- Email: [email protected]
Olfactory bulb preferentially incorporates eliminated subset of newborn granule cells
e92
Abstracts / Neuroscience Research 68S (2010) e55–e108
lated movement of neurons in three-dimensional space. In the present study, we have chosen the pontine nucleus (PN), a typical nuclear structure in the hindbrain, as a model and analyzed the process of nucleogeneis in the threedimensional space. We electroporated a mixture of cre and floxed-gfp genes to the lower rhombic lip of mouse embryos at E12.5 in utero to sparsely label PN neurons. We then analyzed the behavior of PN neurons at the nuclear region between E15.5 and E18.5 by time-lapse imaging and observation of fixed samples. We found that PN neurons entering the PN region migrated unidirectionally toward midline and were added ventrally to earlier arriving neurons. Interestingly, a major proportion of PN neurons that have once arrived at the PN region initiated retrograde migration either radially, tangentially or horizontally. Our results demonstrate that PN is initially formed by orderly addition of neurons as a result of unidirectional migration into the nuclear region. We propose that the subsequent occurrence of retrograde and reoriented migration may contribute to the final three-dimensional structure of the mature nuclei. doi:10.1016/j.neures.2010.07.170
O2-4-4-4 Novel IgSF molecule MDGA1 is involved in radial migration and positioning of a subset of cortical upper-layer neurons Tohru Yamamoto 1 , Takao Ishikawa 1 , Hirotaka Matsumoto 1 , Naoya Gotoh 1 , Chiaki Murayama 1 , Misato Iwashita 2 , Fumio Matsuzaki 2 , Toshiharu Suzuki 1 1 2
Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan Center for Developmental Biology, RIKEN, Kobe, Japan
MDGA1 is a GPI-anchored IgSF molecule containing MAM (meprin, A5 protein, PTP) domain, which we isolated as a gene expressed by a specific subset of spinal and DRG neurons. In mouse cerebral cortex, expression of MDGA1 is also specifically observed in neurons located in the upper layer. To investigate the functional role of MDGA1 in neural development, we generated the LacZ-KI-KO mice, which were subsequently backcrossed to C57BL6 mice more than ten generations to make the resultant strain congenic. Although the homozygous mice showed no readily detectable alteration in gross anatomy of nervous system, MDGA1 mutant neurons behaved differently during developmental process of cerebral cortex formation. At E16.5, MDGA1-expressing wild type cells were observed throughout the cortical plate. However, in homozygous littermate embryos, majority of LacZ-expressing MDGA1 mutant cells resided in deeper layer of the cortical plate, underneath the ER81-expressing earlier born future layer V neurons. At E17.5, a part of mutant cells migrated to the upper layer but some population still resided in the deeper layer in homozygous embryos, while virtually all of MDGA1-expressing cells migrated to the uppermost area of the cortical plate in wild type littermates. These observations collectively indicate that MDGA1 is involved in proper radial migration of MDGA1-expressing neurons. By E18.5, majority of MDGA1 mutant neurons migrated to the upper layer; however, their position in the upper layer is apparently lower than those of wild type neurons. This positioning is unchanged until P0, and corrected by P7. Interestingly, Cux2-expressing upper layer neurons did not show alterations between wild type and homozygous littermates during the process, indicating that MDGA1 is expressed and required by a subset of radially migrating neurons, and further suggesting that radial migration and positioning might be differently regulated among cell types in upper layer neurons. doi:10.1016/j.neures.2010.07.171
O2-5-1-1 Activity-dependent development of olfactory bulb interneurons upon the neural circuit formation Seiichi Yoshihara 1 , Nobushiro Nishimura 1 , Hiroo Takahashi 1 , Kensaku Mori 2 , Akio Tsuboi 1 1
Lab for Mol Biol of Neural System, Nara Med Univ 2 Dept Physiol, Univ of Tokyo Olfactory bulb (OB) interneurons are generated and integrated to the preexisting neural circuit throughout the life. In this study, by using the lentiviral system, we have analyzed the developmental process of OB interneurons in the mouse. We found by naris occlusion that the neural activity is necessary for the dendrite elongation and spine formation of OB interneurons. Based on the DNA microarray and in situ hybridization analyses, we also found that membrane protein 5T4 and transcription factor NPAS4 genes are expressed in an activity-dependent manner in the OB interneurons. Gain-of function studies indicated that 5T4 and NPAS4 genes regulate the dendrite arborization and spine formation of OB interneurons, respectively. Furthermore, deletion
analyses revealed that the dendrite arborization of interneurons is regulated by the 5T4 intracellular domain which interacts with unknown molecules. doi:10.1016/j.neures.2010.07.172
O2-5-1-2 Olfactory bulb preferentially incorporates eliminated subset of newborn granule cells Koshi Murata 1 , Shigetada Nakanishi 2 , Kazuto Kobayashi 3 , Hideki Mochizuki 4 , Kensaku Mori 1 , Masahiro Yamaguchi 1 1
Dept Physiol, Univ of Tokyo, Tokyo, Japan 2 Systems Biology, Osaka Bioscience Institute, Osaka, Japan 3 Department of Molecular Genetics, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima, Japan 4 Department of Neurology, Kitasato University School of Medicine, Kanagawa, Japan In mice, granule cells (GCs), local inhibitory interneurons in the olfactory bulb (OB), are newly generated in the subventricular zone (SVZ) and incorporated into the preexisting OB neuronal circuit throughout life. Previous studies demonstrated that GCs are differentiated into subtypes, and the heterogeneity of newborn GC subtypes derives from heterogeneous neural stem cells in the SVZ. However, it is unclear whether the incorporation of newborn GCs is regulated in a subtype-specific manner by OB local environment where preexisting neurons have already formed functional circuitry. To address the point, we locally ablated mGluR2-expressing subset of preexisting GCs by immunotoxin-medated cell targeting, and found that mGluR2-expressing subset of newborn GCs was preferentially incorporated into the ablated area of the OB. The ablation of preexisting GCs did not increase the proliferation of newborn GCs in the SVZ. These results indicate that the incorporation of newborn GC subtypes is regulated in a subtype-specific manner by the preexisting OB local environment and that the eliminated-subtypes of newborn GCs are preferentially incorporated to reorganize the OB neuronal circuit with appropriate composition of GC subtypes. doi:10.1016/j.neures.2010.07.173
O2-5-1-3 15-deoxy-12,14 -prostaglandin J2 regulates the proliferation of mouse hippocampal neural stem/progenitor cells Takashi Katura , Takahiro Moriya, Norimichi Nakahata Department cellular signaling, Grad. Sch. Pharmaceut. Sci., Tohoku Univ Neural stem cells (NSCs) are self-renewal and multipotent cells, which are located not only in the developing but also in the adult brain, and are especially abundant in the anterior subventricular zone and subgranular zone of the hippocampal dentate gyrus (DG). The self-renewal and multipotential activities of NSCs are dynamically regulated by various humoral factors. Although prostaglandin D2 (PGD2 ) is known to mediate various physiological brain functions such as sleep, its actions on NSCs have not been fully understood. In the process of investigating the effects of PGD2 on NSCs, we found that 15-deoxy-12,14 -prostaglandin J2 (15d-PGJ2 ), an endogenous metabolite of PGD2 , exhibits a novel regulation of the proliferation of NSCs derived from mouse hippocampus. 15d-PGJ2 showed biphasic effects on EGF-induced proliferation of NSCs; facilitation at low concentrations (around 0.3 M) and suppression at higher concentrations (0.5–10 M) in vitro. GW9662, an inhibitor of peroxisome proliferator-activated receptor ␥, known to be a molecular target for 15d-PGJ2 , failed to abolish the effects of 15d-PGJ2 . CAY10410, a structural analog of 15d-PGJ2 lacking the electrophilic carbon in the cyclopentenone ring, did not show 15d-PGJ2 -like actions. Treatment with 15d-PGJ2 increased the levels of reactive oxygen species (ROS) and decreased endogenous glutathione (GSH) levels. Furthermore, supplementation with a membrane-permeable analog of glutathione, GSH ethyl ester (GSH-EE) (2 mM), diminished the biphasic effects of 15d-PGJ2 . Finally, cell division in the dentate gyrus of adult mice was increased by i.c.v. injection of low-dose (1 ng) 15d-PGJ2 and suppressed by high-dose (30 ng) 15d-PGJ2 in vivo. These results suggest that 15d-PGJ2 regulates the proliferation of NSCs via its electrophilic nature, which enables covalent binding to molecules such as GSH. doi:10.1016/j.neures.2010.07.174
Abstracts / Neuroscience Research 68S (2010) e55–e108
lated movement of neurons in three-dimensional space. In the present study, we have chosen the pontine nucleus (PN), a typical nuclear structure in the hindbrain, as a model and analyzed the process of nucleogeneis in the threedimensional space. We electroporated a mixture of cre and floxed-gfp genes to the lower rhombic lip of mouse embryos at E12.5 in utero to sparsely label PN neurons. We then analyzed the behavior of PN neurons at the nuclear region between E15.5 and E18.5 by time-lapse imaging and observation of fixed samples. We found that PN neurons entering the PN region migrated unidirectionally toward midline and were added ventrally to earlier arriving neurons. Interestingly, a major proportion of PN neurons that have once arrived at the PN region initiated retrograde migration either radially, tangentially or horizontally. Our results demonstrate that PN is initially formed by orderly addition of neurons as a result of unidirectional migration into the nuclear region. We propose that the subsequent occurrence of retrograde and reoriented migration may contribute to the final three-dimensional structure of the mature nuclei. doi:10.1016/j.neures.2010.07.170
O2-4-4-4 Novel IgSF molecule MDGA1 is involved in radial migration and positioning of a subset of cortical upper-layer neurons Tohru Yamamoto 1 , Takao Ishikawa 1 , Hirotaka Matsumoto 1 , Naoya Gotoh 1 , Chiaki Murayama 1 , Misato Iwashita 2 , Fumio Matsuzaki 2 , Toshiharu Suzuki 1 1 2
Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan Center for Developmental Biology, RIKEN, Kobe, Japan
MDGA1 is a GPI-anchored IgSF molecule containing MAM (meprin, A5 protein, PTP) domain, which we isolated as a gene expressed by a specific subset of spinal and DRG neurons. In mouse cerebral cortex, expression of MDGA1 is also specifically observed in neurons located in the upper layer. To investigate the functional role of MDGA1 in neural development, we generated the LacZ-KI-KO mice, which were subsequently backcrossed to C57BL6 mice more than ten generations to make the resultant strain congenic. Although the homozygous mice showed no readily detectable alteration in gross anatomy of nervous system, MDGA1 mutant neurons behaved differently during developmental process of cerebral cortex formation. At E16.5, MDGA1-expressing wild type cells were observed throughout the cortical plate. However, in homozygous littermate embryos, majority of LacZ-expressing MDGA1 mutant cells resided in deeper layer of the cortical plate, underneath the ER81-expressing earlier born future layer V neurons. At E17.5, a part of mutant cells migrated to the upper layer but some population still resided in the deeper layer in homozygous embryos, while virtually all of MDGA1-expressing cells migrated to the uppermost area of the cortical plate in wild type littermates. These observations collectively indicate that MDGA1 is involved in proper radial migration of MDGA1-expressing neurons. By E18.5, majority of MDGA1 mutant neurons migrated to the upper layer; however, their position in the upper layer is apparently lower than those of wild type neurons. This positioning is unchanged until P0, and corrected by P7. Interestingly, Cux2-expressing upper layer neurons did not show alterations between wild type and homozygous littermates during the process, indicating that MDGA1 is expressed and required by a subset of radially migrating neurons, and further suggesting that radial migration and positioning might be differently regulated among cell types in upper layer neurons. doi:10.1016/j.neures.2010.07.171
O2-5-1-1 Activity-dependent development of olfactory bulb interneurons upon the neural circuit formation Seiichi Yoshihara 1 , Nobushiro Nishimura 1 , Hiroo Takahashi 1 , Kensaku Mori 2 , Akio Tsuboi 1 1
Lab for Mol Biol of Neural System, Nara Med Univ 2 Dept Physiol, Univ of Tokyo Olfactory bulb (OB) interneurons are generated and integrated to the preexisting neural circuit throughout the life. In this study, by using the lentiviral system, we have analyzed the developmental process of OB interneurons in the mouse. We found by naris occlusion that the neural activity is necessary for the dendrite elongation and spine formation of OB interneurons. Based on the DNA microarray and in situ hybridization analyses, we also found that membrane protein 5T4 and transcription factor NPAS4 genes are expressed in an activity-dependent manner in the OB interneurons. Gain-of function studies indicated that 5T4 and NPAS4 genes regulate the dendrite arborization and spine formation of OB interneurons, respectively. Furthermore, deletion
analyses revealed that the dendrite arborization of interneurons is regulated by the 5T4 intracellular domain which interacts with unknown molecules. doi:10.1016/j.neures.2010.07.172
O2-5-1-2 Olfactory bulb preferentially incorporates eliminated subset of newborn granule cells Koshi Murata 1 , Shigetada Nakanishi 2 , Kazuto Kobayashi 3 , Hideki Mochizuki 4 , Kensaku Mori 1 , Masahiro Yamaguchi 1 1
Dept Physiol, Univ of Tokyo, Tokyo, Japan 2 Systems Biology, Osaka Bioscience Institute, Osaka, Japan 3 Department of Molecular Genetics, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima, Japan 4 Department of Neurology, Kitasato University School of Medicine, Kanagawa, Japan In mice, granule cells (GCs), local inhibitory interneurons in the olfactory bulb (OB), are newly generated in the subventricular zone (SVZ) and incorporated into the preexisting OB neuronal circuit throughout life. Previous studies demonstrated that GCs are differentiated into subtypes, and the heterogeneity of newborn GC subtypes derives from heterogeneous neural stem cells in the SVZ. However, it is unclear whether the incorporation of newborn GCs is regulated in a subtype-specific manner by OB local environment where preexisting neurons have already formed functional circuitry. To address the point, we locally ablated mGluR2-expressing subset of preexisting GCs by immunotoxin-medated cell targeting, and found that mGluR2-expressing subset of newborn GCs was preferentially incorporated into the ablated area of the OB. The ablation of preexisting GCs did not increase the proliferation of newborn GCs in the SVZ. These results indicate that the incorporation of newborn GC subtypes is regulated in a subtype-specific manner by the preexisting OB local environment and that the eliminated-subtypes of newborn GCs are preferentially incorporated to reorganize the OB neuronal circuit with appropriate composition of GC subtypes. doi:10.1016/j.neures.2010.07.173
O2-5-1-3 15-deoxy-12,14 -prostaglandin J2 regulates the proliferation of mouse hippocampal neural stem/progenitor cells Takashi Katura , Takahiro Moriya, Norimichi Nakahata Department cellular signaling, Grad. Sch. Pharmaceut. Sci., Tohoku Univ Neural stem cells (NSCs) are self-renewal and multipotent cells, which are located not only in the developing but also in the adult brain, and are especially abundant in the anterior subventricular zone and subgranular zone of the hippocampal dentate gyrus (DG). The self-renewal and multipotential activities of NSCs are dynamically regulated by various humoral factors. Although prostaglandin D2 (PGD2 ) is known to mediate various physiological brain functions such as sleep, its actions on NSCs have not been fully understood. In the process of investigating the effects of PGD2 on NSCs, we found that 15-deoxy-12,14 -prostaglandin J2 (15d-PGJ2 ), an endogenous metabolite of PGD2 , exhibits a novel regulation of the proliferation of NSCs derived from mouse hippocampus. 15d-PGJ2 showed biphasic effects on EGF-induced proliferation of NSCs; facilitation at low concentrations (around 0.3 M) and suppression at higher concentrations (0.5–10 M) in vitro. GW9662, an inhibitor of peroxisome proliferator-activated receptor ␥, known to be a molecular target for 15d-PGJ2 , failed to abolish the effects of 15d-PGJ2 . CAY10410, a structural analog of 15d-PGJ2 lacking the electrophilic carbon in the cyclopentenone ring, did not show 15d-PGJ2 -like actions. Treatment with 15d-PGJ2 increased the levels of reactive oxygen species (ROS) and decreased endogenous glutathione (GSH) levels. Furthermore, supplementation with a membrane-permeable analog of glutathione, GSH ethyl ester (GSH-EE) (2 mM), diminished the biphasic effects of 15d-PGJ2 . Finally, cell division in the dentate gyrus of adult mice was increased by i.c.v. injection of low-dose (1 ng) 15d-PGJ2 and suppressed by high-dose (30 ng) 15d-PGJ2 in vivo. These results suggest that 15d-PGJ2 regulates the proliferation of NSCs via its electrophilic nature, which enables covalent binding to molecules such as GSH. doi:10.1016/j.neures.2010.07.174