Dhakal, Samik Bhattarai, Prabhakar Pradhan, Ankur Jain, Young-Tae Kim, Samarendra Mohanty
Formation of neural networks during development and regeneration after injury depends on accuracy of axonal pathfinding, which is primarily believed to be influenced by chemical cues. Recently, there is growing evidence that physical cues can play crucial role in axonal guidance. However, detailed mechanism involved in such guidance cues is lacking. By using weakly-focused near-infrared continuous wave (CW) laser microbeam in the path of an advancing axon, we discovered that the beam acts as a repulsive guidance cue...
2016: Scientific Reports
Sa Kan Yoo, Heath G Pascoe, Telmo Pereira, Shu Kondo, Antonio Jacinto, Xuewu Zhang, Iswar K Hariharan
In most multicellular organisms, homeostasis is contingent upon maintaining epithelial integrity. When unanticipated insults breach epithelial barriers, dormant programmes of tissue repair are immediately activated. However, many of the mechanisms that repair damaged epithelia remain poorly characterized. Here we describe a role for Plexin A (PlexA), a protein with particularly well-characterized roles in axonal pathfinding, in the healing of damaged epithelia in Drosophila. Semaphorins, which are PlexA ligands, also regulate tissue repair...
2016: Nature Communications
Nicolas Preitner, Jie Quan, Xinmin Li, Finn C Nielsen, John G Flanagan
RNA-based regulatory mechanisms play important roles in the development and plasticity of neural circuits and neurological disease. Developing axons provide a model well suited to the study of RNA-based regulation, and contain specific subsets of mRNAs that are locally translated and have roles in axon pathfinding. However, the RNA-binding proteins involved in axon pathfinding, and their corresponding mRNA targets, are still largely unknown. Here we find that the RNA-binding protein IMP2 (Igf2bp2) is strikingly enriched in developing axon tracts, including in spinal commissural axons...
August 1, 2016: Development
Sreeharsha Gurrapu, Luca Tamagnone
Semaphorins constitute a large family of membrane-bound and secreted proteins that provide guidance cues for axon pathfinding and cell migration. Although initially discovered as repelling cues for axons in nervous system, they have been found to regulate cell adhesion and motility, angiogenesis, immune function and tumor progression. Notably, semaphorins are bifunctional cues and for instance can mediate both repulsive and attractive functions in different contexts. While many studies focused so far on the function of secreted family members, class 1 semaphorins in invertebrates and class 4, 5 and 6 in vertebrate species comprise around 14 transmembrane semaphorin molecules with emerging functional relevance...
June 13, 2016: Cell Adhesion & Migration
Larisa C Kruger, Heather A O'Malley, Jacob M Hull, Amanda Kleeman, Gustavo A Patino, Lori L Isom
UNLABELLED: Voltage-gated sodium channel (VGSC) β subunits signal through multiple pathways on multiple time scales. In addition to modulating sodium and potassium currents, β subunits play nonconducting roles as cell adhesion molecules, which allow them to function in cell-cell communication, neuronal migration, neurite outgrowth, neuronal pathfinding, and axonal fasciculation. Mutations in SCN1B, encoding VGSC β1 and β1B, are associated with epilepsy. Autosomal-dominant SCN1B-C121W, the first epilepsy-associated VGSC mutation identified, results in genetic epilepsy with febrile seizures plus (GEFS+)...
June 8, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Kritika S Katiyar, Carla C Winter, Laura A Struzyna, James P Harris, D Kacy Cullen
Following brain injury or neurodegenerative disease, successful regeneration requires orchestrated migration of neurons and reformation of long-distance communication fibres, or axons. Such extensive regeneration does not occur in the mature brain; however, during embryonic development, pathways formed by glial cells extend several millimeters (mm) to create 'living scaffolds' for targeted neural cell migration and axonal pathfinding. Techniques to recapitulate long process outgrowth in glial cells have proven elusive, preventing the exploitation of this developmental mechanism for regeneration...
June 7, 2016: Journal of Tissue Engineering and Regenerative Medicine
Fahimeh Darki, Satu Massinen, Elina Salmela, Hans Matsson, Myriam Peyrard-Janvid, Torkel Klingberg, Juha Kere
The axon guidance receptor, Robo1, controls the pathfinding of callosal axons in mice. To determine whether the orthologous ROBO1 gene is involved in callosal development also in humans, we studied polymorphisms in the ROBO1 gene and variation in the white matter structure in the corpus callosum using both structural magnetic resonance imaging and diffusion tensor magnetic resonance imaging. We found that five polymorphisms in the regulatory region of ROBO1 were associated with white matter density in the posterior part of the corpus callosum pathways...
May 30, 2016: Brain Structure & Function
Yuhki Saito, Soledad Miranda-Rottmann, Matteo Ruggiu, Christopher Y Park, John J Fak, Ru Zhong, Jeremy S Duncan, Brian A Fabella, Harald J Junge, Zhe Chen, Roberto Araya, Bernd Fritzsch, A J Hudspeth, Robert B Darnell
The neuron specific RNA-binding proteins NOVA1 and NOVA2 are highly homologous alternative splicing regulators. NOVA proteins regulate at least 700 alternative splicing events in vivo, yet relatively little is known about the biologic consequences of NOVA action and in particular about functional differences between NOVA1 and NOVA2. Transcriptome-wide searches for isoform-specific functions, using NOVA1 and NOVA2 specific HITS-CLIP and RNA-seq data from mouse cortex lacking either NOVA isoform, reveals that NOVA2 uniquely regulates alternative splicing events of a series of axon guidance related genes during cortical development...
2016: ELife
Wei Wang, Asit Rai, Eun-Mi Hur, Zeev Smilansky, Karen T Chang, Kyung-Tai Min
Local information processing in the growth cone is essential for correct wiring of the nervous system. As an axon navigates through the developing nervous system, the growth cone responds to extrinsic guidance cues by coordinating axon outgrowth with growth cone steering. It has become increasingly clear that axon extension requires proper actin polymerization dynamics, whereas growth cone steering involves local protein synthesis. However, molecular components integrating these two processes have not been identified...
May 23, 2016: Journal of Cell Biology
Carole Gauron, Francesca Meda, Edmond Dupont, Shahad Albadri, Nicole Quenech'Du, Eliane Ipendey, Michel Volovitch, Filippo Del Bene, Alain Joliot, Christine Rampon, Sophie Vriz
It is now becoming evident that hydrogen peroxide (H2O2), which is constantly produced by nearly all cells, contributes to bona fide physiological processes. However, little is known regarding the distribution and functions of H2O2 during embryonic development. To address this question, we used a dedicated genetic sensor and revealed a highly dynamic spatio-temporal pattern of H2O2 levels during zebrafish morphogenesis. The highest H2O2 levels are observed during somitogenesis and organogenesis, and these levels gradually decrease in the mature tissues...
June 15, 2016: Developmental Biology
Brett Milash, Jingxia Gao, Tamara J Stevenson, Jong-Hyun Son, Tiffanie Dahl, Joshua L Bonkowsky
BACKGROUND: Despite the fundamental biological importance and clinical relevance of characterizing the effects of chronic hypoxia exposure on central nervous system (CNS) development, the changes in gene expression from hypoxia are unknown. It is not known if there are unifying principles, properties, or logic in the response of the developing CNS to hypoxic exposure. Here, we use the small vertebrate zebrafish (Danio rerio) to study the effects of hypoxia on connectivity gene expression across development...
2016: BMC Genomics
Caitlin A Short, Edwin A Suarez-Zayas, Timothy M Gomez
Axon extension, guidance and tissue invasion share many similarities to normal cell migration and cancer cell metastasis. Proper cell and growth cone migration requires tightly regulated adhesion complex assembly and detachment from the extracellular matrix (ECM). In addition, many cell types actively remodel the ECM using matrix metalloproteases (MMPs) to control tissue invasion and cell dispersal. Targeting and activating MMPs is a tightly regulated process, that when dysregulated, can lead to cancer cell metastasis...
August 2016: Current Opinion in Neurobiology
Qionglin Peng, Yijin Wang, Meixia Li, Deliang Yuan, Mengbo Xu, Changqing Li, Zhefeng Gong, Renjie Jiao, Li Liu
UNLABELLED: Correct pathfinding and target recognition of a developing axon are exquisitely regulated processes that require multiple guidance factors. Among these factors, the second messengers, cAMP and cGMP, are known to be involved in establishing the guidance cues for axon growth through different intracellular signaling pathways. However, whether and how cGMP-dependent protein kinase (PKG) regulates axon guidance remains poorly understood. Here, we show that the motor axons of intersegmental nerve b (ISNb) in the Drosophila embryo display targeting defects during axon development in the absence of foraging(for), a gene encoding PKG...
April 20, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
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