- Email: [email protected]
The signaling pathways involved in dendritic spine formation via Shc, phospho-tyrosine adaptor molecule
Abstracts / Neuroscience Research 58S (2007) S1–S244
S51
O2P-AØ4 A role of Disable-1 as a transcription factor in Reelin
O2P-AØ7 Functional analysis of mouse Mahya genes
signaling
Naoya Ichikawa, Tatsuhiko Kadowaki Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
Toshifumi Morimura 1 , Chihiro Hisatsune 2,3 , Mitsuharu Hattori 4 , Katsuhiko Mikoshiba 2,3,5 , Masaharu Ogawa 1 1 Laboratory for Cell Culture Development, BSI, RIKEN, Saitama, Japan; 2 Division of Molecular Neurobiology, IMS, The University of Tokyo, Tokyo, Japan; 3 Laboratory for Developmental Neuroscience, BSI, RIKEN, Saitama, Japan; 4 Department of Biomedical Science, Graduate School of Pharmaceutical Science, Nagoya City University, Aichi, Japan; 5 ICORP-SORST, JST, Tokyo, Japan Reelin controls neuronal migration and positioning in the developing brain by inducing tyrosine phosphorylation of an intracellular adaptor protein, Disabled-1 (Dab1). We clarified that Dab1 tyrosine phosphorylation initiated the internalization of Reelin, and that Dab1 dissociated from Reelin receptors after their internalization. Furthermore, we found that Reelin induced the nuclear import of tyrosine-phosphorylated Dab1. In the nucleus, Dab1 bound to DNA and regulated gene expression in cooperation with a transcriptional co-activator to control neuronal migration. These results suggest that Reelin regulates correct neuronal migration and positioning by inducing the nuclear import of tyrosine-phosphorylated Dab1.
We identified one of the Urbilaterian genes, Mahya, which is specifically conserved between Hymenoptera and Deuterostome. It has been implicated in the higher order of brain functions enabling social behavior and cognitive ability. Mahya encodes a secretory protein with a follistatin-like domain, two immunoglobulin domains, and a C-terminal novel domain. Mouse Mahya genes (mMahya-1 and mMahya-2) are expressed in the olfactory bulb, hippocampus (CA3 region and dentate gyrus), and cerebellum (granule cells and Purkinje cells) of the adult brain. To understand the functions of mMahya genes in the brain functions we have generated KO mice for mMahya-1 and mMahya-2 in collaboration with the RIKEN CDB group. Both of homozygous KO mice are viable, and thus we are analyzing the structural changes in the brain areas and behaviors of these KO mice.
Research funds: KAKENNHI (18780222)
O2P-AØ5 The somatodendritic targeting of DNER requires transcytosis Tetsuko Fukuda, Seisuke Yokoyama, Mineko Kengaku Laboratory for Neural Cell Polarity, BSI, RIKEN, Wako, Japan Establishment of neuronal polarity depends on targeting of proteins into different plasma membrane domains, axons and dendrites. It has been shown that many dendritic proteins reach the somatodendritic membrane based on selective sorting and transport of carrier vesicles. Using cultured hippocampal neurons, we examined the trafficking pathways of DNER, a transmembrane protein specifically expressed in CNS dendrites. Mutations of DNER that increased surface expression disrupted its somatodendritic localization. Inhibition of endocytosis resulted in disruption of polarized distribution of DNER, indicating that somatodendritic targeting of DNER was dependent on endocytosis. DNER binds to a clathrin adaptor AP-2 via multiple sites. However, clathrin-dependent endocytosis only partly mediated the somatodendritic targeting of DNER. Instead, a clathrin independent endocytosis was also responsible for its somatodendritic distribution. Thus, selective retention mediated by clathrin-dependent- and independent-endocytosis is critical for polarized targeting of a somatodendritic protein.
O2P-BØ1 The signaling pathways involved in dendritic spine formation via Shc, phospho-tyrosine adaptor molecule Yoko Shiraisi-Yamaguchi 1,2 , Nozomu Mori 2 1 JSPS, Tokyo, Japan; 2 Department of Anatomy and Neurobiology, Nagasaki University School of Medicine, Nagasaki, Japan Shc binds to phospho-tyrosine residues of the activated receptors. In central nervous system, N-Shc (neural Shc) is predominantly expressed and transmits neurotrophin signals from the TrkB receptor to Ras/MAPK pathway. Studies on the N-Shc knock out mice reveals a novel function of N-shc; N-Shc is also involved in the regulation of NMDA receptor functions and hippocampal synaptic plasticity. Since N-Shc also interacts with key regulators for actin-cytoskeletal rearrangements such as Crk and Grit (RICS), we then tested whether N-Shc is involved in the formation of synaptic architecture, dendritic spines. Following exogenously overexpression of N-Shc in primary cultured hippocampal neurons, the spine number was significantly reduced, and the effect was more severe when N-Shc/Crk cascade was disturbed. However, additive inhibition of N-Shc/Ras/MAPK cascade rescued the spine formation. Those results indicate that both N-Shc/Crk and N-Shc/Ras/MAPK pathways cooperatively regulate dendritic spine formation. Research funds: Grant-in-Aid for JSPS Fellows
O2P-AØ6 Microtubule dynamics regulating migration of cerebellar granule cells Hiroki Umeshima 1 , Tomoo Hirano 2 , Mineko Kengaku 1 Laboratory for Neural Cell Polarity, RIKEN, BSI, Wako, Japan; 2 Department of Biophysics, Kyoto University, Kyoto, Japan
1
During neuronal migration in the developing brain, it is thought that the centrosome precedes the nucleus and provides a cue for nuclear migration along the microtubules. In time-lapse imaging studies of radially migrating granule cells in mouse cerebellar slices, we observed that the movements of the nucleus and centrosome appeared to occur independently of each other. The nucleus often migrated ahead of the centrosome during its saltatory movement, negating the supposed role of the centrosome in pulling the nucleus. We observed the perinuclear structure consisting of dynamic and stable microtubules, neither of which was converged at the centrosome. In addition, stable microtubules showed the polarized distribution in contrast with the overall distribution of dynamic microtubules. Disruption or excess formation of stable microtubules attenuated nuclear migration, suggesting that polarized arrangement of microtubules is prerequisite for nuclear migration.
O2P-BØ2 Roles of monoacylglycerol lipase in the regulation of endocannabinoid signaling Yuki Hashimotodani 1 , Takako Ohno-Shosaku 2 , Masanobu Kano 3 Department of Neurophysiology, Graduate School of Medicine, Osaka University, Osaka, Japan; 2 Department of Impair. Study, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan; 3 Department of Cellular Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
1
Endogenous cannabinoids (eCBs) are released from postsynaptic neurons and retrogradely suppress synaptic transmission by acting on presynaptic CB1 cannabinoid receptors. 2-Arachidonoylglycerol (2-AG), a major molecule of eCBs, is degraded by monoacylglycerol lipase (MGL), which is expressed at presynaptic terminals. In this study, we investigated how MGL regulates eCB signaling at hippocampal inhibitory synapses. Inhibition of MGL resulted in a gradual suppression of basal IPSCs. This suppression was blocked by a CB1 antagonist and attenuated by inhibiting 2-AG synthesis, suggesting that 2-AG is constitutively released and degraded by MGL. MGL inhibition also prolonged the recovery of IPSCs from the suppression by exogenous 2-AG application or by eCB released by depolarization. These results indicate that presynaptic MGL plays an important role in both regulating basal eCB tone and terminating the retrograde eCB signal. Research funds: KAKENHI 17023021 17100004
S51
O2P-AØ4 A role of Disable-1 as a transcription factor in Reelin
O2P-AØ7 Functional analysis of mouse Mahya genes
signaling
Naoya Ichikawa, Tatsuhiko Kadowaki Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
Toshifumi Morimura 1 , Chihiro Hisatsune 2,3 , Mitsuharu Hattori 4 , Katsuhiko Mikoshiba 2,3,5 , Masaharu Ogawa 1 1 Laboratory for Cell Culture Development, BSI, RIKEN, Saitama, Japan; 2 Division of Molecular Neurobiology, IMS, The University of Tokyo, Tokyo, Japan; 3 Laboratory for Developmental Neuroscience, BSI, RIKEN, Saitama, Japan; 4 Department of Biomedical Science, Graduate School of Pharmaceutical Science, Nagoya City University, Aichi, Japan; 5 ICORP-SORST, JST, Tokyo, Japan Reelin controls neuronal migration and positioning in the developing brain by inducing tyrosine phosphorylation of an intracellular adaptor protein, Disabled-1 (Dab1). We clarified that Dab1 tyrosine phosphorylation initiated the internalization of Reelin, and that Dab1 dissociated from Reelin receptors after their internalization. Furthermore, we found that Reelin induced the nuclear import of tyrosine-phosphorylated Dab1. In the nucleus, Dab1 bound to DNA and regulated gene expression in cooperation with a transcriptional co-activator to control neuronal migration. These results suggest that Reelin regulates correct neuronal migration and positioning by inducing the nuclear import of tyrosine-phosphorylated Dab1.
We identified one of the Urbilaterian genes, Mahya, which is specifically conserved between Hymenoptera and Deuterostome. It has been implicated in the higher order of brain functions enabling social behavior and cognitive ability. Mahya encodes a secretory protein with a follistatin-like domain, two immunoglobulin domains, and a C-terminal novel domain. Mouse Mahya genes (mMahya-1 and mMahya-2) are expressed in the olfactory bulb, hippocampus (CA3 region and dentate gyrus), and cerebellum (granule cells and Purkinje cells) of the adult brain. To understand the functions of mMahya genes in the brain functions we have generated KO mice for mMahya-1 and mMahya-2 in collaboration with the RIKEN CDB group. Both of homozygous KO mice are viable, and thus we are analyzing the structural changes in the brain areas and behaviors of these KO mice.
Research funds: KAKENNHI (18780222)
O2P-AØ5 The somatodendritic targeting of DNER requires transcytosis Tetsuko Fukuda, Seisuke Yokoyama, Mineko Kengaku Laboratory for Neural Cell Polarity, BSI, RIKEN, Wako, Japan Establishment of neuronal polarity depends on targeting of proteins into different plasma membrane domains, axons and dendrites. It has been shown that many dendritic proteins reach the somatodendritic membrane based on selective sorting and transport of carrier vesicles. Using cultured hippocampal neurons, we examined the trafficking pathways of DNER, a transmembrane protein specifically expressed in CNS dendrites. Mutations of DNER that increased surface expression disrupted its somatodendritic localization. Inhibition of endocytosis resulted in disruption of polarized distribution of DNER, indicating that somatodendritic targeting of DNER was dependent on endocytosis. DNER binds to a clathrin adaptor AP-2 via multiple sites. However, clathrin-dependent endocytosis only partly mediated the somatodendritic targeting of DNER. Instead, a clathrin independent endocytosis was also responsible for its somatodendritic distribution. Thus, selective retention mediated by clathrin-dependent- and independent-endocytosis is critical for polarized targeting of a somatodendritic protein.
O2P-BØ1 The signaling pathways involved in dendritic spine formation via Shc, phospho-tyrosine adaptor molecule Yoko Shiraisi-Yamaguchi 1,2 , Nozomu Mori 2 1 JSPS, Tokyo, Japan; 2 Department of Anatomy and Neurobiology, Nagasaki University School of Medicine, Nagasaki, Japan Shc binds to phospho-tyrosine residues of the activated receptors. In central nervous system, N-Shc (neural Shc) is predominantly expressed and transmits neurotrophin signals from the TrkB receptor to Ras/MAPK pathway. Studies on the N-Shc knock out mice reveals a novel function of N-shc; N-Shc is also involved in the regulation of NMDA receptor functions and hippocampal synaptic plasticity. Since N-Shc also interacts with key regulators for actin-cytoskeletal rearrangements such as Crk and Grit (RICS), we then tested whether N-Shc is involved in the formation of synaptic architecture, dendritic spines. Following exogenously overexpression of N-Shc in primary cultured hippocampal neurons, the spine number was significantly reduced, and the effect was more severe when N-Shc/Crk cascade was disturbed. However, additive inhibition of N-Shc/Ras/MAPK cascade rescued the spine formation. Those results indicate that both N-Shc/Crk and N-Shc/Ras/MAPK pathways cooperatively regulate dendritic spine formation. Research funds: Grant-in-Aid for JSPS Fellows
O2P-AØ6 Microtubule dynamics regulating migration of cerebellar granule cells Hiroki Umeshima 1 , Tomoo Hirano 2 , Mineko Kengaku 1 Laboratory for Neural Cell Polarity, RIKEN, BSI, Wako, Japan; 2 Department of Biophysics, Kyoto University, Kyoto, Japan
1
During neuronal migration in the developing brain, it is thought that the centrosome precedes the nucleus and provides a cue for nuclear migration along the microtubules. In time-lapse imaging studies of radially migrating granule cells in mouse cerebellar slices, we observed that the movements of the nucleus and centrosome appeared to occur independently of each other. The nucleus often migrated ahead of the centrosome during its saltatory movement, negating the supposed role of the centrosome in pulling the nucleus. We observed the perinuclear structure consisting of dynamic and stable microtubules, neither of which was converged at the centrosome. In addition, stable microtubules showed the polarized distribution in contrast with the overall distribution of dynamic microtubules. Disruption or excess formation of stable microtubules attenuated nuclear migration, suggesting that polarized arrangement of microtubules is prerequisite for nuclear migration.
O2P-BØ2 Roles of monoacylglycerol lipase in the regulation of endocannabinoid signaling Yuki Hashimotodani 1 , Takako Ohno-Shosaku 2 , Masanobu Kano 3 Department of Neurophysiology, Graduate School of Medicine, Osaka University, Osaka, Japan; 2 Department of Impair. Study, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan; 3 Department of Cellular Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
1
Endogenous cannabinoids (eCBs) are released from postsynaptic neurons and retrogradely suppress synaptic transmission by acting on presynaptic CB1 cannabinoid receptors. 2-Arachidonoylglycerol (2-AG), a major molecule of eCBs, is degraded by monoacylglycerol lipase (MGL), which is expressed at presynaptic terminals. In this study, we investigated how MGL regulates eCB signaling at hippocampal inhibitory synapses. Inhibition of MGL resulted in a gradual suppression of basal IPSCs. This suppression was blocked by a CB1 antagonist and attenuated by inhibiting 2-AG synthesis, suggesting that 2-AG is constitutively released and degraded by MGL. MGL inhibition also prolonged the recovery of IPSCs from the suppression by exogenous 2-AG application or by eCB released by depolarization. These results indicate that presynaptic MGL plays an important role in both regulating basal eCB tone and terminating the retrograde eCB signal. Research funds: KAKENHI 17023021 17100004