Chloride homeostasis and GABA maturation in fragile X syndrome

脆性 X 综合征中氯离子稳态和 GABA 成熟

基本信息

批准号：
9055846
负责人：
Anis Contractor
金额：
$ 23.18万
依托单位：
NORTHWESTERN UNIVERSITY AT CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-09-25 至 2017-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9055846
关键词：
5&apos Untranslated Regions Address Adolescent Affect Autistic Disorder Brain Diseases Bumetanide CGG repeat Cells Childhood Chloride Ion Chlorides Development Disease Diuretics Fragile X Mental Retardation Protein Fragile X Syndrome Genes Homeostasis Human Hypermethylation Inherited Intellectual functioning disability Interneurons Knowledge Lead Link Messenger RNA MicroRNAs Mus Neurodevelopmental Disorder Neurons Neurotransmitters Phenotype Play Polyribosomes RNA-Binding Proteins Regulation Research Role Signal Transduction Synapses Testing Translations Validation base cell motility critical period effective therapy excitatory neuron gamma-Aminobutyric Acid in vitro Assay induced pluripotent stem cell inhibitor/antagonist insight meetings mouse model neuron development novel postnatal public health relevance research study response sodium-potassium-chloride cotransporter 1 protein synaptogenesis transmission process uptake

项目摘要

DESCRIPTION (provided by applicant): Fragile X syndrome (FXS) is the most common form of inherited intellectual disability and also the single most common known cause of autism. FXS results from an expansion of a CGG repeat sequence in the 5' untranslated region of the gene, which causes hypermethylation, transcriptional silencing, and a resultant loss of expression of the Fragile X mental retardation protein (FMRP). FMRP is a polyribosome associated RNA binding protein that regulates the translation of a large number of messenger RNAs, has roles in mRNA transport, as well as regulating the expression of miRNAs. Altered trajectories for the maturation and stability of synapses have been observed in the cortex of the mouse model of FXS (Fmr1 ko). However, the underlying mechanisms of these alterations in cellular and synaptic development are unknown. One important regulator of cortical development is the inhibitory neurotransmitter GABA. During early development GABA responses in many cortical neurons are excitatory, only maturing to their inhibitory, hyperpolarizing type later. Excitatory effects of GABA have been demonstrated to be important for neuronal proliferation, cell migration, and synaptogenesis. In recent studies we discovered that the regulated development of hyperpolarizing GABA responses is delayed in the cortex of Fmr1 ko mice. We propose that this will lead to an alteration in GABA signaling that contributes to a delay in synaptic and cellular maturation in the cortex. The objectives of this proposal are twofold. The first is to determine how the efficacy of GABA signaling is altered during the critical period, and whether there is a causal link between delayed maturation of GABA signaling and delayed maturation of fast spiking interneurons. The second is to determine whether the underlying mechanism for these changes result from alterations in miRNA expression that normally regulate the transporters underlying the reversal potential for GABA. We will achieve these objectives using two specific aims. Aim 1 will test whether a commonly used diuretic bumetanide (which acts centrally to inhibit the juvenile chloride cotransporter, NKCC1) can rectify the changes in GABA responses and delayed maturation of fast spiking interneurons. In Aim 2 using in vitro assays combined with validation in mouse and human derived neurons we will determine whether several candidate miRNAs can regulate expression of the juvenile chloride cotransporter NKCC1, which sets the reversal potential for GABA. These studies will address important knowledge gaps and potentially provide novel insights into developing cures for FXS. Because similar abnormalities of neuron connectivity and synapse maturation are implicated in other childhood brain disorders, it is possible that this research will open new avenues of study in other disorders characterized by autism and intellectual disability.

描述（由申请人提供）：脆性 X 综合征 (FXS) 是遗传性智力障碍的最常见形式，也是自闭症最常见的已知原因，是由 5' 非翻译区中 CGG 重复序列的扩展引起的。该基因会导致过度甲基化、转录沉默以及由此导致的脆性 X 智力迟钝蛋白 (FMRP) 的表达丧失，FMRP 是一种多核糖体相关的 RNA 结合蛋白。调节大量信使 RNA 的翻译，在 mRNA 运输中发挥作用，并调节 miRNA 的表达。在 FXS (Fmr1 ko) 小鼠模型的皮层中观察到突触成熟和稳定性的改变轨迹。然而，细胞和突触发育中这些变化的潜在机制尚不清楚，皮质发育的一个重要调节因素是许多皮质早期发育过程中的抑制性神经递质 GABA 反应。神经元是兴奋性的，只有在以后才成熟为抑制性、超极化型。GABA 的兴奋作用已被证明对神经元增殖、细胞迁移和突触发生很重要。在最近的研究中，我们发现超极化 GABA 反应的调节发展被延迟。我们认为这将导致 GABA 信号的改变，从而导致皮质中突触和细胞成熟的延迟。首先是确定 GABA 信号传导的功效在关键时期如何改变，以及 GABA 信号传导的延迟成熟与快速尖峰中间神经元的延迟成熟之间是否存在因果关系。因为这些变化是由 miRNA 表达的改变引起的，而 miRNA 表达通常调节 GABA 逆转潜力的转运蛋白。我们将通过两个具体目标来测试是否常用的利尿剂布美他尼（起中枢作用）。抑制幼年氯协同转运蛋白（NKCC1）可以纠正 GABA 反应的变化和快速尖峰中间神经元的延迟成熟。在目标 2 中，使用体外测定结合小鼠和人源神经元的验证，我们将确定几种候选 miRNA 是否可以调节表达。这些研究将弥补重要的知识空白，并可能为开发 FXS 治疗方法提供新的见解。由于类似的神经连接和突触成熟异常与其他儿童脑部疾病有关，因此这项研究可能会为其他以自闭症和智力障碍为特征的疾病的研究开辟新途径。