Polarity determinants in synaptic stability and plasticity

 描述（由申请人提供）：突触的稳定性和可塑性对于认知功能都很重要。可塑性是学习所必需的，而稳定形成的突触被认为是长期记忆的编码。然而，目前还不清楚神经元如何保持这种微妙的平衡，并在相距仅几微米的突触中实现稳定性和可塑性。显然，需要高水平的区室化，这使得极性蛋白成为发挥这种能力的理想候选者，因为它们用于分离和维持不同的膜结构域。事实上，我们以前表明，一类称为Par（分区缺陷）蛋白的极性蛋白在树突棘形态发生中起着关键作用，Par 1，Par 3和Par 6对这一过程很重要。有趣的是，我们的初步研究表明，成熟神经元中的大多数棘由Par 3和Par 6主导，而一小部分棘由Par 1主导。这种分布模式类似于发育中的合子和上皮细胞中的Par蛋白，其中Par 1和Par 3/6复合物通过从各自的结构域相互排斥而显示相反的定位。此外，我们以前的研究表明，与非典型PKC（aPKC）形成复合物的Par 3和Par 6，促进脊柱稳定性和成熟，而我们的初步结果表明，Par 1促进脊柱可塑性。这些数据提出了令人兴奋的可能性，即Par 3/6复合体和Par 1调节棘的稳定性和可塑性之间的平衡，Par 3/6-显性棘更稳定，Par 1-显性棘更可塑。我们计划通过两个目标来测试这个总体假设。在aim 1中，我们将测试假设Par 1促进突触可塑性，并通过增加PSD支架的动力学和排除Par 3/6复合物来维持可塑性。在目标2中，我们将检验以下假设：Par 3/Par 6/aPKC复合物促进突触稳定性，并且通过将Par 1从棘中排除来部分维持稳定性。我们将利用先进的分子成像技术，包括FRET，FRAP，荧光诱导蛋白（FLIPs）和双光子谷氨酸解开。此外，我们将在活体小鼠中使用双光子成像来直接测试我们的假设， 行为动物我们将联合收割机这些成像方法与生化分析以及电生理学相结合。这种跨学科的方法将使我们能够从根本上了解突触稳定性和可塑性的细胞和分子机制。此外，多条证据表明Par极性蛋白在神经精神障碍中发挥重要作用，包括精神分裂症、自闭症、重度抑郁症和双相情感障碍。因此，我们的研究将为突触可塑性和稳定性提供机制性的见解，并可能揭示影响人类大脑的几种破坏性异常。

 DESCRIPTION (provided by applicant): The stability and plasticity of synapses are both important for cognitive functions. Plasticity is necessary for learning, while stably formed synapses are believed to encode for long term memory. Yet it is unclear how neurons can maintain this delicate balance and achieve both stability and plasticity in synapses just a few microns apart. Clearly, a high level of compartmentalization is required, which makes polarity proteins ideal candidates to function in this capacity, as they serve to separate and maintain distinct membrane domains. Indeed, we previously showed that a class of polarity proteins called Par (partitioning defective) proteins plays a key role in dendritic spine morphogenesis, with Par1, Par3 and Par6 important for this process. Interestingly, our preliminary studies show that most of the spines in mature neurons are dominated by Par3 and Par6, whereas a smaller fraction of spines are dominated by Par1. This distribution pattern resembles that of Par proteins in developing zygotes and epithelial cells, where Par1 and the Par3/6 complex show opposite localization by mutually excluding each other from their respective domains. Furthermore, our previous studies suggest that Par3 and Par6, which form a complex with atypical PKC (aPKC), promote spine stability and maturation, whereas our preliminary results suggest that Par1 promotes spine plasticity. These data raise the exciting possibility that the Par3/6 complex and Par1 regulate the balance between stability and plasticity of spines, with Par3/6-dominant spines being more stable and Par1-dominant spines being more plastic. We plan to test this overarching hypothesis through two aims. In aim1, we will test the hypothesis that Par1 promotes synaptic plasticity and that plasticity is maintained by increasing the dynamics of the PSD scaffold and by excluding the Par3/6 complex. In aim 2, we will test the hypothesis that the Par3/Par6/aPKC complex promotes synaptic stability and that stability is maintained in part by excluding Par1 from the spines. We will utilize advanced molecular imaging techniques, including FRET, FRAP, fluorescent light-inducible proteins (FLIPs) and 2-photon glutamate uncaging. In addition, we will use 2-photon imaging in live mice to directly test our hypothesis in behaving animals. We will combine these imaging approaches with biochemical analysis as well as electrophysiology. This interdisciplinary approach will allow us to gain fundamental insight into the cellular and molecular mechanisms of synaptic stability and plasticity. Moreover, multiple lines of evidence are pointing to an important role for Par polarity proteins in neuropsychiatric disorders, including schizophrenia, autism, major depressive disorder and bipolar disorder. Thus, our studies will provide mechanistic insight into synaptic plasticity and stability and may shed light on several devastating abnormalities that affect the human brain.