Importin-mediated signaling from synapse to nucleus during neuronal plasticity

描述（由申请人提供）：突触可塑性，神经元与经验之间连接强度的变化，为大脑中的信息存储提供了一种机制。长期形式的可塑性需要RNA和蛋白质的合成，这表明信号可以从突触（它们产生的地方）传递到细胞核，在那里它们被转化为基因表达的变化。神经元的极端极性和远端突触和细胞体之间存在的显著距离对核胞质运输提出了独特的挑战。本研究的目的是描述在学习相关突触可塑性的长期形式中，活跃的核输入通路在将信号从突触传递到细胞核中的作用。在这一途径中，携带核定位信号（NLSs）的蛋白质被称为输入蛋白α的核转运接头识别，然后结合称为输入蛋白β的核转运体。输入β将异三聚体固定在核孔，并介导其转运进入细胞核。我们计划研究进口蛋白介导的核转运，使用分离的小鼠海马培养物和急性海马切片来研究突触可塑性的各个方面。在我们的第一个目标中，我们将确定进口蛋白是否定位于突触并随后在刺激下转运，从而导致转录依赖的可塑性。在第二个目标中，我们建议鉴定突触定位蛋白，这些蛋白在突触刺激后被转运到细胞核。在最后的目标中，我们将确定进口-货物复合物是如何在突触上组装的，以及哪些细胞生物学途径参与了该复合物向细胞核的易位。与公共卫生相关：了解突触产生的信号在记忆形成过程中触发细胞核基因表达变化的机制，为识别各种疾病的治疗靶点提供了一种手段，包括智力迟钝、与年龄相关的记忆丧失、阿尔茨海默病、癫痫、药物成瘾以及许多神经精神疾病。

DESCRIPTION (provided by applicant): Synaptic plasticity, changes in the strength of connections between neurons with experience, provides a mechanism for information storage in the brain. Long-lasting forms of plasticity have been shown to require RNA and protein synthesis, indicating that signals can be transported from the synapse, where they are generated, to the nucleus, where they are converted into changes in gene expression. The extreme polarity of neurons and the significant distances that can exist between distal synapses and cell soma present a unique set of challenges to nucleocytoplasmic trafficking. The aim of this proposal is to delineate the role of the active nuclear import pathway in transporting signals from synapse to nucleus during long-lasting forms of learning-related synaptic plasticity. In this pathway, proteins bearing nuclear localization signals (NLSs) are recognized by a nuclear transport adaptor, called importin alpha, which then binds a nuclear transporter called importin betal. Importin betal docks the heterotrimeric complex at the nuclear pore and mediates its translocation into the nucleus. We plan to study importin-mediated nuclear transport, using both dissociated mouse hippocampal cultures and acute hippocampal slices to study various aspects of synaptic plasticity. In our first aim, we will determine whether importins are localized to the synapse and subsequently translocate following stimuli that lead to transcription-dependent plasticity. In the second aim, we propose to identify synaptically localized proteins that are transported to the nucleus following synaptic stimulation. In the final aim, we will determine how the importin-cargo complex is assembled at the synapse and what cell biological pathways are involved in the translocation of this complex to the nucleus. Relevance to public health: Understanding the mechanisms whereby synaptically generated signals trigger changes in gene expression in the nucleus during memory formation provides a means of identifying therapeutic targets for a variety of disorders including mental retardation, age-related memory loss, Alzheimer's disease, epilepsy, drug addiction as well as many neuropsychiatric diseases.