Dynamic regulation of small Rho GTPases via serotonin receptors in neurons: Effects on the cytoskeleton, neuronal morphology and functions

通过神经元血清素受体动态调节小 Rho GTPases：对细胞骨架、神经元形态和功能的影响

• 批准号: 230769568
• 负责人: Professor Dr. Evgeni Ponimaskin
• 金额: --
• 依托单位: Institut für Neurophysiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/230769568?language=en
• 关键词: Dynamic; regulation; small; Rho; GTPases

Reorganization of actin cytoskeleton is one of the critical steps in regulation of neuronal morphology and motility. Dynamic changes of actin cytoskeleton in neurons are controlled by small GTPases of the Rho family, including RhoA, Rac1 and Cdc42. Rho GTPases have also emerged as important regulators for dendrite and spine structural plasticity, and are a part of the initial molecular cascade required for the growth of new synapses. Multiple studies suggest that Rac1 and Cdc42 are positive regulators promoting neurite outgrowth and formation of dendritic filopodia, while the activation of RhoA induces stress fibre formation, leading to neurite retraction. Although the importance of Rho GTPases is widely accepted, the signalling pathways regulating Rho GTPases activity in neurons are not fully characterized. We have recently shown that the serotonin receptor 5-HT4 can activate RhoA via the heterotrimeric G13 protein, and that stimulation of 5-HT4 receptors causes RhoA-mediated neurite retraction. We also identified Cdc42 as a novel down-stream effector of the 5-HT7 receptor and G12 protein. Stimulation of the 5-HT7/G12 signalling pathway facilitates neurite outgrowth, promotes synaptogenesis and enhances synaptic activity in hippocampal neurons. However, molecular mechanisms responsible for the coordinated (inter-)action between these opposite acting signalling pathways remain poorly understood. Thus, the central goal of the present project is to molecularly define the precise mechanisms through which 5-HT4 and 5-HT7 receptors regulate spatial arrangement and activity-dependent redistribution of small GTPases leading to the cytoskeleton reorganization. We will start by determining down-stream effectors for 5-HT4/G13/RhoA and 5-HT7/G12/Cdc42 signalling modules, followed by the quantitative evaluation of their activities with the focus on the reorganization of actin cytoskeleton. Furthermore, we will analyse the spatio-temporal activation profiles of Cdc42 and RhoA using FRET-based biosensors. These experiments will provide us with detailed information about the functional cross-talk between these GTPases within complex signalling networks. The second major goal of this project is to elucidate the role of receptor-mediated cytoskeleton reorganization for modulation of neuronal morphology, formation of dendritic spines, synaptogenesis and synaptic plasticity. These studies will be carried out in primary and organotypic cultures of hippocampal neurons from mice. The functional role of the 5-HT4/G13 signalling will also be tested in vivo. In addition, we will analyse the contribution of the 5-HT7/G12 pathway to neuronal protection and regeneration using excitotoxicity-induced neuronal damage as a model. These experiments will provide us with information about the possible therapeutic role of 5-HT7/G12 signalling as a neuroprotective and neuroregenerative agent.

肌动蛋白细胞骨架的重组是神经元形态和运动调节的关键步骤之一。神经元中肌动蛋白细胞骨架的动态变化由Rho家族的小GTP酶控制，包括RhoA，Rac 1和Cdc 42。Rho GTP酶也已成为树突和棘结构可塑性的重要调节因子，并且是新突触生长所需的初始分子级联的一部分。多项研究表明，Rac 1和Cdc 42是促进神经突生长和树突状丝状伪足形成的正调节因子，而RhoA的激活诱导应力纤维形成，导致神经突收缩。虽然Rho GTPases的重要性被广泛接受，但调节神经元中Rho GTPases活性的信号传导途径尚未完全表征。我们最近发现5-羟色胺受体5-HT 4可以通过异源三聚体G13蛋白激活RhoA，并且5-HT 4受体的刺激引起RhoA介导的神经突收缩。我们还确定Cdc 42作为5-HT 7受体和G12蛋白的新型下游效应子。5-HT 7/G12信号通路的刺激促进海马神经元中的神经突生长，促进突触发生并增强突触活性。然而，负责这些相反的作用信号通路之间的协调（相互）作用的分子机制仍然知之甚少。因此，本项目的中心目标是从分子水平上确定5-HT 4和5-HT 7受体调节小GTP酶空间排列和活性依赖性再分布的精确机制，从而导致细胞骨架重组。我们将首先确定5-HT 4/G13/RhoA和5-HT 7/G12/Cdc 42信号传导模块的下游效应物，然后定量评价它们的活性，重点是肌动蛋白细胞骨架的重组。此外，我们将使用基于FRET的生物传感器分析Cdc 42和RhoA的时空激活概况。这些实验将为我们提供有关复杂信号网络中这些GTP酶之间的功能性串扰的详细信息。本项目的第二个主要目标是阐明受体介导的细胞骨架重组在调节神经元形态、树突棘形成、突触发生和突触可塑性中的作用。这些研究将在小鼠海马神经元的原代和器官型培养物中进行。还将在体内测试5-HT 4/G13信号传导的功能作用。此外，我们将使用兴奋性毒性诱导的神经元损伤作为模型，分析5-HT 7/G12通路对神经元保护和再生的贡献。这些实验将为我们提供有关5-HT 7/G12信号作为神经保护和神经再生剂的可能治疗作用的信息。

项目成果

Palmitoylation of cdc42 Promotes Spine Stabilization and Rescues Spine Density Deficit in a Mouse Model of 22q11.2 Deletion Syndrome

• DOI: 10.1093/cercor/bhw183
• 发表时间: 2017-07-01
• 期刊: CEREBRAL CORTEX
• 影响因子: 3.7
• 作者: Moutin, E.;Nikonenko, I.;Muller, D.
• 通讯作者: Muller, D.

Serotonin 5‐HT7 receptor increases the density of dendritic spines and facilitates synaptogenesis in forebrain neurons

血清素 5âHT7 受体增加树突棘的密度并促进前脑神经元的突触发生

• DOI: 10.1111/jnc.13962
• 发表时间: 2017
• 期刊: Journal of Neurochemistry
• 影响因子: 4.7
• 作者: Speranza L;Labus J;Volpicelli F;Guseva D;Lacivita E;Leopoldo M;Bellenchi G;di Porzio U;Bijata M;Perrone-Capano C;Ponimaskin E
• 通讯作者: Ponimaskin E

The serotonin receptor 5-HT7R regulates the morphology and migratory properties of dendritic cells

• DOI: 10.1242/jcs.167999
• 发表时间: 2015-08-01
• 期刊: JOURNAL OF CELL SCIENCE
• 影响因子: 4
• 作者: Holst, Katrin;Guseva, Daria;Ponimaskin, Evgeni
• 通讯作者: Ponimaskin, Evgeni