Drebrin is a novel connexin-43 binding partner that links gap junctions to the submembrane cytoskeleton

AbstractBackground: Connexins form gap junctions that mediate the transfer of ions, metabolites, and second messengers between contacting cells. Many aspects of connexin function, for example cellular transport, plaque assembly and stability, and channel conductivity, are finely tuned and likely involve proteins that bind to connexins' cytoplasmic domains. However, little is known about such regulatory proteins. To identify novel proteins that interact with the COOH-terminal domain of Connexin-43 (Cx43), the most widely expressed connexin family member, we applied a proteomics approach to screen fractions of mouse tissue homogenates for binding partners.Results: Drebrin was recovered as a binding partner of the Cx43 COOH-terminal domain from mouse brain homogenate. Drebrin had previously been described as an actin binding protein that diminishes in brains during Alzheimer's disease. The novel Drebrin-Cx43 interaction identified by proteomics was confirmed by colocalization of endogenous proteins in astrocytes and Vero cells, coimmunoprecipitation, electron microscopy, electrophysiology, coexpression of both proteins with fluorescent tags, and live-cell FRET analysis. Depletion of Drebrin in cells with siRNA results in impaired cell-cell coupling, internalization of gap junctions, and targeting of Cx43 to a degradative pathway.Conclusions: We conclude that Drebrin is required for maintaining Cx43-containing gap junctions in their functional state at the plasma membrane. It is thus possible that Drebrin may interact with gap junctions in zones of cell-cell contacts in a regulated fashion in response to extracellular signals. The rearrangement or disruption of interactions between connexins and the Drebrin-containing submembrane cytoskeleton directs connexins to degradative cellular pathways

初期糖尿病網膜症における視機能異常に関する電気生理学的解析

金沢大学医学部研究課題/領域番号:02771184, 研究期間(年度):1990出典：研究課題「初期糖尿病網膜症における視機能異常に関する電気生理学的解析」課題番号02771184（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-02771184/）を加工して作

初期糖尿病性網膜症における視機能異常の検出

金沢大学医学部研究課題/領域番号:01771399, 研究期間(年度):1989出典：研究課題「初期糖尿病性網膜症における視機能異常の検出」課題番号01771399（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-01771399/）を加工して作

ヒヨコ網膜色素上皮の高浸透圧応答に関する研究: 細胞膜電位からの検討

取得学位 : 博士（医学）, 学位授与番号 : 医博乙第1157号, 学位授与年月日：平成4年1月14日,学位授与年：199

Regulation of myotube formation by the actin-binding factor drebrin

<p>Abstract</p> <p>Background</p> <p>Myogenic differentiation involves cell-cycle arrest, activation of the muscle-specific transcriptome, and elongation, alignment and fusion of myoblasts into multinucleated myotubes. This process is controlled by promyogenic transcription factors and regulated by signaling pathways in response to extracellular cues. The p38 mitogen-activated protein kinase (p38 MAPK) pathway promotes the activity of several such transcription factors, including MyoD and MEF2, thereby controlling the muscle-specific transcription program. However, few p38-regulated genes that play a role in the regulation of myogenesis have been identified.</p> <p>Methods</p> <p>RNA interference (RNAi), chemical inhibition and immunofluorescence approaches were used to assess the role of drebrin in differentiation of primary mouse myoblasts and C2C12 cells.</p> <p>Results</p> <p>In a search for p38-regulated genes that promote myogenic differentiation, we identified <it>Dbn1</it>, which encodes the actin-binding protein drebrin. Drebrin is an F-actin side-binding protein that remodels actin to facilitate the change of filopodia into dendritic spines during synaptogenesis in developing neurons. <it>Dbn1 </it>mRNA and protein are induced during differentiation of primary mouse and C2C12 myoblasts, and induction is substantially reduced by the p38 MAPK inhibitor SB203580. Primary myoblasts and C2C12 cells depleted of drebrin by RNAi display reduced levels of myogenin and myosin heavy chain and form multinucleated myotubes very inefficiently. Treatment of myoblasts with BTP2, a small-molecule inhibitor of drebrin, produces a phenotype similar to that produced by knockdown of drebrin, and the inhibitory effects of BTP2 are rescued by expression of a mutant form of drebrin that is unable to bind BTP2. Drebrin in myoblasts is enriched in cellular projections and cell cortices and at regions of cell-cell contact, all sites where F-actin, too, was concentrated.</p> <p>Conclusions</p> <p>Our findings reveal that <it>Dbn1 </it>expression is a target of p38 MAPK signaling during myogenesis and that drebrin promotes myoblast differentiation.</p

ヒト褐色白内障における新規蛍光物質,キサンツレン酸8-O-β-D-グルコシドの同定

取得学位 : 博士（医学）, 学位授与番号 : 医博乙第1547号 , 学位授与年月日 : 平成14年2月20日, 学位授与大学 : 金沢大

Drebrin Isoforms Critically Regulate NMDAR- and mGluR-Dependent LTD Induction

Drebrin is an actin-binding protein that is preferentially expressed in the brain. It is highly localized in dendritic spines and regulates spine shapes. The embryonic-type (drebrin E) is expressed in the embryonic and early postnatal brain and is replaced by the adult-type (drebrin A) during development. In parallel, NMDA receptor (NMDAR)-dependent long-term depression (LTD) of synaptic transmission, induced by low-frequency stimulation (LFS), is dominant in the immature brain and decreases during development. Here, we report that drebrin regulates NMDAR-dependent and group 1 metabotropic glutamate receptor (mGluR)-dependent LTD induction in the hippocampus. While LFS induced NMDAR-dependent LTD in the developing hippocampus in wild-type (WT) mice, it did not induce LTD in developing drebrin E and A double knockout (DXKO) mice, indicating that drebrin is required for NMDAR-dependent LTD. On the other hand, LFS induced robust LTD dependent on mGluR5, one of group 1 mGluRs, in both developing and adult brains of drebrin A knockout (DAKO) mice, in which drebrin E is expressed throughout development and adulthood. Agonist-induced mGluR-dependent LTD was normal in WT and DXKO mice; however, it was enhanced in DAKO mice. Also, mGluR1, another group 1 mGluR, was involved in agonist-induced mGluR-dependent LTD in DAKO mice. These data suggest that abnormal drebrin E expression in adults promotes group 1 mGluR-dependent LTD induction. Therefore, while drebrin expression is critical for NMDAR-dependent LTD induction, developmental conversion from drebrin E to drebrin A prevents robust group 1 mGluR-dependent LTD

ソウリツシャ カエツ タカ ノ キョウイク

創立者嘉悦 孝の始祖に始まり、孝の目指した教育、そして孝自らも学びそれを生徒に伝えようとした長い学研生活と、教壇生活の軌跡の根底にある理念を直視考察し、時代背景を交え概説したものである