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.

项目摘要 神经退行性疾病仍然是公共卫生负担，缺乏有效的治疗方法。罕见的遗传 疾病会导致儿童神经退化，这是特别具有破坏性的。无论 无论是罕见的还是常见的，神经退行性变的机制仍然不完全清楚。为 例如，为什么神经元可能更容易受到细胞死亡时，基因突变存在于整个 尸体呢TBCK脑病（TBCKE）就是这种情况，TBCKE是一种罕见的常染色体隐性遗传病， 导致儿童发育迟缓和神经退化。我们之前描述了 波多黎各儿童TBCK纯合无效突变（p.R126X）的表型，后来发现 线粒体呼吸缺陷和异常线粒体质量控制（即线粒体自噬）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的关系尚不清楚。我们的数据支持Tbck蛋白可能 是一种新的mRNA转运复合物的一部分（五亚基内体Rab 5和RNA/核糖体中介体- FERRY）。这种复合物可以附着在早期的内体上以递送RNA转录物，因此有助于 新合成的蛋白质，到细胞隔室远离核，如轴突。RNA缺陷 最近有人提出了转运和局部蛋白质翻译，特别是向远处轴突线粒体的转运 作为一种常见的神经退行性疾病（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 mRNA和/或局部蛋白质翻译破坏线粒体功能。我们预测这将导致 隔室特异性线粒体缺陷，远端轴突线粒体对TBCK更敏感， 比神经元索马中的那些缺乏。在目标1中，我们将测试TBCK缺乏如何影响线粒体 功能和线粒体自噬，使用人iPSC衍生的神经元（iNeu）。然后在目标2中，我们将测试TBCK- 缺乏可能会影响FERRY复合物的功能，通过检查RNA转录组中的作用， 区室特异性方式（神经元索马vs轴突）。我们还将直接测定局部蛋白质合成， 测试TBCK是否由于轴突中蛋白质翻译受损而导致线粒体功能障碍 隔间这些实验将填补关于神经元RNA作用的知识空白 运输缺陷介导神经变性，这些缺陷如何特别影响线粒体， Tbck蛋白在新的FERRY复合物中可能发挥的作用。R 01奖的支持将 作为一名医生，科学家，我在一个一流的机构中发展独立的研究计划， 环境这也将有助于我的长期目标，解开疾病的机制，儿科 与线粒体功能障碍相关的神经退行性疾病;为了最终确定新的 治疗目标