title: EphrinB3/EphA4-mediated guidance of ascending and descending spinal tracts.
abstract: The spinal cord contains many descending and ascending longitudinal tracts whose development appears to be controlled by distinct guidance systems. We identified a population of dorsal spinal neurons marked by coexpression of the transcription factor Zic2 and the guidance receptor EphA4. Zic2+;EphA4+ neurons are surrounded by mechanosensory terminals, suggesting innervation by mechanoreceptor afferents. Their axons form an ipsilateral ascending pathway that develops during embryogenesis and projects within the ventral aspect of the dorsal funiculus, the same location as the descending corticospinal tract (CST), which develops postnatally. Interestingly, the same guidance mechanism, namely, ephrinB3-induced EphA4 forward signaling, is required for the guidance of both ascending and descending axon tracts. Our analysis of conditional EphA4 mutant mice also revealed that the development of the dorsal funiculus occurs independently of EphA4 expression in descending CST axons and is linked to the distribution of Zic2+;EphA4+ spinal neurons and the formation of the ascending pathway.
authors.affiliation: Department 'Molecules - Signals - Development,' Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany.
authors.forename: Sónia
authors.initials: S
authors.lastname: Paixão
authors.affiliation: Department 'Molecules - Signals - Development,' Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany.
authors.forename: Aarathi
authors.initials: A
authors.lastname: Balijepalli
authors.affiliation: Department of Physiology, Pharmacology, and Neuroscience, City College of the City University of New York, New York, NY 10031, USA.
authors.forename: Najet
authors.initials: N
authors.lastname: Serradj
authors.affiliation: Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Jingwen
authors.initials: J
authors.lastname: Niu
authors.affiliation: Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Wenqin
authors.initials: W
authors.lastname: Luo
authors.affiliation: Department of Physiology, Pharmacology, and Neuroscience, City College of the City University of New York, New York, NY 10031, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Martin
authors.affiliation: Department 'Molecules - Signals - Development,' Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany; Munich Cluster for Systems Neurology (Synergy), 80336 Munich, Germany. Electronic address: rklein@neuro.mpg.de.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Klein
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism; D058948:Cell Tracking; D002478:Cells, Cultured; D002490:Central Nervous System / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D047108:Embryonic Development / Q000235:genetics; D036389:Ephrin-B3 / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D007395:Interneurons / Q000166:cytology; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009434:Neural Pathways / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D020671:Posterior Horn Cells / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D036122:Receptor, EphA4 / Q000235:genetics / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D036389:Ephrin-B3; D014157:Transcription Factors; C491811:Zic2 protein, mouse; D036122:Receptor, EphA4