Ribosome Dysfunction in Neurological Disorders

神经系统疾病中的核糖体功能障碍

• 批准号: 9213291
• 负责人: SUSAN L ACKERMAN
• 金额: $ 29.21万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-03-01 至 2020-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9213291
• 关键词: Ribosome; Dysfunction; Neurological; Disorders

 DESCRIPTION (provided by applicant): Neurodegenerative disorders affect many millions of people around the world, particularly in the aging population. The vast majority of these diseases are not familial and the mutations that have been associated with rare familial forms of these disorders underscore the complexity of this group of diseases. To begin to understand this complexity, we have used forward genetic approaches to pinpoint the molecular pathways that maintain neuronal homeostasis in the aging mammalian brain. Using this approach we recently demonstrated that unresolved ribosome stalling is a novel mechanism for neurodegeneration. Despite the fundamental importance of translation, the cellular consequences of ribosome stalling in mammalian cells had been unknown until our discovery that a mutation in a novel mammalian ribosome rescue factor Gtpbp2 causes ataxia and degeneration of cerebellar granule cells, cortical and hippocampal neurons, and multiple retinal neurons. Importantly we demonstrated that loss of Gtpbp2 epistatically interacts with a mutation in a CNS- specific, cytoplasmic tRNAArgUCU in the widely used C57BL6/J (B6J) mouse strain to cause neurodegeneration. Our ribosome footprinting experiments revealed that loss of this tRNA led to low levels of ribosome stalling at Arginine AGA codons that was not associated with neurodegeneration. However, stalling was dramatically increased in the absence of Gtpbp2, demonstrating that this protein normally resolves ribosomal stalls. In this application we propose to determine the function of these and other ribosome rescue factors in neuron survival, the impact of increasing age on ribosome stalling in the brain, and additional molecular mechanisms which cause ribosome stalling in mammalian neurons. In Aim 1 we will determine the effects of loss of the ribosome rescue factors Gtpbp1, Hbs1l, and Pelo with- and without- tRNA deficiency. These studies will be complemented by novel computational methods to infer ribosomal locations at increased precision and ascertain mechanisms that distinguish strains using parameter-dependent simulations of the translation process. In Aim 2 we will determine the effects of aging on ribosome stalling and neurodegeneration in the brains of aged wild type and ribosome rescue mutant mice without the tRNA mutation and generate and analyze ribosome footprinting and RNA-Seq data from cerebella of aged mice. In Aim 3 we will investigate pathways that lead to cell death and determine their uniqueness for neurons. We will determine if deficiency of ubiquitously expressed tRNAs induces ribosome stalling and pathology in other organs, analyze the effects of the GCN2/ATF4 and P53 pathways on neurodegeneration, and identify additional modifier genes of neurodegeneration in Gtpbp2-/- mice. Together, we expect these studies to reveal the mechanisms by which dysregulation of translation elongation leads to cellular death and their specificity for neurodegenerative disease.

 描述（由申请人提供）：神经退行性疾病影响着世界各地数百万人，特别是老龄化人口。这些疾病绝大多数不是家族性的，与这些疾病的罕见家族形式相关的突变强调了其复杂性。为了开始了解这一组疾病的复杂性，我们使用正向遗传学方法来查明维持衰老哺乳动物大脑中神经元稳态的分子途径，我们最近证明了未解决的核糖体停滞。尽管翻译具有根本重要性，但在我们发现一种新型哺乳动物核糖体救援因子 Gtpbp2 的突变导致小脑颗粒细胞、皮质细胞的共济失调和变性之前，哺乳动物细胞中核糖体停滞的细胞后果一直是未知的。重要的是，我们证明 Gtpbp2 的缺失与 CNS 特异性细胞质中的突变相互作用。在广泛使用的 C57BL6/J (B6J) 小鼠品系中，tRNAArgUCU 会导致神经变性。我们的核糖体足迹实验表明，这种 tRNA 的丢失会导致精氨酸 AGA 密码子处的核糖体停滞水平较低，但这种停滞与神经变性无关。在没有 Gtpbp2 的情况下增加，证明该蛋白质通常可以解决核糖体失速问题。在本应用中，我们建议确定这些和其他蛋白的功能。神经元存活中的核糖体救援因素、年龄增长对大脑中核糖体停滞的影响以及导致哺乳动物神经元核糖体停滞的其他分子机制在目标 1 中，我们将确定核糖体救援因子 Gtpbp1、Hbs1l 丢失的影响。这些研究将得到新的计算方法的补充，以提高精度推断核糖体位置，并确定使用参数依赖性区分菌株的机制。在目标 2 中，我们将确定衰老对衰老野生型和核糖体拯救突变小鼠（没有 tRNA 突变）大脑中核糖体停滞和神经变性的影响，并生成和分析来自小脑的核糖体足迹和 RNA-Seq 数据。在目标 3 中，我们将研究导致细胞死亡的途径并确定其对神经元的独特性。我们将确定普遍表达的 tRNA 的缺乏是否会诱导核糖体。我们期望这些研究能够揭示翻译失调的机制。伸长导致细胞死亡及其对神经退行性疾病的特异性。