Mechanisms of MEF2-dependent synapse elimination

MEF2依赖性突触消除机制

基本信息

批准号：
8521907
负责人：
Carly Fenwick Hale
金额：
$ 2.94万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-08-01 至 2014-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8521907
关键词：
Adult Autistic Disorder Behavior Behavior Disorders Behavioral Binding Biological Assay Brain Cells Code Defect Dendrites Dendritic Spines Development Disease Drug Addiction Drug abuse Electrophysiology (science)Excision Excitatory Synapse Fragile X Mental Retardation Protein Fragile X Syndrome Frequencies Gene Expression Gene Proteins Gene Targeting Genes Glutamates Goals Health Hippocampus (Brain)Human Image Immunoprecipitation Individual Inherited Kinetics Knockout Mice Learning Life Link Maintenance Mediating Mediator of activation protein Memory Mental Retardation Messenger RNA Methods Microscopy Molecular Neurobiology Neurocognitive Neurodevelopmental Disorder Neurons Photons Play Process RNA RNA Interference RNA Sequences RNA-Binding Proteins Rewards Role Schizophrenia Site Slice Synapses Techniques Testing Time Study Transcript Translations VP 16 Vertebral column X Inactivation cellular imaging crosslink density mouse model myocyte-specific enhancer-binding factor 2 neural circuit neuron development patch clamp programs protein function protein transport public health relevance synaptogenesis time use transcription factor

项目摘要

DESCRIPTION (provided by applicant): Deficits in proper synapse formation, elimination, and maintenance, are hypothesized to underlie numerous neurocognitive disorders, including mental retardation and autism, and are also thought to contribute to behaviors associated with drug addiction. Neuronal activity promotes synapse elimination to prune excess synapses formed during development, and to homeostatically maintain a steady-state number of synaptic connections. The transcription factor myocyte enhancer factor 2 (MEF2) is a critical activity-dependent regulator of excitatory synapse elimination in developing and adult brains. However, the molecular and cellular mechanisms by which MEF2 controls synapse number are not well understood. Our lab recently discovered that the RNA-binding protein, Fragile X Mental Retardation Protein (FMRP) is required for MEF2-induced elimination of synapses. Fragile X Syndrome (FXS), the most prevalent inherited form of autism, results from inactivation of the Fmr1 gene, which codes for FMRP. Individuals with FXS and a mouse model for the disorder, Fmr1 knockout mice, display increased cortical dendritic spine density, indicating that deficits in synapse elimination may underlie FXS. We propose that MEF2 and FMRP function together to regulate common transcripts to induce elimination of excitatory synapses and propose Specific Aim 1 to investigate this hypothesis. In this aim, we will utilize CLIP-seq, a technique pairing cross-linking immunoprecipitation (CLIP) followed by high throughput sequencing to identify MEF2-regulated gene targets whose transcripts associate with FMRP. We will then test a requirement for MEF2-regulated and FMRP-associated candidates in structural and functional synapse elimination by performing 2-photon live-cell dendritic spine imaging and whole-cell patch clamp recordings of mEPSCs. In Specific Aim 2, we will characterize the process of MEF2-dependent synapse elimination, examining the kinetics of MEF2-induced structural and functional synapse elimination, as well as the morphological process of MEF2-mediated structural synapse elimination by performing 2-photon microscopy and whole-cell electrophysiology recordings. As synapse elimination defects may contribute to autism, Fragile X Syndrome, and behavioral adaptations associated with drug abuse, we believe that our studies will provide significant implications towards understanding these and related disorders.

描述（由申请人提供）：据推测，适当的突触形成、消除和维持方面的缺陷是许多神经认知障碍的基础，包括智力低下和自闭症，并且还被认为导致与药物成瘾相关的行为。神经元活动促进突触消除，以修剪发育过程中形成的多余突触，并稳态维持突触连接数量的稳态。转录因子肌细胞增强因子 2 (MEF2) 是发育中和成人大脑中兴奋性突触消除的关键活动依赖性调节因子。然而，MEF2 控制突触数量的分子和细胞机制尚不清楚。我们的实验室最近发现，RNA 结合蛋白、脆性 X 智力迟钝蛋白 (FMRP) 是 MEF2 诱导的突触消除所必需的。脆性 X 综合征 (FXS) 是最常见的遗传性自闭症，是由编码 FMRP 的 Fmr1 基因失活引起的。患有 FXS 的个体和该疾病的小鼠模型（Fmr1 敲除小鼠）表现出皮质树突棘密度增加，表明突触消除可能是 FXS 的基础。我们提出 MEF2 和 FMRP 共同发挥作用来调节共同转录物，从而诱导兴奋性突触的消除，并提出特定目标 1 来研究这一假设。为此，我们将利用 CLIP-seq，这是一种将交联免疫沉淀 (CLIP) 与高通量测序相结合的技术，以识别 MEF2 调节的基因靶标，其转录本与 FMRP 相关。然后，我们将通过执行 2 光子活细胞树突棘成像和 mEPSC 的全细胞膜片钳记录来测试结构和功能突触消除中 MEF2 调节和 FMRP 相关候选者的要求。在具体目标 2 中，我们将通过执行 2 光子显微镜和全细胞电生理学记录。由于突触消除缺陷可能导致自闭症、脆性 X 综合征以及与药物滥用相关的行为适应，我们相信我们的研究将为理解这些疾病和相关疾病提供重要意义。