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Robo1 regulates the morphological development of pyramidal neurons in the mouse neocortex
Abstracts / Neuroscience Research 68S (2010) e55–e108
O1-4-3-2 Development of the peripheral nervous system in turtles; with reference to the evolution of the vertebrate trunk region Masahumi Kawaguchi 1 , Aki Watanabe 2 , Hiromi Makiya 2 , Hiroshi Nagashima 3 , Takahiko Kawasaki 4 , Tatsumi Hirata 4 , Shigeru Kuratani 3 , Yasunori Murakami 2
e63
O1-4-3-4 Evolutionary developmental basis in the adaptation of pallial GABAergic interneurons to mammalian layered neocortex Daisuke Tanaka Harada 1 , Ryo Oiwa 2 , Erika Sasaki 2 , Kazunori Nakajima 1 1
Dept Anatomy, Keio Univ Sch of Med, Tokyo 2 CIEA, Kanagawa
1
Center for Marine Environmental Studies, Ehime University 2 Graduate school of Science and Engineering, Ehime University, Matsuyama, Japan 3 Laboratory for Evolutionary Morphology, RIKEN CDB, Kobe, Japan 4 Division of Brain Function, National Institute of Genetics, Mishima, Japan The morphology of the turtle trunk has been modified to obtain a shell. Their rib primordia at dorsal side extend horizontally and form the dorsal half of the shell, the carapace. This modification appears to have affected the peripheral nerve patterning in the turtle trunk. However, little is known about the organization of the nervous system during the turtle embryogenesis. To explore this, we analyzed the axon development and the expression pattern of the genes regulating the neural circuit formation in the embryonic Chinese softshelled turtle, Pelodiscus sinensis.In mouse and chicken, the dorsal ramus of the motoneurons initially exit from the spinal cord and then turn dorsally beneath the ventral side of the dorsal root ganglion (DRG). And also the dorsal branch of the sensory nerves exits ventrally from DRG and are integrated with the dorsal ramus of the motoneurons. In the turtle embryo, on the other hand, we found that the dorsal branch of the spinal nerve extends directly toward the DRG without making bundle with the sensory nerve. In addition, dorsal sensory branch leaves the DRG at the dorso-lateral side, without descending ventrally. These facts suggest that the nervous system of turtle trunk region is patterned by different developmental mechanism from that of mouse and chicken. To clarify the developmental plan of turtle nervous system, we studied the expression pattern of the genes involved in the neurogenesis of amniotes. Lhx3, a marker for the dorsal motoneurons, was expressed in the turtle spinal cord as in mouse embryo. Sema3A, which is an axon guidance molecule and functions in the patterning of peripheral nerves, showed clear correspondence between its expression and the position of developing axons. We then analyzed the expression pattern of other axon guidance molecules, EphA4 and Fgf8, and discuss the evolution of the turtle specific trunk nervous system. doi:10.1016/j.neures.2010.07.044
O1-4-3-3 Evolution of dorsal telencephalic structure associated with changes in neural progenitor regulation
During development, most GABAergic interneurons in the pallium are generated in a ventral part of the subpallium, the medial ganglionic eminence (MGE), and migrate tangentially toward the pallium. This migration during development is crucial for pallial functions in adults and is highly conserved in most amniotes including aves, reptiles and mammals. Since the mammalian pallium uniquely evolved into six-layered neocortex, MGE-derived interneurons in the ancestor of amniotes should adapt to the layered neocortex, yet the developmental bases of the adaptation are poorly understood. Here, we identified critical evolutionary steps for MGE-derived interneurons from the ancestor of amniotes to adapt to the mammalian layered neocortex during development. Chicken (aves), turtle (reptile) or marmoset (primate) MGE cells were labeled with red fluorescent protein and grafted into the wild-type mouse MGE in utero and their distributions were examined at later stages. While marmoset cells showed similar migratory pathway and distribution to those of mouse cells, we found some common and specific migratory defects in chicken and turtle cells compared to mouse cells. These data suggest that some specific migratory differences we found point out crucial evolutionary steps for pallial GABAergic interneurons from the ancestor of amniotes to adapt to the mammalian layered neocortex during development. doi:10.1016/j.neures.2010.07.046
O1-4-4-1 Robo1 regulates the morphological development of pyramidal neurons in the mouse neocortex Yuko Gonda 1,2 , Masayuki Sekiguchi 3 , Hidenori Tabata 4 , Takashi Namba 5 , Keiji Wada 3 , Kazunori Nakajima 4 , Carina Hanashima 2 , Shigeo Uchino 1 , Shinichi Kohsaka 1 1
Department of Neurochem., Natl. Inst. Neurosci 2 Lab. Neocort. Dev., RIKEN CDB 3 Department of Degenet. Neurol. Dis., Natl. Inst. Neurosci 4 Department of Anat., Keio University Sch. of Med 5 Department of Cell Pharma., Nagoya University Grad. Sch. of Med
The neocortical layer structure originated from the mammalian common ancestor and has been retained in all of the extant mammals. The nonmammalian vertebrates commonly possess the pallium, a homologue of the mammalian neocortex, exhibiting different cytoarchitecture from the layer structure. To understand the evolutionary origin of the neocortical layer structure, I studied the development of the chick pallium in comparison with the mammalian neocortex. I found that the chick pallium contained similar neuronal subsets to the mammalian neocortex, whereas the spatial distribution of the neuronal subtypes was entirely different from the layer arrangement in the mammalian neocortex; the deep and upper layer neurons were distantly located in the medial and lateral side of the chick pallium, respectively. I also found that the medio-lateral segregation of the neuronal subtypes was attributed to the spatially biased neurogenetic activity. Interestingly, in vitro, the chick neural progenitors intrinsically possessed the competence produce a full set of neurons regardless of their positions, suggesting that the medio-laterally different neurogenetic activity was extrinsically regulated by the positional factors in vivo. From those observations, I concluded that the alterations in the developmental process, such as the spatial regulation of the neurogenesis, may have driven the evolutionary emergenece of animal group-specific brain structures.
Roundabout (Robo) was first identified in Drosophila as a receptor for the secreted ligand Slits. Recent studies have shown that Slit/Robo signaling plays important roles in cellular migration and morphological differentiation including axonal elongation and dendritic branching in the development of cortical interneurons. However, the role of Robo in the developing pyramidal neurons remains unclear. We previously showed that Robo1 mRNA was expressed in layers II/III, V and VI of the developing mouse neocortex. In this study, to clarify the role of Robo1 in the morphological development of intracortical pyramidal neurons, we suppressed Robo1 expression in the neurons of layer II/III by using RNA interference. We transfected Robo1 -interfering RNA (Robo1-shRNA) plasmid or control-shRNA plasmid together with EGFP-expressing vector into the lateral ventricle of mouse embryos using in utero electroporation at embryonic day 15.5, and examined the localization, morphology, and electrophysiological properties of the shRNA-transfected neurons. Almost all the control-shRNA-transfected neurons migrated toward the pial surface, localized in layer II/III, and matured into pyramidal neurons. In contrast, Robo1 -shRNA-transfected neurons were mainly localized in the upper portion of layer II/III near the marginal zone and extended several apical neurites and longer basal neurites from the soma, displaying a significant difference in morphology from the typical pyramidal neurons. Furthermore, electrophysiological studies demonstrated that the Robo1-shRNA-transfected neurons had a significantly higher frequency of miniature excitatory postsynaptic current (mEPSC) on postnatal days 15 or 16. These findings suggest that Robo1 plays an important role in the morphogenesis of pyramidal neurons in the developing neocortex.
doi:10.1016/j.neures.2010.07.045
doi:10.1016/j.neures.2010.07.047
Ikuo Suzuki 1 , Takashi Gojobori 2 , Tatsumi Hirata 1 1
Div. Brain Function, NIG, Mishima 2 Lab. DNA Data Analysis, NIG, Mishima
O1-4-3-2 Development of the peripheral nervous system in turtles; with reference to the evolution of the vertebrate trunk region Masahumi Kawaguchi 1 , Aki Watanabe 2 , Hiromi Makiya 2 , Hiroshi Nagashima 3 , Takahiko Kawasaki 4 , Tatsumi Hirata 4 , Shigeru Kuratani 3 , Yasunori Murakami 2
e63
O1-4-3-4 Evolutionary developmental basis in the adaptation of pallial GABAergic interneurons to mammalian layered neocortex Daisuke Tanaka Harada 1 , Ryo Oiwa 2 , Erika Sasaki 2 , Kazunori Nakajima 1 1
Dept Anatomy, Keio Univ Sch of Med, Tokyo 2 CIEA, Kanagawa
1
Center for Marine Environmental Studies, Ehime University 2 Graduate school of Science and Engineering, Ehime University, Matsuyama, Japan 3 Laboratory for Evolutionary Morphology, RIKEN CDB, Kobe, Japan 4 Division of Brain Function, National Institute of Genetics, Mishima, Japan The morphology of the turtle trunk has been modified to obtain a shell. Their rib primordia at dorsal side extend horizontally and form the dorsal half of the shell, the carapace. This modification appears to have affected the peripheral nerve patterning in the turtle trunk. However, little is known about the organization of the nervous system during the turtle embryogenesis. To explore this, we analyzed the axon development and the expression pattern of the genes regulating the neural circuit formation in the embryonic Chinese softshelled turtle, Pelodiscus sinensis.In mouse and chicken, the dorsal ramus of the motoneurons initially exit from the spinal cord and then turn dorsally beneath the ventral side of the dorsal root ganglion (DRG). And also the dorsal branch of the sensory nerves exits ventrally from DRG and are integrated with the dorsal ramus of the motoneurons. In the turtle embryo, on the other hand, we found that the dorsal branch of the spinal nerve extends directly toward the DRG without making bundle with the sensory nerve. In addition, dorsal sensory branch leaves the DRG at the dorso-lateral side, without descending ventrally. These facts suggest that the nervous system of turtle trunk region is patterned by different developmental mechanism from that of mouse and chicken. To clarify the developmental plan of turtle nervous system, we studied the expression pattern of the genes involved in the neurogenesis of amniotes. Lhx3, a marker for the dorsal motoneurons, was expressed in the turtle spinal cord as in mouse embryo. Sema3A, which is an axon guidance molecule and functions in the patterning of peripheral nerves, showed clear correspondence between its expression and the position of developing axons. We then analyzed the expression pattern of other axon guidance molecules, EphA4 and Fgf8, and discuss the evolution of the turtle specific trunk nervous system. doi:10.1016/j.neures.2010.07.044
O1-4-3-3 Evolution of dorsal telencephalic structure associated with changes in neural progenitor regulation
During development, most GABAergic interneurons in the pallium are generated in a ventral part of the subpallium, the medial ganglionic eminence (MGE), and migrate tangentially toward the pallium. This migration during development is crucial for pallial functions in adults and is highly conserved in most amniotes including aves, reptiles and mammals. Since the mammalian pallium uniquely evolved into six-layered neocortex, MGE-derived interneurons in the ancestor of amniotes should adapt to the layered neocortex, yet the developmental bases of the adaptation are poorly understood. Here, we identified critical evolutionary steps for MGE-derived interneurons from the ancestor of amniotes to adapt to the mammalian layered neocortex during development. Chicken (aves), turtle (reptile) or marmoset (primate) MGE cells were labeled with red fluorescent protein and grafted into the wild-type mouse MGE in utero and their distributions were examined at later stages. While marmoset cells showed similar migratory pathway and distribution to those of mouse cells, we found some common and specific migratory defects in chicken and turtle cells compared to mouse cells. These data suggest that some specific migratory differences we found point out crucial evolutionary steps for pallial GABAergic interneurons from the ancestor of amniotes to adapt to the mammalian layered neocortex during development. doi:10.1016/j.neures.2010.07.046
O1-4-4-1 Robo1 regulates the morphological development of pyramidal neurons in the mouse neocortex Yuko Gonda 1,2 , Masayuki Sekiguchi 3 , Hidenori Tabata 4 , Takashi Namba 5 , Keiji Wada 3 , Kazunori Nakajima 4 , Carina Hanashima 2 , Shigeo Uchino 1 , Shinichi Kohsaka 1 1
Department of Neurochem., Natl. Inst. Neurosci 2 Lab. Neocort. Dev., RIKEN CDB 3 Department of Degenet. Neurol. Dis., Natl. Inst. Neurosci 4 Department of Anat., Keio University Sch. of Med 5 Department of Cell Pharma., Nagoya University Grad. Sch. of Med
The neocortical layer structure originated from the mammalian common ancestor and has been retained in all of the extant mammals. The nonmammalian vertebrates commonly possess the pallium, a homologue of the mammalian neocortex, exhibiting different cytoarchitecture from the layer structure. To understand the evolutionary origin of the neocortical layer structure, I studied the development of the chick pallium in comparison with the mammalian neocortex. I found that the chick pallium contained similar neuronal subsets to the mammalian neocortex, whereas the spatial distribution of the neuronal subtypes was entirely different from the layer arrangement in the mammalian neocortex; the deep and upper layer neurons were distantly located in the medial and lateral side of the chick pallium, respectively. I also found that the medio-lateral segregation of the neuronal subtypes was attributed to the spatially biased neurogenetic activity. Interestingly, in vitro, the chick neural progenitors intrinsically possessed the competence produce a full set of neurons regardless of their positions, suggesting that the medio-laterally different neurogenetic activity was extrinsically regulated by the positional factors in vivo. From those observations, I concluded that the alterations in the developmental process, such as the spatial regulation of the neurogenesis, may have driven the evolutionary emergenece of animal group-specific brain structures.
Roundabout (Robo) was first identified in Drosophila as a receptor for the secreted ligand Slits. Recent studies have shown that Slit/Robo signaling plays important roles in cellular migration and morphological differentiation including axonal elongation and dendritic branching in the development of cortical interneurons. However, the role of Robo in the developing pyramidal neurons remains unclear. We previously showed that Robo1 mRNA was expressed in layers II/III, V and VI of the developing mouse neocortex. In this study, to clarify the role of Robo1 in the morphological development of intracortical pyramidal neurons, we suppressed Robo1 expression in the neurons of layer II/III by using RNA interference. We transfected Robo1 -interfering RNA (Robo1-shRNA) plasmid or control-shRNA plasmid together with EGFP-expressing vector into the lateral ventricle of mouse embryos using in utero electroporation at embryonic day 15.5, and examined the localization, morphology, and electrophysiological properties of the shRNA-transfected neurons. Almost all the control-shRNA-transfected neurons migrated toward the pial surface, localized in layer II/III, and matured into pyramidal neurons. In contrast, Robo1 -shRNA-transfected neurons were mainly localized in the upper portion of layer II/III near the marginal zone and extended several apical neurites and longer basal neurites from the soma, displaying a significant difference in morphology from the typical pyramidal neurons. Furthermore, electrophysiological studies demonstrated that the Robo1-shRNA-transfected neurons had a significantly higher frequency of miniature excitatory postsynaptic current (mEPSC) on postnatal days 15 or 16. These findings suggest that Robo1 plays an important role in the morphogenesis of pyramidal neurons in the developing neocortex.
doi:10.1016/j.neures.2010.07.045
doi:10.1016/j.neures.2010.07.047
Ikuo Suzuki 1 , Takashi Gojobori 2 , Tatsumi Hirata 1 1
Div. Brain Function, NIG, Mishima 2 Lab. DNA Data Analysis, NIG, Mishima