Role of Filamin A in integrin-dependent dendritic growth and hippocampus function

细丝蛋白A(flamin A，Flna)是一种能使肌动蛋白纤维发生交联的大分子二聚体蛋白，是连接细胞骨架和细胞膜整合素的桥梁。人类FLNA基因的突变导致脑室周围异位，由于迁移障碍，神经元沿着侧脑室聚集。因此，以往的研究重点一直集中在FLNA对神经元迁移的重要性上，而其对神经元分化的贡献还不是很清楚。然而，我们和其他研究小组已经证明，肌动蛋白细胞骨架和整合素在树突的发育和可塑性中发挥着重要作用。在这个项目的具体前期工作中，我们还收集了证据表明，Flna显著参与了海马神经元树突状分支的形成。我们现在想要研究Flna参与树突状细胞生长的细胞机制，并确定这些过程在海马区依赖的信息处理和记忆形成中的作用。在项目的第一部分，我们将研究在海马区细胞培养和野生型小鼠的海马区发育过程中Flna表达和磷酸化的调节。具体考虑了刺激丰富的环境(“丰富的环境”)的促进生长效应，并涉及到细胞外信号(生长因子BDNF和NGF，以及整合素介导的信号)。然后，我们将在原代神经元培养中研究Flna磷酸化的细胞内调控机制及其与整合素的相互作用。我们将把我们的发现转移到测试Flna在树突棘的形成中的预期参与。我们还将使用病毒载体来研究缺乏Flna对体内海马区树突结构和突触密度的影响。在我们最终测试FLNA的击倒如何影响环境浓缩后这些参数的改善之前，我们将从电生理学的角度研究这种干预在切片准备中的功能后果，以及在海马体依赖行为方面的功能后果。

Filamin A (FlnA) is a large dimeric protein that can cross-link actin fibers and serves as a bridge between the cytoskeleton and integrins of the cell membrane. Mutations in the human FLNA gene lead to periventricular heterotopia, in which neurons accumulate along the lateral ventricles due to impaired migration. Therefore, the focus of previous research has been on the importance of FlnA for neuronal migration and its contribution to the differentiation of neurons is not well known. However, we and other groups have shown that the actin cytoskeleton and integrins play an important role in the development and plasticity of dendrites. In specific preliminary work for this project, we have also collected evidence that FlnA is significantly involved in the formation of dendritic branches in hippocampal neurons. We now want to investigate the cellular mechanisms that underlie the involvement of FlnA in dendritic growth and determine the role of these processes in hippocampus-dependent information processing and memory formation.In the first part of the project we will study the regulation of FlnA expression and phoshorylation during development in hippocampal cell cultures and in the hippocampus of wild-type mice. The growth-promoting effects of a stimulus-rich environment (“enriched environment”) are specifically taken into account and extracellular signals involved (the growth factors BDNF and NGF, as well as integrin-mediated signals) are addressed. Then we will investigate the intracellular regulatory mechanisms for the phosphorylation of FlnA and its interaction with integrins in primary neuronal cultures. We will transfer our findings to test the expected involvement of FlnA in the formation of dendritic spines. We will also use viral vectors to investigate how the lack of FlnA affects the dendritic architecture and synapse density in the hippocampus in vivo. We will examine the functional consequences of this intervention electrophysiologically in slice preparations and with regard to hippocampus-dependent behavior, before we finally test how the FlnA knock down affects the improvement of these parameters after environmental enrichment.