一般口演（Oral）

Oral Long-term potentiation 一般口演長期増強

7月28日（日）10:50～11:05　第9会場（朱鷺メッセ　3F　306+307） 4O-09a1-1 LTPを維持する相互活性化型キナーゼ／基質複合体 Takeo Saneyoshi（実吉岳郎），Yasunori Hayashi（林康紀）京都大学医学研究科　システム神経薬理学 Long-term synaptic plasticity requires a mechanism that converts short Ca2+ pulses into persistent biochemical signaling to maintain the changes in the structure and function of synapses over long periods of time. Here, we present a novel mechanism of a positive feedback loop, formed by a 'reciprocally activating kinase-effector complex' (RAKEC) in dendritic spines, enabling the persistence and confinement of a molecular memory. We found that stimulation of a single spine causes the rapid formation of a RAKEC consisting of CaMKII and Tiam1, a Rac-GEF. This interaction is mediated by a pseudoinhibitory domain of Tiam1, which is homologous to the CaMKII autoinhibitory domain. Therefore, Tiam1 binding results in constitutive CaMKII activation, which in turn, persistently phosphorylates Tiam1. Phosphorylated Tiam1 promotes stable actin polymerization through Rac1, thereby maintaining the structure of the spine over a long period of time during LTP. The RAKEC can store biochemical information in small subcellular compartments, thus potentially serving as a general mechanism for prolonged and compartmentalized signaling. I will discuss about other possible RAKECs during LTP in this presentation.		7月28日（日）11:05～11:20　第9会場（朱鷺メッセ　3F　306+307） 4O-09a1-2 シナプス長期増強のin vitro再構成 Tomohisa Hosokawa（細川智永），PinWu Liu（劉品吾），Yasunori Hayashi（林康紀）京都大学医学部システム神経薬理学 Synaptic plasticity such as long-term potentiation (LTP) is known to be a basis for learning and memory formation. One major mechanism to induce LTP is an increase of neurotransmitter receptors such as AMPA receptor at postsynaptic site and postsynaptic density (PSD), an accumulation of synaptic proteins. Recent microscope technology revealed that not only AMPA receptor, but also various synaptic proteins translocate into postsynapse in the response to LTP stimulation, calcium influx and the enlargement of dendritic spine (structural LTP). However, the mechanism of translocation and accumulation of synaptic proteins remains unclear. Previously it was reported that mixing purified several PSD proteins results in the formation of condensate of PSD proteins. This condensate is in phase transition of free-diffusion and condensate, and it is highly reversible. Using this system as in vitro reconstitution of PSD structure, here we demonstrate the reconstitution of protein translocation and accumulation into PSD during LTP. We found that Calcium/calmodulin-dependent protein kinase II (CaMKII) plays crucial role for protein translocation and accumulation. Conformational change of CaMKII results in exposure of its interacting site and it enables CaMKII to interact with PSD proteins and cross-link them by using its dodecamer-structure. Adding CaMKII and calcium ion to PSD condensates resulted in the formation of enlarged, more stable PSD condensates. This result suggests that CaMKII plays important role during induction of LTP not only as kinase but also as structural protein. Also, this mechanism would be related with basal maintenance of synapse and synaptic dysfunction.

7月28日（日）11:20～11:35　第9会場（朱鷺メッセ　3F　306+307） 4O-09a1-3 CaMKII内在性阻害因子CaMKNsがLTP時の蛋白質局在変化と集積への役割 Pin-Wu Liu（Liu Pin-Wu），Tomohisa Hosokawa（細川智永），Yasunori Hayashi（林康紀）京都大院医システム神経薬理学 This study aims to understand the neural mechanism underlying memory formation. Synaptic plasticity is widely believed as a molecular basis of memory formation. One of the synaptic plasticity, long-term potentiation (LTP) is known as up-regulation of synaptic strength to construct new neuronal networks. Our recent research indicates that translocation and accumulation of synaptic proteins, such as neurotransmitter receptors into synapse is critical for the induction and maintenance of LTP. Especially, we found that translocation of calcium/calmodulin-dependent protein kinase II (CaMKII) plays central role of accumulating other synaptic proteins by cross-linking them. However, how CaMKII specifically locate to synapse during memory formation is still unknown. CaMKII inhibitors (CaMKNs) are known as CaMKII endogenous inhibitors. CaMKNs, CaMKN1 (N1) and CaMKN2 (N2), are small 8 kDa proteins. CaMKNs mask the catalytic domain of CaMKII. However, recent studies reported that the protein expression of CaMKNs increased in several brain regions, such as hippocampus and amygdala, during memory formation, which suggests that CaMKNs might participate in memory formation. CaMKNs has CaMKII binding domain and possible interaction domain, PDZ domain binding motif, with one of the major synaptic protein PSD-95. Thus, we hypothesized that CaMKNs leads CaMKII into synapse. To examine this, we used CRISPR/Cas9 knockout (KO) system with glutamate uncaging to induce LTP under two-photon microscopy. We found that CaMKNs are necessary for the induction of LTP. To clarify the role of CaMKNs, the purified protein of CaMKNs was prepared and subjected to Native-PAGE. We found that CaMKNs might form dimer. And we further confirmed that the CaMKNs dimer is formed via disulfide bond. Since CaMKII forms dodecamric structure, the dimerization of CaMKNs would form huge complex with CaMKII. With the possible interaction domain with PSD-95 of CaMKNs, formation of this CaMKII-CaMKNs complex during LTP might help CaMKII translocate into synapse to induce and maintain LTP.		7月28日（日）11:35～11:50　第9会場（朱鷺メッセ　3F　306+307） 4O-09a1-4 シナプトタグミン11により制御されるシナプス可塑性と空間記憶 Masafumi Shimojo（下條雅文）¹，Joseph C Madara（Madara C Joseph）²，Sandra Pankow（Pankow Sandra）³，John Yates（Yates John）³，Makoto Higuchi（樋口真人）¹，Thomas C Sudhof（Sudhof C Thomas）⁴，Anton Maximov（Maximov Anton）² ¹放射線医学総合研 ²Dept of Neuroscience, The Scripps Research Institute. La Jolla, CA, USA ³Dept of Molecular Medicine, The Scripps Research Institute. La Jolla, CA, USA ⁴Dept of Molecular and Cellular Physiology, Stanford University, Palo Alto, CA, USA Syt-11 is a synaptotagmin isoform that lacks apparent ability to bind calcium, phospholipids and SNARE proteins. While human genetic studies have linked mutations in the Syt-11 locus with Schizophrenia and Parkinson's disease, the biological role of Syt-11 in the brain remains unclear. Here, we demonstrate a detailed analysis of expression and localization of Syt-11 in central neurons, identified Syt-11 interacting partners, and examined mutant mice that lacked Syt-11 either globally or in specific neuronal populations. We show that Syt-11 is broadly expressed in mouse brain and distribute as a membrane constituent of mobile secretory vesicles that recycle in an activity-dependent manner. Constitutive deletion of Syt-11 in all tissues resulted in early postnatal lethality, suggesting this gene is required for normal development. By contrast, mice lacking Syt-11 in excitatory forebrain neurons had normal lifespan but exhibited an impairment of spatial learning and memory. Ablation of Syt-11 had no effect of basal neurotransmission but blocked the induction of hippocampal long-term synaptic potentiation. Our results indicate that Syt-11 acts in a secretory pathways that is essential for synaptic plasticity and provide important insights into the molecular mechanisms underlying neurological disorders.