scholarly journals Unique Responses of Differentiating Neuronal Growth Cones to Inhibitory Cues Presented by Oligodendrocytes

1998 ◽  
Vol 142 (1) ◽  
pp. 191-202 ◽  
Author(s):  
A. Shibata ◽  
M.V. Wright ◽  
S. David ◽  
L. McKerracher ◽  
P.E. Braun ◽  
...  
Keyword(s):  
Growth Cone ◽  
Hippocampal Neurons ◽  
Dendritic Growth ◽  
System Development ◽  
Axonal Growth ◽  
Growth Cones ◽  
Nervous System Development ◽  
Environmental Cues ◽  
Growth Cone Collapse ◽  
Neuronal Growth Cones

During central nervous system development, neurons differentiate distinct axonal and dendritic processes whose outgrowth is influenced by environmental cues. Given the known intrinsic differences between axons and dendrites and that little is known about the response of dendrites to inhibitory cues, we tested the hypothesis that outgrowth of differentiating axons and dendrites of hippocampal neurons is differentially influenced by inhibitory environmental cues. A sensitive growth cone behavior assay was used to assess responses of differentiating axonal and dendritic growth cones to oligodendrocytes and oligodendrocyte- derived, myelin-associated glycoprotein (MAG). We report that >90% of axonal growth cones collapsed after contact with oligodendrocytes. None of the encounters between differentiating, MAP-2 positive dendritic growth cones and oligodendrocytes resulted in growth cone collapse. The insensitivity of differentiating dendritic growth cones appears to be acquired since they develop from minor processes whose growth cones are inhibited (nearly 70% collapse) by contact with oligodendrocytes. Recombinant MAG(rMAG)-coated beads caused collapse of 72% of axonal growth cones but only 29% of differentiating dendritic growth cones. Unlike their response to contact with oligodendrocytes, few growth cones of minor processes were inhibited by rMAG-coated beads (20% collapsed). These results reveal the capability of differentiating growth cones of the same neuron to partition the complex molecular terrain they navigate by generating unique responses to particular inhibitory environmental cues.

scholarly journals Plexin-B1/RhoGEF–mediated RhoA activation involves the receptor tyrosine kinase ErbB-2

2004 ◽  
Vol 165 (6) ◽  
pp. 869-880 ◽  
Author(s):  
Jakub M. Swiercz ◽  
Rohini Kuner ◽  
Stefan Offermanns
Keyword(s):  
Tyrosine Kinase ◽  
Growth Cone ◽  
Receptor Tyrosine Kinase ◽  
Hippocampal Neurons ◽  
Molecular Mechanisms ◽  
Axonal Growth ◽  
Dominant Negative ◽  
Growth Cone Collapse ◽  
Rhoa Activation ◽  
Axonal Growth Cone

Plexins are widely expressed transmembrane proteins that mediate the effects of semaphorins. The molecular mechanisms of plexin-mediated signal transduction are still rather unclear. Plexin-B1 has recently been shown to mediate activation of RhoA through a stable interaction with the Rho guanine nucleotide exchange factors PDZ-RhoGEF and LARG. However, it is unclear how the activity of plexin-B1 and its downstream effectors is regulated by its ligand Sema4D. Here, we show that plexin-B family members stably associate with the receptor tyrosine kinase ErbB-2. Binding of Sema4D to plexin-B1 stimulates the intrinsic tyrosine kinase activity of ErbB-2, resulting in the phosphorylation of both plexin-B1 and ErbB-2. A dominant-negative form of ErbB-2 blocks Sema4D-induced RhoA activation as well as axonal growth cone collapse in primary hippocampal neurons. Our data indicate that ErbB-2 is an important component of the plexin-B receptor system and that ErbB-2–mediated phosphorylation of plexin-B1 is critically involved in Sema4D-induced RhoA activation, which underlies cellular phenomena downstream of plexin-B1, including axonal growth cone collapse.

scholarly journals Regulation of Growth Cone Actin Dynamics by ADF/Cofilin

2003 ◽  
Vol 51 (4) ◽  
pp. 411-420 ◽  
Author(s):  
Ravine A. Gungabissoon ◽  
James R. Bamburg
Keyword(s):  
Actin Cytoskeleton ◽  
Growth Cone ◽  
Rho Gtpases ◽  
System Development ◽  
Cell Types ◽  
Growth Cones ◽  
Nervous System Development ◽  
Actin Dynamics ◽  
Target Cells ◽  
Lim Kinase

Nervous system development is reliant on neuronal pathfinding, the process in which axons are guided to their target cells by specific extracellular cues. The ability of neurons to extend over long distances in response to environmental guidance signals is made possible by the growth cone, a highly motile structure found at the end of neuronal processes. Growth cones detect directional cues and respond with either attractive or repulsive movements. The motility of growth cones is dependent on rapid reorganization of the actin cytoskeleton, presumably mediated by actin-associated proteins under the control of incoming guidance signals. This article reviews how one such family of proteins, the ADF/cofilins, are emerging as key regulators of growth cone actin dynamics. These proteins are essential for rapid actin turnover in a variety of different cell types. ADF/cofilins are heavily co-localized with actin in growth cones and are necessary for neurite outgrowth. ADF/cofilin activities are regulated through reversible phosphorylation by LIM kinases and slingshot phosphatases. LIM kinases are downstream effectors of the Rho GTPases Rho, Rac, and Cdc42. Growing evidence suggests that extracellular guidance cues may locally alter actin dynamics by regulating the activity of LIM kinase and ADF/cofilin phosphatases via the Rho GTPases. In this way, ADF/cofilins and their upstream effectors may be pivotal to our understanding of how guidance information is translated into physical alterations of the growth cone actin cytoskeleton.

scholarly journals Rapid changes in the distribution of GAP-43 correlate with the expression of neuronal polarity during normal development and under experimental conditions.

1990 ◽  
Vol 110 (4) ◽  
pp. 1319-1331 ◽  
Author(s):  
K Goslin ◽  
G Banker
Keyword(s):  
Growth Cone ◽  
Hippocampal Neurons ◽  
Time Course ◽  
Axonal Growth ◽  
Growth Cones ◽  
Growth Characteristics ◽  
Neuronal Polarity ◽  
Experimental Conditions ◽  
Axonal Growth Cone ◽  
Axonal Transection

Hippocampal neurons growing in culture initially extend several, short minor processes that have the potential to become either axons or dendrites. The first expression of polarity occurs when one of these minor processes begins to elongate rapidly, becoming the axon. Before axonal outgrowth, the growth-associated protein GAP-43 is distributed equally among the growth cones of the minor processes; it is preferentially concentrated in the axonal growth cone once polarity has been established (Goslin, K., D. Schreyer, J. Skene, and G. Banker. 1990. J. Neurosci. 10:588-602). To determine when the selective segregation of GAP-43 begins, we followed individual cells by video microscopy, fixed them as soon as the axon could be distinguished, and localized GAP-43 by immunofluorescence microscopy. Individual minor processes acquired axonal growth characteristics within a period of 30-60 min, and GAP-43 became selectively concentrated to the growth cones of these processes with an equally rapid time course. We also examined changes in the distribution of GAP-43 after transection of the axon. After an axonal transection that is distant from the soma, neuronal polarity is maintained, and the original axon begins to regrow almost immediately. In such cases, GAP-43 became selectively concentrated in the new axonal growth cone within 12-30 min. In contrast, when the axon is transected close to the soma, polarity is lost; the original axon rarely regrows, and there is a significant delay before a new axon emerges. Under these circumstances, GAP-43 accumulated in the new growth cone much more slowly, suggesting that its ongoing selective routing to the axon had been disrupted by the transection. These results demonstrate that the selective segregation of GAP-43 to the growth cone of a single process is closely correlated with the acquisition of axonal growth characteristics and, hence, with the expression of polarity.

Analysis of subcellular structural tension in axonal growth of neurons

2018 ◽  
Vol 29 (2) ◽  
pp. 125-137 ◽  
Author(s):  
Yi Chen Guo ◽  
Yu Xuan Wang ◽  
Yan Ping Ge ◽  
Lu Jia Yu ◽  
Jun Guo
Keyword(s):  
Nervous System ◽  
Functional Recovery ◽  
Growth Cone ◽  
System Development ◽  
Axonal Growth ◽  
Nervous System Development ◽  
Axonal Elongation ◽  
The Core ◽  
Pathological Conditions ◽  
New Material

AbstractThe growth and regeneration of axons are the core processes of nervous system development and functional recovery. They are also related to certain physiological and pathological conditions. For decades, it has been the consensus that a new axon is formed by adding new material at the growth cone. However, using the existing technology, we have studied the structural tension of the nerve cell, which led us to hypothesize that some subcellular structural tensions contribute synergistically to axonal growth and regeneration. In this review, we classified the subcellular structural tension, osmotic pressure, microfilament and microtubule-dependent tension involved controllably in promoting axonal growth. A squeezing model was built to analyze the mechanical mechanism underlying axonal elongation, which may provide a new view of axonal growth and inspire further research.

Oligodendrocytes repel axons and cause axonal growth cone collapse

1989 ◽  
Vol 92 (1) ◽  
pp. 93-100 ◽  
Author(s):  
J.W. Fawcett ◽  
J. Rokos ◽  
I. Bakst
Keyword(s):  
Growth Cone ◽  
Dorsal Root ◽  
Axonal Growth ◽  
Time Lapse ◽  
Growth Cones ◽  
Newborn Rats ◽  
Growth Cone Collapse ◽  
Axonal Growth Cone ◽  
Video Studies ◽  
Culture Surface

We have examined the interactions between axons regenerating from dorsal root ganglia (DRGs) derived from newborn rats and oligodendrocytes cultured by three different techniques. Cultures examined after 2 days have a profuse outgrowth of axons from the DRGs, forming a dense mat on the culture surface. However, the axons avoid growing on oligodendrocytes; axons are seen all around these cells, but do not grow over them. We have also performed time-lapse video studies of the interactions between axonal growth cones and oligodendrocytes. Axons grow normally until their growth cone comes into direct contact with an oligodendrocyte, following which the growth cone remains motile for 30–60 min, but without making any progress over the cell. The growth cone then suddenly collapses, and the axon retracts, leaving a thin strand in contact with the cell. After this a new growth cone is usually elaborated and the process repeated. Oligodendrocytes are therefore inhibitory to axonal growth, and this may partially explain the failure of axons to regenerate in the mammalian central nervous system.

Genes that guide growth cones along the C. elegans ventral nerve cord

Development ◽  
1997 ◽  
Vol 124 (13) ◽  
pp. 2571-2580 ◽  
Author(s):  
B. Wightman ◽  
R. Baran ◽  
G. Garriga
Keyword(s):  
Nervous System ◽  
Growth Cone ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
System Development ◽  
Growth Cones ◽  
Nervous System Development ◽  
Nerve Bundle ◽  
C Elegans ◽  
Bundle Structure

During nervous system development, growth cone pioneering and fasciculation contribute to nerve bundle structure. Pioneer growth cones initially navigate along neuroglia to establish an axon scaffold that guides later extending growth cones. In C. elegans, the growth cone of the PVPR neuron pioneers the left ventral nerve cord bundle, providing a path for the embryonic extensions of the PVQL and AVKR growth cones. Later during larval development, the HSNL growth cone follows cues in the left ventral nerve cord bundle provided by the PVPR and PVQL axons. Here we show that mutations in the genes enu-1, fax-1, unc-3, unc-30, unc-42 and unc-115 disrupt pathfinding of growth cones along the left ventral nerve cord bundle. Our results indicate that unc-3 and unc-30 function in ventral nerve cord pioneering and that enu-1, fax-1, unc-42 and unc-115 function in recognition of the PVPR and PVQL axons by the AVKR and HSNL growth cones.

A Mechanical Model for Cytoskeleton and Membrane Interactions in Neuronal Growth Cones

2007 ◽  
Author(s):  
Kathleen B. Allen ◽  
Bradley Layton
Keyword(s):  
Mechanical Properties ◽  
Cell Membrane ◽  
Actin Filament ◽  
System Development ◽  
Growth Cones ◽  
Nervous System Development ◽  
Cytoskeletal Proteins ◽  
Neuronal Growth ◽  
Cytoskeletal Elements ◽  
Neuronal Growth Cones

Revealing the molecular events of neuronal growth is critical to obtaining a deeper understanding of nervous system development, neural injury response, and neural tissue engineering. Central to this is the need to understand the mechanical interactions among the cytoskeleton and the cell membrane, and how these interactions affect the overall growth mechanics of neurons. Using ANSYS, the force produced by a cytoskeletal protein acting against a deformable membrane was modeled, and the deformation, stress, and strain were computed for the membrane. Parameters to represent the flexural rigidities of the well-studied actin and tubulin cytoskeletal proteins as well as the mechanical properties of neuronal growth cones were used in the simulations. Our model predicts that while a single actin filament is able to produce a force sufficient to cause membrane deformation and thus growth, it is also possible that the actin filament may cause the membrane to rupture, if a dilatational strain of more than 3–4% occurs. Additionally, neurotoxins or pharmaceuticals that alter the mechanical properties of either the cell membrane or cytoskeletal proteins could disrupt the balance of forces required for neurons to not only push out and grow correctly, but also to sustain their shapes as high-aspect-ratio structures once growth is complete. Understanding how cytoskeletal elements have coevolved mechanically with their respective cell membranes will yield insights into the events that gave rise to the sequences and quaternary structures of the major cytoskeletal elements.

scholarly journals Growth cone collapse and inhibition of neurite growth by Botulinum neurotoxin C1: a t-SNARE is involved in axonal growth.

1996 ◽  
Vol 134 (1) ◽  
pp. 205-215 ◽  
Author(s):  
M Igarashi ◽  
S Kozaki ◽  
S Terakawa ◽  
S Kawano ◽  
C Ide ◽  
...  
Keyword(s):  
Growth Cone ◽  
Axonal Growth ◽  
Normal Growth ◽  
Neurite Growth ◽  
Total Surface Area ◽  
Central Domain ◽  
Growth Cone Collapse ◽  
Gradual Disappearance ◽  
Microscopic Studies ◽  
Presynaptic Protein

The growth cone is responsible for axonal growth, where membrane expansion is most likely to occur. Several recent reports have suggested that presynaptic proteins are involved in this process; however, the molecular mechanism details are unclear. We suggest that by cleaving a presynaptic protein syntaxin, which is essential in targeting synaptic vesicles as a target SNAP receptor (t-SNARE), neurotoxin C1 of Clostridium botulinum causes growth cone collapse and inhibits axonal growth. Video-enhanced microscopic studies showed (a) that neurotoxin C1 selectively blocked the activity of the central domain (the vesicle-rich region) at the initial stage, but not the lamellipodia in the growth cone; and (b) that large vacuole formation occurred probably through the fusion of smaller vesicles from the central domain to the most distal segments of the neurite. The total surface area of the accumulated vacuoles could explain the membrane expansion of normal neurite growth. The gradual disappearance of the surface labeling by FITC-WGA on the normal growth cone, suggesting membrane addition, was inhibited by neurotoxin C1. The experiments using the peptides derived from syntaxin, essential for interaction with VAMP or alpha-SNAP, supported the results using neurotoxin C1. Our results demonstrate that syntaxin is involved in axonal growth and indicate that syntaxin may participate directly in the membrane expansion that occurs in the central domain of the growth cone, probably through association with VAMP and SNAPs, in a SNARE-like way.

scholarly journals Phosphorylation by Rho Kinase Regulates CRMP-2 Activity in Growth Cones

2005 ◽  
Vol 25 (22) ◽  
pp. 9973-9984 ◽  
Author(s):  
Nariko Arimura ◽  
Céline Ménager ◽  
Yoji Kawano ◽  
Takeshi Yoshimura ◽  
Saeko Kawabata ◽  
...  
Keyword(s):  
Growth Cone ◽  
Actin Filaments ◽  
Rho Kinase ◽  
Growth Cones ◽  
Binding Activity ◽  
Microtubule Assembly ◽  
Coated Pits ◽  
Growth Cone Collapse ◽  
Mediator Protein ◽  
Neuron Growth

ABSTRACT Collapsin response mediator protein 2 (CRMP-2) enhances the advance of growth cones by regulating microtubule assembly and Numb-mediated endocytosis. We previously showed that Rho kinase phosphorylates CRMP-2 during growth cone collapse; however, the roles of phosphorylated CRMP-2 in growth cone collapse remain to be clarified. Here, we report that CRMP-2 phosphorylation by Rho kinase cancels the binding activity to the tubulin dimer, microtubules, or Numb. CRMP-2 binds to actin, but its binding is not affected by phosphorylation. Electron microscopy revealed that CRMP-2 localizes on microtubules, clathrin-coated pits, and actin filaments in dorsal root ganglion neuron growth cones, while phosphorylated CRMP-2 localizes only on actin filaments. The phosphomimic mutant of CRMP-2 has a weakened ability to enhance neurite elongation. Furthermore, ephrin-A5 induces phosphorylation of CRMP-2 via Rho kinase during growth cone collapse. Taken together, these results suggest that Rho kinase phosphorylates CRMP-2, and inactivates the ability of CRMP-2 to promote microtubule assembly and Numb-mediated endocytosis, during growth cone collapse.

scholarly journals The role of microtubules in growth cone turning at substrate boundaries.

1995 ◽  
Vol 128 (1) ◽  
pp. 127-137 ◽  
Author(s):  
E Tanaka ◽  
M W Kirschner
Keyword(s):  
Growth Cone ◽  
Collagen Type ◽  
Axon Growth ◽  
Growth Cones ◽  
Collagen Type Iv ◽  
Early Step ◽  
Growth Cone Collapse ◽  
Type Iv ◽  
And Behaviors

To understand the role of microtubules in growth cone turning, we observed fluorescently labeled microtubules in neurons as they encountered a substrate boundary. Neurons growing on a laminin-rich substrate avoided growing onto collagen type IV. Turning growth cones assumed heterogeneous morphologies and behaviors that depended primarily in their extent of adhesion to the substrate. We grouped these behaviors into three categories-sidestepping, motility, and growth-mediated reorientation. In sidestepping and motility-mediated reorientation, the growth cone and parts of the axon were not well attached to the substrate so the acquisition of an adherent lamella caused the entire growth cone to move away from the border and consequently reoriented the axon. In these cases, since the motility of the growth cone dominates its reorientation, the microtubules were passive, and reorientation occurred without significant axon growth. In growth-mediated reorientation, the growth cone and axon were attached to the substrate. In this case, microtubules reoriented within the growth cone to stabilize a lamella. Bundling of the reoriented microtubules was followed by growth cone collapse to form new axon, and further, polarized lamellipodial extension. These observations indicate that when the growth cone remains adherent to the substrate during turning, the reorientation and bundling of microtubules is an important, early step in growth cone turning.

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