Dendritic spine morphology and the Ubiquitin pathway

描述(申请人提供)：兴奋性突触中的树突棘可以经历与突触可塑性相关的基于肌动蛋白的动态形态变化。最近对这种可塑性的分子基础的研究发现了Spar的作用，Spar是一种针对树突棘PSD的RapGAP。反过来，Spar的稳定性受丝氨酸/苏氨酸激酶SNK的调节。SNK磷酸化SPAR，通过蛋白酶体途径促进SPAR的降解。然而，针对SPAR的E3Ub-连接酶的身份以及它们是如何被调控的仍然是未知的。我们对以SPAR为靶标调控突触可塑性的E3Ub-连接酶的研究包括以下三个主要工作：AIM 1研究SCF Ub-连接酶在SPAR降解中的作用以及它们在底物中识别的激活信号；AIM 2详细介绍了一种全面的方法来识别所有以SPAR为靶标的E3 Ub-连接酶；以及AIM 3检测已确定的候选E3 Ub-连接酶的缺失如何影响原代海马神经元中树突棘的形态。除了为Ub通路参与树突棘形态调控提供具体证据外，识别介导Spar降解的E3Ub连接酶对于了解与脊柱形态和密度异常相关的许多疾病的机制是内在的，包括一般智力低下、脆性X综合征、唐氏综合症和癫痫。

DESCRIPTION (provided by applicant): Dendritic spines in excitatory synapses can undergo dynamic actin-based morphological changes associated with synaptic plasticity. Recent examination into the molecular basis of this plasticity uncovered a role for SPAR, a RapGAP that targets to the PSD of dendritic spines. In turn, SPAR stability is regulated by serine/threonine kinase SNK. SNK phosphorylates SPAR, which promotes SPAR degradation through a proteasomal pathway. Nevertheless, the identity of the E3 Ub-ligases that target SPAR and how they are regulated is still unknown. Our investigation into the E3 Ub-ligases that target SPAR to regulate synaptic plasticity includes the following three major efforts: Aim 1 investigates roles for SCF Ub-ligases in SPAR degradation and the activation signals they recognize in the substrate; Aim 2 details a comprehensive approach to identify all E3 Ub-ligases that target SPAR; and Aim 3 examines how depletion of identified candidate E3 Ub-ligases affects dendritic spine morphology in primary hippocampal neurons. In addition to providing concrete evidence for the involvement of the Ub-pathway in the regulation of dendritic spine morphology, identification of the E3 Ub-ligases that mediate SPAR degradation is intrinsic to understanding the mechanism that may underlie a number of disorders associated with abnormal spine morphology and density, including general mental retardation, fragile-X syndrome, Down's syndrome, and epilepsy.