Differential non-target-derived repulsive signals play a critical role in shaping initial axonal growth of dorsal root ganglion neurons |
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Authors: | Masuda Tomoyuki Tsuji Hiroshi Taniguchi Masahiko Yagi Takeshi Tessier-Lavigne Marc Fujisawa Hajime Okado Nobuo Shiga Takashi |
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Affiliation: | Department of Anatomy, Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan. |
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Abstract: | Initial trajectories of dorsal root ganglion (DRG) axons are shaped by chemorepulsive signals from surrounding tissues. Although we have previously shown that axonin-1/SC2 expression on DRG axons is required to mediate a notochord-derived chemorepulsive signal, Dev. Biol. 224, 112-121), other molecules involved in the non-target-derived repulsive signals are largely unknown. Using coculture assays composed of tissues derived from the chick embryo or mutant mice treated with function-blocking antibodies and phosphatidylinositol-specific phospholipase C, we report here that the chemorepellent semaphorin 3A (Sema3A) and its receptor neuropilin-1 are required for mediating the dermamyotome- and notochord-derived, but not the ventral spinal cord-derived, chemorepulsive signal for DRG axons. The dermamyotome-derived chemorepulsion is exclusively dependent on Sema3A/neuropilin-1, whereas other molecules are also involved in the notochord-derived chemorepulsion. Chemorepulsion from the ventral spinal cord does not depend on Sema3A/neuropilin-1 but requires axonin-1/SC2 to repel DRG axons. Thus, differential chemorepulsive signals help shape the initial trajectories of DRG axons and are critical for the proper wiring of the nervous system. |
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Keywords: | Semaphorin 3A Neuropilin-1 Dorsal root ganglion Notochord Chemorepulsion Ventral spinal cord Dermamyotome Collagen gel culture Axonin-1/SC2 Axon guidance |
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