TOP ＞ 若手道場

若手道場11 2021/10/1　14:00～15:00　ZOOM 若手道場 WD11-1 タウの欠損が微小管の安定性およびその他の微小管結合タンパク質に及ぼす影響 A new aspect of tau function in vivo; stabilizing the labile domain of microtubule ○辰本 彩香1, Tomohiro Miyasaka1,2 1.同志社大学大学院 生命医科学研究科 神経病理学研究室, 2.Center for Research in Neurodegenerative Diseases, Doshisha University ○Ayaka Tatsumoto1, Tomohiro Miyasaka1,2 1.Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, 2.Center for Research in Neurodegenerative Diseases, Doshisha University Tau, one of the microtubule-associated proteins (MAPs) in nerve cells, has long been thought to bind on microtubules (MTs) and contribute to their polymerization and stabilization. However, it has never been revealed how tau actually work on MTs in vivo. To clarify the physiological function of tau, here we analyzed the MT stability and the binding state of other MAPs (MAP1B, MAP2, MAP6, and MAP7) on MTs at postnatal to adult stage of mouse brains. Wild-type and tau-knockout (TKO) mouse cortices at 1, 7, 14, 28-day-old and 3-month-old were subjected to the MT fractionation method that enables to separate free tubulin, labile MT, and stable MT fractions. Then the tubulin and MAPs collected in each fraction were quantified by western blotting. At any age, the amounts of total α-tubulin fractioned as free tubulin, labile MTs, and stable MTs of TKO mice were largely comparable to those of wild-type mice. However, TKO mice showed obvious reduction in acetylated α-tubulin, a marker of stable MTs with less dynamic instability, in the fraction of labile MTs at developmental stages. We also found that the proportions of the MAP1B, MAP2, and MAP7 bound on labile MTs decreased and those bound on stable MTs tended to increase in TKO mice in immature brains. To our surprise, when the brain matured, α-tubulin acetylation level and binding status of the MAPs on MTs of TKO mice became comparable to those of wild-type mice. These results indicate that tau is not an essential factor for MT stabilization. But it seems to control in a direction that suppress dynamic instability of labile domain of MTs. Furthermore, other MAPs may complementarily act to maintain the MT structure even in the condition of tau deficiency. 2021/10/1　14:00～15:00　ZOOM 若手道場 WD11-2 Kcnab1 を発現するサブプレート由来皮質ニューロンの特徴と分布 Characteristics and Distribution of Subplate-derived Kcnab1-expressing Cortical Neurons ○Hamza,Yahaya Murtala1, Yuichiro Oka1,3, Sato Makoto1,3 1.Department of Anatomy and Neuroscience， Graduate School of Medicine， Osaka University, 2.Department of Human Anatomy, Faculty of Basic Medical Sciences, Yusuf Maitama Sule University, Kano, Nigeria, 3.United Graduate School of Medicine, Osaka University ○Murtala Hamza Yahaya1, Yuichiro Oka1,3, Sato Makoto1,3 1.Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, 2.Department of Human Anatomy, Faculty of Basic Medical Sciences, Yusuf Maitama Sule University, Kano, Nigeria, 3.United Graduate School of Medicine, Osaka University Cerebral cortex comprises 6 unique layers generated from a highly ordered migration pattern from proliferative zones during embryonic development. These layers are composed of neurons that are of unique characteristics, including gene expression, morphology, projection patterns, input source and output, and physiological properties. Subplate (SP) is a transient layer that expresses multiple lineage determinants such as WNT ligand and inhibitors during corticogenesis. This layer is believed to give rise to cortical projection neurons (PNs), especially deep cortical PNs of layers V - VI. However, the fate of the mature SP neurons is still not completely understood. Interestingly, we recently found that specific cortical neurons, Kcnab1-expressing neurons, include those that are derived from the SP. Here, we further examined these subplate-derived neurons across the cortical layers. Specifically, using transgenic lines, immunohistochemistry, in situ hybridization, and neuronal tracing, we revealed their distribution and morphological features. Analysis showed widespread distribution of subplate-derived Kcnab1-expressing neurons across the cortical layers. Majority of these neurons were found in the deep cortical layers consistent with the finding in human where deep PNs are derived from the SP. Unexpectedly, we observed some of these neurons in the upper layers. Also, all of these kcnab1-expressing neurons derived from SP expressed markers of their respective layers. Together, this result is suggesting a potential role of SP in contributing to a broader range of cortical neurons than previously known. In general, our study presents a further diversification of differentiation paths for cortical neurons. 2021/10/1　14:00～15:00　ZOOM 若手道場 WD11-3 マウス海馬歯状回におけるデスモプラキンの局在 Localization of Desmoplakin in dentate gyrus of mouse hippocampus ○高山 晃行,Chinami Saika, Kenshiro Uemura, Nana Koyama, Jin Nakatani, Toshinori Sawano, Hidekazu Tanaka 立命館大学　生命科学科　生命医科学コース　薬理学研究室 ○Akinori Takayama, Nana Koyama, Chinami Saika, Kenshiro Uemura, Jin Nakatani, Toshinori Sawano, Hidekazu Tanaka Pharmacology Laboratory, Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University The desmosome is an intercellular junction that provide strong adhesions between cells. An integral desmosomal protein, Desmoplakin, is expressed not only in the desmosomes of epithelium and cardiac muscle but also in the hippocampal neurons, which do not have desmosomes. Desmoplakin and Plakoglobin that are expressed in cultured hippocampal neurons have been co-immunoprecipitated with N-cadherin. However, there is little evidence that shows the localization and function of Desmoplakin in the hippocampal neurons. Here, we confirmed the expression of Desmoplakin mRNA in mature granule cells of dentate gyrus in mouse hippocampus. We also found that three splicing variants of Desmoplakin were expressed in hippocampus. One of these variants corresponded to desmoplakin-Ia that has been identified only in human so far. Surprisingly, the Desmoplakin immunoreactivity localized in ciliated structures originating from granular cell soma. These results suggest that the granule cells in mouse hippocampus protrude primary cilia-like structure.