Uncovering the molecular basis of SEPT2-associated Tyshchenko syndrome

揭示 SEPT2 相关 Tyshchenko 综合征的分子基础

• 批准号: 393989644
• 负责人: Dr. Luisa Weiß
• 金额: --
• 依托单位: Laboratory for Genomic Medicine
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/393989644?language=en
• 关键词: Uncovering; molecular; basis; SEPT2; associated

Tyshchenko syndrome (TS) was first described in 2011 by Tyshchenko et al. as an autosomal-dominant syndrome presenting with distinct facial features, specific malformations and learning disabilities. The minor anomalies resemble Baraitser-Winter Cerebrofrontofacial syndrome (BWCFF). Whereas mutations in either non-muscular Actin gene ACTB or ACTG1 are known to cause BWCFF, no underlying cause of TS could be found.Via whole exome sequencing, we identified a missense mutation in SEPT2 in one of the two original families described by Tyshchenko et al. In addition, in two other unrelated patients with the same striking facial features we found de novo missense mutations in SEPT2. In a 3-D protein model of human Septin 2, all three mutations are located in close spatial proximity.Septin 2, like other Septins, plays a major role in a variety of cell processes including cytokinesis. Septins are important components of the cytoskeleton and serve as scaffolds and diffusion barriers in the cell. They all possess a guanine nucleotide binding domain with GTPase activity and an NC interface, that is their N- and C-terminal extensions. Via both domains, Septins interact forming linear hetero-oligomers, most commonly with Septin 2 located is its centre, functioning as an initiator of the complex formation. Amongst others, filamentous Septins also closely co-localize with Actin and control F-Actin assembly and Actin organization.The main goal of this project is to delineate the molecular mechanisms leading to SEPT2-related TS and to unravel the molecular mechanisms in Septin-Actin interaction, that lead to a similar yet differing clinical presentation of TS and BWCFF.To do so, we will perform in vitro experiments to demonstrate the effect of SEPT2 mutations on Septin-oligomerization using immunoprecipitation of recombinant proteins and protein-domains. As all of the mutations found in TS patients in Septin 2 are located in the NC interface, we hypothesize that the homodimerization of Sept2 or the hetero-oligomerization with other Septins might be disturbed in TS patients. In addition, we will investigate the effects of SEPT2 mutations on the Septin function during cytokinesis. We will also measure Septin-Actin interactions via immunostaining and using purified recombinant proteins in order to establish a functional link between TS and BWCFF. Eventually, we want to deepen our insights into the interaction between different cytoskeletal components and broaden our knowledge of the formation and function of the cytoskeleton. Through this, we want to lead to an ultimate benefit to the patients, understand their condition, anticipate future complications and facilitate the development of therapeutic possibilities.

Tyshchenko综合征（TS）于2011年由Tyshchenko等人首次描述为一种常染色体显性遗传综合征，表现为独特的面部特征，特定的畸形和学习障碍。轻微异常类似于Baraitser-Winter脑额面综合征（BWCFF）。而非肌肉肌动蛋白基因ACTB或ACTG 1的突变是已知的BWCFF的原因，没有潜在的原因TS可以被发现。通过全外显子组测序，我们确定了错义突变SEPT 2在Tyshchenko等人描述的两个原始家庭之一。此外，在其他两个不相关的患者具有相同的惊人的面部特征，我们发现了从头错义突变SEPT 2。在人Septin 2的三维蛋白模型中，所有三个突变都位于空间上非常接近的位置。Septin 2与其他Septins一样，在包括胞质分裂在内的各种细胞过程中起主要作用。隔膜蛋白是细胞骨架的重要组成部分，并在细胞中充当支架和扩散屏障。它们都具有一个鸟嘌呤核苷酸结合结构域，具有GTdR活性和一个NC界面，即它们的N-和C-末端延伸。通过这两个结构域，胞裂蛋白相互作用形成线性杂寡聚体，最常见的是胞裂蛋白2位于其中心，用作复合物形成的引发剂。除此之外，丝状Septins还与肌动蛋白密切共定位，并控制F-肌动蛋白组装和肌动蛋白组织。本项目的主要目标是描述导致SEPT 2相关TS的分子机制，并解开Septin-Actin相互作用的分子机制，导致TS和BWCFF的相似但不同的临床表现。我们将使用重组蛋白和蛋白结构域的免疫沉淀进行体外实验以证明SEPT 2突变对Septin寡聚化的影响。由于在TS患者中发现的Septin 2中的所有突变都位于NC界面中，因此我们假设在TS患者中可能会干扰Septin 2的同源二聚化或与其他Septin的异源寡聚化。此外，我们将研究SEPT 2突变对胞质分裂期间Septin功能的影响。我们还将通过免疫染色和使用纯化的重组蛋白来测量Septin-Actin相互作用，以建立TS和BWCFF之间的功能联系。最终，我们希望加深我们对不同细胞骨架成分之间相互作用的认识，并扩大我们对细胞骨架形成和功能的认识。通过这一点，我们希望为患者带来最终利益，了解他们的病情，预测未来的并发症，并促进治疗可能性的发展。