Mechanism of Par3-mediated regulation of dendritic spine plasticity

项目摘要/摘要 树突棘是作为突触后部位的兴奋性神经元上的小的、高度极化的突起 输入。树突棘的可塑性对学习是必要的，而稳定的树突棘被认为编码 长期记忆。树突棘的极化性质表明它们的可塑性和稳定性可能是 由极性蛋白质介导。分割缺陷(PAR)极性蛋白3(Par3)调节成熟树突状细胞 几种单核苷酸多态(SNPs)和拷贝数变异(CNV) 编码PARD3的PARD3与智力、精神分裂症和自闭症谱系障碍有关 (ASD)。此外，Par3还与非典型蛋白激酶C(APKC)形成复合体。一种结构活跃的截断 APKC变异体被认为是一种“记忆分子”，而全长的aPKC变异体与Long 术语增强(LTP)。综上所述，这些数据表明，Par3参与了成熟的树突棘突的稳定，这可能是 在认知和社会互动中发挥作用。然而，Par3在树突棘中的体内机制 可塑性和稳定性仍然完全未知。为了研究这种机制，我们开发了一种新的 在出生后的前脑锥体神经元中耗尽Par3的条件性基因敲除线(Par3-/-)。第3-/-段展品 树突棘密度增加，未成熟树突棘形态增多。磷酸蛋白质组 对Par3-/-海马区组织的分析显示，CAMSAPs的磷酸化增加，从而结合和稳定 微管(MT)末端减数。我们的中心假设是Par3通过CAMSAP调节MT的稳定性 稳定树突棘，这是正常认知和社会互动所必需的。在没有第3段的情况下， APKC异常激活导致CAMSAP磷酸化增加和MT减少 稳定性。目的1研究Par3缺失导致树突棘不稳定导致受损的假说 小鼠的认知功能和社会行为。Aim 2使用生化分析和活细胞成像来测试 假设Par3在S992调节CAMSAP2的APKC磷酸化，影响MT和树突棘 稳定性。 总之，这些实验将阐明Par3对树突棘的体内调控机制。 稳定性、认知和社会行为。这可能为进一步理解这些机制提供重要的见解。 神经发育障碍，如精神分裂症和自闭症。拟议的研究金还将培训 申请生物化学、细胞、分子和行为神经科学方面的多项创新技术。这个 既定的师生导师关系将确保必要的适当科学和专业培训 成为一名成功的、独立的学习和记忆神经生物学家。

Project Summary/Abstract Dendritic spines are small, highly polarized protrusions on excitatory neurons serving as sites of postsynaptic input. Plasticity of dendritic spines is necessary for learning, while stable dendritic spines are thought to encode long-term memories. The polarized nature of dendritic spines suggests their plasticity and stability may be mediated by polarity proteins. The Partitioning defective (Par) polarity protein 3 (Par3) regulates mature dendritic spine formation in vitro, and several single nucleotide polymorphisms (SNPs) and copy number variation (CNV) of Pard3, which encodes Par3, are associated with intelligence, schizophrenia, and autism spectrum disorder (ASD). Moreover, Par3 forms a complex with atypical protein kinase C (aPKC). A constitutively active truncated aPKC variant has been proposed as a “memory molecule,” while a full length aPKC variant is implicated in long term potentiation (LTP). Together, these data implicate Par3 in mature dendritic spine stabilization, which may play a role in cognition and social interactions. However, the in vivo mechanisms of Par3 in dendritic spine plasticity and stability remains completely unknown. To investigate the mechanisms, we developed a novel conditional knockout line that depletes Par3 in postnatal forebrain pyramidal neurons (Par3-/-). Par3-/- exhibits increased dendritic spine density and increased immature dendritic spine morphology. Phosphoproteomic analysis of Par3-/- hippocampal tissue revealed increased phosphorylation of CAMSAPs, which bind and stabilize microtubule (MT) minus-ends. Our central hypothesis is that Par3 regulates MT stability through CAMSAPs to stabilize dendritic spines, which is necessary for normal cognition and social interactions. In the absence of Par3, aPKC becomes abnormally activated leading to increased CAMSAP phosphorylation and decreased MT stability. Aim 1 investigates the hypothesis that loss of Par3 destabilizes dendritic spines leading to impaired cognitive functions and social behavior in mice. Aim 2 uses biochemical assays and live cell imaging to test the hypothesis that Par3 regulates aPKC phosphorylation of CAMSAP2 at S992, influencing MT and dendritic spine stability. Together, these experiments will elucidate the in vivo mechanisms of Par3 regulation of dendritic spine stability, cognition, and social behavior. This may provide important insight to further understand the mechanisms of neurodevelopmental disorders, such as schizophrenia and ASD. The proposed fellowship will also train the applicant in several innovative techniques in biochemical, cellular, molecular, and behavioral neuroscience. The established faculty-student mentorships will ensure proper scientific and professional training necessary to become a successful, independent neurobiologist of learning and memory.