一般演題（口述）

一般演題（口述） Genes and Higher Brain Function

1O1-01 Novel intracellular D2LR signaling is critical for dendritic spine formation. Shioda Norifumi，Fukunaga Kohji Dept. Pharmacol., Tohoku Univ. Grad. Sch. Pharm. Sci. Abnormalities in activity of the dopamine D2 receptor（D2R）are associated with neuropsychiatric disorders, making it a target for antipsychotic drugs. Here, we report that novel signaling through the intracellular D2R long isoform（D2LR）elicits persistent extracellular signal-regulated kinase（ERK）activation and dendritic spine formation through Rabex-5/Rab5-mediated endocytosis. D2LR directly binds and activates Rabex-5, promoting early endosome formation. Endosomes containing D2LR and platelet-derived growth factor receptor-beta（PDGFRbeta）are then transported to the Golgi apparatus, where those complexes trigger Galphai3-mediated ERK signaling. Loss of intracellular D2LR-mediated ERK activation decreases neuronal activity and dendritic spine density in striatopallidal medium spiny neurons（MSNs）. Taken together, novel intracellular D2LR signaling is critical for prolonged ERK activation and dopamine-regulated synaptic activity in striatopallidal MSNs.		1O1-02 Rbfox1, an autism causal gene, plays an essential role in cortical development Hamada Nanako，Ito Hidenori，Tabata Hidenori，Nagata Koh-ichi Dept. Mol. Neurobiol., Inst. Dev. Res., Aichi Hum. Serv. Ctr Rbfox1（aka Fox1 or A2BP1）is an RNA-binding protein necessary for regulation of alternative splicing. Critical neurological functions for Rbfox1 have been approved by human mutations in RBFOX1 gene that cause neurodevelopmental disorders including autism spectrum disorder（ASD）. To elucidate the pathophysiological relevance of Rbfox1, we here performed cell biological analyses of the neuron-dominant Rbfox1 isoform 1（Rbfox1-iso1；A2BP1-A016）during mouse cerebral development. Knockdown of Rbfox1-iso1 by in utero electroporation method caused abnormal neuronal distribution during corticogenesis. Rbfox1-iso1 knockdown did not affect cell proliferation in the neural progenitor/stem cells. Confocal laser microscope-associated live-imaging analyses revealed that migration defects occurred during radial migration and terminal translocation. While Rbfox1-iso1-deficient neurons did not show any morphological abnormality during migration, they could not efficiently enter the cortical plate and were prevented from smooth migration in the cortical plate, perhaps due to impaired nucleokinesis. Indeed, the distance between nucleus to centrosome was abnormally elongated in Rbfox1-iso1-deficient neurons during radial migration. Rbfox1 was also found to regulate neuronal network formation in vivo since interhemispheric axon extension and dendritic arborization were suppressed in Rbfox1-iso1-deficient neurons. Aberrant morphology was further confirmed in in vitro analyses；Rbfox1-iso1-silencing in primary cultured hippocampal neurons resulted in the reduction of primary axon length, total length of dendrites, spine density and mature spine number. Taken together, aberrant phenotypes observed in this study may relate to structural and functional defects of the cerebral cortex, leading to the emergence of the clinical symptoms of neurodevelopmental disorders.

1O1-03 Dysregulation of fear memory and CaM kinase II activity in NCX1 heterozygous mice Moriguchi Shigeki¹，Izumi Hisanao¹，Kita Satomi²，Sakagami Hiroyuki³，Iwamoto Takahiro²，Fukunaga Kohji¹ ¹Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University，²Department of Pharmacology, School of Medicine, Fukuoka University，³Department of Anatomy,Kitasato University School of Medicine Na⁺/Ca²⁺ exchangers（NCXs）are mainly expressed in the plasma membrane and mediate the electrogenical exchange of one Ca2+ for three Na+, depending on the electrochemical gradients across the plasma membrane. NCXs have three different isoforms（NCX1, NCX2, NCX3）encoded by distinct genes in mammals. We here report that mutant mice lacking NCX1（NCX1-KO）exhibit impaired fear-related memory. NCX1-KO showed significantly impairment of fear-related behaviors measured by elevated-plus maze, light-dark task, open-field task and marble burying tasks. In addition, NCX1-KO mice show abnormality in fear-related tone memory but not in contextual memory with fear-conditioning task. In immunohistochemical analyses, NCX1-KO mice revealed significant increase in the number of cFos positive cells in the lateral amygdala but not the central amygdala following fear-related tone stimuli. The cFos expression peaked at 1 hr. Furthermore, enhancement of CaM kinase II or IV activities in the latelal amygdala were observed in NCX1-KO mice by immnoblot analyses. By contrast, CaM Kinase II null mice failed to increase in the number of cFos positive cells in the lateral amygdala without changes in CaM Kinase IV null mice. Taken together, the increased CaM kinase II activitiy and in turn cFos expression likely account for the dysregulation of fear memory in NCX1-KO mice.		1O1-04 A newly identified stres hormone responsive molecule, Hit, regulates nuclear transport of Glucocorticoid Receptor Koizumi Keita¹，Nakao Keiko²，Nakajima Hideo^3,4 ¹Center for Child Mental Development, Kanazawa Univ，²Department of Physiology, Saitama Medical Univ，³Center for AIDS Research, Kumamoto Univ.，⁴Ageo Central General Hospital Maternal stress during pregnancy increases secretion of stress hormones such as glucocorticoid（GC）. A numbers of studies indicate high level exposure to GC during prenatal period affects neural development and stress response after birth. Moreover, recent studies suggest it causes psychiatric disorders such as depression（Front Neurosci. 8：420, 2015）, schizophrenia（Psychopharmacology 214：89-106, 2011）and autism（Neuroscience and Biobehavioral Reviews 32：1519-1532, 2008）. Although detail molecular mechanisms that link prenatal stress and these psychiatric disorders are not well understood, molecules responding to GC must have critical roles. Here, we show a newly identified GC responsive molecule, Hit. Treatment with GC agonist, DEX, or restraint stress on pregnant mice resulted in reduction of Hit mRNA expression in the brain of their embryos. Similar to effects of DEX, Hit RNAi/over-expression affects proliferation, differentiation and migration of neuron-like PC12 cells and also neural cells in primary culture. We also found Hit RNAi facilitates nuclear transport of GC receptor（GR）, which is a critical step for GR function to regulate various genes transcription. Thus, our data suggest Hit has critical roles on prenatal development by negatively regulating the GR transport to nuclear. 　Interestingly, recent studies show molecules involved in the GR transport to nuclear（FKBP5 and HSP90 for example）are closely related to psychiatric disorders such as depression（Neurosci Biobehav Rev. 37：2375-97, 2013）and PTSD（Nat Neurosci 16：33-41, 2013）. Hit may have interaction with these molecules and potentially link to these psychiatric disorders.