Modulation of RhoA Signaling by the mRNA Binding Protein hnRNPQ1

描述(由申请人提供)：神经元形态异常是智障和自闭症的共同主题，尽管这些障碍背后的病理机制不同。具体地说，许多神经精神疾病已被证明表现为树突棘的形态异常，树突棘是从树突突出的富含肌动蛋白的小间隔。小的GTP酶，RhoA，一个很好的肌动蛋白动力学调节器，被认为在调节这些富含肌动蛋白的脊椎的形态中发挥关键作用。我们的实验室发现，在培养细胞中，mRNA结合蛋白hnRNPQ1与RhoA mRNA相互作用，下调hnRNPQ1可增加稳态RhoA蛋白水平，而不增加RhoA mRNA水平。此外，hnRNPQ1的缺失导致培养的细胞系和原代神经元培养中与RhoA信号增加相关的表型。此外，hnRNPQ1缺失所观察到的海马神经元树突棘密度的降低可以通过药物抑制RhoA信号通路来挽救。这些初步研究需要研究hnRNPQ1在原代神经元培养中介导RhoA蛋白合成和信号传递的可能作用。本研究旨在表征hnRNPQ1蛋白与RhoA mRNA的相互作用(特异性目标1)，并确定hnRNPQ1是否调节树突中RhoA mRNA的局部翻译(特异性目标2)。此外，将通过耗尽hnRNPQ1并分析树突棘的形态和分子表型，在原代神经元培养中评估hnRNPQ1在调节树突棘形态和RhoA信号方面的作用(特定目标3)。我们假设hnRNPQ1负向调节树突中RhoA mRNA的局部翻译，从而通过改变RhoA信号来调节树突棘的形态。本研究试图将RhoA的表达调控与RhoA的信号调控联系起来，从而导致突触的发育、维持和可塑性，这是目前我们知识中的一个关键空白。研究调节树突棘形态发生的机制将提高我们对智能障碍和自闭症的理解，这将有助于开发治疗这些疾病的新方法。

DESCRIPTION (provided by applicant): Abnormal neuronal morphology is a common theme among intellectual disabilities and autism despite the diverse pathological mechanisms underlying these disorders. Specifically, numerous neuropsychiatric diseases have been demonstrated to present with abnormalities in the morphology of dendritic spines, small actin-rich compartments that protrude from the dendrites. The small GTPase, RhoA, a well-characterized regulator of actin dynamics, has been suggested to play a critical role in regulating the morphology of these actin-rich spines. Our lab has revealed that the mRNA binding protein hnRNPQ1 interacts with RhoA mRNA and downregulation of hnRNPQ1 increases steady state RhoA protein levels without increasing RhoA mRNA levels in cultured cells. Additionally, depletion of hnRNPQ1 causes phenotypes associated with increased RhoA signaling in cultured cell lines and primary neuronal cultures. Furthermore, the reduction in hippocampal neuron dendritic spine density observed upon hnRNPQ1 depletion can be rescued by pharmacological inhibition of the RhoA signaling pathway. These preliminary studies warrant investigation of the possible role of hnRNPQ1 in mediating RhoA protein synthesis and signaling in primary neuronal cultures. The proposed research aims to characterize the interaction between hnRNPQ1 protein and RhoA mRNA (Specific Aim 1) and determine whether hnRNPQ1 regulates RhoA mRNA translation locally in dendrites (Specific Aim 2). Additionally, the role of hnRNPQ1 in regulating dendritic spine morphology and RhoA signaling will be assessed in primary neuronal cultures by depleting hnRNPQ1 and analyzing dendritic spine morphological and molecular phenotypes (Specific Aim 3). We hypothesize that hnRNPQ1 negatively regulates the local translation of RhoA mRNA in dendrites, therefore modulating dendritic spine morphology through altered RhoA signaling. This study attempts to link RhoA expression regulation to RhoA signaling modulation and consequently synaptic development, maintenance and plasticity, which is currently a critical gap in our knowledge. Studying the mechanisms involved in regulating dendritic spine morphogenesis will improve our understanding of intellectual disabilities and autism, which will aid in the development of new treatments for these disorders.