An adaptor protein for dendritic spine exocytosis and postsynaptic plasticity

描述(申请人提供)：AMPA型谷氨酸受体(AMPAR)从细胞内隔室定向输送到突触后膜是哺乳动物大脑中与学习相关的突触可塑性的主要细胞机制。然而，人们对确保AMPAR特定的脊椎运输到突触的分子机制知之甚少。我们实验室以前的工作已经证明，当使用一种称为长时程增强(LTP)的学习协议时，脊椎内和底部的循环内小体(RES)为突触提供膜和AMPAR。尽管已证实依赖活性的RE向树突棘募集对于LTP的表达是必不可少的，但RE对接递送受体和树突膜的确切位置仍然不清楚。在这里，我们已经确定了位于突触后密度附近的树突棘中的胞吐区域。此外，我们描述了一种可能的分子传感器，即接头分子Rabi1-FIP2，它有助于RES的正确膜定位，以实现适当的脊椎胞吐。该建议旨在(1)确定Rabi 1-FIP2脊柱定位所需的信号通路；(2)确定Rabi 1-FIP2的干扰是否介导了脊柱的胞吐；以及(3)确定Rabi 1-FIP2的中断在促进AMPA受体向脊膜递送以表达LTP方面的功能后果。实验将使用基本的生化方法和海马神经元的活细胞成像相结合的方法来确定Rabi 1-FIP2对脊椎胞吐的关键信号通路和需求。此外，器官型海马片结合电生理学将被用来测试Rabi 1-FIP2对LTP的功能。由于Res的胞吐作用对于AMPAR正确地输送到突触后膜是至关重要的，我们认为这种依赖Rabi 1-FIP2的细胞机制是哺乳动物大脑中与学习相关的突触可塑性的关键因素。公开信息：AMPA受体(AMPAR)从被称为循环内小体的细胞内间隔运送到突触的突触后膜是大脑中与学习相关的突触可塑性的主要细胞机制。此外，内体功能的失调和AMPAR在树突棘中的运输导致了各种神经疾病，如阿尔茨海默病、唐氏综合症和精神分裂症。这项建议将侧重于确定对哺乳动物大脑中与学习相关的突触可塑性至关重要的分子机制，并将提供关于内体功能中断如何导致神经系统疾病的见解。

DESCRIPTION (provided by applicant): The targeted delivery of AMPA-type glutamate receptors (AMPAR) from intracellular compartments to the postsynaptic membrane is a major cellular mechanism for learning-related synaptic plasticity in the mammalian brain. Yet, little is known about the molecular machinery that ensures the spine- specific transport of AMPARs to the synapse. Prior work in our laboratory has demonstrated that recycling endosomes (REs) within and at the base of spines provide membrane and AMPARs to the synapse when using a protocol for learning known as long term potentiation (LTP). Although it is established that activity- dependent recruitment of REs to dendritic spines is essential for the expression of LTP, the precise location of RE docking for the delivery of receptors and membrane in dendrites remains obscure. Here, we have identified regions of exocytosis in dendritic spines that are positioned adjacent to the postsynaptic density. Further, we describe a putative molecular sensor, the adaptor molecule Rabi 1-FIP2 which aids in the correct membrane positioning of REs for proper spine exocytosis. This proposal will aim to (1) identify the signaling pathways required for Rabi 1-FIP2 spine localization (2) determine if disruption of Rabi 1-FIP2 mediates spine exocytosis and (3) define the functional consequences of Rabi 1-FIP2 disruption on facilitating delivery of AMPA receptors to spine membranes for the expression of LTP. Experiments will use a combination of basic biochemical approaches and live cell imaging in hippocampal neurons to identify the critical signaling pathways and requirement of Rabi 1-FIP2 for spine exocytosis. Further, organotypic hippocampal slices in combination with electrophysiology will be used to test the function of Rabi 1-FIP2 on LTP. Since exocytosis from REs is crucial for the proper deliver of AMPARs to the postsynaptic membrane, we propose that this Rabi 1-FIP2 dependent cellular mechanism is a key element for learning-related synaptic plasticity in the mammalian brain. Public information: The delivery of AMPA receptors (AMPARs) from intracellular compartments known as recycling endosomes to the postsynaptic membrane of synapses is a major cellular mechanism for learning- related synaptic plasticity in the brain. In addition, dysregulation of endosomal function and AMPAR trafficking in dendritic spines contributes to various neurological disorders such as Alzheimer's disease, Down's syndrome, and schizophrenia. This proposal will focus on identifying the molecular machinery that is critical for learning-related synaptic plasticity in the mammalian brain and will provide insight into how disruption of endosomal function leads to neurological disease.