Dysregulation of mTORC2 and cofilin signaling in Fragile X Syndrome

脆性 X 综合征中 mTORC2 和 cofilin 信号传导失调

基本信息

批准号：
9533699
负责人：
R. Suzanne Zukin
金额：
$ 23.34万
依托单位：
ALBERT EINSTEIN COLLEGE OF MEDICINE, INC
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-01-01 至 2018-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9533699
关键词：
Actins Age Apoptosis Autistic Disorder Behavior Binding Cellular Metabolic Process Clinic Clustered Regularly Interspaced Short Palindromic Repeats Cognitive Complex Cytoskeleton Defect Dendritic Spines Diabetes Mellitus Excitatory Synapse FMR1 FMRP FRAP1 gene Foundations Fragile X Syndrome Genetic Glutamates Goals Growth Heart Diseases Heritability Human Impairment Intellectual functioning disability Knockout Mice Link Malignant Neoplasms Measures Medical Memory Mental Retardation Mental disorders Molecular Genetics Mus Neurologic Neurons Pathway interactions Peptides Perception Pharmacology Phenocopy Phenotype Research Research Personnel Role Sensory Signal Pathway Signal Transduction Social Interaction Somatosensory Cortex Structure Subfamily lentivirinae Symptoms Synapses Synaptic plasticity System Technology Testing Therapeutic Translations Vertebral column Work actin depolymerizing factor clinically relevant cofilin critical period effective therapy experimental study genetic information genetic manipulation knock-down mouse model mutant new therapeutic target novel novel therapeutics polymerization rho GTP-Binding Proteins small hairpin RNA small molecule inhibitor translational study treatment strategy

项目摘要

Fragile X syndrome is the most common heritable form of intellectual disabilities and a leading genetic cause of autism. An effective treatment for the cognitive and social interaction deficits associated with FXS is an unmet need. The mammalian target of rapamycin (mTOR) pathway is a central regulator of cell metabolism, growth, proliferation, survival, cap-dependent translation and the actin cytoskeleton. Whereas dysregulation of mTOR Complex 1 (mTORC1) in Fragile X is well established, a role for mTORC2 is, as yet, unclear. mTORC2 is a central regulator of actin polymerization and spine structure and acts on the actin-depolymerizing factor cofilin implicated in synaptic plasticity and memory. Our finding that cofilin and its upstream regulator Rac1, a small Rho GTPase and direct target of mTORC2 implicated in actin remodeling and spine structure, are impaired in a mouse model of Fragile X provides a functional link between FMRP, mTOR, and cofilin signaling and underscore the clinical relevance of this work. The overall goals of the proposed research are to examine whether overactivated mTORC2 signaling is causally linked to cofilin signaling, spine structure, and synaptic maturation in Fmr1 KO mice, and establish mTORC2 as a novel therapeutic target for the amelioration of FXS. The underlying hypothesis is that loss of FMRP leads to overactivated mTORC2 and cofilin signaling, which induce spine abnormalities, impaired synaptic maturation, sensory processing and autism-relevant behaviors. We seek to test this hypothesis in the following Aims: 1. Examine a causal relation between dysregulation of cofilin signaling and the synaptic phenotype in the somatosensory cortex of young Fragile X mice. Experiments will examine 1) ability of a constitutively active cofilin mutant (S3A) delivered directly into the somatosensory cortex of Fmr1 KO mice via the lentivirus expression system to rescue spine defects; 2) ability of cofilinS3A to rescue delayed synaptic maturation of layer V neurons in the somatosensory cortex of Fmr1 KO mice during the critical period; 3) ability of cofilinS3A to rescue impaired spike- timing LTP at excitatory synapses in the somatosensory cortex of Fmr1 KO mice: 4) ability of a phospho-cofilin peptide, which inhibits endogenous cofilin, to phenocopy aberrant actin polymerization, spine defects and impaired synaptic maturation in somatosensory cortex of WT mice. 2. Identify signaling pathways upstream of aberrant cofilin signaling and ability of pharmacologic and genetic manipulation of mTORC2 signaling to rescue the FXS phenotype. Experiments will establish 1) mTORC2 as an upstream effector critical to aberrant cofilin signaling; 2) Rac1/PAK signaling as a potential pathway upstream of cofilin and downstream of mTORC2 and ability of PAK inhibition to rescue impaired spine structure, synaptic maturation and spike timing LTP; 3) deficits in sensory perception in FXS mice and ability of PAK inhibition to rescue impaired perception; 4) ability of shRNA to Rictor delivered into the somatosensory cortex of Fmr1 KO mice via the lentivirus expression system to correct neurologic defects. These experiments will document the ability of therapeutic strategies targeting mTORC2, Rac1/PAK and cofilin signaling to rescue spine defects, impaired synaptic maturation and autism-relevant behaviors in young Fmr1 null mice.

脆弱的X综合征是最常见的遗传智障形式，也是主要的遗传原因自闭症。对与FXS相关的认知和社会互动缺陷的有效治疗方法是未满足的需求。雷帕霉素（MTOR）途径的哺乳动物靶标是细胞代谢，生长，增殖，生存，帽依赖性翻译和肌动蛋白细胞骨架。而MTOR复合物的失调1 （MTORC1）在脆弱的X中已经建立了良好的X，MTORC2的作用尚不清楚。 MTORC2是肌动蛋白聚合和脊柱结构，并作用于与突触的肌动蛋白 - 脱聚合因子cofilin 可塑性和记忆。我们发现Cofilin及其上游调节剂Rac1，一个小的Rho GTPase，直接与肌动蛋白重塑和脊柱结构有关的MTORC2的靶标在脆弱X的小鼠模型中受损在FMRP，MTOR和Cofilin信号传导之间提供了功能联系，并强调了此的临床相关性工作。拟议研究的总体目标是检查过度激活的MTORC2信号传导是否是与FMR1 KO小鼠中的Cofilin信号，脊柱结构和突触成熟的因果关系，并建立 MTORC2是改善FXS的新型治疗靶标。基本假设是FMRP的丧失导致诱导脊柱异常的MTORC2和Cofilin信号过度活化成熟，感官处理和与自闭症相关的行为。我们试图在以下来检验这一假设目的：1。检查Cofilin信号传导失调与突触表型之间的因果关系年轻脆弱X小鼠的体感皮质。实验将检查1）组成型活性Cofilin的能力突变体（S3A）直接通过慢病毒表达系统直接输送到FMR1 KO小鼠的体感皮层中挽救脊柱缺陷； 2）Cofilins3a挽救V层神经元的突触成熟的能力在关键时期，FMR1 KO小鼠的体感皮质； 3）Cofilins3a挽救尖峰受损受损的能力 - FMR1 KO小鼠体感皮质中的兴奋性突触时的Timing LTP：4）磷酸化蛋白的能力抑制内源性cofilin的肽对苯并肌动物异常聚合，脊柱缺陷和受损 WT小鼠的体感皮层中的突触成熟。 2。确定异常富林上游的信号通路 MTORC2信号传导的药理和遗传操作的信号传导以及能力挽救FXS表型。实验将建立1）MTORC2作为对异常Cofilin信号至关重要的上游效应子； 2）Rac1/pak 信号作为Cofilin和MTORC2下游的潜在途径以及PAK抑制的能力救援脊柱结构受损，突触成熟和尖峰计时LTP； 3）FXS的感觉知觉缺陷小鼠和PAK抑制能力挽救感知受损的能力； 4）shRNA能够传递到 FMR1 KO小鼠的体感皮质通过慢病毒表达系统纠正神经系统缺陷。这些实验将记录针对MTORC2，RAC1/PAK和COFILIN信号传导的治疗策略的能力为了挽救脊柱缺陷，年轻的FMR1无效小鼠中的突触成熟和与自闭症相关的行为受损。