The unc-5, unc-6, and unc-40 genes guide circumferential migrations of pioneer axons and mesodermal cells on the epidermis in C. elegans

@article{Hedgecock1990TheUU,
  title={The unc-5, unc-6, and unc-40 genes guide circumferential migrations of pioneer axons and mesodermal cells on the epidermis in C. elegans},
  author={Edward M. Hedgecock and Joseph G Culotti and David H. Hall},
  journal={Neuron},
  year={1990},
  volume={4},
  pages={61-85}
}
Three known genes guide circumferential migrations of pioneer axons and mesodermal cells on the nematode body wall. unc-5 affects dorsal migrations, unc-40 primarily affects ventral migrations, and unc-6 affects migrations in both directions. Circumferential movements still occur, but are misdirected whereas longitudinal movements are normal in these mutants. Pioneer growth cones migrating directly on the epidermis are affected; growth cones migrating along established axon fascicles are normal… 
Role of netrin UNC-6 in patterning the longitudinal nerves of Caenorhabditis elegans.
TLDR
It is shown that cells ectopically expressing UNC-6 can redirect the migrations of some neighboring longitudinal axons, suggesting that the gradients postulated to direct circumferential migration also help specify the dorsoventral positions of these longitudinal nerves.
Netrin UNC-6 and the Regulation of Branching and Extension of Motoneuron Axons from the Ventral Nerve Cord of Caenorhabditis elegans
TLDR
It is shown that expression of unc-6ΔC, which encodes UNC-6 without domain C, partially rescues circumferential migration defects inunc-6 null animals and is proposed that local interactions mediated by domain C regulate motoneuron branching and responsiveness to the UNC- 6 cue.
UNC-40, a C. elegans Homolog of DCC (Deleted in Colorectal Cancer), Is Required in Motile Cells Responding to UNC-6 Netrin Cues
TLDR
Results suggest that UNC-40 is a component of UNC-6 receptors on motile cells and helps determine the dorsoventral position of cells undergoing purely longitudinal migrations.
Expression of the UNC-5 guidance receptor in the touch neurons of C. elegans steers their axons dorsally
TLDR
The results support previous evidence that UNC-5 and UNC-6 play instructive rules in guiding growth cone migrations on the epidermis in C. elegans and indicate that pioneering growth cones, which normally migrate in different directions, may use equivalent intracellular signalling mechanisms for guidance.
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TLDR
Observations show that extracellular guidance molecules can direct complex arrangements of migrating growth cones in vivo by eliciting different types of responses, by spatially and temporally regulating their expression and by working in concert with otherextracellular molecules.
Regulation of the UNC-5 netrin receptor initiates the first reorientation of migrating distal tip cells in Caenorhabditis elegans.
TLDR
Results reveal the existence of two mechanisms that regulate the UNC-5 receptor that are critical for responsiveness to theUNC-6 netrin guidance cue and for linking the directional guidance of migrating distal tip cells to developmental stage advancements.
Suppressors of ectopic UNC-5 growth cone steering identify eight genes involved in axon guidance in Caenorhabditis elegans.
TLDR
Eight genes that are required for ectopic unc-5-induced growth cone steering are described and it is proposed that some or all of these genes may function in a developmentally important unc- 5 signaling pathway.
VAB-8, UNC-73 and MIG-2 regulate axon polarity and cell migration functions of UNC-40 in C. elegans
TLDR
It is shown that highly conserved receptors that guide pioneer axons along the dorsoventral axis, such as UNC-40 and SAX-3 (receptors for UNC-6 and SLT-1 guidance cues, respectively), can be co-opted to affect axon and cell migrations along the anterior-posterior axis.
UNC-6 and UNC-40 promote dendritic growth through PAR-4 in Caenorhabditis elegans neurons
TLDR
It is found that the guidance cue UNC-6 (Netrin) is required for both axon and dendrite development, and the serine-threonine kinase PAR-4 (LKB1) was selectively required for the activity of the UNC-40 pathway in dendrites outgrowth.
Neuroglia and Pioneer Neurons Express UNC-6 to Provide Global and Local Netrin Cues for Guiding Migrations in C. elegans
TLDR
The results indicate that the biological activities of netrins are mediated through distinct protein domains, and EGF-like module V-2 is essential for dorsal guidance activity; it is inferred this module is important for interactions between UNC-6 and the dorsal guidance receptor UNC-5.
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References

SHOWING 1-10 OF 60 REFERENCES
Pathfinding by pioneer neurons in isolated, opened and mesoderm-free limb buds of embryonic grasshoppers.
TLDR
Results indicate that proximal extension of pioneer growth cones along the limb axis does not require tissue extrinsic to the limb, contact guidance by the limb contour, an axial electrical field, a diffusion gradient generated by a localized source, mesodermal cells, or guidepost neurons, and adequate guidance information for proximal growth apparently can be provided by the limbs epidermal epithelium.
The guidance of axons from transplanted neurons through aneural Drosophila wings
  • S. Blair, M. Murray, J. Palka
  • Biology, Medicine
    The Journal of neuroscience : the official journal of the Society for Neuroscience
  • 1987
TLDR
It appears that the aneural wing epithelium contains cues capable of directing both the polarity and the location of axonal outgrowth, and it is shown that such axons prefer to grow in the normal, proximal direction.
Differential adhesivity of neuroepithelial cells and pioneering circumferential axons.
TLDR
The preferential retention of surface contact between adjacent endfeet, as well as between pioneering circumferential axons and neuroepithelial cells, suggests that these particular surfaces are mutually adherent, consistent with a proposed dorsal-to-ventral adhesive gradient mechanism of circumferent axonal guidance.
Muscle pioneers: large mesodermal cells that erect a scaffold for developing muscles and motoneurones in grasshopper embryos
TLDR
The discovery of a class of large mesodermal cells, which are called muscle pioneers, that arise early in development when the embryonic environment is relatively simple and distances short are reported.
Chemotropic guidance of developing axons in the mammalian central nervous system
TLDR
It is demonstrated that the rat floor-plate cells secrete a diffusible factor(s) that influences the pattern and orientation of commissural axon growth in vitro without affecting other embryonic spinal cord axons, which support the hypothesis that chemotropic mechanisms guide developing axons to their intermediate targets in the vertebrate CNS.
Neuronal pathfinding in developing wings of the moth Manduca sexta.
  • J. Nardi
  • Biology, Medicine
    Developmental biology
  • 1983
TLDR
The asymmetric, graded distribution of extracellular matrix molecules associated with the basal lamina of the wing's upper epithelium could provide the short-range cues that guide sensory axons in a particular direction.
Neuronal specificity and growth cone guidance in grasshopper and Drosophila embryos
TLDR
The results suggest the differential expression of many different surface recognition molecules in the developing CNS (labelled pathways hypothesis), a notion reminiscent of Sperry's chemoaffinity hypothesis.
Spatial regulation of axonal glycoprotein expression on subsets of embryonic spinal neurons
TLDR
TAG-1 is immunochemically distinct from the cell adhesion molecules N-CAM and L1 (NILE) and is expressed on commissural and motor neurons over the period of initial axon extension, evidence that axonal guidance and pathway selection in vertebrates may be regulated in part by the transient and selective expression of distinct surface glycoproteins on subsets of developing neurons.
Local positional cues in the neuroepithelium guide retinal axons in embryonic Xenopus brain
TLDR
This work demonstrates that long-range navigation of retinal axons in the vertebrate brain is based partly on stable, local positional factors, rather than on remote diffusible factors.
Guidance of optic axons in vivo by a preformed adhesive pathway on neuroepithelial endfeet.
TLDR
The studies suggest that guidance of optic axons along the margin of the brain is at least in part influenced by a preformed adhesive pathway on neuroepithelial cells associated with NCAM antigens.
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