Rac-GEF signaling in dendritic spines

摘要 棘状兴奋性突触的数量、大小和可塑性是神经元回路连通性的基础， 它们的改变是神经发育障碍（NDD）（包括自闭症）发病机制的核心 谱系障碍（ASD）、智力残疾（ID）和脆性X综合征（FXS）。我们的长期目标是 揭示Rho样小GT3通路在中枢兴奋性突触的生物学功能， 他们对NDD的贡献。Rho GTP酶，包括Rac 1，在棘状兴奋性突触中起关键作用 形成，可塑性，神经传递，电路发展和行为。相反，Rho的改变 GT3信号传导发生在许多NDD中，包括ASD、ID和FXS。值得注意的是，这条通路的过度激活 发生在FXS模型小鼠（Fmr 1 KO）以及TRIO中具有功能获得性突变的患者中， RAC 1和PAK 1基因，并与突触过度连接、过度兴奋、ASD、ID和 癫痫因此，详细了解Rho GTP酶的调节和调节它们的能力， 对理解NDD的脑功能和功能障碍具有广泛的意义。Rho GTP酶是 由鸟嘌呤-核苷酸交换因子（GEFs）直接激活。基金会成员kalirin和Trio是 神经元连接的重要调节因子，并且在几种NDD中失调。两种蛋白质直接 激活Rac 1，随后激活p21激活激酶（Pak），这也在大脑发育中发挥关键作用， 可塑性和NDD。值得注意的是，Rac 1和Pak的抑制挽救了Fmr 1 KO小鼠的表型。这里我们 概述了一组旨在确定kalirin/Trio-> Rac 1->Pak轴在基底细胞中的作用的实验。 脑功能和以过度突触连接为特征的NDD临床前模型 （hyperconnectivity）。具体地，我们将测试kalirin/Trio-> Rac 1->Pak轴的抑制是否与细胞凋亡有关。 逆转与NDD相关的几种小鼠模型的结构、功能和行为缺陷。我们将 追求以下具体目的：1）表征Kalirin/Trio抑制在基础中的生物学效应。 小鼠的大脑功能。2)为了确定kalirin和Trio基因缺失对疾病相关性的影响， 在具有突触超连接的NDD小鼠模型中的表型。3)为了比较生物效应 在具有突触的NDD小鼠模型中，kalirin/Trio抑制与已知Rac 1和Pak抑制剂的抑制的比较 超连通性

ABSTRACT The number, size, and plasticity of spiny excitatory synapses underlies connectivity in neuronal circuits, and their alterations are central to the pathogenesis of neurodevelopmental disorders (NDDs), including autism spectrum disorder (ASD), intellectual disability (ID), and fragile X syndrome (FXS). Our long-term goals is to uncover the biological functions of Rho-like small GTPase pathways at central excitatory synapses and their contributions to NDDs. Rho GTPases, including Rac1, play key role in spiny excitatory synapse formation, plasticity, neurotransmission, circuit development, and behavior. Conversely, alterations in Rho GTPase signaling occur in many NDDs, including ASD, ID, and FXS. Notably, overactivation of this pathway occurs in FXS model mice (Fmr1 KO), as well as in patients with gain-of-function mutations in the TRIO, RAC1, and PAK1 genes, and is associated with synaptic hyperconnectivty, hyperexcitability, ASD, ID, and epilepsy. Hence detailed knowledge of the regulation of Rho GTPases and ability to modulate them would have broad implications for understanding brain function and dysfunction in NDDs. Rho GTPases are directly activated by guanine-nucleotide exchange factors (GEFs). The paralog GEFs kalirin and Trio are important regulators of neuronal connectivity, and are dysregulated in several NDDs. Both proteins directly activate Rac1 and subsequently, p21-activated kinase (Pak), which also play key roles in brain development, plasticity, and NDDs. Notably, inhibition of Rac1 and Pak rescued phenotypes in Fmr1 KO mice. Here we outline a set of experiments designed to determine the role of the kalirin/Trio->Rac1->Pak axis in basal brain function and in preclinical models of NDDs characterized by excessive synaptic connectivity (hyperconnectivity). Specifically, we will test whether inhibition of the kalirin/Trio->Rac1->Pak axis to reverse structural, functional, and behavioral deficits in several mouse models relevant for NDDs. We will pursue the following Specific Aims: 1) To characterize the biological effects of kalirin/Trio inhibition in basal brain function in mice. 2) To determine the effects of genetic deletion of kalirin and Trio on disease-relevant phenotypes in mouse models of NDD with synaptic hyperconnectivity. 3) To compare the biological effects of kalirin/Trio inhibition with that of known Rac1 and Pak inhibitors in mouse models of NDD with synaptic hyperconnectivity.