一般口演
シナプス形成 |
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| 7月8日（土） 14:50-15:50 Room E
3O②-1
ポストシナプスに局在する転写活性化因子MRTFBの細胞内Ca2+シグナリング依存的な局在変化を介した遺伝子発現誘導機構の解析
Ca2+ signaling-dependent gene expression mediated by nuclear translocation of SRF coactivator MRTFB from postsynapses
伊原 大輔1, 田邉 広樹1, 今西 詩織1, 長島 由佳1, 小坂 彩1, 佐野 友香里1, 阪上 洋行2, 田渕 明子1
1. 富山大 薬 分子神経生物, 2. 北里大 医 解剖
DAISUKE IHARA1, Hiroki Tanabe1, Shiori Imanishi1, Yuka Nagashima1, Aya Kosaka1, Yukari Sano1, Hiroyuki Sakagami2, Akiko Tabuchi1
1. Lab. Mol. Neurobiol., Grad. Sch. of Med. and Pharm. Sci., Univ. of Toyama, 2. Dept. Anatomy, Kitasato Univ., Sch. of Med.
Activity-dependent gene expression plays key roles in neuronal plasticity. Myocardin-related transcription factors (MRTFs), highly expressed in the brain, have actin-binding motifs and function as transcriptional cofactors of SRF. Recently, we reported that MRTFs are localized in postsynapses and involved in synaptic maturation. However, it remains unclear how MRTFs are involved in activity-dependent gene expression. Therefore, we analyzed the molecular mechanism underlying the nuclear translocation of MRTFs and the following IEG expression in neurons. Immunostaining revealed that addition of bicuculline/4-aminopyridine (Bic/4AP), which causes synaptic activation, induced transient nuclear translocation of MRTFB, but which was blocked by the pretreatment with APV/nicardipine and FK506, inhibitors of NMDA receptor/L-VDCC and calcineurin, respectively. We further confirmed that MRTFB undergoes activity-dependent loss from postsynapses. Moreover, overexpression of constitutively active-calcineurin also induced MRTFB translocation into nucleus. Using qPCR analysis, we found that APV or FK506 decreased JunB mRNA expression induced by Bic/4AP. ChIP assay revealed that accumulation of MRTFB on the enhancer of JunB gene increased by Bic/4AP. Taken together, these results indicate that MRTFB is a key molecule which contributes to the synapse-to-nuclear signaling for neuronal plasticity. | | 7月8日（土） 14:50-15:50 Room E
3O②-2
神経系RNA結合タンパク質SAM68の3'UTRのスプライシング制御によるシナプス維持
SAM68 insures proper synapse development and function through alternative 3'UTR isoform selections
飯島 崇利1, ダルウィシュ モハメド1, 伊藤 誠敏2, 高瀬 彰紀2, 鮎川 典子3, 鈴木 暁子3, 田中 正視3, 飯島 陽子1
1. 東海大学医学部 基礎医学系 分子生命科学, 2. 東海大学 生命科学統合支援センター, 3. 東海大学 創造科学技術研究機構 医学部門
Takatoshi Iijima1, Mohamed Darwish1, Masatoshi Ito2, Akinori Takase2, Noriko Ayukawa3, Satoko Suzuki3, Masami Tanaka3, Yoko Iijima1
1. Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, School of Medicine, Tokai University, Kanagawa, Japan, 2. The Support Center for Medical Research and Education, Tokai University, Kanagawa , Japan, 3. Tokai University Institute of Innovative Science and Technology, Kanagawa, Japan
Thousands of mammalian genes encode alternatively spliced isoforms in their 3’ untranslated region (3’UTR). Alternative 3’UTR diversity contributes to several neurological processes in developing and adult brains. SAM68 is the key splicing regulator for the diversity of neuronal 3’UTR isoforms through alternative last exon (ALE) selection. However, the mechanisms underlying the control of splicing at the 3’ end and its function in the nervous system remain unclear. Here, we demonstrate that SAM68-dependent ALE splicing is differentially regulated depending on its target transcripts through identifying the two ALE selections of IL-1 receptor associated protein (Il1rap) and protocadherin-15 (Pcdh15): while Il1rap is regulated via the interaction with U1 small nuclear ribonucleoprotein, Pcdh15 is modulated by the CaMK pathway. We found that the aberrant ALEs of Pcdh15 caused membrane-to-soluble isoform conversion of the produced protein and disrupted its localization into excitatory and inhibitory synapses. In addition, the neuronal expression of the soluble form of PCDH15 (sPCDH15) preferentially affected the number of inhibitory synapses. sPCDH15 further reduced neuroligin-2-induced inhibitory, but not excitatory, synapses in artificial synapse formation assays. Our findings provide insights into the role of alternative 3’UTR isoform selections in synapse development. | | 7月8日（土） 14:50-15:50 Room E
3O②-3
Rho-Kinase/ROCK Phosphorylates PSD-93 Downstream of NMDARs to Orchestrate Synaptic Plasticity
Emran Hossen
ICBS, Fujita Health University
The Rho family of small GTPase RhoA and its downstream effector Rho-kinase/ROCK are considered as one of the major regulators of synaptic plasticity and dendritic spine formation, including long-term potentiation (LTP). However, the mechanism by which Rho-kinase regulates synaptic plasticity is not yet fully understood. Here, we found that Rho-kinase directly phosphorylated DLG2/PSD-93, a major postsynaptic scaffold protein that connects postsynaptic proteins with NMDARs; an ionotropic glutamate receptor, which plays a critical role in synaptic plasticity. Stimulation of striatal slices with an NMDAR agonist induced Rho-kinase-mediated phosphorylation of PSD-93 at Thr612. We also identified PSD-93-interacting proteins by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Among them, Rho-kinase increased the binding of PSD-93 to PSD-95 and NMDARs. Furthermore, we found that chemical-LTP induced by glycine, which activates NMDARs, in-creased PSD-93 phosphorylation at Thr612, spine size, and PSD-93 colocalization with PSD-95, while these events were blocked by pretreatment with a Rho-kinase inhibitor. These results indi-cate that Rho-kinase phosphorylates PSD-93 downstream of NMDARs, and suggest that Rho-kinase mediated phosphorylation of PSD-93 increases the association with PSD-95 and NMDARs to regulate structural synaptic plasticity. | | 7月8日（土） 14:50-15:50 Room E
3O②-4
軸索内のミトコンドリアの分布・動態制御およびシナプス形成との関連
Regulation of mitochondrial distribution and dynamics in axons and its relationship to synaptogenesis
小西 慶幸1,3, 堀 生実1, 松本 望1, 梶田 真司1,3, 村瀬 朋弥1, 中村 航1, 辻 隆宏2,3, 三宅 誠司2,3, 稲谷 大2,3
1. 福井大学 工, 2. 福井大学 医 眼科学, 3. 福井大学 ライフセ
Yoshiyuki Konishi1,3, Ikuma Hori1, Nozomu Matsumoto1, Masashi Kajita1,3, Tomoya Murase1, Wataru Nakamura1, Takahiro Tsuji2,3, Seiji Miyake2,3, Masaru Inatani2,3
1. Fac. Eng., Univ. Fukui, 2. Dept. Ophthalmol., Fac. Med. Sci., Univ. Fukui., 3. Life Sci. Innov. Cent., Univ. Fukui.
In axons of mature neurons, mitochondria are frequently found in places consuming high energy, such as the presynaptic sites. Before the synaptic maturation, the majority of mitochondria are anchored to the microtubules via the function of anchoring protein, syntaphilin, whereby they stay at the same position. These stationary mitochondria play critical roles to maintain the axonal arbor shape by locally providing the ATP. The intracellular systems that control the corrective behavior of axonal mitochondria remain to be elucidated. We found that unmyelinated and nonsynaptic axons possess a system that distributes mitochondria uniformly. Local inactivation of mitochondria inhibited the translocation of mitochondrial spots in adjacent axonal regions, suggesting that functional mitochondria enhance the motility of other mitochondria in the vicinity. In a mathematical model, we found that the ATP gradient generated by mitochondria, and ATP-dependent regulation of mitochondrial motility could establish uniform mitochondrial distribution. As axons maturate, mitochondria co-localize with the cluster of synaptic vesicles. We found that there is a correlation between the translocation of mitochondria and that of synaptic vesicles, indicating that there is a relationship between the motility of axonal mitochondria and presynaptic components. | |
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