The role of Usp 14 in regulating neuronal function

Usp 14在调节神经元功能中的作用

基本信息

批准号：
7887812
负责人：
Scott Michael Wilson
金额：
$ 32.05万
依托单位：
UNIVERSITY OF ALABAMA AT BIRMINGHAM
依托单位国家：
美国
项目类别：
财政年份：
2004
资助国家：
美国
起止时间：
2004-01-01 至 2014-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7887812
关键词：
Acute Address Affect Age Amyotrophic Lateral Sclerosis Axon Behavioral Biochemistry Cell Culture Techniques Cells Cessation of life Chronic Cues Data Defect Deubiquitinating Enzyme Deubiquitination Development Disease Ensure Figs - dietary Genetic Hydrolase Hydrolysis Lead Limb structure MAP Kinase Gene Maintenance Motor Motor Endplate Motor Neuron Disease Motor Neurons Mus Muscle Rigidity Mutation Nerve Nervous system structure Neurologic Neuromuscular Diseases Neuromuscular Junction Neurons Pathogenesis Pathology Pathway interactions Phenotype Phosphotransferases Presynaptic Terminals Process Proteins Publishing Recycling Regulation Reporting Research Rest Tremor Role Series Signal Pathway Signal Transduction Site Sodium Channel Spinal Muscular Atrophy Synapses Synaptic Transmission System Testing Therapeutic Intervention Transgenes Transgenic Mice Transgenic Organisms Ubiquitin Work Yeasts design effective therapy in vivo inhibitor/antagonist insight motor neuron development motor neuron function mouse model multicatalytic endopeptidase complex muscle form mutant nervous system development nervous system disorder neurofilament neuron development neuron loss neurotransmission postnatal prevent protein aggregate protein degradation public health relevance research study response restoration small molecule synaptic failure synaptic function therapy development trafficking voltage

项目摘要

DESCRIPTION (provided by applicant): Alterations in the neuromuscular junction (NMJ) have recently been reported in motor neuron diseases such as Spinal muscular atrophy (SMA); however, little is known about the pathways that regulate synaptic activity and development in motor neurons. Although transcriptional mechanisms have been shown to regulate critical steps in the development of the nervous system, recent studies have highlighted the importance of the ubiquitin proteasome system (UPS) in the development and maintenance of synaptic connections. By regulating ubiquitin signaling pathways, such as kinase activation and the trafficking and abundance of cellular proteins, the UPS can control developmental transition points during the maturation of the nervous system. However, it is not known how the cell regulates available ubiquitin pools required for these processes. Given the distance that separates the motor neuron cell body and endplate, specialized mechanisms must ensure the stable expression of ubiquitin necessary for axon path finding, synaptic targeting and motor endplate maturation. Our studies now demonstrate that the proteasomal deubiquitinating enzyme Usp14 is required for the postnatal development of the motor neuron endplate. Homozygous axJ mice, which are deficient for Usp14, display a resting tremor, hind limb rigidity, reduced muscle mass and die by 8 weeks of age. These mice do not have ubiquitinated protein aggregates or accelerated neuronal cell death, but instead show ubiquitin loss that correlates with impaired motor endplate maturation during the first two weeks of postnatal development. Restoration of ubiquitin levels in the axJ mice increases body mass and motor function and prevents postnatal lethality, indicating that ubiquitin loss can be a major contributor to neuromuscular disease. Our recent studies also demonstrate ubiquitin loss in a mouse model of SMA, which displays impaired NMJ maturation and function similar to the axJ mice, validating the importance of identifying the developmental pathways regulated by ubiquitin. Our working hypothesis is that Usp14 functions to maintain ubiquitin levels required for the development and activity of mammalian synapses. The first aim of this proposal will determine the contribution of ubiquitin loss in the axJ mice to the development and activity of the NMJ. In the second aim, we will investigate a newly proposed catalytic-independent function of Usp14 on the proteasome and determine if it is required for development and synaptic transmission at the NMJ. The third aim is designed to determine the role of motor neurons and motor endplates in the disease process in the axJ mice. The final aim will examine the ubiquitin-dependent pathways that control synaptic maturation and function of the NMJ. This proposal will use a combination of genetics and biochemistry to investigate the essential enzymatic functions of Usp14 on the proteasome and determine how changes in the activity of Usp14 alter signaling pathways required for synaptic development and function. PUBLIC HEALTH RELEVANCE: The ubiquitin proteasome system functions to control cellular pathways by regulating protein levels within cells. Since alterations in protein turnover are believed to be central to several chronic neurological diseases, the identification and analysis of components of the ubiquitin proteasome system will provide new insights into the mechanisms of neurological disease and identify potential targets for therapeutic intervention.

描述（由申请人提供）：最近报道了运动神经元疾病如脊髓性肌萎缩症（SMA）中神经肌肉接头（NMJ）的改变；然而，人们对调节运动神经元突触活动和发育的途径知之甚少。尽管转录机制已被证明可以调节神经系统发育的关键步骤，但最近的研究强调了泛素蛋白酶体系统（UPS）在突触连接的发育和维持中的重要性。通过调节泛素信号通路，例如激酶激活以及细胞蛋白的运输和丰度，UPS 可以控制神经系统成熟过程中的发育转变点。然而，尚不清楚细胞如何调节这些过程所需的可用泛素库。考虑到运动神经元细胞体和终板之间的距离，专门的机制必须确保轴突寻路、突触靶向和运动终板成熟所需的泛素的稳定表达。我们的研究现在表明，蛋白酶体去泛素化酶 Usp14 对于运动神经元终板的出生后发育是必需的。缺乏 Usp14 的纯合 axJ 小鼠表现出静息性震颤、后肢僵硬、肌肉质量减少，并在 8 周龄时死亡。这些小鼠没有泛素化蛋白质聚集体或加速的神经元细胞死亡，而是表现出泛素丢失，这与出生后发育的前两周运动终板成熟受损相关。恢复 axJ 小鼠的泛素水平可增加体重和运动功能，并防止产后致死，表明泛素丢失可能是神经肌肉疾病的一个主要因素。我们最近的研究还证明了 SMA 小鼠模型中的泛素丢失，该模型表现出 NMJ 成熟受损和与 axJ 小鼠相似的功能，验证了识别泛素调节的发育途径的重要性。我们的工作假设是，Usp14 的功能是维持哺乳动物突触发育和活动所需的泛素水平。该提案的首要目标是确定 axJ 小鼠中泛素丢失对 NMJ 发育和活性的贡献。在第二个目标中，我们将研究新提出的 Usp14 对蛋白酶体的催化独立功能，并确定它是否是 NMJ 发育和突触传递所必需的。第三个目标是确定运动神经元和运动终板在 axJ 小鼠疾病过程中的作用。最终目标将检查控制突触成熟和 NMJ 功能的泛素依赖性途径。该提案将结合遗传学和生物化学来研究 Usp14 对蛋白酶体的基本酶功能，并确定 Usp14 活性的变化如何改变突触发育和功能所需的信号通路。公共健康相关性：泛素蛋白酶体系统通过调节细胞内的蛋白质水平来控制细胞通路。由于蛋白质周转的改变被认为是几种慢性神经系统疾病的核心，因此对泛素蛋白酶体系统成分的识别和分析将为神经系统疾病的机制提供新的见解，并确定治疗干预的潜在靶点。