PUBLICATION

No Nogo66- and NgR-mediated inhibition of regenerating axons in the zebrafish optic nerve

Authors
Abdesselem, H., Shypitsyna, A., Solis, G.P., Bodrikov, V., and Stuermer, C.A.
ID
ZDB-PUB-091221-9
Date
2009
Source
The Journal of neuroscience : the official journal of the Society for Neuroscience   29(49): 15489-15498 (Journal)
Registered Authors
Keywords
none
MeSH Terms
  • Actin Depolymerizing Factors/metabolism
  • Animals
  • Axons/physiology*
  • Glycosylphosphatidylinositols/metabolism
  • Growth Cones/physiology
  • HeLa Cells
  • Hippocampus/physiology
  • Humans
  • In Vitro Techniques
  • Mice
  • Myelin Proteins/genetics
  • Myelin Proteins/metabolism*
  • Nerve Regeneration/physiology*
  • Neurites/physiology
  • Neurons/physiology
  • Optic Nerve/physiology*
  • Rats
  • Receptors, Cell Surface/metabolism*
  • Retina/physiology
  • Retinal Ganglion Cells/physiology
  • Signal Transduction
  • Species Specificity
  • Zebrafish
  • Zebrafish Proteins/metabolism*
PubMed
20007473 Full text @ J. Neurosci.
Abstract
In contrast to mammals, lesioned axons in the zebrafish (ZF) optic nerve regenerate and restore vision. This correlates with the absence of the NogoA-specific N-terminal domains from the ZF nogo/rtn-4 (reticulon-4) gene that inhibits regeneration in mammals. However, mammalian nogo/rtn-4 carries a second inhibitory C-terminal domain, Nogo-66, being 70% identical with ZF-Nogo66. The present study examines, (1) whether ZF-Nogo66 is inhibitory and effecting similar signaling pathways upon Nogo66-binding to the Nogo66 receptor NgR and its coreceptors, and (2) whether Rat-Nogo66 on fish, and ZF-Nogo66 on mouse neurons, cause inhibition via NgR. Our results from "outgrowth, collapse and contact assays" suggest, surprisingly, that ZF-Nogo66 is growth-permissive for ZF and mouse neurons, quite in contrast to its Rat-Nogo66 homolog which inhibits growth. The opposite effects of ZF- and Rat-Nogo66 are, in both fish and mouse, transmitted by GPI (glycosylphosphatidylinositol)-anchored receptors, including NgR. The high degree of sequence homology in the predicted binding site is consistent with the ability of ZF- and mammalian-Nogo66 to bind to NgRs of both species. Yet, Rat-Nogo66 elicits phosphorylation of the downstream effector cofilin whereas ZF-Nogo66 has no influence on cofilin phosphorylation--probably because of significantly different Rat- versus ZF-Nogo66 sequences outside of the receptor-binding region effecting, by speculation, recruitment of a different set of coreceptors or microdomain association of NgR. Thus, not only was the NogoA-specific domain lost in fish, but Nogo66, the second inhibitory domain in mammals, and its signaling upon binding to NgR, was modified so that ZF-Nogo/RTN-4 does not impair axon regeneration.
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