title: The action of Semaphorin7A on thalamocortical axon branching.
abstract: Developing axons form extensive branches to make synaptic contacts with their target cells. Despite the important role of axon branching in neural circuit formation, its underlying molecular mechanism is still largely unknown. In this study, we investigated the involvement of Semaphorin7A (Sema7A) in thalamocortical (TC) axon branching. In situ hybridization demonstrated that sema7a was expressed specifically in layer 4, the TC recipient layer, when TC axons form extensive arbors. A similar protein expression pattern was observed by immunohistochemistry with an anti-Sema7A antibody. The effect of Sema7A on axon branching was investigated in dissociated cell cultures from embryonic rat thalamus. TC axon branching increased dramatically on Sema7A-coated dishes. We further studied the activity of Sema7A in vivo using loss- and gain-of-function analyses. The number of vesicular glutamate transporter 2-positive puncta was markedly reduced in the Sema7A-deficient cortex. In contrast, their number increased significantly when Sema7A was over-expressed in layer 4 cells by in utero electroporation. Taken together, these findings suggest that Sema7A acts as a positive regulator for TC axon branching and/or pre-synaptic puncta formation.
authors.affiliation: Laboratory of Cellular and Molecular Neurobiology, Graduate School of Frontier Biosciences, Osaka University, Yamadaoka, Suita, Osaka, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Fukunishi
authors.forename: Takuro
authors.initials: T
authors.lastname: Maruyama
authors.forename: Hong
authors.initials: H
authors.lastname: Zhao
authors.forename: Manisha
authors.initials: M
authors.lastname: Tiwari
authors.forename: Sujin
authors.initials: S
authors.lastname: Kang
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kumanogoh
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D001369:Axons / Q000187:drug effects*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development; D018274:Electroporation; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D018345:Mice, Knockout; D009434:Neural Pathways / Q000166:cytology; D051381:Rats; D017207:Rats, Sprague-Dawley; D039961:Semaphorins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D013788:Thalamus / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development; D050599:Vesicular Glutamate Transport Protein 2 / Q000378:metabolism
chemical_list: D015703:Antigens, CD; C558466:Sema7a protein, rat; D039961:Semaphorins; C493475:Slc17a6 protein, rat; D050599:Vesicular Glutamate Transport Protein 2