Expression of Developmentally Important Axon Guidance Cues in the Adult Optic Chiasm

The optic chiasm of mammals is the region of the nervous system in which optic axons have a choice of route, either they enter the optic tract on the same side of the brain or they cross the chiasm and enter the opposite optic tract. in eutherian (placental) mammals, axons approach the midline of the chiasm and then either continue across the chiasm or turn back to enter the tract on the same side of the brain. The midline of the chiasm provides guidance cues that repel uncrossed but not crossed axons. However, it has recently been shown that in a marsupial, the quokka wallaby, axons destined to stay on the same side of the brain remain in the lateral part of the optic nerve and chiasm and never approach the midline. The structure of the chiasm reflects this partitioning of axons with different routes by having a tripartite structure. The two lateral regions contain only uncrossed axons in rostral chiasmatic regions and the central region contains only crossed axons. Therefore, axons passing through the chiasm of this species must use guidance cues that differ from those of eutherian mammals. Here I show that the chiasms of species of both diprotodont and polyprotodont Australian marsupials have a similar tripartite structure and that uncrossed axons are confined to lateral regions. It seems likely, therefore, that the chiasm of marsupials has fundamental differences in structure and optic axon trajectory compared with that of eutherian mammals studied to date.

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Axon Guidance: Guidance Cues and Guidepost Cells

Encyclopedia of Neuroscience ◽

10.1016/b978-008045046-9.00339-9 ◽

2009 ◽

pp. 1081-1086

Author(s):

L. Ma ◽

K. Shen

Keyword(s):

Axon Guidance ◽

Guidance Cues

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A pair of E3 ubiquitin ligases compete to regulate filopodial dynamics and axon guidance

The Journal of Cell Biology ◽

10.1083/jcb.201902088 ◽

2019 ◽

Vol 219 (1) ◽

Cited By ~ 3

Author(s):

Nicholas P. Boyer ◽

Laura E. McCormick ◽

Shalini Menon ◽

Fabio L. Urbina ◽

Stephanie L. Gupton

Keyword(s):

Axon Guidance ◽

Growth Cone ◽

Ubiquitin Ligases ◽

Critical Element ◽

E3 Ubiquitin Ligases ◽

Related Protein ◽

Guidance Cues ◽

Guidance Cue ◽

Neuronal Connections ◽

Novel Model

Appropriate axon guidance is necessary to form accurate neuronal connections. Axon guidance cues that stimulate cytoskeletal reorganization within the growth cone direct axon navigation. Filopodia at the growth cone periphery have long been considered sensors for axon guidance cues, yet how they respond to extracellular cues remains ill defined. Our previous work found that the filopodial actin polymerase VASP and consequently filopodial stability are negatively regulated via nondegradative TRIM9-dependent ubiquitination. Appropriate VASP ubiquitination and deubiquitination are required for axon turning in response to the guidance cue netrin-1. Here we show that the TRIM9-related protein TRIM67 outcompetes TRIM9 for interacting with VASP and antagonizes TRIM9-dependent VASP ubiquitination. The surprising antagonistic roles of two closely related E3 ubiquitin ligases are required for netrin-1–dependent filopodial responses, axon turning and branching, and fiber tract formation. We suggest a novel model in which coordinated regulation of VASP ubiquitination by a pair of interfering ligases is a critical element of VASP dynamics, filopodial stability, and axon guidance.

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Concentration-Dependent Requirement for Local Protein Synthesis in Motor Neuron Subtype-Specific Response to Axon Guidance Cues

Journal of Neuroscience ◽

10.1523/jneurosci.4176-11.2012 ◽

2012 ◽

Vol 32 (4) ◽

pp. 1496-1506 ◽

Cited By ~ 32

Author(s):

S. Nedelec ◽

M. Peljto ◽

P. Shi ◽

M. W. Amoroso ◽

L. C. Kam ◽

...

Keyword(s):

Protein Synthesis ◽

Motor Neuron ◽

Axon Guidance ◽

Specific Response ◽

Local Protein Synthesis ◽

Guidance Cues ◽

Local Protein

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[P238]: Loss of heparan sulphate‐6‐sulphotransferase 1 results in retinal ganglion cell axon guidance errors at the optic chiasm and dorsal thalamus of the developing mouse visual system

International Journal of Developmental Neuroscience ◽

10.1016/j.ijdevneu.2006.09.297 ◽

2006 ◽

Vol 24 (8) ◽

pp. 597-598

Author(s):

C. Conway ◽

T. Pratt ◽

D. Price ◽

J. Mason

Keyword(s):

Visual System ◽

Ganglion Cell ◽

Axon Guidance ◽

Retinal Ganglion Cell ◽

Heparan Sulphate ◽

Optic Chiasm ◽

Retinal Ganglion ◽

Dorsal Thalamus ◽

Cell Axon ◽

Ganglion Cell Axon

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A requirement for filopodia extension toward Slit during Robo-mediated axon repulsion

The Journal of Cell Biology ◽

10.1083/jcb.201509062 ◽

2016 ◽

Vol 213 (2) ◽

pp. 261-274 ◽

Cited By ~ 28

Author(s):

Russell E. McConnell ◽

J. Edward van Veen ◽

Marina Vidaki ◽

Adam V. Kwiatkowski ◽

Aaron S. Meyer ◽

...

Keyword(s):

Axon Guidance ◽

Actin Polymerization ◽

Growth Cones ◽

Guidance Cues ◽

Guidance Cue ◽

3D Environments ◽

Direct Binding ◽

Mouse Dorsal Root Ganglion ◽

Axon Repulsion

Axons navigate long distances through complex 3D environments to interconnect the nervous system during development. Although the precise spatiotemporal effects of most axon guidance cues remain poorly characterized, a prevailing model posits that attractive guidance cues stimulate actin polymerization in neuronal growth cones whereas repulsive cues induce actin disassembly. Contrary to this model, we find that the repulsive guidance cue Slit stimulates the formation and elongation of actin-based filopodia from mouse dorsal root ganglion growth cones. Surprisingly, filopodia form and elongate toward sources of Slit, a response that we find is required for subsequent axonal repulsion away from Slit. Mechanistically, Slit evokes changes in filopodium dynamics by increasing direct binding of its receptor, Robo, to members of the actin-regulatory Ena/VASP family. Perturbing filopodium dynamics pharmacologically or genetically disrupts Slit-mediated repulsion and produces severe axon guidance defects in vivo. Thus, Slit locally stimulates directional filopodial extension, a process that is required for subsequent axonal repulsion downstream of the Robo receptor.

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Transcriptional logic of cell fate specification and axon guidance in early born retinal neurons revealed by single-cell mRNA profiling

10.1101/497081 ◽

2018 ◽

Author(s):

Quentin Lo Giudice ◽

Marion Leleu ◽

Pierre J. Fabre

Keyword(s):

Axon Guidance ◽

Cell Fate ◽

Ganglion Cells ◽

Amacrine Cells ◽

Retinal Ganglion ◽

Cell Fate Specification ◽

Retinal Neurons ◽

Fate Specification ◽

Guidance Cues ◽

Insight Into

ABSTRACTRetinal ganglion cells (RGC), together with cone photoreceptors, horizontal cells (HC) and amacrine cells (AC), are the first classes of neurons produced in the retina. Here we have profiled 5348 single retinal cells and provided a comprehensive transcriptomic atlas showing the broad diversity of the developing retina at the time when the four early-born cells are being produced. Our results show the transcriptional sequences that establish the hierarchical ordering of early cell fate specification in the retina. RGC maturation follows six waves of gene expression, giving new insight into the regulatory logic of RGC differentiation. Early-generated RGCs transcribe an increasing amount of guidance cues for young peripheral RGC axons that express the matching receptors. Finally, spatial signatures in sub-populations of RGCs allowed to define novel molecular markers that are spatially restricted during the development of the retina. Altogether this study is a valuable resource that identifies new players in mouse retinal development, shedding light on transcription factors sequence and guidance cues dynamics in space and time.

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Axon guidance modalities in CNS regeneration revealed by quantitative proteomic analysis

10.1101/2021.03.26.437129 ◽

2021 ◽

Author(s):

Noemie Vilallongue ◽

Julia Schaeffer ◽

Anne-Marie Hesse ◽

Celine Delpech ◽

Antoine Paccard ◽

...

Keyword(s):

Nervous System ◽

Axon Guidance ◽

Optic Chiasm ◽

Axonal Guidance ◽

Dorsal Lateral Geniculate Nucleus ◽

Long Distance ◽

Nerve Crush ◽

Guidance Molecules ◽

Visual Targets ◽

The Brain

Long-distance regeneration of the central nervous system (CNS) has been achieved from the eye to the brain through activation of neuronal molecular pathways or pharmacological approaches. Unexpectedly, most of the regenerative fibers display guidance defects, which prevents reinnervation and further functional recovery. Therefore, characterizing the mature neuronal environment is essential to understand the adult axonal guidance in order to complete the circuit reconstruction. To this end, we used mass spectrometry to characterize the proteomes of major nuclei of the adult visual system: suprachiasmatic nucleus (SCN), ventral and dorsal lateral geniculate nucleus (vLGN, dLGN) and superior colliculus (SC)), as well as the optic chiasm. These analyses revealed the presence of guidance molecules and guidance-associated factors in the adult visual targets. Moreover, by performing bilateral optic nerve crush, we showed that the expression of some proteins was significantly modulated by the injury in the visual targets, even in the ones most distal to the lesion site. On another hand, we found that the expression of guidance molecules was not modified upon injury. This implies that these molecules may possibly interfere with the reinnervation of the brain targets. Together, our results provides an extensive characterization of the molecular environment in intact and injured conditions. These findings open new ways to correct regenerating axon guidance notably by manipulating the expression of the corresponding guidance receptors in the nervous system.

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