Importin-mediated signaling from synapse to nucleus during neuronal plasticity

描述(申请人提供)：突触可塑性，神经元与经验之间联系强度的变化，为大脑中的信息存储提供了一种机制。已经证明，持久的可塑性形式需要RNA和蛋白质的合成，这表明信号可以从产生信号的突触传输到细胞核，在那里它们被转化为基因表达的变化。神经元的极端极性以及远端突触和细胞体之间的显著距离给核质运输带来了一系列独特的挑战。这一建议的目的是描述在学习相关突触可塑性的长期形式中，活跃的核输入途径在将信号从突触传递到核中的作用。在这个途径中，携带核定位信号(NLSS)的蛋白质被称为importinα的核转运体识别，然后它与名为importin betal的核转运体结合。Importin Betal将异三聚体复合体停靠在核孔中，并介导其移位到细胞核中。我们计划研究Importin介导的核运输，使用分离的小鼠海马区培养和急性海马区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，我们将确定重要蛋白是否定位于突触，并随后转移导致转录依赖可塑性的刺激。在第二个目标中，我们建议识别突触刺激后运输到细胞核的突触定位蛋白。在最终目标中，我们将确定Importin-Cargo复合体是如何在突触组装的，以及什么细胞生物学途径参与了这个复合体向细胞核的移位。与公共健康相关：了解记忆形成过程中突触产生的信号触发核内基因表达变化的机制，为确定各种疾病的治疗靶点提供了一种手段，包括智力低下、与年龄相关的记忆力丧失、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.