Roles of Cdk5 in neurodevelopment and neurodegeneration

Cdk5 在神经发育和神经变性中的作用

• 批准号: 8746837
• 负责人: edward giniger
• 金额: $ 76.03万
• 依托单位: NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8746837
• 关键词: Action Potentials; Acute; Adult; Age; Aging-Related Process; Axon; Cell physiology; Cells; Characteristics; Data; Defect; Dendrites; Development; Disease; Disease Progression; Drosophila genus; Event; Gene Expression; Gene Expression Profiling; Genes; Genomics; Homeostasis; Homologous Gene; Human; Investigation; Ions; Maintenance; Microarray Analysis; Mitochondria; Modeling; Molecular Target; Mus; Nerve Degeneration; Neurodegenerative Disorders; Neurofibrillary Tangles; Neurons; Neurophysiology - biologic function; Oxidation-Reduction; Pathologic Processes; Pathway interactions; Phosphotransferases; Physiological Processes; Play; Process; Protein Kinase; Proteins; Proteomics; Publishing; RNA; Role; Sensory; Stress; Structure; Swelling; Synaptic Transmission; Syndrome; System; Testing; Time; Tissues; Validation; base; fly; genome-wide; inhibitor/antagonist; mutant; neurodevelopment; neuron development; neuron loss; novel; prevent; tau-1

We seek to answer two questions: how do neurons become connected during development, and why do they become disconnected during neurodegenerative disease? We previously developed a potential Drosophila model of mammalian neurodegenerative disease by inactivating the protein kinase Cdk5. This is the fly homolog of one of the two main proteins responsible for phosphorylating tau into the form found in the neurofibrillary tangles that are characteristic of many forms of human neurodegeneration. This year, we published data documenting many phenotypic similarities between the neurodegenerative syndrome in this endogenous process of flies and that observed in humans and mice, thus validating our Drosophila mutant as a model of the mammalian disease process. We also extended our analysis of a novel pathological process that occurs early in disease progression in our fly model that had not previously been described in studies of the mammalian diseases. Last year, we found that lack of Cdk5 activity prevents a neuron from segregating the portion of the cell where action potentials initiate (the axon initial segment). This is apt to be relevant to the mechanism of neurodegeneration, since we find that the defective initial segment domain becomes prone to development of gross axonal swellings as the fly ages, and later is the focus of histological abnormalities such as large, vacuolated holes in the tissue. We now find that this is not just a developmental function of Cdk5. This year, we showed that Cdk5 is required chronically for maintenance of the initial segment, as introduction of pharmacologic inhibitors of Cdk5 cause acute loss of the initial segment even after it has formed. We also initiated systematic, genome-wide investigations into the consequences of Cdk5 inactivation. We have used microarrays to perform gene expression profiling of adult flies having, or lacking, Cdk5 activity. We have focused our efforts on early events in degeneration by isolating RNA from young flies, at a time before the onset of overt cellular or organismal defects in the mutants. Preliminary analysis reveals two classes of gene expression changes in mutants lacking Cdk5 activity. We observe alterations in genes directly important for neural function, including sensory transduction, synaptic transmission and ion homeostasis. We also observe changes in the expression of genes associated with a variety of organismal physiological processes we had previously hypothesized to be associated with Cdk5 function, based on our phenotypic analysis. These include proteostasis, redox state, mitochondrial structure and function and stress-sensitivity. The microarray analysis, therefore, serves as a powerful independent validation of the phenotypic analysis. Moreover, as this unbiased, genome-wide array analysis failed to identify major classes of genes not predicted by the earlier studies, these data suggest that we have identified the major functional pathways downstream of Cdk5 that are responsible for its pathological consequences.

我们试图回答两个问题：神经元在发育过程中是如何连接的，以及为什么它们在神经退行性疾病中会断开连接？ 我们以前开发了一个潜在的果蝇模型的哺乳动物神经退行性疾病失活的蛋白激酶Cdk5。这是负责将tau磷酸化为神经元缠结中发现的形式的两种主要蛋白质之一的苍蝇同系物，神经元缠结是许多形式的人类神经变性的特征。今年，我们发表的数据记录了果蝇内源性过程中的神经退行性综合征与人类和小鼠中观察到的神经退行性综合征之间的许多表型相似性，从而验证了我们的果蝇突变体作为哺乳动物疾病过程的模型。我们还扩展了我们对一种新的病理过程的分析，这种病理过程发生在我们的果蝇模型中疾病进展的早期，以前在哺乳动物疾病的研究中没有描述过。去年，我们发现缺乏Cdk5活性会阻止神经元分离动作电位起始的细胞部分（轴突起始段）。这可能与神经退行性变的机制有关，因为我们发现，随着果蝇年龄的增长，有缺陷的初始节段区域变得容易发展成粗大的轴突轴突，并且后来成为组织学异常的焦点，例如组织中的大空泡孔。我们现在发现这不仅仅是Cdk 5的发育功能。今年，我们发现，Cdk5是需要长期维持的初始段，因为引入Cdk5的药理学抑制剂会导致急性损失的初始段，即使它已经形成。 我们还启动了系统的，全基因组的调查Cdk5失活的后果。我们已经使用微阵列进行基因表达谱的成年苍蝇，或缺乏，Cdk5活性。我们已经集中我们的努力在退化的早期事件通过分离RNA从年轻的苍蝇，在发病前的明显的细胞或有机体缺陷的突变体。初步分析揭示了两类基因表达的变化，突变体缺乏Cdk5活性。我们观察到基因的改变直接重要的神经功能，包括感觉转导，突触传递和离子稳态。我们还观察到与各种生物体生理过程相关的基因表达的变化，我们以前假设与Cdk5功能相关，基于我们的表型分析。这些包括蛋白质稳态、氧化还原状态、线粒体结构和功能以及应激敏感性。因此，微阵列分析可作为表型分析的一种强有力的独立验证。此外，由于这种无偏见的全基因组阵列分析未能识别出早期研究未预测的主要基因类别，因此这些数据表明我们已经确定了Cdk 5下游的主要功能途径，这些途径是导致其病理后果的原因。