Actin-based Neuronal State Changes

描述(由申请人提供)：肌动蛋白细胞骨架的动态组装和拆解是不同细胞过程的基础，包括细胞分裂、发育极性和细胞内运输。这些更改可以是局部的，也可以是全局的，从而改变单元状态。细胞外信号介导经验诱导的神经元突触微区内肌动蛋白动力学的变化。最近的证据表明，细胞体的肌动蛋白动力学与突触中的肌动蛋白动力学不同，可能也是神经元感知和响应细胞外刺激所必需的。我们预测，这个过程通过改变转录来促进行为的可塑性。我们的首要目标是了解经验如何发出神经元长期状态变化的信号，进而改变行为。我们假设谷氨酸能神经传递改变了肌动蛋白的组织，这是允许转录激活的。我们将在视交叉上核(SCN)中检验这一假设，这是一个大脑部位，具有建立起的分子底物，是行为时间组织所必需的。SCN是一种以细胞为基础的~24小时时钟，由调节转录的空间和时间振荡驱动。具体地说，我们假设谷氨酸启动的信号级联作用于SCN细胞的肌动蛋白细胞骨架，改变了改变时钟状态的关键转录调节因子的定位。我们将研究肌动蛋白这种变化的性质和必要性，以及它们对时钟基因转录激活的影响。我们将在大鼠和小鼠模型中评估这些机制：细胞培养、脑片和动物行为。特定的目标将：1)表征和定位刺激诱导的肌动蛋白变化；2)发现肌动蛋白变化在时钟功能和行为中的作用；3)确定肌动蛋白变化在调控转录中的作用。我们将使用细胞生物学方法、动态成像、生物化学、神经生物学测量和行为分析。这种基于系统的分析的广度将产生关于经验如何转化为对大脑状态和行为的长期调整的见解。这将加强对长期神经状态变化的基础的理解，对公共卫生和疾病预防具有广泛的相关性。肌动蛋白系统的功能障碍会导致严重的神经障碍，包括认知、神经退化、运动和自主控制方面的障碍。睡眠障碍、学习/记忆障碍、吸毒和衰老将是直接受益者。

DESCRIPTION (provided by applicant): Dynamic assembly and disassembly of the actin cytoskeleton underlies diverse cellular processes, including cell division, developmental polarity and intracellular transport. These changes can be local or global, transforming cell state. Extracellular signals mediate experience-induced changes of actin dynamics within synaptic microdomains of neurons. Recent evidence suggests that actin dynamics of the cell body, distinct from those in the synapse, also may be necessary for neurons to sense and respond to extracellular stimuli. We predict that this process contributes to plasticity of behavior by altering transcription. Our overarching goal is to understand how experience signals long-term state changes in neurons that, in turn, change behavior. We hypothesize that glutamatergic neurotransmission changes actin organization, and this is permissive for transcriptional activation. We will test this hypothesis in the suprachiasmatic nucleus (SCN), a brain site with established molecular substrates necessary for temporal organization of behavior. The SCN is a cell-based, ~24-h clock driven by spatial and temporal oscillations that regulate transcription. Specifically, we hypothesize that signaling cascades initiated by glutamate engage the actin cytoskeleton of SCN cells, changing localization of key transcriptional regulators that alter clock state. We will examine the nature and necessity of such changes in actin and their effects on transcriptional activation of clock genes. We will evaluate these mechanisms in rat and mouse models: cell cultures, brain slices and behaving animals. Specific aims will: 1) characterize and localize stimulus-induced changes in actin; 2) find the role of actin changes in clock function and behavior, and 3) determine the role of actin changes in regulating transcription. We will use cell biological methods, dynamic imaging, biochemistry, neurobiological measures, and behavioral analyses. The breadth of this systems-based analysis will generate insights into how experience is transformed into long-lasting modification in brain state and behavior. This will enhance the understanding of substrates of long-lasting neural state change, with broad relevance for public health and disease prevention. Dysfunctions in the actin system cause severe neurological disorders, including those of cognition, neurodegeneration, movement and autonomic control. Sleep disorders, learning/memory impairments, drug-addiction and aging will be direct beneficiaries.