Unraveling the Mechanisms of Neurodegeneration in TBCK Encephaloneuronopathy

揭示 TBCK 脑神经病神经变性的机制

• 批准号: 10700602
• 负责人: XILMA R ORTIZ-GONZALEZ
• 金额: $ 66.93万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-18 至 2028-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10700602
• 关键词: Address; Affect; Age; Amyotrophic Lateral Sclerosis; Award; Axon; Bioenergetics; Biological Assay; Cell Death; Cell Nucleus; Cessation of life; Child; Childhood; Complex; DNA Sequence Alteration; Data; Defect; Developmental Delay Disorders; Disease; Distal; Distant; Early Endosome; Encephalopathies; Endosomes; Environment; Fibroblasts; Functional disorder; Genetic Diseases; Goals; Homeostasis; Human; Impairment; Induced pluripotent stem cell derived neurons; Institution; Intellectual functioning disability; Knowledge; Lead; Link; Lysosomes; Mediating; Membrane Potentials; Messenger RNA; Microfluidics; Mitochondria; Mitochondrial Proteins; Modeling; Morphology; Mutation; NADP; Nerve Degeneration; Neurodegenerative Disorders; Neurologic; Neurons; Oxygen Consumption; Patients; Peptide Synthesis; Phenotype; Physicians; Physiological; Play; Population; Predisposition; Production; Protein Biosynthesis; Protein Import; Proteins; Proteome; Proteomics; Proxy; Public Health; Puerto Rican; Quality Control; RNA; RNA Transport; Reporter; Reporting; Research; Ribosomes; Role; Scientist; Seizures; Severities; Stress; Testing; Transcript; Translations; Visualization; Work; autosome; confocal imaging; differential expression; effective therapy; experimental study; indexing; induced pluripotent stem cell; insight; late endosome; mRNA Translation; mitochondrial dysfunction; mitochondrial membrane; neurodegenerative phenotype; neuronal cell body; new therapeutic target; novel; novel therapeutics; null mutation; polypeptide; premature; programs; progressive neurodegeneration; protein complex; rare genetic disorder; respiratory; single molecule; stem; superoxide dismutase 1; trafficking; transcriptome; transcriptome sequencing

PROJECT SUMMARY Neurodegenerative disorders remain a public health burden and lack effective treatments. Rare genetic disorders can cause neurodegeneration in children, which is particularly devastating. Regardless of whether rare or common, the mechanisms underlying neurodegeneration remain incompletely understood. For instance, why neurons may be more susceptible to cell death when a genetic mutation is present throughout the body? Such is the case in TBCK encephalopathy (TBCKE), a rare autosomal recessive disorder that causes developmental delay and neurodegeneration in children. We previously characterized the neurologic phenotype of Puerto Rican children with a homozygous null mutation (p.R126X) in TBCK, and later found mitochondrial respiratory defects and evidence for abnormal mitochondrial quality control (i.e. mitophagy) in patient-derived fibroblasts. Nevertheless, the (1) physiologic role of TBCK and (2) how TBCK-deficiency leads to mitochondrial dysfunction and neurodegeneration, remain unclear. Our data support that Tbck protein may be part of a novel mRNA transport complex (Five-subunit Endosomal Rab5 and RNA/ribosome intermediary- FERRY). This complex may attach to early endosomes to deliver RNA transcripts, and therefore contribute to newly synthesized proteins, to cellular compartments distant from the nucleus, such as axons. Deficits in RNA transport and local protein translation, particularly to distant axonal mitochondria, have been recently proposed as a novel mechanism underlying a common neurodegenerative disorder (ALS, amyotrophic lateral sclerosis). Hence, our central hypothesis is that neuronal vulnerability in TBCK-deficiency stems from impaired transport of mRNA and/or local protein translation disrupting mitochondrial function. We predict this leads to compartment-specific mitochondrial deficits, with distal axonal mitochondria being more susceptible to TBCK- deficiency than those in the neuronal soma. In Aim 1 we will test how TBCK-deficiency impacts mitochondrial function and mitophagy, using human iPSC-derived neurons (iNeu). Then in Aim 2, we will test how TBCK- deficiency may affect the function of the FERRY complex, by examining effects in the RNA transcriptome in a compartment-specific fashion (neuronal soma vs axons). We will also directly assay local protein synthesis to test if TBCK is leading to mitochondrial dysfunction because of impaired protein translation in axonal compartments. These experiments will address a gap in knowledge regarding the role of neuronal RNA transport defects in mediating neurodegeneration, how these defects may particularly impact mitochondria and the role that Tbck protein may play in the novel FERRY complex. Support from this R01 award will be instrumental in growing my independent research program as a physician-scientist in a superb institutional environment. It will also contribute to my long-term goal of untangling disease mechanisms of pediatric neurodegenerative disorders linked to mitochondrial dysfunction; in order to, ultimately, identify novel therapeutic targets.

项目总结 神经退行性疾病仍然是公共卫生的负担，缺乏有效的治疗方法。罕见的遗传 疾病会导致儿童的神经退化，这是特别具有破坏性的。不管是否 无论是罕见还是常见，神经变性的机制仍然不完全清楚。为 例如，为什么当基因突变贯穿始终时，神经元可能更容易受到细胞死亡的影响 身体？TBCK脑病(TBCKE)就是这种情况，这种罕见的常染色体隐性遗传病 会导致儿童发育迟缓和神经退化。我们之前描述了神经学上的 后来发现的具有TBCK纯合子零突变(p.R126X)的波多黎各儿童的表型 线粒体呼吸缺陷和线粒体质量控制异常(即有丝分裂)的证据 患者来源的成纤维细胞。然而，(1)TBCK的生理作用和(2)TBCK缺乏如何导致 线粒体功能障碍和神经退行性变，目前仍不清楚。我们的数据支持Tbck蛋白可能 是一种新的mRNA转运复合体的一部分(5亚基内体Rab5和RNA/核糖体中介- 渡轮)。这种复合体可能附着在早期的内体上，以传递RNA转录本，从而有助于 新合成的蛋白质，到远离细胞核的细胞室，如轴突。RNA缺陷症 最近提出了运输和局部蛋白质翻译，特别是到远端轴突线粒体的翻译。 作为一种常见神经退行性疾病(ALS，肌萎缩侧索硬化症)的新机制。 因此，我们的中心假设是，tbck缺乏症的神经元脆弱性源于运输受损。 信使核糖核酸和/或局部蛋白质翻译干扰线粒体功能。我们预测这将导致 脑室特异性线粒体缺陷，远端轴突线粒体更容易受到TBCK- 比神经元胞体更缺乏。在目标1中，我们将测试TBCK缺乏对线粒体的影响 功能和有丝分裂，使用人IPSC来源的神经元(INeu)。然后在目标2中，我们将测试TBCK如何- 缺陷可能会影响渡轮复合体的功能，通过检查在RNA转录组中的影响 隔室特有的方式(神经元胞体VS轴突)。我们还将直接检测当地的蛋白质合成以 检测TBCK是否由于轴突蛋白质翻译受损而导致线粒体功能障碍 车厢。这些实验将解决有关神经元rna作用的知识空白。 转运缺陷在介导神经退行性变中的作用，这些缺陷如何特别影响线粒体和 Tbck蛋白在新的渡轮复合体中可能扮演的角色。来自此R01奖项的支持将是 作为一流机构的内科科学家，我的独立研究项目的发展起到了重要作用 环境。这也将有助于我解开儿科疾病机制的长期目标 与线粒体功能障碍有关的神经退行性疾病；为了最终识别新的 治疗靶点。