TOP ＞ 一般演題（口述）

一般演題（口述） Neurite Outgrowth・Network Formation 2O1-01 Muller cell regulates axon elongation of retinal ganglion cells via P2Y6 receptor signals Shinozaki Youichi1,3，Taguchi Masanori1，Shigetomi Eiji1,3，Kashiwagi Kenji2，Koizumi Schuihi1,3 1Dept. Neuropharmacol. Interdiscp. Grad. Sch. of Med. Univ. of Yamanashi，2Dept. Ophthalmol. Interdiscp. Grad. Sch. of Med. Univ. of Yamanashi，3JST-CREST Muller cells, retina-specific glia, are known to support various functions of retinal ganglion cells（RGCs）, one of the retinal neurons which transmit visual information from the eye to the brain. Precise axon outgrowth is critical to forming functional neuronal circuits but primary cultured RGCs do not extend their axons by default, so extrinsic signals supporting the elongation are required. Here we show that Muller cells enhance axon elongation of RGCs via nucleotide-mediated gliotransmission. Cultured RGCs significantly enhanced their axon outgrowth when they were co-cultured with Muller cells. This effect was abolished by nucleotide-degrading enzyme apyrase. The enhancement was mimicked by exogenously applied nucleotides on RGC monocultures. Pharmacological analysis revealed that P2Y6 receptor in RGCs was responsible for the axon elongation. P2Y6 receptor was expressed in ganglion cell layer of retina and in cultured RGCs. High performance liquid chromatography revealed that Muller cells constitutively release uridine triphosphate（UTP）, a precursor of endogenous P2Y6 receptor agonist. Similarly, RGCs obtained from P2Y6 receptor knockout mice showed only short axons even though they were co-cultured with Muller cells. Furthermore, RGCs exposed to an in vitro glaucoma exhibited only short axons associated with down-regulated P2Y6 receptor expression. Taken together, our data highlight the role of purinergic gliotransmission between Muller cells and RGCs as a key factor for regulating axon outgrowth and sensing glaucomatous conditions. 2O1-02 Atypical myosin drives dendritic growth cone splitting to create complex arbor branching patterns. Moore Adrian W1，Yoong Li-Foong1，Lim Hui-Keem1，Lackner Simone1，Hong Pengyu2 1RIKEN Brain Science Institute，2Department of Computer Science, Brandeis University Neurons require highly branched dendritic arbor morphologies that underlie circuit organization. Yet the intricate cell biological mechanisms by which complex dendritic arbor architectures are established remain largely unknown. We developed in vivo time-lapse imaging in to study this process, and created a customized algorithm for automated recognition and tracing of different neuronal features over the imaging series. This algorithm facilitated analysis of the large and complex time-lapse data sets created through live imaging of Drosophila sensory neurons. From this we identify novel in vivo dynamic dendritic growth cone-like structures that undergo splitting in order to create branching. From an in vivo time lapse imaging screen we identify Myosin VI, the atypical myosin, as driving the splitting process. Myosin VI is targeted to the cortical lamellipodia of the growth cone and we demonstrate that Myosin VI directs promotes stabilization of polymerized-actin concentration at internal base of growth cone filopodia, and directs microtubule polymerization to these sites in order to drive growth cone splitting in order to generate new major branches. 2O1-03 The region specific stabilization of branched axons mediated by the axonal transport dependent system Konishi Yoshiyuki1，Seno Takeshi1，Menya Kosuke1，Kurishita Masayuki1，Sakae Narumi1 1Graduate School of Engineering, University of Fukui，2Research and Education Program for Life Sciences, University of Fukui The maintenance of cellular morphology is especially important for neurons to make connection with specific targets. The mechanisms by which neurons locally control cellular nanostructures, such as F-actin/microtubules remained unsolved. Our aim is to demonstrate molecular systems by which neurons process spatial information and regulate cellular structure at right position at right time. We focused on the axonal branch morphology and tested the possibility that axonal transport might play roles to regulate the axonal branch pattern. Previous studies have revealed that the motor domain of kinesin heavy chain（K5H）is accumulated in axon in hippocampal neurons. By using dissociated cerebellar granule neurons, we found that there is a positive correlation between signal intensity of K5H-GFP and axonal branch length, suggesting the possibility that axonal branch pattern is regulated via axonal transport. We further performed long-term multipoint time-lapse imaging of branched axons. By quantitative analysis of growth/retraction, we found that axonal branch which contain high ratio of K5H-GFP show lower retraction value. 2O1-04 Development of axon collaterals as the inter-areal connections in the cerebral cortex. Oka Yuichiro1，Iguchi Tokuichi1，Sato Makoto1,2,3 1Anatomy ＆ Neurosci., Dept. of Anatomy, Grad. Sch. of Med., Osaka Univ.，2United Grad. Sch. of Child Dev., Osaka, Kanazawa, Hamamatsu Med, Chiba, ＆ Fukui Univs，3Res Center for Child Mental Dev, Univ of Fukui Cerebral neocortex integrates different sensory inputs with internal status to elicit an appropriate behavior. Direct neuronal connections between functional areas within a cerebral hemisphere should play an important role in this process. Long association fibers（LAFs）are the long-range connections between distant areas located in different cortical lobes. Recent studies reported that the LAFs are aberrant in the mental/developmental diseases like schizophrenia and autism spectrum disorders, suggesting the importance of LAFs in cognitive functions. However, the detailed axonal structure of long association neurons（LANs）that constitute the LAFs and how its final structure is established during cortical development are yet to be revealed. To study the structure and development of the LANs, we searched for the mouse genes expressed in LANs. In our retrograde tracing from the primary motor cortex（M1）, the LANs in the primary somatosensory area（S1）were located in the layers 2/3, 5a, and 6b. Therefore, we supposed that the genes expressed in the LANs should be found among the known marker genes for these layers. By combining in situ hybridization using probes for the layer marker genes and retrograde tracing from M1 to S1, we found a candidate gene that was expressed in the LANs in the layers 2/3 and 5a of S1. We induced the EGFP expression in the LANs in the layer 2/3 using the promoter of this gene and visualized the axons projecting from S1 to M1. Imaging of the entire axonal structure revealed that the labeled LANs project their axons to both ipsilateral M1 and contralateral S1. Interestingly, the projection to M1 was one of the collaterals branching at layer 5. We report the developmental changes of the axonal structure of the labeled LANs.