Fragile X and Synaptic Plasticity

脆性 X 和突触可塑性

• 批准号: 7789613
• 负责人: Christine M Gall
• 金额: $ 37.51万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2013-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7789613
• 关键词: AMPA Receptors; Actinin; Actins; Acute; Adult; Affect; Agonist; Behavior; Chemosensitization; Cognition; Cognitive; Complement component C4; Cytoskeletal Modeling; Cytoskeleton; Defect; Dendritic Spines; Disease; F-Actin; FMR1 Gene; Failure; Fragile X Syndrome; Hippocampus (Brain); Impairment; Integrins; Knock-out; Knockout Mice; Label; Lead; Learning; Length; Level of Evidence; Link; Long-Term Potentiation; Measures; Memory; Mental Retardation; Microfilaments; Modeling; Morphology; Mus; Mutant Strains Mice; Mutation; Neocortex; Pattern; Pharmaceutical Preparations; Phase; Phosphorylation; Phosphotransferases; Pilot Projects; Play; Production; Protein Biosynthesis; Protein Tyrosine Kinase; Proteins; Pyramidal Cells; Regulation; Relative (related person); Research; Role; Signal Transduction; Slice; Somatosensory Cortex; Spectrin; Structure; Synapses; Synaptic plasticity; Syndrome; Techniques; Tertiary Protein Structure; Testing; Therapeutic; Translations; Vertebral column; Work; autism spectrum disorder; calmodulin-dependent protein kinase II; crosslink; drug testing; genetic regulatory protein; human EMS1 protein; improved; in vivo; inhibitor/antagonist; link protein; mouse model; mutant; novel; profilin; public health relevance; pyridine; receptor; research study; restoration; somatosensory; synaptic function

DESCRIPTION (provided by applicant): Efforts to identify causes of memory and cognition deficits in Fragile X Syndrome (FXS) led to the discovery of synaptic plasticity impairments in cortex of a knock-out mouse model (Fmr1-KO) of the disorder. The applicants have extended these results by showing that hippocampal long-term potentiation (LTP), induced by learning-related patterns of afferent activity, fails to stabilize in Fmr1-KO mice. Analysis of cytoskeletal changes required for lasting LTP pointed to the hypothesis that a critical FXS-defect involves failed stabilization of new actin filaments during the first few minutes after LTP induction. Preliminary results showing abnormal expression of several actin-associated proteins in the knockouts (KOs) support this argument. Objectives of the proposed studies are to (1) identify causes for the failure in filamentous (F) actin stabilization and LTP in Fmr1-KO mice, and (2) develop treatments for normalizing cytoskeletal changes and stable LTP. Pilot studies have shown that treatment with the mGluR5 antagonist MPEP, or with a positive AMPA receptor modulator (ampakine), can restore stable LTP to Fmr1-KO hippocampus. Further results indicate that both drugs also reverse measures of aberrant spine morphology in the KOs. The proposed research will build on these findings in 4 specific aims. Aim 1 will test the hypothesis that MPEP can normalize stabilization of spine F-actin and LTP in hippocampal slices from adult Fmr1-KO mice. Further studies will test if LTP impairments are offset by translation inhibitors and linked to aberrant signaling by integrin-associated tyrosine kinases. Aim 2 will test if abnormal basal levels of actin regulatory proteins in Fmr1-KO dendritic spines lead to aberrations in TBS- induced signaling to the actin cytoskeleton. Studies will employ deconvolution immunofluorescent techniques to test effects of theta burst afferent stimulation on levels of target proteins in spines of KO and WT mice. Aim 3 will use acute slices to test if MPEP and ampakine treatments have additive or synergistic effects in the rescue of hippocampal LTP in Fmr1-KO mice (3A). Follow on acute slice experiments will test if the treatments that rescue LTP also normalize (3B) pyramidal cell spine measures and (3C) levels and activity-induced changes in spine actin-regulatory proteins in hippocampal field CA1. Studies in Aim 4 complement those in Aim 3 to test if drugs that rescue hippocampal LTP also restore stable potentiation (4A) and spine measures (4B) in slices from somatosensory neocortex of Fmr1-KO mice. Aim 4C will then test if in vivo treatments with an ampakine, MPEP, or both, normalize spine measures in somatosensory cortex and hippocampal field CA1. Aims 3 and 4 will use Fmr1-KO and WT mice that constitutively express yellow fluorescent protein (YFP) in scattered pyramidal cells to provide a bright label of dendritic spines. These studies are expected to produce a specific explanation for why spine plasticity and structure are disturbed by the Fragile X mutation, and to generate potential therapies for correcting the defects. PUBLIC HEALTH RELEVANCE: Efforts to identify causes of mental retardation associated with Fragile X Syndrome led to the discovery of synaptic plasticity impairments in a mouse model of the disorder. The present studies will test the hypothesis that impairments are due to abnormal levels of actin regulatory proteins, which are critical for changes in synaptic function during learning. Studies will also test potential therapeutics for correcting these synaptic defects that might improve learning in this syndrome and other autism spectrum disorders.

描述（由申请人提供）：识别脆弱X综合征（FXS）的记忆和认知缺陷的努力，导致发现了该疾病的敲除小鼠模型（FMR1-KO）皮质中的突触可塑性障碍。申请人通过表明与学习相关的传入活动模式引起的海马长期增强（LTP）通过表明海马长期增强（LTP）无法稳定在fMR1-KO小鼠中，从而扩展了这些结果。持久LTP所需的细胞骨架变化的分析表明，在LTP诱导后的前几分钟，临界FXS缺陷涉及新肌动蛋白丝的稳定失败。初步结果表明敲除（KOS）中几种与肌动蛋白相关蛋白的表达异常支持这一论点。拟议的研究的目标是（1）确定丝状肌动蛋白稳定和FMR1-KO小鼠中丝（F）肌动蛋白稳定性失败的原因，以及（2）开发用于标准化细胞骨架变化和稳定LTP的治疗方法。试点研究表明，用MGLUR5拮抗剂MPEP或阳性AMPA受体调节剂（Ampakine）的治疗可以将稳定的LTP恢复为FMR1-KO-KO海马。进一步的结果表明，这两种药物还逆转了KO中异常脊柱形态的测量。拟议的研究将以4个特定目的的这些发现为基础。 AIM 1将检验以下假设：MPEP可以从成年FMR1-KO小鼠的海马切片中稳定脊柱F-肌动蛋白和LTP。进一步的研究将测试LTP损伤是否被翻译抑制剂所抵消，并与整合素相关酪氨酸激酶的异常信号传导相关。 AIM 2将测试FMR1-KO树突状棘中肌动蛋白调节蛋白的基础水平是否导致TBS诱导的肌动蛋白细胞骨架的信号畸变。研究将采用反卷积的免疫荧光技术来测试theta爆发传入刺激对KO和WT小鼠棘突中靶蛋白水平的影响。 AIM 3将使用急性切片来测试MPEP和Ampakine治疗是否在FMR1-KO小鼠中拯救海马LTP（3A）中具有附加效应或协同作用。遵循急性切片实验将测试拯救LTP的处理是否也正常化（3B）锥体细胞脊柱测量值以及（3C）水平肌动蛋白肌动蛋白调节蛋白的水平和活性诱导的海马CA1中的变化。 AIM 4中的研究补充了AIM 3中的研究，以测试挽救海马LTP的药物是否还恢复了稳定的增强（4A）和脊柱测量值（4B）（4B）（4B）在FMR1-KO小鼠的体感新皮层的切片中。然后，AIM 4C将测试用安帕宁，MPEP或两者兼而有之的体内治疗，使体感皮质和海马场CA1中的脊柱测量正常化。 AIM 3和4将使用FMR1-KO和WT小鼠，这些小鼠在散射的锥体细胞中组成型表达黄色荧光蛋白（YFP），以提供树突状刺的明亮标签。这些研究有望产生特定的解释，说明为什么脊柱可塑性和结构受到脆弱的X突变的干扰，并产生潜在的疗法以纠正缺陷。公共卫生相关性：确定与脆弱X综合征相关的智力低下原因的努力导致在疾病的小鼠模型中发现突触可塑性障碍。本研究将检验以下假设：损伤是由于肌动蛋白调节蛋白的异常水平引起的，这对于学习过程中突触功能的变化至关重要。研究还将测试潜在的治疗剂，以纠正可能改善该综合征和其他自闭症谱系障碍学习的突触缺陷。