THE ROLE OF Cdk5 IN THE DNA DAMAGE RESPONCE DURING AGING AND NEURODEGENERATION

Cdk5 在衰老和神经退行性病变过程中 DNA 损伤反应中的作用

• 批准号: 7910444
• 负责人: Bruce A YANKNER
• 金额: $ 53.48万
• 依托单位: HARVARD MEDICAL SCHOOL
• 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/7910444
• 关键词: ATM Signaling Pathway; Accounting; Age; Aging; Alzheimer' s Disease; Amyloid beta-Protein; Apical; Attenuated; Autopsy; Brain; Calpain; Cell Cycle Progression; Chromatin; Chromatin Structure; Cleaved cell; Collaborations; Country; Cyclin-Dependent Kinase 5; DNA; DNA Damage; DNA Repair; Deacetylase; Dementia; Down-Regulation; Elements; Epigenetic Process; Etiology; Event; Genes; Genetic; Genome Stability; Genotoxic Stress; Hippocampus (Brain); Homologous Gene; Human; In Vitro; Learning; Longevity; Mammals; Mediating; Memory; Microarray Analysis; Mitochondria; Molecular Profiling; Mus; Nerve Degeneration; Neurofibrillary Tangles; Neurons; Nuclear Protein; Nuclear Proteins; Organism; Orthologous Gene; Pathology; Peptides; Phosphotransferases; Play; Positioning Attribute; Production; Property; Proteins; Research Personnel; Resveratrol; Role; Sampling; Stimulus; Stress; Synapses; Synaptic plasticity; System; Testing; Transgenic Mice; Up-Regulation; Uracil; Viral; Yeasts; aged; aging brain; axon guidance; in vivo; mitochondrial dysfunction; mouse model; neuron loss; neurotoxic; neurotoxicity; overexpression; oxidative DNA damage; programs; promoter; protein expression; repaired; response; synaptotagmin; syntaxin; uracil-DNA glycosylase

Alzheimer's disease (AD) is the leading cause for dementia that afflicts more than 4.5 million people in this country. Various genetic and epigenetic factors are implicated in the etiology of AD, among which aging is the single most significant factor. Cyclin dependent kinase 5 (Cdk5) is a small protein Ser/Thr kinase. When associated with its regulatory activator p35 or p39, Cdk5 plays an essential role in neuronal positioning, axon guidance, and synaptic plasticity. Under neurotoxic conditions, p35 is cleaved by calpain to become p25, which encompasses the carboxyl-terminal two thirds of p35. p25 is more stable and displays an altered subcellular localization from p35. These properties of p25 cause aberrant activation of Cdk5. We created an inducible p25 transgenic mouse model (CK-p25) that manifests profound neurodegeneration, neurofibrillary tangle pathology, and elevated Abeta peptides in the cortex and hippocampus. These observations indicate that elevation of p25 alone can cause AD-like pathology. Recently, we examined the transcriptional profile of the CK-p25 mice by microarray analyses. Remarkably, a total of 82 genes known to be involved in DNA repair/replication and/or cell cycle progression are dramatically upregulated in 2-week induced CK-p25 mice. Genes include a number of well known DNA damage response genes such as Rad51, nuclear protein 95, and uracil DNA glycosylase, some of which were upregulated over 30-fold (Affymetrix expression values). Such an expression profile strongly suggests DNA damage-induced responses as an early and possibly causative event in p25-mediated neurodegeneration. p25 may cause DNA damage, and/or play an apical role in the DNA damage response. The NAD+-dependent deacetylase SIRT1, shown to be an important modulator of lifespan in many different organisms from yeast to mammals, is upregulated in postmortem AD brain samples and in CK-p25 Tg brains. In addition, in collaboration with Dr. David Sinclair, we found that SIRT1 overexpression or activation by resrevatrol resulted in protection against neurotoxicity in p25 expressing neurons. SIRT1 has been shown to modify chromatin and its yeast homologue, Sir2, functions to maintain genomic stability. Thus, it is possible that SIRT1 represses p25-mediated DNA damage and that this activity accounts for the neuroprotective activity of SIRT1. We will collaborate with Drs. Bruce Yankner, David Sinclair, and Junying Yuan to test the hypothesis that DNA damage response elicited by the p25/Cdk5 kinase plays an important role in neurodegeneration. We will also determine the role of SIRT1 in ameliorating neurodegeneration and the DNA damage response induced by p25.

阿尔茨海默病（AD）是痴呆症的主要原因，困扰着超过450万人 这个国家多种遗传和表观遗传因素与AD的病因学有关，其中包括衰老 是最重要的因素 细胞周期蛋白依赖性激酶5（Cdk 5）是一种小分子蛋白质丝氨酸/苏氨酸激酶。当与其监管机构相关联时， Cdk 5是p35或p39激活剂，在神经元定位、轴突导向和突触形成中起重要作用。 可塑性在神经毒性条件下，p35被钙蛋白酶切割成p25，其包括p25的蛋白质。 p35的羧基末端三分之二。p25更稳定，并显示出改变的亚细胞定位， 第35页。p25的这些特性导致Cdk 5的异常激活。我们创造了一个诱导型p25转基因 表现出严重神经退行性变、神经原纤维缠结病理学的小鼠模型（CK-p25），以及 皮质和海马体中的A β肽升高这些观察结果表明，p25的升高 都能引起AD样病变 最近，我们通过微阵列分析研究了CK-p25小鼠的转录谱。 值得注意的是，已知共有82个基因参与DNA修复/复制和/或细胞周期进程 在2周诱导的CK-p25小鼠中显著上调。基因包括一些众所周知的DNA 损伤反应基因，如Rad 51、核蛋白95和尿嘧啶DNA糖基化酶，其中一些 上调超过30倍（AffyItera表达值）。这样的表达谱强烈表明 DNA损伤诱导的反应作为p25介导的细胞凋亡的早期和可能的致病事件 神经变性p25可能导致DNA损伤，和/或在DNA损伤反应中起重要作用。 NAD+依赖性去乙酰化酶SIRT 1在许多人中显示为寿命的重要调节剂。 从酵母到哺乳动物的不同生物体，在死后AD脑样品和CK-p25中上调 Tg大脑。此外，在与大卫辛克莱博士的合作中，我们发现SIRT 1过表达或 白藜芦醇的激活导致对表达p25的神经元的神经毒性的保护。SIRT 1具有 已显示修饰染色质及其酵母同源物Sir 2，其功能是维持基因组稳定性。 因此，SIRT 1可能抑制p25介导的DNA损伤，并且这种活性解释了 SIRT 1的神经保护活性。 我们将与布鲁斯扬克纳博士、大卫辛克莱博士和袁俊英博士合作，检验以下假设： 由p25/Cdk 5激酶引起的DNA损伤反应在神经退行性变中起重要作用。我们 还将确定SIRT 1在改善神经变性和DNA损伤反应中的作用 由p25诱导。