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1O1-1 Memantine improves cognitive deficits in APP23 mice via K_ATP channel inhibition Shigeki Moriguchi，Yasushi Yabuki，Kohji Fukunaga Dept Pharmacol. Grad Sch Pharm Sci, Tohoku Univ Memantine elicits pharmacological activity in Alzheimer’s disease (AD) through moderate inhibition of N-methyl-D-aspartate receptors (NMDARs), thereby ameliorating abberant glutamatergic neurotransmission in brain. Here we report that a novel target of mementine, ATP-sensitive K⁺ (K_ATP) channels, implicate in memory improvement by memantine. K_ATP channels Kir6.1 or Kir6.2 are composed with sulfonylurea receptors (SURs), which are distributed both in peripheral tissues and the central nervous system. We confirmed that memantine improves both memory impairment and perturbed NMDAR-dependent LTP in the APP23 mouse hippocampus. Unexpectedly, memantine in vivo increased CaMKII activity in APP23 hippocampus, and memantine-induced enhancement of hippocampal LTP and CaMKII activity was in vitro abolished by treatment with pinacidil, a specific opener of K_ATP channels. We therefore confirmed that memantine inhibits K_ATP channels Kir6.1 and Kir6.2 and elevates intracellular Ca²⁺ concentrations in through Kir6.1 or Kir6.2 inhibition. Kir6.2 was preferentially expressed in postsynaptic regions, whereas Kir6.1 was predominant in hippocampal neuron dendrites. Finally, we confirmed that Kir6.2 heterozygous mutant mice exhibit severe memory deficits and hippocampal LTP impairment that could not be rescued by memantine administration. Taken together, we propose a novel strategy that memantine inhibits Kirs 6.2/6.1 activities, thereby improving memory impairment in AD patients.		1O1-2 Analysis of PSD lattice, a backbone structure for type I excitatory synapses Tatsuo Suzuki^1,2,3，Kiyokazu Kametani⁴，Weiheng Guo²，Weidong Li^3,5 ¹Dept Mol Cell Physiol, Shinshu Univ Med，²Dept Neuroplasticity, Shinshu Univ Sch Med，³Inst Biomed Sci, Shinshu Univ，⁴Dept Instr Anal, Res Ctr Human Envir Sci, Shinshu Univ，⁵Bio-X Inst, Shanghai Jiao Tong Univ Postsynaptic density (PSD) works an essential devise for synaptic transmission and synaptic plasticity, and its dynamic changes are one of important mechanisms for the expression of synaptic plasticity. It is essential to know the details of molecular architecture of PSD for understanding the mechanism, at the molecular level, for dynamic nature of PSD, one of basis of synaptic plasticity. A well-known model for architecture of PSD of type I excitatory synapse is “scaffold protein model”. On the contrary, “PSD lattice” observed in electron microscope has been considered to be a basic backbone of type I PSDs. However, relationship between the PSD lattice and the scaffold protein model has not been clear. We purified a fraction containing unique structure from synaptic plasma membrane of rat forebrain after treatment with 1% octyl-D, β-glucoside and separation by sucrose density gradient ultracentrifugation. The structure recovered in the fraction was slightly lighter than PSD, and was planar and its diameter was similar to PSD. The structure was judged to be “PSD lattice” based on comparison with the authentic PSD lattice. Protein components of the PSD lattice were examined by Western blotting and immuno-gold negative staining electron microscopy. The results indicated that tubulin, actin, α-internexin and Ca2+/calmodulin-dependent kinase II are major constituents of the PSD lattice, while scaffold proteins such as PSD-95, SAP102, GKAP, shank1 and homer were rather minor components. Similar structure was also purified from synaptic plasma membrane of forebrains from 7-day-old rats. We propose that cytoskeletal proteins, in particular tubulin and α-internexin, may play major roles in the construction of PSD backbone.

1O1-3 Molecular mechanism of alternative pre-mRNA splicing on neuronal cell adhesion molecules regulated by STAR family proteins Takatoshi Iijima¹，Yoko Iijima¹，Masami Tanaka¹，Satoko Suzuki¹，Noriko Ayukawa¹，Peter Scheiffele² ¹Tokai Univ, IIST，²Biozentrum, Basel Univ Alternative pre-mRNA splicing is a crucial mechanism for huge protein diversity. In central nervous system (CNS), significant amount of neuronal molecules are highly diversified by alternative splicing. The molecular diversity of Neurexin, a synaptic adhesion molecule, could contribute to specific connectivity and property of neural network. We previously reported that alternative splicing of Neurexin is dynamically regulated by a family of neuronal RNA-binding proteins (Iijima et al., 2011 & 2014): we found that a RNA-binding protein SAM68, a signal transduction and activation of RNA (STAR) family protein, is a crucial key of activity-dependent alternative pre-mRNA splicing on Neurexin. In addition, we revealed that SAM68-like molecules 1 and 2, (SLM1 and SLM2) regulate neuronal cell-type-specific splicing. However, neuronal functions of spatio-temporal alternative splicing by SAM68/SLMs still remain uncovered.To decipher alternative splicing programs of STAR proteins, we recently looked for new candidate RNAs by high-throughput transcriptomic analyses. Exon array-based screening combined with RNA-sequence reveals that SAM68 and SLM1 exhibit similar but distinct alternative splicing programs: SAM68 preferentially controls alternative 3’ end pre-mRNA processing. We found that 3’ end processing of several cell surface adhesion proteins are aberrantly regulated in SAM68 KO brains, which results in dramatic production of these atypical splice isoforms. Therefore, the results suggest that STAR family proteins potentially contribute to some aspects of synapse synaptic wiring, plasticity, and remodeling through proper isoform choice.		1O1-4 Autism-like behaviors and enhanced memory formation and synaptic plasticity in Lrfn2/SALM1-deficient mice Naoko Morimura¹，Hiroki Yasuda²，Kazuhiro Yamaguchi³，Kei-ichi Katayama³，Minoru Hatayama³，Takaya Hiramatsu¹，Seiji Hitoshi¹，Naoko H Tomioka³，Kazuyuki Yamada³，Takeo Yoshikawa³，Jun Aruga⁴ ¹Dept Integrative Physiol, SUMS，²Grad Sch Med, Gunma Univ，³BSI, RIKEN，⁴Dept Med Pharmacol, Grad Sch Biomed Sci, Nagasaki Univ Lrfn2/SALM1 is a PSD-95-interacting synapse adhesion molecule, and human LRFN2 is associated with learning disabilities. However, its role in higher brain function and underlying mechanisms remain unknown. Here, we show that Lrfn2 knockout mice exhibit autism-like behavioural abnormalities, including social withdrawal, decreased vocal communications, increased stereotyped activities and prepulse inhibition deficits, together with enhanced learning and memory. In the hippocampus, the levels of synaptic PSD-95 and GluA1 are decreased. The synapses are structurally and functionally immature with spindle shaped spines, smaller postsynaptic densities, reduced AMPA/NMDA ratio, and enhanced LTP. In vitro experiments reveal that synaptic surface expression of AMPAR depends on the direct interaction between Lrfn2 and PSD-95. Furthermore, we detect functionally defective LRFN2 missense mutations in autism and schizophrenia patients. Together, these findings indicate that Lrfn2/LRFN2 serve as core components of excitatory synapse maturation and maintenance, and their dysfunction causes immature/silent synapses with pathophysiological state. Now we are challenging development of transgenic cynomolgus monkeys to elucidate pathophysiological mechanisms underlying synaptic dysfunctions.