Cortactin and Spine Dysfunction in Fragile X

脆性 X 细胞的 Cortactin 和脊柱功能障碍

• 批准号: 8595179
• 负责人: Ronald Robert Seese
• 金额: $ 3.29万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-10 至 2016-07-09
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8595179
• 关键词: Accounting; Acetylation; Actins; Actomyosin; Acute; Adult; Affect; Anatomy; Angelman Syndrome; Animals; Attenuated; Autistic Disorder; Cell physiology; Cells; Characteristics; Cognitive; Cognitive deficits; Comorbidity; Cytoskeleton; Defect; Dendritic Spines; Depressed mood; Development; Disease; Event; Exhibits; F-Actin; Failure; Family; Fragile X Syndrome; Functional disorder; GTP Binding; Guanosine Triphosphate Phosphohydrolases; HDAC6 gene; Hippocampus (Brain); Impaired cognition; Impairment; Incidence; Knock-out; Knockout Mice; Laboratories; Learning; Location; Long-Term Potentiation; MAP Kinase Gene; Measures; Mediating; Memory; Memory impairment; Microtubules; Mitogen-Activated Protein Kinase Kinases; Mitogens; Modeling; Modification; Molecular; Monomeric GTP-Binding Proteins; Morphology; Movement; Mus; Neurobiology; Neurons; Pathway interactions; Patients; Pattern; Phenotype; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphotransferases; Process; Protein Phosphatase 2A Regulatory Subunit PR53; Proteins; Public Health; Regulation; Regulatory Pathway; Research; Serine; Signal Pathway; Signal Transduction; Slice; Stream; Synapses; Synaptic plasticity; Synaptosomes; System; Testing; Therapeutic; Vertebral column; Work; autism spectrum disorder; base; cognitive function; cost; genetic regulatory protein; histone deacetylase 6; human EMS1 protein; improved; in vivo; innovative technologies; interest; memory encoding; memory recognition; mouse model; mutant; novel; p21 activated kinase; prevent; public health relevance; success; therapeutic target; trafficking; transmission process

DESCRIPTION (provided by applicant): Autism is a devastating condition which takes a significant toll on patients, their families, and the national economy. There are no treatments for cognitive impairments (e.g., learning and memory deficits) that affect over 75% of autistic patients. In models of many autism-associated disorders and conditions with comorbidity for autism, such Fragile X, Rett, and Angelman Syndromes, there are significant abnormalities in dendritic spine morphology, which are associated with impairments in the stabilization of long-term potentiation (LTP), a synaptic mechanism of memory encoding. Together, these findings suggest that defects in the spine actin cytoskeleton may underlie cognitive deficits in autism-associated conditions of different origin. Spine abnormalities and LTP impairments are best characterized in the Fmr1-knockout (KO) mouse model of fragile X syndrome (FXS), a condition with high (~30%) comorbidity for autism. Specifically, these mutants exhibit defects in signaling through Rac GTPase, stabilization of activity-driven changes in spine filamentous (F) actin, and consolidation of LTP. Studies by the applicant have demonstrated that movement of cortactin, a spine protein which stabilizes actin network branch points and protects F-actin from degradation, via both actomyosin and microtubule systems, is impaired at Fmr1-KO spines following LTP-induction. This suggests that the F- actin stabilization deficits in KOs may reflect disturbances in signaling to cortactin. The proposed research will build on these findings to test the specific hypotheses that (a) abnormal cortactin serine phosphorylation and acetylation, which regulate the protein's subcellular movement, both originate from a single molecular impairment and contribute to the phenotype of impaired movement following LTP induction in KOs and that (b) learning (in vivo) activates these synaptic processes in WT but not KO mice. There are 3 specific aims. Aim 1 will test if basal levels or activation of synaptic Ras or PP2A are impaired in KOs (both of these targets influence the cortactin phosphorylation and acetylation paths). Aim 2 will test if signaling through MAPK and/or HDAC6, which contribute to cortactin serine phosphorylation and acetylation, are necessary for activity- induced cortactin translocation. hippocampus-dependent spatial learning activates synaptic signaling to cortactin in the WTs and if this signaling is attenuated or absent in Fmr1-KOs in vivo. Through interrogating synaptic mechanisms associated with impairments in F-actin stabilization and determining if these abnormalities are also present in the behaving animal, the proposed studies will contribute to our understanding of synaptic plasticity in both normal and FXS model mice and offer therapeutic targets for normalization of memory function in FXS and other autistic conditions. Finally, Aim 3 will test if hippocampus-dependent spatial learning activatessynaptic signaling to cortactin in the WTs and if this signaling is attenuated or absent in Fmr1-KOs in vivo. Through interrogating synaptic mechanisms associated with impairments in F-actin stabilization and determining if these abnormalities are also present in the behaving animal, the proposed studies will contribute to our understanding of synaptic plasticity in both normal and FXS model mice and offer therapeutic targets for normalization of memory function in FXS and other autistic conditions.

描述（由申请人提供）：自闭症是一种毁灭性的疾病，对患者、其家庭和国民经济造成重大损失。没有治疗方法 影响超过 75% 的自闭症患者的认知障碍（例如学习和记忆缺陷）。在许多与自闭症相关的疾病和自闭症合并症的模型中，例如脆性 X 综合征、雷特综合征和安格曼综合征，树突棘形态存在显着异常，这与长时程增强 (LTP)（一种记忆编码的突触机制）稳定性受损有关。总之，这些发现表明脊柱肌动蛋白细胞骨架的缺陷可能是不同来源的自闭症相关疾病中认知缺陷的基础。脊柱异常和 LTP 损伤在脆性 X 综合征 (FXS) 的 Fmr1 敲除 (KO) 小鼠模型中得到了最好的表征，FXS 是一种自闭症高 (~30%) 合并症的疾病。具体来说，这些突变体在 Rac GTPase 信号传导、脊柱丝状 (F) 肌动蛋白活性驱动变化的稳定性以及 LTP 巩固方面表现出缺陷。申请人的研究表明，皮质蛋白（一种稳定肌动蛋白网络分支点并保护F-肌动蛋白不被降解的脊柱蛋白）的运动在LTP诱导后在Fmr1-KO脊柱处受到损害。这表明 KO 中的 F-肌动蛋白稳定性缺陷可能反映了皮质蛋白信号传导的干扰。拟议的研究将建立在这些发现的基础上，测试具体的假设：(a) 异常的 cortactin 丝氨酸磷酸化和乙酰化，调节蛋白质的亚细胞运动，均源于单分子损伤，并导致 KO 中 LTP 诱导后运动受损的表型；(b) 学习（体内）激活 WT 中的这些突触过程，但不是 KO 老鼠。有3个具体目标。目标 1 将测试 KO 中突触 Ras 或 PP2A 的基础水平或激活是否受损（这两个目标都会影响 cortactin 磷酸化和乙酰化路径）。目标 2 将测试通过 MAPK 和/或 HDAC6 的信号传导（有助于 Cortactin 丝氨酸磷酸化和乙酰化）对于活动诱导的 Cortactin 易位是否是必需的。海马依赖性空间学习会激活 WT 中皮质蛋白的突触信号传导，并且如果这种信号传导在体内 Fmr1-KO 中减弱或缺失。通过询问与 F-肌动蛋白稳定性受损相关的突触机制，并确定这些异常是否也存在于行为动物中，拟议的研究将有助于我们了解正常小鼠和 FXS 模型小鼠的突触可塑性，并为 FXS 和其他自闭症患者的记忆功能正常化提供治疗靶点。最后，目标 3 将测试海马依赖性空间学习是否激活 WT 中皮质蛋白的突触信号传导，以及体内 Fmr1-KO 中该信号传导是否减弱或缺失。通过询问与 F-肌动蛋白稳定性受损相关的突触机制，并确定这些异常是否也存在于行为动物中，拟议的研究将有助于我们了解正常小鼠和 FXS 模型小鼠的突触可塑性，并为 FXS 和其他自闭症患者的记忆功能正常化提供治疗靶点。