一般口演（Oral）

Oral Neurogenesis, Gliogenesis, Cellular Differentation-2 一般口演神経発生・グリア発生・細胞分化-2

7月25日（木）17:50～18:05　第8会場（朱鷺メッセ　3F　303+304） 1O-08e2-1 Wntシグナルの活性化は同側脳に投射する網膜神経節細胞を減少させる Lena Iwai（岩井玲奈）¹，Revathi Balasubramanian（Balasubramanian Revathi）³，Austen Sitko（Sitko Austen）⁴，Rehnuma Khan（Khan Rehnuma）²，Samuel Weinreb（Weinreb Samuel）²，Kiera Robinson（Robinson Kiera）²，Carol Mason（Mason Carol）^2,3,4,5 ¹国立遺伝学研究所 ²Dept Pathology and Cell Biol. Columbia Univ., New York, USA ³Dept Ophthalmology, Columbia Univ., New York, USA ⁴Dept Neuroscience, Columbia Univ., New York, USA ⁵Mortimer B.Zuckerman Mind Brain Behavior Institute, Columbia Univ., New York, USA In mammalian albinism, disrupted melanogenesis in the retinal pigment epithelium (RPE) is associated with fewer retinal ganglion cells (RGCs) projecting ipsilaterally to the brain.A reduced ipsilateral RGC projection in albinism results in numerous abnormalities in the retina and visual pathway, especially binocular vision. To further understand the molecular link between disrupted RPE and a reduced ipsilateral RGC projection in albinism, we compared gene expression in the embryonic albino and pigmented mouse RPE. We found that the Wnt pathway, which directs peripheral retinal differentiation and, generally, cell proliferation, is dysregulated in the albino RPE. Wnt2b expression is expanded in the albino RPE compared with the pigmented RPE, and the expanded region adjoins the site of ipsilateral RGC neurogenesis and settling. Pharmacological activation of Wnt signaling in pigmented mice by lithium (Li+) treatment in vivo reduces the number of Zic2-positive RGCs, which are normally fated to project ipsilaterally, to numbers observed in the albino retina. These results implicate Wnt signaling from the RPE to neural retina as a potential factor in the regulation of ipsilateral RGC production, and thus the albino phenotype.		7月25日（木）18:05～18:20　第8会場（朱鷺メッセ　3F　303+304） 1O-08e2-2 ニューロン分化過程におけるクロマチン構造変化 Yusuke Kishi（岸雄介），Seishin Sakai（坂井星辰），Yoshikuni Wada（和田恵邦），Yukiko Gotoh（後藤由季子）東京大院薬 The process of neuronal differentiation of neocortical neural precursor cells (NPCs) includes many steps, such as neuronal fate commitment, migration to the pial surface and morphological and functional maturation. Each step is associated with dynamic changes in gene expression patterns, although the underlying mechanisms remain unclear. The neocortex consists of a great diversity of neurons which are born at different developmental stages and regulated by different transcriptional programs. Therefore, we labeled a specific subtype of neurons that are born from NPCs at around the same time to precisely investigate the changes in their transcription state during neuronal differentiation. We discovered that thousands of genes change their expression state during this process, suggesting the global changes in gene transcription pattern. Chromatin structures have important function in regulating gene transcription. Especially, open or closed chromatin contribute to active or inactive state, respectively. Therefore, we hypothesized that the change in the chromatin accessibility may be responsible for this drastic change in the expression pattern. Furthermore, we examined the DNase I hypersensitive sites (DHS) during neuronal differentiation, and found that chromatin accessibility dynamically changes. We also found that several transcription factors and chromatin regulators play a role in the changes of chromatin accessibility. This suggests that regulation of the chromatin structure underlies transcriptional changes in differentiating neurons.

7月25日（木）18:20～18:35　第8会場（朱鷺メッセ　3F　303+304） 1O-08e2-3 Applications of human pluripotent stem cell-derived neurons for the developmental study and the disease modeling Yohan Oh（Oh Yohan） Hanyang University Directed differentiation of human pluripotent stem cells (hPSCs) into specific cell types makes human developmental study and the disease modeling possible. Neurons derived from hPSCs are powerful tools for studying human neural development and diseases. My research goal is to develop the extraordinary and biologically feasible model system for studying human diseases or developmental process using hPSCs. In this meeting, I will present my current studies, which are the generation of human sympathetic neurons for the modeling neuromodulation and the Zika virus (ZIKV) research for the modeling infectious disease using hPSC-derived peripheral neurons. In detail for the first part, I derived sympathetic neurons from hPSCs and demonstrated that they can form physical and functional connections with cardiac muscle cells. Using multiple hPSC reporter lines, I recapitulated human autonomic neuron development in vitro and successfully isolated PHOX2B::eGFP⁺ neurons that exhibit sympathetic marker expression and electrophysiological properties and norepinephrine secretion. Upon pharmacologic and optogenetic manipulation, PHOX2B::eGFP⁺ neurons controlled beating rates of cardiomyocytes, and the physical interactions between these cells increased neuronal maturation. In detail for the second part, I revealed that intraperitoneally or intraventricularly injected ZIKV in the mouse can infect and impact peripheral neurons in vivo. Moreover, ZIKV productively infects hPSC-derived human neural crest cells and peripheral neurons in vitro, leading to increased cell death, transcriptional dysregulation and cell-type-specific molecular pathology. These studies highlight the power of stem-cell-based approaches for asking fundamental questions in human development and diseases.		7月25日（木）18:35～18:50　第8会場（朱鷺メッセ　3F　303+304） 1O-08e2-4 皮質下投射ニューロンの分化決定における転写制御機構 Koji Oishi（大石康二），Kazunori Nakajima（仲嶋一範）慶應大医解剖 The mammalian cerebral cortex consists of hundreds of different types of neurons. Given that different cortical subtypes are generated in a sequential manner, a long-standing hypothesis to account for this temporal fate specification process is that neural progenitor cells change their differentiation potential over time. However, it is also conceivable that cortical lamination or appropriate cell positioning in the cortical plate is required for correct differentiation of neurons. According to the latter hypothesis, we recently discovered that immature `future (normally destined to become)' layer 4 neurons were plastic and able to acquire layer 2/3 characteristics when they were forced to locate in layer 2/3 (Oishi et al., 2016, eLIFE; Oishi et al., 2016, PNAS; Oishi and Nakajima, 2018, Neurochem Res). However, the precise mechanisms to understand the generation of entire neuronal subtypes in the cortex remain elusive. In the current study, we studied the fate specification mechanisms of subcortical projection neurons in the deep cortical plate, which are driven by Fezf2, a master transcriptional regulator for deep layer neurons. We found that two transcription factors downstream of Fezf2 reciprocally regulated each other and that these factors were essential to specify the subcortical neuronal fate. Moreover, we found that the Fezf2-induced subtype conversion of upper layer neurons into deep layer-like neurons was dramatically promoted by these downstream effectors. Finally, we would like to discuss how the mechanisms to specify a certain neuronal subtype are regulated in the neurons differentiating other subtypes.