The Journal of Neuroscience, 2001, 21:RC183:1-4
RAPID COMMUNICATION
Reelin Does Not Directly Influence Axonal Growth
Yves
Jossin and
André M.
Goffinet
Neurobiology Unit, University of Namur School of Medicine, B5000
Namur, Belgium
Reelin is a large extracellular glycoprotein involved in the
development of architectonic patterns, particularly in the cerebral cortex and hippocampus, where it is synthesized primarily by
Cajal-Retzius cells. In the hippocampus, Reelin also regulates the
growth and/or distribution of afferent entorhinal and commissural
axons. To assess further the possible action of Reelin on axonal
growth, we used the three-dimensional collagen gel assay to
measure axonal elongation from reeler cortical explants in the presence
of Reelin. Because Reelin is proteolytically processed in
vivo, normal explants and Reelin-transfected human
embryonic kidney 293T cells were used, respectively, as sources
of processed and full-length protein. The reliability of the assay was
tested by demonstrating a clear repulsive action of semaphorin 3F
(p < 0.0001). However, neither full-length
nor processed Reelin exhibited any significant attraction or repulsion
on cortical axons. Our results suggest that the reported effects of
Reelin on axonal pathways are indirect, secondary to the architectonic
disturbances that result from Reelin deficiency, and that the effects
of Cajal-Retzius cells on connectivity are primarily independent of Reelin.
Key words:
Reelin; axon guidance; collagen gel assay; cortical
explants; hippocampus; Cajal-Retzius cells
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