Fragile X and Synaptic Plasticity

脆性 X 和突触可塑性

基本信息

批准号：
7654969
负责人：
Christine M Gall
金额：
$ 37.57万
依托单位：
UNIVERSITY OF CALIFORNIA-IRVINE
依托单位国家：
美国
项目类别：
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/7654969
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

项目摘要

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）：为了确定脆性 X 综合征（FXS）记忆和认知缺陷的原因，我们发现该疾病的基因敲除小鼠模型（Fmr1-KO）的皮层存在突触可塑性损伤。申请人扩展了这些结果，表明由学习相关的传入活动模式诱导的海马长时程增强(LTP)在Fmr1-KO小鼠中未能稳定。对持久 LTP 所需的细胞骨架变化的分析指出了一个假设，即关键的 FXS 缺陷涉及在 LTP 诱导后的最初几分钟内新肌动蛋白丝的稳定性失败。初步结果显示，敲除（KO）中几种肌动蛋白相关蛋白的异常表达支持了这一论点。拟议研究的目的是 (1) 确定 Fmr1-KO 小鼠丝状 (F) 肌动蛋白稳定和 LTP 失败的原因，以及 (2) 开发使细胞骨架变化正常化和稳定 LTP 的治疗方法。初步研究表明，使用 mGluR5 拮抗剂 MPEP 或阳性 AMPA 受体调节剂（ampakine）治疗可以恢复 Fmr1-KO 海马的稳定 LTP。进一步的结果表明，这两种药物还可以逆转 KO 中异常脊柱形态的测量结果。拟议的研究将以这些发现为基础，实现 4 个具体目标。目标 1 将检验以下假设：MPEP 可以使成年 Fmr1-KO 小鼠海马切片中脊柱 F-肌动蛋白和 LTP 的稳定性正常化。进一步的研究将测试 LTP 损伤是否可以被翻译抑制剂抵消，以及是否与整合素相关酪氨酸激酶的异常信号传导有关。目标 2 将测试 Fmr1-KO 树突棘中肌动蛋白调节蛋白的异常基础水平是否会导致 TBS 诱导的肌动蛋白细胞骨架信号传导异常。研究将采用反卷积免疫荧光技术来测试 θ 爆发传入刺激对 KO 和 WT 小鼠脊柱中靶蛋白水平的影响。目标 3 将使用急性切片来测试 MPEP 和 ampakine 治疗在挽救 Fmr1-KO 小鼠海马 LTP 方面是否具有相加或协同作用 (3A)。接下来的急性切片实验将测试拯救 LTP 的治疗是否也可以使 (3B) 锥体细胞脊柱测量和 (3C) 海马区 CA1 中脊柱肌动蛋白调节蛋白的水平和活动诱导的变化正常化。目标 4 中的研究补充了目标 3 中的研究，以测试拯救海马 LTP 的药物是否也能恢复 Fmr1-KO 小鼠体感新皮质切片中的稳定增强 (4A) 和脊柱测量 (4B)。然后，Aim 4C 将测试使用 ampakine、MPEP 或两者进行体内治疗是否可以使体感皮层和海马区 CA1 的脊柱测量正常化。目标 3 和 4 将使用 Fmr1-KO 和 WT 小鼠，它们在分散的锥体细胞中组成型表达黄色荧光蛋白 (YFP)，以提供树突棘的明亮标签。这些研究有望对为什么脊柱可塑性和结构受到脆性 X 突变的干扰产生具体的解释，并产生纠正缺陷的潜在疗法。公共健康相关性：为了确定与脆性 X 综合征相关的精神发育迟滞的原因，我们在该疾病的小鼠模型中发现了突触可塑性损伤。目前的研究将检验以下假设：损伤是由于肌动蛋白调节蛋白水平异常造成的，而肌动蛋白调节蛋白对于学习过程中突触功能的变化至关重要。研究还将测试纠正这些突触缺陷的潜在疗法，这些缺陷可能会改善这种综合症和其他自闭症谱系障碍的学习。