Mechanisms of MEF2-dependent synapse elimination

MEF2依赖性突触消除机制

• 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
• 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

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）：假设适当的突触形成，消除和维持的缺陷是基于众多神经认知疾病的基础，包括智力障碍和自闭症，并且也被认为对与药物成瘾有关的行为有影响。神经元活性促进了突触消除发育过程中形成的修剪过量突触，并稳态维持稳态数量的突触连接。转录因子肌细胞增强因子2（MEF2）是发展和成人大脑中兴奋性突触消除的关键活动依赖性调节剂。但是，MEF2控制突触数的分子和细胞机制尚不清楚。我们的实验室最近发现，RNA结合蛋白脆弱的X智力低下蛋白（FMRP）是MEF2诱导的消除突触所必需的。脆弱的X综合征（FXS）是自闭症的最普遍的遗传形式，是由FMR1基因灭活而导致的，该基因编码为FMRP。具有FXS的个体和用于该疾病的小鼠模型，FMR1敲除小鼠，表现出增加的皮质树突状脊柱密度，表明缺陷 消除突触可能是FXS的基础。我们建议MEF2和FMRP共同调节常见的转录本以诱导兴奋性突触，并提出特定的目标1来研究这一假设。在此目的中，我们将利用夹子seq，这是一种配对交联的免疫沉淀（剪辑）的技术，然后进行高吞吐量测序来识别其转录本与FMRP相关的MEF2调节基因靶标。然后，我们将通过执行2个Photon活细胞树突状棘成像和MEPSC的全细胞贴剂记录来测试结构和功能突触消除中与MEF2调节和FMRP相关的候选者的要求。在特定的目标2中，我们将表征MEF2依赖性突触消除的过程，研究MEF2诱导的结构和功能性突触消除的动力学，以及通过执行2个光子显微镜以及全细胞电动物理学记录的MEF2介导的结构突触消除的形态学过程。由于消除突触的缺陷可能会导致自闭症，脆弱的X综合征和与药物滥用相关的行为适应性，因此我们认为我们的研究将对理解这些和相关疾病产生重大影响。