Draxin from neocortical neurons controls the guidance of thalamocortical projections into the neocortex

M. Asrafuzzaman Riyadh^{1, 2#}, Giasuddin Ahmed1, Iftekhar Bin Naser1, Mahmud Hossain¹, Hirohide Takebayashi⁴, Kunimasa Ohta^{1, 2}, Hideaki Tanaka¹ and Yohei Shinmyo^1,3,*
(Department of Developmental Neurobiology, Graduate School of Life Sciences, Kumamoto University¹, Stem Cell-Based Tissue Regeneration Research and Education Unit, Kumamoto University², Department of Biophysical Genetics, Graduate School of Medical Sciences, Kanazawa University³, Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University⁴)

Name of the academic meeting: The 37^th Annual Meeting of the Molecular Biology Society of Japan, Pacifico Yokohama, Yokohama, Japan (November 25-27, 2014).

Date of presentation: 2014-11-26
Type of presentation: Poster presentation
Poster Number: 2P-0646
Discussion Times: 16:15-19:16

The thalamocortical tract carries sensory information to the neocortex. It has long been recognized that neocortical pioneer axons from subplate neurons are essential for thalamocortical development. Herein, we report that an axon guidance cue, draxin, is expressed in early-born neocortical neurons, including subplate neurons, and is necessary for thalamocortical development. draxin^-/- mice show an absence of thalamocortical axons entering into the neocortex. This phenotype is sufficiently rescued by transgenic expression of draxin in neocortical neurons. Genetic interaction data suggest that draxin acts through Deleted in colorectal cancer (Dcc) and Neogenin (Neo1) to regulate thalamocortical projections in vivo. Draxin shows an outgrowth-promoting effect on thalamic axons in vitro, and this effect is abolished in thalamic neurons from double mutants of Dcc and Neo1. These results suggest that draxin from neocortical neurons controls thalamocortical projections into the neocortex, and this effect is mediated through Dcc and Neo1 receptors.

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